Petrological and Geochemical Features of the Neogene Volcanites of the Osogovo Mountains, Eastern Macedonia Petrološke in geokemicne značilnosti neogenskih vulkanskih kamnin Osogovskih planin (vzhodna Makedonija) 'Serafimovski, Т., :Tasev, G., 2-3Dolenec, T. 'Faculty of Mining and Geology, Goce Delcev 89, 2000 Stip, Macedonia 2Faculty of Natural sciences and Engineering, Department of Geology, University of Ljubljana QDepartment of Physical and Organic Chemistry, Jožef Stefan Institute, Jamova 39, 1000 Ljubljana (Slovenia) Received: May 18, 2005 Accepted: October 28, 200S Abstract: The subject of the presented study was the petrological and geochemical characterization of the Neogene volcanic rocks from the Osogovo Mountains. In this paper we present new results of petrological and geochemical analyses of igneous rocks, mostly from Sasa, Toranica and Ruen. The mineralogical and geochemical characteristics of the studied rocks confirmed the results of some previous investigations that indicated that the exposed lithologies are mostly dacites, quartzlatites, trachyandesites, lamprophyres and rhyolites. An absolute age determination using a standard K-Ar method gives ages between 31.16 ± 1.40 and 14.0 ± 3.0 m.y., and also confirmed their proposed Oligocene-Miocene age. The parent material of these rocks is supposed to originate from the contact zone between the lower crust and upper mantle. A possible assimilation of crustal material during magma formation was also suggested. This supposition was further confirmed by the results of the strontium isotope (87Sr/86Sr) ratios, which are in the range from 0.709S4 to 0.71126, as well as by other geochemical characteristics. Izvleček: Članek obravnava petrološke in geokemicne značilnosti neogenskih vulkanskih kamnin na območju Osogovskih planin v vzhodni Makedoniji. Podani so najnovejši rezultati geokemičnih analiz in izotopske sestave stroncija ter podatki o njihovi absolutni starosti, dobljeni na podlagi konvencionalne K-Ar metode. Na podlagi mineralne sestave in geokemičnih značilnosti uvrščamo raziskane kamnine med riolite, kremenove latite, trahiandezite in lamprofirske žilnine. Ti različki so bili ugotovljeni tudi v okviru prejšnjih, zvečine petroloških raziskav. Kamnine so oligocensko-miocenske starosti. Glede na podatke o absolutni starosti, dobljeni na podlagi K-Ar metode, lahko rečemo, da so nastale v razponu od pred 31.16 ± 1.40 do 14.0 ± 3.0 milijonov let. Izotopska sestava stroncija in nekatere geokemične značilnosti kažejo, da je magma, iz katere so kristalizirale, najverjetneje izvirala iz kontaktne cone med spodnjim delom zemeljske skorje in zgornjim plaščem. Pri tem dopuščamo tudi možnost njene delne kontaminacije z materialom zemeljske skorje. Key words: Osogovo mountains, volcanic rocks, absolute age, magma origin, Neogene volcanism Ključne besede: Osogovske planine, vulkanske kamnine, absolutna starost, izvor magme, neogenski vulkanizem Introduction Volcanic and volcano-intrusive rocks of the Osogovo volcanic and ore-bearing district are a part of a greater metallogenic unit known as the Besna Kobila-Osogovo-Tasos metallogenic zone. The zone has a northwest direction and a total length of 100 km, and is extended on both sides of the Macedonia-Bulgaria border (Bogoevski, 1965; Serafimovski, 1990; Serafimovski, 1993; Alexandrov, 1992; Janković et al., IWWS), Volcanic rocks in the zone have similar morphological, petrological and geochemical features, and all of them are of Tertiary age. In Macedonia they were found in the northeastern part on the border with Bulgaria (Pig. 1). It should be mentioned that volcanic rocks of similar composition were also found in Bulgaria. The volcanic rocks in the investigated area occur as elongated dykes with a northwestern direction, a thickness of 50 m and an azimuth of 260°. Prom the Osogovo to the Besna Kobila Mountains volcanic rocks are represented by pyroclastites, volcanic domas, dykes, necks and veins. In the Osogovo-Be-sna Kobila mountains they cut the Paleozoic and Riphean-Cambrian metamorphic and igneous rocks and/or cover the older sedimentary rocks of the Upper Eocene age. In the vicinity of the Sasa and Toranica Pb-Zn ore deposits they are represented mostly by dacitic tuffs, dacites, quartzlatites, rhyolites, trachyandesites, andesite-latites and occasionally by lamprophyre veins. Figure I. Distribution of the Tertiary magmatism in Macedonia. Slika I. Geografska razprostranjenost terciarnega magmatizma v Republiki Makedoniji. Geological setting A detailed description of the major lithologies exposed in the investigated area is summarized by Bogoevski @ 1965), Serafimovski (1990), Serafimovski (1993), Alexandrov (1992), Janković et al. (1995). Large areas of the Osogovo Mountains are covered by various rocks of different origin. Metamorphic rocks such as two mica-type gneisses and quartz graphite schists are the most abundant. These rocks belong to the crystalline basement of the Serbo-Macedonian Massif (SMM). Quartz graphite schists are of special importance, because they are one of the most important host rocks Figure 2. Geologic setting of the Sasa-Toranica ore district. I) Quartzlatites, 2) Quartz graphite schists, 3) Sericite-chlorite schists, 4) Gneiss, S) Lead-zinc deposits and occurrences, 6) Faults. Slika 2. Geološka zgradba rudonosnega območja Sasa-Toranica. I) kremenovi latiti, 2) kremenovo-grafitni skrilavci, 3) sericitno-kloritni skrilavci, 4) gnajsi, S) svinčevo-cinkovo orudenje in mineralizacija, 6) prelomi. for the Pb-Zn mineralization. They are usually interbedded with cipolin marbles, which are also very favorable for metasomatic Pb-Zn mineralization. The geological composition of the area is further comprised of quartzlatite, trachyandesite, dacite, trachydacite dykes and necks, which cut older lithological formations. Small lamprophyre dykes and veinlets were also observed (Fig. 2). The most characteristic tectonic features of the investigated area are the plicative and disjunctive structures. Plicative structures are represented by different scale-size folds observed in quartz graphite schists. The disjunctive - fault structures are the most abundant in the Sasa and Toranica ore deposits. The productive Pb-Zn mineralizations have been found in different ore deposits and mineralizations. The most important deposits are Sasa, Toranica and Ruen. The detailed geological investigations revealed that the ore mineralization is closely related to the Neogene volcanism. Materials and methods For the purpose of this study various igneous, metamorphic and sedimentary rock and ore samples were collected in the field and in the Pb-Zn ore deposits Sasa and Toranica according to the sampling programme designed at the Faculty of Mining and Geology in Stip. All samples were evaluated by petrographic methods to assess their mineralogical characteristics, ore genesis and hydrothermal alterations. For further geochemical and geochronological analyses unweathered and hydrothermally unaltered or only slightly altered samples were chosen. They were then ground in a mechanical agate grinder to a fine powder for further analyses. Major, minor and trace element analyses were performed in a certified commercial Canadian laboratory (Acme Analytical Laboratories, Ltd.) by ICP-MS. Rock reference samples JR-2 (rhyolite) and JA-2 (andesite) were used to validate the analytical procedure. Major and minor elements were also determined by XRF at the Laboratories of the Geological Department of the University of Padova, Italy. The determinationof the 87Sr/86Sr ratios by TIMS on ten selected volcanic bulk rock samples was made in the Geology Department, Royal Holloway University of London, U.K. Conventional KAr dating was performed on seven volcanic bulk rock samples at the Geological Institute in Budapest, Hungary. The accuracy and precision of the analyses were acceptable. The details of the geochemical and isotopic analyses as well as of age determination analyses can be found in Boev et al. (1997) and Tasev (2003). Results and discussion Petrography The results of the microscopic study revealed that the dacites in the Luke-Kiselica area, which extend from the Karamanica Mountain to the southeast of the Osogovo mountains (Serafimovski and Alexandrov, 1995) are characterized by plagioclase phenocrystals with approximately 37 % An content followed by a small amount of orthoclase, quartz, biotite and amphiboles. Their matrix is holocrystalline to hypocrystalline with glassy remains. Accessory minerals, such as apatite, sphene and zircon, were found only in traces, while sericite, chlorite, kaolinite, carbonates and ore minerals are of secondary origin. Quartzlatites were found near the springs of the river Lucka and Kuprina Padina as dykes, and at Samar and Karamanica as dykes and/ or volcanic flows (Samar and Crcorija) which cover the underlying volcano-sedimentary rocks. They are characterized by a coarse grained porphyric structure due to the presence of sanidine and plagioclase phenocrystals with approximately 35-40 % An content. Amphiboles and augite were also found as phenocrystals. The accessory minerals are sphene and zircon. These rocks were also mineralized. Hyaloandesites appear as necks and lava flows over the Upper Pliocene sediments at Gradeška mountain. These rocks are of porphyry-vitrophyric structure with plagioclase phenocrystals containing about 37 % An component, followed by more or less well developed biotite, amphibole and augite crystals, and accessory apatite and zircon grains. At the Sasa-Toranica ore district prevail the volcanic rocks, such as dacite and quartzlatite of hypoabyssal and subvolcanic characteristics. In the whole district these volcanites are hydrothermally altered. Dacites exhibit a holocrystaline structure with about 30 % of the andesine phenocrystals containing 5-16% of An component. Next abundant are the femic minerals (13-20 %) followed by quartz (2-3 %) and a small amount of orthoclase, mainly replaced by epidote, chlorite and carbonates. Hydrothermal alte- rations of the andesites were of various character; illitization, sericitization and propyli-tization are the most abundant. Apatite, zircon, sphene and magnetite are accessory minerals, while pyrite, chalkopyrite, sphalerite and galena are ore minerals related to mineralization of hydrothermal origin. The most abundant rocks in the investigated area are represented by quartzlatites. They occur as elongated dykes a few kilometers long. These rocks are characterized by large phenocrystals, mostly sanidine, andesine and femic minerals such as biotite, amphiboles and rarely augite. The sanidine crystals are fresh and large; they are up to 6 cm long. Quartzlatites were also considerably hydrothermally altered. Transition rocks, from quartzlatites to rhyolites, were also found in few locations at the Osogovo Mountains. They are slightly more acidic and are exposed near the Sekirica Tower close to the Macedonian-Bulgarian border. The rocks were intensively propylitized. The volcanic rocks from the Kozja and Svinja River (Sasa mining district) are mainly represented by dacites and quartzlatites. They are highly propylitized and hydrothermally altered. These rocks also contain ore minerals such as pyrite, galena, sphalerite and others. Trachyandesites of the Sasa-Toranica and broader area form smaller bodies at sub-volcanic-volcanic levels. They are characterized by a porphyry structure (fine-grained porphyry) and a crystallized microlitic or microtrachytic matrix. The phenocrystals are up to 3 mm long, and are represented by andesine, sanidine, biotite, augite and hornblende euhedral grains. Apatite, sphene and zircon occur as accessory minerals. In comparison to the quartzlatites, trachy-andesites are depleted in Si02 content. Similar rocks are also exposed in Pečovska Mala in the Osogovo Mountains in Bulgaria. Lamprophyres occur as small dykes near Sre-dno Brdo and Toranica. They are dark gray to brown with a fine-grained porphyry structure and a glassy matrix. The phenocrystals are pyroxenes, amphiboles and biotite. Accessory minerals are represented by apatite, sphene and zircon. Geochemistry Major, minor and selected trace elemental compositions of the most important volcanic rocks of the Sasa-Toranica ore district are presented in Table I, while Table 2 shows the results of the REE analyses. In Figure 3 the Total Alkali Silica diagram (Le Maitre et al., 1989) with the position of the analyzed samples is shown. The Figure 4 represents the Irving and B aragar (1971) classification for volcanic rocks. From Figures 3 and 4 it is clear that the investigated volcanites mostly plot in the fields that define dacites, trachydacites and rhyolites. Only sample 3, with the highest Na20 + K20 content, plots in the border between the trachydacite and trachyandesite fields. Furthermore, a classification according to Irving and Baragar (1971) revealed that the volcanites from the Sasa-Toranica ore district are of calcalkaline rock suites. The whole rock C1 chondrite Figure 3. Chemical classification and nomenclature of the volcanic rocks in the Sasa-Toranica ore region, using diagram total alkalis vs. silica (Le Maitre et al., 1989). Slika 3. Klasifikacija vulkanskih kamnin rudonosnega območja Sasa-Toranica na podlagi vsebnosti alkalij in kremenice (TAS) (Le Maitre et al., 1989). Figure 4. Classification of volcanic rocks from the Sasa-Toranica ore region (Alk=Nap0 + K20; FeO* = FeO + 0.8998 x Fe203 (Irving and Baragar, 1971). Slika 4. Klasifikacija vulkanskih kamnin rudonosnega območja Sasa-Toranica po Irvingu in Baragarju (1971); (Alk=NaP0 + KP0; FeO* = FeO + 0.8998 x Fe,0,). normalized REE patterns (Fig. 5) show a strong LREE enrichment above the average continental crust and moderate negative europium anomalies with Eu/Eu* values between 0.728 and 0.829 (Table 2). Such a strong LREE enrichment could be related to crystal fractionation and/or assimilation of the LREE-enriched continental material or a combination of the two mechanisms (Draut et al., 2002). Figure S. Rare-earth element patterns normalized to CI chondrite for the volcanic rocks from the Sasa-Toranica ore region. Slika S. Vzorec redkih zemelj za vulkanske kamnine rudonosnega območja Sasa-Toranica normaliziran na C1 hondrit. Table I. Chemical composition of the volcanic rocks in the Sasa-Toranica ore region (major oxides in %), trace elements in ppm). Tabela I. Kemična sestava vulkanskih kamnin iz rudonosnega območja Sasa-Toranica (glavni oksidi v %, sledne prvine v ppm). Elem. Ml M2 M3 M4 M5 Мб M7 M8 M9 MIO Mil M12 M13 Si02 63.93 69.10 60.48 68.46 69.09 67.62 65.73 69.19 68.35 68.59 68.65 63.00 66.83 Ti02 0.65 0.43 0.54 0.44 0.44 0.46 0.63 0.40 0.41 0.42 0.40 0.52 0.56 ai2o3 14.35 14.92 16.43 15.47 15.00 15.53 14.94 14.72 15.15 15.29 15.29 16.24 15.52 Fe203 1.29 0.67 0.81 0.57 0.82 0.92 0.91 0.67 0.73 0.53 0.58 2.31 0 .61 FeO 3.05 2.37 2.37 2.58 2.20 2.19 3.07 2.49 2.62 2.69 2.44 2.81 3 .53 FeOt 4.43 3.11 3.22 3.26 3.07 3.17 4.04 3.22 3.50 3.31 3.09 5.17 4 .33 MnO 0.11 0.08 0.10 0.08 0.10 0.07 0.09 0.31 0.34 0.30 0.24 0.10 0 .40 MgO 3.15 1.38 2.86 1.24 1.40 1.42 2.86 1.87 1.46 1.38 1.32 2.00 2 .58 CaO 3.91 2.78 6.85 2.69 2.89 3.27 3.14 2.51 3.70 2.85 2.55 4.04 2 .47 Na20 2.56 3.38 3.67 2.66 3.40 3.24 2.88 1.58 1.46 1.95 2.85 3.28 2 .43 K20 6.32 4.58 5.57 5.47 4.37 4.98 5.19 5.93 5.37 5.66 5.35 5.36 .66 p2o5 0.60 0.24 0.28 0.23 0.24 0.24 0.49 0.27 0.25 0.24 0.24 0.28 .21 loi 3.96 3.43 3.05 4.03 4.06 3.87 3.69 2.77 5.31 4.33 3.56 4.96 4.93 Cr 50 27 27 38 24 14 69 71 50 30 27 17 73 Ni 30 32 34 49 18 16 46 52 45 29 37 12 61 Ba 2339 1236 1586 1199 1151 1336 1587 2290 1873 1900 2550 1297 2722 Rb 247 211 137 270 214 224 213 218 236 242 191 165 196 Sr 964 499 1216 415 464 555 580 408 268 347 460 664 314 La 59 59 52 57 71 66 39 56 48 47 59 95 53 Ce 106 71 110 98 63 78 95 62 84 66 62 139 58 Nd 29 16 31 9 26 24 29 16 7 0 0 38 5 Zr 297 186 135 195 199 195 221 251 189 200 181 163 173 Y 22 21 24 19 19 19 22 23 19 22 22 24 32 Nb 15 11 10 12 12 10 13 12 11 12 10 10 11 Th 44 31 34 30 34 30 34 49 33 39 40 49 37 U 9 7 5 9 7 8 7 8 8 9 7 6 7 Legend: I. M-I Trachydacite; 2. M-2 Trachyte-rhyolite-dacite; 3. M-3 Trachyandesite-trachydacite; 4. M-4 Trachydacite; S. M-S Dacite; 6. M-6 Trachydacite; 7. M-7 Trachydacite; 8. M-8 Dacite; 9. M-9 Dacite; 10. M-IO Dacite; II. M-II Trachydacite; 12. M-12 Trachydacite; 13. M-13 Dacite. Legenda: 1. M-1 trahidacit; 2. M-2 trahit-riolit-dacit; 3. M-3 trahiandezit-trahidacit; 4. M-4 trahidacit; 5. M-S dacit; 6. M-6 trahidacit; 7. M-7 6 trahidacit; 8. M-8 dacit; 9. M-9 dacit; 1O. M-1O dacit; 11. M-11 6 trahidacit; 12. M-12 6 trahidacit; 13. M-13 dacit. Table 2. Rare-earth elements content (in ppm) in the volcanic rocks from the Sasa-Toranica ore region. Tabela 2. Vsebnost REE (v ppm) v vulkanskih kamninah iz rudonosnega območja Sasa-Toranica. Elem. MAKU MAK7I МАК9П МАК13П La 53.10 52.00 39.60 44.90 Ce 106.00 95.40 72.10 79.30 Pr 13.30 11.40 8.08 9.72 Nd 52.50 42.10 28.30 35.20 Sm 9.20 7.50 5.10 6.80 Eu 2.22 1.68 1.11 1.65 Gd 7.30 5.90 4.30 6.50 Tb 0.90 0.80 0.60 1.00 Dy 4.50 4.00 3.30 5.20 Ho 0.80 0.70 0.60 1.00 Er 2.10 2.10 1.80 2.80 Tm 0.30 0.31 0.28 0.38 Yb 2.00 2.00 1.90 2.30 Lu 0.30 0.30 0.29 0.35 Eu* 0.83 0.77 0.73 0.76 Legend: МАК-II Trachydacite; MAK-7I Trachydacite; MAK-9II Dacite; MAK-13II Dacite Legenda: 1. МАК-II trahidacit; MAK-7I trahidacit; MAK-9II dacit; MAK-13II dacit The Eu anomaly is mainly controlled by the presence of feldspars. Eu2+ is compatible in plagioclase and K-feldspar, relative to the Eu3+that is incompatible. Thus the removal of feldspar from a felsic melt by crystal fractionation or partial melting of a rock containing K-feldspars gave rise to a negative Eu anomaly in the melt. A crystal fractionation and/or partial melting of the continental material could thus explain a negative europium anomaly in the investigated samples (Draut et al., 2002). Table 3. 87Sr/ 86Sr ratios in the volcanic rocks from the Osogovo mountain. Tabela 3. Izotopsko razmerje 87Sr/ V6Sr v vulkanskih kamninah Osogovskih planin No. Locality Rock type 87Sr/86Sr 1. Golema R.950, Sasa Quartzlatite 0.71051 2. Kozja R. rV0, Sasa Quartzlatite 0.70994 3. Svinja R. rV0, Sasa Quartzlatite 0.71126 4. Toranica - 2 Quartzlatite 0.71016 5. Toranica, TO-1 / 0.70979 6. Sasa Andesite-latite 0.71064 7. Sasa Quartzlatite 0.71024 8. Sasa, SA-2 / 0.70954 9. Toranica, MK-1 Trahydacite 0.71055 10. Sasa, MK-9 Dacite 0.71096 (1-8) Boev et al. (1997), (9-10) Tasev (2003). The 87Sr/8TSr initial ratios of the analysed rocks are reported in Table 3. Their isotopie results range from 0.70954 to 0.71125. These values are mostly in the range of the igneous rocks of the crustal origin, and are somewhat higher than the values eommonly found in the andesites (0.703 - 0.708) and the plutons aligned along the continental margins (Carmichael et al., 1974). Such values also suggest that the magma that has produced Neogene igneous complexes at the Osogovo mountains is a product of the primary magmatic melt that originated from the border zone between the upper mantle and the continental crust where processes of mixing and the contamination of primary magma occurred. This is also supported by strontium isotope data for the Upper Tertiary calc-alkaline complexes of the Serbo-Macedonian metallogenic province and Kožuf Mountain (87Sr/8TSr is in the range from 0.7088 to 0.7090) as well as by those for volcanic rocks from the Rogozna, where the initial range of 87Sr/86Sr is between 0.7074 and 0.7085 (Serafimovski, 1990). The above mentioned magmatic activity was related to the processes that took place after the closure of the Tethys Ocean and subduction of the oceanic plate under the SMM (Serbo-Macedonian masif -Cretaceous), due to the collision of the African plate with the Euroasian plate. The collision of these two continental segments produced the calc-alkaline magmatism during the Middle and Upper Jurassic. The collision also resulted in thickening of the continental crust and in isostatic uplifting. Due to discontinued compression, temporal, partial melting of the basal parts of the continental parts took place. The pulsations of the tectono-magmatic activities were repeated many times during the Oligocene, Miocene and Pliocene (Karamata, 1982; Serafimovski and Tasev, 2002). From the metallogenic point of view, of special interest is the zone of deep fractures along the west margin of the SMM, which represents the active continental margin. The fractures served as feeding channels for the uplifting of calk-alkaline magmas and hydrothermal ore bearing solutions (Janković et al., 1997). Nevertheless, some other authors (Boev and Yanev, 2001) relate these magmatic and hydrothermal activities to Late Tertiary Aegean subduction, referred to active continental margin of the Andean type. They supposed that the Macedonian igneous rocks were formed by mildly alkaline magmas No. Locality Rock type K-Ar age (m.y.) 1. Mal Ruen Quartzlatite 28.38±1.09 2. Toranica-I Quartzlatite 28.36±1.09 3. Saša (Кода R.) Quartzlatite 30.72±1.19 4. Sasa (Koq'a R) Andesite 29.25±1.13 5. Sasa (Crvena R) Granodiorite 31.16il.40 6. Sasa Andesite-latite 14.0±3.0 7. Sasa Quartzlatite 24.013.0 Table 4. Absolute age determination of the volcanic rocks in the Sasa-Toranica ore region by the K/Ar method (Tasev, 2003). Tabela 4. Absolutna starost vulkanskih kamnin iz rudonosnega območja Sasa-Toranica, določena na podlagi K/ Ar metode (Tasev, 2003). originating from the upper part of the supra-subduction area. The subduction process in the Miocene and Pliocene moved to the south and southwest, probably due to the extension in the north Aegean region (Gautier et al., 1999) causing migration of the volcanic activity in Macedonia in the same direction, from the Kratovo-Zletovo to the Kožuf area. Tertiary igneous rocks from the Osogovo mountains are characterized by an unusual distribution of the Pb, Ba, Sr, Rb, Li, Cs and Be contents. They exhibit relative to the Clark background values elevated concentrations of Pb, Ba, Sr and Be and similar contents of Li, Rb and Cs. During the magmatic processes the increase in the concentrations of Li, Pb, Cs, Be, Rb and Ba was observed from fine-grained porphyry quartzlatites to coarse-grained porphyry quartzlatites (Serafimovski, 1993 a ; Serafimovski et al., 2003). The observed distribution of trace elements most probably indicates that the igneous rocks were formed of magma from the same magmatic chamber, which in different time intervals produced different rock types. The age of the volcanic rocks of the Sasa-Toranica ore district according to the standard K/Ar method is in the range from 31.16 ± 1.13 to 14.0 ±3.0 to m. y. (Table 4). This range is of the Oligocene-Miocene age, and was also confirmed by other methods. References Aleksandrov, M. (1992): Metalogenetski karakteristiki na polimetaličnoto rudno pole Sasa-Istočna Makedonija. Doktorska disertacija, Stip Boev, В. and Yanev, У. (2001): Tertiary magmatism within the Republic of Macedonia: a review. Acta Vulcanologica Vol. 13(1-2), p. S7-71. Conclusions The presented study of the volcanic rocks from the Sasa-Toranica ore district revealed very different granitoid lithologies, such as rhyolites, dacites, trachydacites and trachy-andesites of the Oligocene-Miocene age. According to the standard K/Ar method the age of those rocks range from 31.16 ± 1.40 to 14.0 ± 3.0 m.y. The volcanic rocks display a relatively large range in Sr isotopic ratios. This could be interpreted as a result of fractional crystallization processes occurring at the contact zone between the lower continental crust and the upper mantle, and associated with a possible assimilation of crustal material. Acknowledgement For all his efforts during the field sampling of the Sasa-Golema River, Sasa-Kozja River, Sasa-Petrova River and Ruen volcanites as well as for help with the laboratory analysis, we express our sincere gratitude to our colleague Prof. Dr. Giuliano Bellieni from the Department of Mineralogy and Petrology, University of Padova, Italy. We would also like to thank our colleague Dr. Petra Souvent from the Department of Geology, Faculty of Natural Sciences and Engineering, University of Ljubljana, Slovenia, for help during the fieldwork. 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New data concerning the major ore minerals and sulphosalts from the Pb-Zn Zletovo Mine, Macedonia Novi podatki o glavnih rudnih mineralih in sulfosoleh iz Pb-Zn rudišča Zletovo (Republika Makedonija) Todor Serafimovski1, Tadej Dolenec2-3, Goran Tasev1 'Faculty of Mining and Geology, Goce Delcev 89, 2000 Stip, Macedonia 2Faculty of Natural sciences and Engineering, Department of Geology, University of Ljubljana department of Environmental sciences, Jožef Stefan Institute, Jamova 39, 1000 Ljubljana (Slovenia) Received: May 18, 2005 Accepted: October 28, 200S Abstract: Based on its mineral content (around 40 minerals) and certain solid solution mineral phases, Zletovo has been classified as a subvolcanic hydrothermal Pb-Zn ore deposit. The main ore minerals are galena and sphalerite. They occur in very characteristic structures, microstructures and textures, which often enclose sulphosalt mineral phases. The most common sulphosalts are bournonite, boulangerite, proustite and luzonite. So far the sulphosalt minerals and their solid solution phases from the Zletovo ore deposit have not been studied in detail. This paper presents the results of a detailed study of ore samples from different levels of the Zletovo mine based on electron microprobe analysis. In the already known mineral assemblage, which is composed mainly of galena, sphalerite, pyrite, chalcopyrite, and siderite, the sulphosalts series, which includes tetra-hedrite-tennantite, luzonite, stibioluzonite and pearceite, was distinguished. The composition of the tetrahedrite-tennantite solid solution ranges from pure tetrahedrite to pure tennantite, with the presence of minerals that are representatives of the processes of the intermixing of solid solutions. The compositions of the determined pearceites and luzonites almost match the compositions of the standards for these minerals. Izvleček: Glede na pestro mineralno paragenezo (okrog 40 mineralov) in določene mineralne faze uvrščamo rudišče Zletovo med subvulkanska hidrotermalna Pb-Zn rudišča. Glavna rudna minerala sta galenit in sfalerit, ki kažeta značilne strukture, mikrostrukture in teksture, značilne za hidrotermalna rudišča. Zelo pogosto ju obdajajajo minerali iz skupine sulfosoli. Najbolj pogosto gre za bournonit, boulangerit, proustit in luzonit. Do sedaj minerali sulfosoli iz rudišča Zletovo podrobno niso bili raziskani. V okviru te študije smo z detajlno raziskavo rudnih vzorcev iz različnih obzorij s pomočjo elektonskega mikroanalizatorja poleg glavnih rudnih mineralov kot so galenit, sfalerit, pirit halkopirit in siderit našli še nekatere nove minerale iz skupine sulfosoli. Gre za trde raztopine sistema tetraedrit-tenantit, mineral pearceit ter že prej poznani luzonit, ki zaenkrat še ni bil podrobneje raziskan. Sestava pearceita in luzonita se v glavnem ujema s standarno sestavo teh mineralov. Key words: Zletovo Mine, mineral paragenesis, ore minerals, sulphosalts Ključne besede: Rudnik Zletovo, mineralna parageneza, rudni minerali, sulfosoli Introduction The Zletovo Pb-Zn ore deposit is situated along the active continental margin and is intimately associated with Tertiary volcanism and related hydrothermal activity. The Zletovo Mine is located in the eastern part of the Kratovo-Zletovo volcanic complex. It lies about 5 km NW of the Zletovo village and about 7 km from the town of Probištip. The first detailed exploration was started in 1928 by the English Selection Mines Limited company and was finished in 1939 when the Zletovo deposit was prepared for exploitation with an annual capacity of 120 000 t of raw ore. Exploitation of the Zletovo Mine have began again during the Second World War with an annual capacity of 400 000 t. The mine is still active up to date and produces lead-zinc concentrates. During the long history of the exploration and exploitation of the Zletovo ore deposit several contributions concerning the origin and the genetic characteristic were published (Cissarz and Rakić, 1956; Radusinović, 1961; Pantić et al., 1973; Denkovski, 1974; Rakić, 1978; Blečić, 1981, 1983; Petković, 1982; Zarić, 1982; Serafimovski, 1990, 1993; Efremov, 1993; Serafimovski and Boev, 1996; Serafimovski and Tasev, 2003). There are also a lot of bibliographic materials and annual reports that have resulted from the exploration of the Zletovo Mine concerning the domain of the volcanic rocks, the fault structures, the mineralogical and the genetical features of the deposit. These can be found in the Zletovo Mine's library, the library of the Geoinstitute-Skopje, and in the Ministry of the Economy of the Republic of Macedonia. Geological setting The major lithologies in the area are related to Tertiary volcanism, and are represented by andesites, dacites, dacitic ignimbrites and volcanic tuffs (Serafimovski, 1990; Serafimovski and Alexandrov, 1995; Tasev, 2003, etc.). Dacitic ignimbrites are the most common volcanic rocks in the mining area. Pb-Zn mineralization is spatially and genetically related to fracture and brecciated zones trending NW-SE, NNW-SSE and ENE-WSW. These structures served as conduits and/or depositional sites for ore and gangue minerals, precipitating from the circulating hydrothermal fluids. Ore also occurred as a metasomatic replacement of the wall rocks by ore minerals. Numerous veins and the associated stockwork mineralization thus represent the ore bodies; their thickness ranges from a few centimetres up to 2 m. The veins generally dip from 40° to vertical, averaging about 60°. They are usually more than 1 km long, the exception is ore vein No.10, which is more than 10 km long and reaches the area of the Plavica pollymetallic ore deposit (Fig. 1). A total of 16 ore veins have been found in the Zletovo Mine. Some ore veins are characterized by apophyses, which are shorter and thinner than the main veins. It should be pointed out that the host rock of the ore veins is very often hydrothermally altered. The alteration is mostly represented by kaolinitization and/ or silicification. The hydrothermally altered zones around the ore veins are usually barren or poorly impregnated with ore minerals. Mineral vein paragenesis is represented by galena which is the main ore mineral and sphalerite with subordinate pyrite, a lesser amount of siderite and chalcopyrite as well Figure I. Geological map and cross section of the Pb-Zn Zletovo ore deposit (Serafimovski, 1990) I) Hydrothermally altered andesite, 2) Hydrothermally altered dacite, 3) Hydrothermally altered and silicified ignimbrite, 4) Stratified tuff, S) Hydrothermally altered dacite-andesite, 6) Ignimbrite, 7) Ore veins Slika I. Geološka karta in profil Pb-Zn rudišča Zletovo (Serafimovski, 1990) 1) hidrotermalno spremenjeni andezit, 2) hidrotermalno spremenjeni dacit, 3) hidrotermalno spremenjeni ignimbrit, 4) plastoviti tuf, S) hidrotermalno spremenjeni dacit-andezit, 6) ignimbrit, 7) rudne žile 0 5Öcm 1_к_i_<-1-1 Figure 2. Detail of ore vein No. IO, Zletovo ore deposit I) Pb-Zn ore, 2) Dacito-andesitic ignimbrite (slightly kaolinized), 3) Dacito-andesitic ignimbrite (intensively kaolinized), 4) Dacito-andesitic ignimbrite (unaltered), S) Siderite, 6) Dacito-andesitic ignimbrite, with galena impregnations Slika 2. Detajl rudne žile št. IO, rudišče Zletovo I) Pb-Zn ruda, 2) slabo kaoliniziran dacitsko-andezitski ignimbrit, 3) močno kaoliniziran dacitsko-andezitski ignimbrit, 4) nespremenjen dacitsko-andezitski ignimbrit, S) siderit, 6) dacitsko-andezitski ignimbrit z impregnacijami galenita as with pyrrhotite, marcasite and magnetite, which were found only sporadically. Minor occurrences of U-mineralisation represented by pitchblende have also been observed. The morphological and geological characteristics of the ore veins from the Zletovo Mine are in general represented by the main characteristics of the ore vein No. IO which was studied in detail (Fig. 2). From Figure 2 it is clearly evident that the central parts of the vein are composed of massive ore while the outer parts are hydrothermally altered and only slightly impregnated by ore minerals. Hydrothermal alterations are mostly silicification and kaolinitization. The concentration of ore minerals in the central part is more than 2O % Pb+Zn, while the altered mineralised vein zones exhibit a considerably lower Pb+Zn content of about 3 %. Materials and methods For the purpose of this study the hydrothermal ore veins in the Zletovo Mine were sampled at different levels. The sampling was possible because the exploitation of the mine was in progress. During the field work representative samples for ore microscopy and for further electron microprobe analysis of sulphides and sulphosalts were taken. All the samples were macroscopically selected for the polished sections. Polished sections of the ore samples were first examined under a ZEISS Axiolab Polarizing Microscope equipped with a photographic camera. After this the selected samples of ore minerals and sulphosalts were analyzed for their S, Fe, Co, Cu, Zn, Ge, As, Ag, Cd, In, Sn, Hg, Pb and Bi contents by WDS electron microprobe using a CAMECA/CAMEBAX equipment. No. Minerals HYDROTHERMAL STAGES Supervene stage 1 stage 11 stage 111 stage IV stage Reduc, Oxidiz. Sllfölnde Contact-term met.-metason sufeftide Sulphide -siilfffiosalts i, P\Trhotine 2. 3. 4. 5. 6. Nalive gold Sphalerite 7. K О alcun 9. Magnetite 10. Ferrojacobšite II Jacobs ile 12 П ausman ni le 13 И IS. Manite 16. Arecnopvrilc 17. Tcirmehdriie ■ iS Jeimann te 19. Cubanite 20. 21. Comi te 22, 23. 24 f'amalinile 25 Chalcosinc 26. 27. tìiwmilhuiile 28 Etotimrnutc 29. Raul immurili; 30. 31. P-KiberBhle 32. FTOUSlile 33, 34. 35. Roduc hromite 36. Barile 37. Cerussite 38. Stnilisonrte 39. Anglesue JÌ_ Ж Malachite 41. Ke-hydroxtde Щ DEPOSITION OF ELEMENTS i Ус 2, Cu 4 /.n 3, Mn 6. Ли 7 Лц Я Aü 9. 10. Sb S i_ ш Figure 3. Paragenetic sequences in the Zletovo ore deposit (Serafmovski, 1990) Slika 3. Paragenetsko zaporedje mineralov v rudišču Zletovo (Serafimovski, 1990) The analytical precision for Sb, Zn, As, and Ag was 1-3 %, 3-10 %, 10-15 % and 10-15 %; however, it was somewhat lower for Pb, Cd, In and Sn, i.e. 2-5 %, 5-15 %, 15-30 % and 15-25 %, respectively. Detectable concentrations of Sn and In were only found in some tetrahedrites, while the Co, Ge, Hg and Bi contents in the tetrahedrites were always below the detection limits of the instrument. The detection limits for Hg and Bi were very high, and usually between 0.4 and 0.6 %. This is most probably due to the interference between the different element's X-ray spectra. As and Pb were also characterized by high detection limits, usually of 0.25 %, relative to those for the other elements such as Fe (0.05 %), Co and Cu (0.07 %) as well as for Zn, Ag, In, Sn, Cd and Ge with detection limits between 0.1 and 0.13%. Results and discussion The results of previous investigations together with the results of the presented study confirm the complex mineral composition of the Pb-Zn mineralization in the Zletovo ore deposit. More than 40 ore bearing and gangue minerals were identified. All of them were crystallized successively from the ore bearing hydrothermal solutions during a few ore bearing stages, thus building complex paragenetic relations. An overview of ore minerals and their sequence of deposition in the frame of the ore forming stages are given in Figure 3. The micro-morphological characteristics and the appearance of the main ore minerals, their relations and the relations of some other minerals are presented in Figure 4. Major ore bearing minerals Galena and sphalerite are the main and the most important ore minerals in the Zletovo Pb-Zn ore deposit, followed by pyrite, chalcopyrite, tetrahedrite, tennantite, marca-site, siderite and partially barite, pyrrhotite, enargite, bornite, arsenopyrite and chalco-cite. Magnetite, jacobsite, hematite, haus-mannite and others occur only sporadically. All other ore minerals not mentioned here were mostly found in trace amounts and have no economic importance. It should be pointed out that in some ore veins the quantitative ratios of the main ore minerals are changeable. For example, in ore vein No. I galena and sphalerite prevail, while the next most common mineral is siderite. On the other hand in ore vein No. IO pyrite is the main ore mineral, followed by other sulphides. However, in general, galena and sphalerite are the most common and the most important ore minerals even if they were deposited in different morpho-logical types of mineralization. Sphalerite was only found in few generations, and in some of them it shows exsol-ved structures of chalcopyrite due to the decomposition of solid solution sphalerite-chalcopyrite. Most often it is metacolloidal to collomorph with zonal patterns and internal reflections. The crystal forms are very rare. More often it is found in over-growth with galena, chalcopyrite and tennantite. Sometimes it metasomatically replaces galena, although in some places it looks like to be suppressed by them. Here and there sphalerite is cataclastic and interstitionally replaced by quartz, galena, tennantite and other minerals. Sphalerite is also myrme-kitically interlocked with galena, chalco-pyrite, tetrahedrite and other ore minerals. Figure 4. Micro-morphologic shapes and the occurrence modes of galena in the Zletovo ore deposit (Serafmovski, 1990): a) Metasomatic replacement of galena (white) by well developed quartz crystals (dark). Reflected polarized light, 100x; b) Corosion of chalcopyrite (white) by galena (grey-white) along intestices and the replacement of galena (white grey) by quartz (dark). In the galena there are remains of pyrite (light), while along its borders there is tennantite (grey). Reflected polarized light, 100x; c) Cataclized galena crystal (white) suppressed by quartz (dark). Reflected polarized light, 100x; d) Pyrite remains (white) in galena (white grey) with the presence of quartz (dark) of metasomatic origin. Reflected polarized light, 100x; e) Corrosion of galena (white grey) by tennantite (dark grey) and tennantite by quartz (dark). At the contact between the galena and tennantite are the remains of ring forms of pyrite. Reflected polarized light, 100x; f) Hypidiomorphic grain of bournonite (dark grey) in massive galena (grey). Reflected polarized light, 100x. Slika 4. Mikromorfološke značilnosti galenita iz rudišča Zletovo (Serafmovski, 1990): a) metasomatsko nadomeščanje galenita (belo) s kremenom (temno), odsevna polarizirana svetloba, 100x, b) nadomeščanje halkopirita (belo) z galenitom (svetlosivo) in galenita (svetlosivo) s kremenom (temno), odsevna polarizirana svetloba, 100x, c) kataklazirana galenitova zrna (belo) cementira in nadomešča kremen (temno), odsevna polarizirana svetloba, 100x, d) ostanki pirita (belo) in galenita (svetlosivo) ter metasomatski kremen (temno), odsevna polarizirana svetloba, 100x, e) nadomeščanje galenita (svetlosivo) s tennantiton (temnosivo) in tennantita s kremenom (temno). Na stiku med galenitom in tennantitom so ostanki pirita obročaste oblike, odsevna polarizirana svetloba, 100x, f) hipidiomorfno zrno bournonita (temnosivo) in masivni galenit (sivo), odsevna polarizirana svetloba, 100x. Table I. Results of electron microprobe analyses of sphalerite (I-IO), pyrite (II, 12), arsenopyrite (13) and galena (14, IS) from the Zletovo ore deposit (in %) Tabela I. Rezultati geokemične analize rudnih mineralov iz rudišča Zletovo z elektronskim mikroanalizatoijem: (1-1O) sfalerit, (11,12) pirit, (13) arzenopirit, (14, IS) galenit). Elementna sestava je v %. Elements S Mn Fe Cu Zn Ga As Cd Sb Pb 1 30,5 0,0 0,3 0,0 68,7 0,0 0,0 0,5 0,0 - 100,0 2 31,0 0,0 0,4 0,0 67,8 0,3 0,0 0,5 0,0 - 100,0 3 30,3 0,0 0,6 0,0 68,0 0,0 0,0 0,0 0,1 - 100,0 4 30,4 0,0 6,5 0,0 69,1 0,0 0,0 0,0 0,0 - 100,0 5 34,2 0,1 0,4 0,0 65,3 0,0 0,0 0,0 0,0 - 100,0 6 38,5 0,2 0,8 0,0 58,8 0,0 0,8 0,4 0,0 - 100,1 7 40,4 0,0 0,6 0,0 59,6 0,0 0,0 0,0 0,0 - 100,1 8 30,7 0,0 0,5 0,0 58,5 0,0 0,0 0,3 0,1 - 100,1 9 35,0 0,0 0,0 0,0 64,7 0,0 0,0 0,3 0,0 - 100,0 10 30,7 0,0 2,8 3,7 62,7 0,0 0,0 0,0 0,1 - 100,1 11 51,8 0,0 47,5 0,2 0,4 0,0 0,0 0,2 0,0 - 100,1 12 49,2 0,0 50,2 0,0 0,0 0,0 0,7 0,0 0,0 - 100,1 13 23,1 0,0 37,1 0,2 4,1 0,0 35,0 0,0 0,6 - 100,1 14 20,5 - - - 1,0 - - - - 78,6 100,1 15 20,5 - - - 1,1 - - - - 78,6 100,1 Figure S. (next page) Microphotographs of sulphides and sulphosalts from the Zletovo ore deposit (ore vein No.1O) analyzed by electron microprobe: a) Late generation of zoned galena crystal rich in quartz inclusions. Earlier generation of galena-sphalerite-pyrite-tetrahedrite ore minerals are the background where the galena crystal was growing. Reflected polarized light, 67x; b) Contact between intensively pyritized volcanic rock fragment and massive sphalerite (gray). Reaction with hypochloric NaOH at the borderline confirmed the presence of zinc sulphide with zoned composition. Reflected polarized light, 67x; c) Sphalerite cutting by the vein containing galena (light gray), tetrahedrite (gray), chalcopyrite (medium gray, upper part), quartz and traces of pyrite. Reflected polarized light, 27O x; d) Ore composed of pyrite (white), chalcopyrite (light gray, left part), tennantite (gray in lower and central part) with inclusions of galena (light gray) and luzonite-stibioluzonite (dark gray, lower central part). Reflected polarized light, oil immersion, 43O x; e) Complex mixture of pyrite (white), sphalerite (dark gray), galena (white, irregular shapes), chalcopyrite (light gray, center) tennantite (middle to dark gray, central area) and luzonite-stibioluzonite (dark gray, strongly pleochroic, central part). Reflected polarized light, oil immersion, 43Ox; 1) Partially crossed nicols. Note the lamellar twinning in one direction of the luzonite-stibioluzonite (light to middle gray, central and lower part), and the "flashy" internal reflections of tennantite (dark gray, left part). Slika S. (naslednja stran) Slike sulfidov in sulfosoli iz rudne žile št. 1O, analiziranih z elektronskim mikroanalizatorjem, rudišče Zletovo: a) Mlajša generacija conarnega galenita z vključki kremena. Osnovo v kateri je kristal rastel predstavlja starejša mineralna parageneza galenit-sfalerit-pirit, odsevna polarizirana svetloba, 67x, b) stik med odlomkom močno piritizirane vulkanske kamnine in masivnim sfaleritom (sivo). strukturno jedkanje je odkrilo na stiku conarno zgradbo sfalerita, odsevna polarizirana svetloba, 67x, c) sfaleritno polje seka žilica, ki vsebuje galenit (svetlosivo), tetraedrit (sivo), halkopirit (srednje sivo), kremen (temno) in sledove pirita, odsevna polarizirana svetloba, 27Ox, d) polimineralno polje sestavljeno iz pirita (belo), halkopirita (svetlo sivo), levi del slike), tennantita (sivo, spodnji in osrednji del slike) z vključki galenita (svetlo sivo) in luzonitom-stibioluzonitom (temno sivo, spodji osrednji del slike), odsevna polarizirana svetloba, oljna imerzija, 43Ox, e) polimineralna ruda sestavljena iz pirita (belo), sfalerita (temno sivo) galenita (belo), halkopirita (svetlo sivo, osrednji del slike) tennantita (srednje do temno sivo) in luzonita-stibioluzonita (temno sivo, močno pleohroično, srednji del slike), odsevna polarizirana svetloba, oljna imerzija, 27Ox, 1) ista slika, ne povsem + nikoli. Opazne so dvojčične lamele luzonita-stibioluzonita potekajoče v eni smeri (srednji in spodji del slike) in notranji refleksi v tennantitu (temno sivo, levi rob slike), odsevna polarizirana svetloba, oljna imerzija, 27Ox. The composition of the sphalerite in the Zletovo deposit is close to the normal values of the theoretically determined values for sphalerite (Criddle and Stanley, 1986). The exception is the Fe content, which in some sphalerites is up to 6.5 % (Table 1). In addition to Fe, sphalerites also contain small quantities of Mn and Cd. Galena was also found in a few generations. In contrast to sphalerite it shows a high degree of crystallinity and very often well-developed crystals. The most beautiful crystal forms of galena can be found in the open veins and vugs as well as in the fracture zones. Here and there the galena crystals are cataclastized and exhibit well developed cleavages and extensive replacement with quartz (Fig. 4). The extend of galena replacement by quartz is sometimes so large that only some remains are left of the primary galena grains. In some places the galena develops along the interstices with pyrite and encloses the pyrite remains, while at other locations it is intensively overgrown with bournonite and other sulphosalts. Galena is usually suppressed by sphalerite, chalcopyrite, tetrahedrite and tennantite, but with these minerals it is also myrmekitically interlocked and forms emulsions. Sometimes dispersive entrapment of pyrite, arsenopyrite and other sulphides can be observed. The elemental composition of galena in the Zletovo Mine is very close to the theoretical values. Microprobe analyses also showed the presence of Zn and Ag in the galena structure (Table I). Sulphosalts and ore bearing minerals from vein No. IO The already known mineral assemblage composed mainly of galena, sphalerite, pyrite, chalcopyrite, siderite and other ore and gangue minerals is supplemented with sulphosalts. During this study special attention was given to ore vein No. IO. From this ore vein five representative samples for ore microscopy and further electron microprobe analyses were taken. Microscopic and electron microprobe analyses revealed tetrahedrite-tennantite solid solution compositions as well as sulphosalt minerals such as luzonite, stibioluzonite and pearceite (Fig. 5). The composition of particular minerals and the phases of interest found during this study are presented in Table 2 and 3. Their main characteristics are given below: Luzonite CuQAsSR Luzonite was found in samples Z-3 and Z-5. The luzonite from samples Z-3 is slightly more Fe rich (O.15-O.66 %) and contains less Sb (O.17-2.5 %) relative to the luzonite from samples Z-5, which has only up to O.14 % Fe and 1.7-3.8 % Sb. The luzonite from samples Z-3 also contains a minor amount of Zn (г i i All samples Waters Soft drinks Non-carbonated Carbonated Parameter DL1 DL2-L- Average N Average N Average N Average N Average N Ni 3 0.3 7.4 19 7.9 14 5.8 5 2.9 11 13.5 8 Pb 1 0.1 0.18 24 0.15 20 0.38 4 0.15 18 0.29 6 Pd 0.1 0.01 0.2 5 0.2 2 0.2 3 0.2 3 0.2 2 Pr 0.01 0.001 0.075 12 0.001 1 0.082 11 0.082 11 0.001 1 Rb 0.05 0.005 30.0 63 48.2 35 7.3 28 6.0 47 100.5 16 Re 0.01 0.001 0.006 19 0.004 13 0.010 6 0.006 18 0.002 1 Sb 0.1 0.01 0.27 54 0.31 32 0.21 22 0.23 41 0.38 13 Sc 10 1 9 10 9 10 2 3 12 7 Se 2 0.2 1.3 9 0.7 7 3.4 2 1.4 6 1.0 3 Si 2000 200 12391 60 13621 33 10888 27 8975 45 22639 15 Sm 0.01 0.001 0.063 14 0.007 5 0.095 9 0.086 10 0.007 4 Sn 1 0.1 27 2 0 27 2 27 2 Sr 0.4 0.04 486 63 750 35 155 28 243 47 1199 16 Та 0.01 0.001 0.043 30 0.004 3 0.048 27 0.046 28 0.006 2 Tb 0.01 0.001 0.026 5 0 0.026 5 0.026 5 Th 0.01 0.001 0.07 13 0.05 2 0.079 11 0.079 11 0.047 2 Ti 1 0.1 4.1 44 4.1 26 4.1 18 2.9 32 7.4 12 TI 0.01 0.001 0.06 27 0.055 19 0.077 8 0.046 18 0.092 9 Tm 0.01 0.001 0.011 5 0.001 2 0.018 3 0.018 3 0.001 2 U 0.02 0.001 0.479 62 0.470 34 0.490 28 0.486 47 0.457 15 V 1 0.1 0.6 19 0.6 17 0.8 2 0.6 15 0.8 4 W 0.2 0.02 0.03 3 0.04 2 0.02 1 0.03 3 Y 0.03 0.003 0.31 29 0.04 17 0.69 12 0.36 23 0.11 6 Yb 0.01 0.001 0.034 13 0.007 5 0.051 8 0.037 11 0.018 2 Zn 5 0.5 13.9 38 13.9 25 13.8 13 9.6 29 27.7 9 Zr 0.1 0.01 1.1 32 1.3 19 0.8 13 0.5 21 2.2 11 er 0.2 35.2 63 35.0 35 35.0 28 23.6 47 69.1 16 F 0.03/0.05 186 37 187 33 185 4 124 22 279 15 НСОз" / 609000 63 1087000 35 12000 28 125000 47 2030000 16 NH/ 0.02 180 4 180 4 180 4 NCV 0.5 46 5 1 4 228 1 47 5 N03 0.001 1 15 1 11 1 4 1 15 PO„3" 0.05 890 27 240 10 1270 17 1020 22 330 5 SO42- 2 126000 49 181000 31 32000 18 23000 36 412000 13 All units are in jj.g/1. DL1 - detection limit for the solution with TDS >500 mg/l, DL2 - detection limit for the solution with TDS <500 mg/1. Nitrogen species are given as nitrogen concentrations. The concentration of Cl" was determined at Joanneum Research, Institute of Water Resources Management, Graz, Austria. According to purpose of the study the accuracy and precision of anion analyses were determined as reasonable. Isotopic composition of dissolved inorganic carbon (513Cdic) was determined on C02 collected after reaction of sample with 100 % HQP04 on a continuous flow Europa 20-20 ANCA-TG stable isotope mass spectrometer at Jožef Stefan Institute. Results are expressed in relative (5) notations as deviations in per mil (%o) from the V-PDB standard. Measurement reproducibility of duplicates was generally better than ±0.3 %. Isotopic composition of oxygen (51V0) was determined by equilibration of C02 with water samples on a dual inlet Finningan DELTAplus stable isotope mass spectrometer, and isotopic composition of hydrogen (52H) was measured on H2 generated by reduction of water over hot chromium on a continuous flow Finnigan DELTAplus XP stable isotope mass spectrometer at the Joanneum Research, Institute of Water Resources Management, Graz, Austria. Results are reported as per mil deviations from the V-SM0W standard. Measurement reproduci-bility of duplicates was better than ±0.05 % for 51v0 and ±1 %o for 52H. Results A large data set was obtained according to sampling and performed analyses. In this paper are presented only results as averages according to the type of water and soft drinks that are similar to water. Averages for different groups of waters are given in Table 1, together with detection limits that are reported in two groups. Average values were calculated for brands and their bottle replicates, therefore total number of all statistical units is 63. Sample replicates are not included in this number; sample and control sample were joined as two sample value before the average value calculations. The first group of detection limits DL1 is valid for samples with total dissolved solids larger than 500 mg/l and the second group DL2 for samples with total dissolved solids smaller than 500 mg/l. 0nly one detection limit is given for anions, except for fluoride. According to different measurement procedures and different physical meaning average values of conductivity, pH and isotopic composition of hydrogen, oxygen and DIC for different groups of waters are reported separately (Table 2). Table 2. Averages and number of samples of different waters and soft drinks classifications - conductivity (20°C), pH and stable isotopes. Tabela 2. Povprečja in število vzorcev glede na različne skupine vod in pijač podobnim vodam - elektroprevodnost (20°C), pH in stabilni izotopi. Parameter All samples Waters Soft drinks Non-carbonated Carbonated Average N Average N Average N Average N Average N Conduct. jiSi/cm 1283 63 1646 35 831 28 687 47 3038 16 pH 5.4 63 6.6 35 3.8 28 5.3 47 5.7 16 S2H %o -66 63 -66 35 -66 28 -65 47 -70 16 6180 %0 -9.6 63 -9.7 35 -9.6 28 -9.4 47 -10.2 16 513Cdic %Q -11.9 63 -12.6 35 -11.1 28 -10.8 47 -15.3 16 Table 3. Classification of elements and anions according to the share of samples under the detection limit [%]. Tabela 3. Klasifikacija elementov in anionov glede na delež vzorcev pod detekcijsko mejo [%]. Share of samples under the detection limit [%] Element Number of elements 90- -100 Au, Ga, Ho, Lu, Nb, Pd, Sn Tb, Tm, W, 10 80 -90 Cr, Dy, Er, Pr, Se, Se, Sm, Yb, NH 4+, N02" 8 70 -80 Al, Co, Eu, Ge, Gd, Hf, Mo, Ni, Re, V, Th, N03" 11 60 -70 Cd, Fe, Li, Ti, P043" 4 50 -60 Br, Cu, Cs, Pb, Та, Zr, Y 7 40 -50 Ce, La, Mn, F" 3 30 -40 Nd,Zn 2 20 -30 As, Ti, 2 10 -20 I, Sb, SO/" 2 0- -10 Ba, Ca, К, Si, U 4 0 Na, Mg, Rb, Sr, Cl", HCO3" 4 The statistics for water and soft drinks similar to water are divided into five main groups (Table I and 2). The first group represents results from all analyzed bottles; the second only of waters and the third are the results of all soft drinks similar to water. The last two groups represent samples divided according to the presence of gaseous COp. Samples with gaseous COP are defined as carbonated and without as non-carbonated. The two classifications of soft drinks and non-carbonated waters are partially covered over. All soft drinks are non-carbonated. This is the reason why they are included into the group of non-carbonated samples. The average values were calculated only for values above detection limit; censured values below detection limit were simply omitted from the calculations. Concentrations of elements Ag, Be, Bi, Hg, In, Os, Pt, Ru, Te were in all samples under the detection limit. The classification of elements and anions according to the share of samples under the detection limit for other elements and anions are given in Table 3. The averages calculated with this procedure are biased to the right of the determined element or ion empirical distribution. This bias is larger for determinations with greater share of values below detection limit than for the determinations with lower share. In the geochemical literature the approach of Miesch (1976) is usually adopted where only variables with more than 70 % of determinations are included in data reduction. In the present study this approach was used only in graphical presentation of the results (see Discussion). Discussion Results show that mainly all elements that are possible to detect with ICP-MS are present in analyzed drinks. But only few elements and ions are present in all samples. This fact leads us to the conclusions that such chemical composition is the consequence of various sources and geochemical processes. Different chemical composition of waters and soft drinks similar to water is also a consequence of various filling and pumping procedures, while in soft drinks it depends also on composition and combinations of flavours. Table 4. Comparison of different groups of waters and soft drinks similar to water according to the overall average. Tabela 4. Primerjava različnih skupin vod in pijač podobnih vodam glede na celotno povprečje analiziranih vzorcev. Parameter Waters Soft drinks . . Carbonated carbonated As - + - + Ba + - - + Ca - + - + I + - - + К - + - + Mg + - - + Na + - - + Rb + - - + Sb + - - + Si + - - + Ti 0 0 - + U - + + - Cl" + - - + HCOj" + - - + S042" + - - + + average of the group is larger than overall average, - average of the group is smaller than overall average, 0 average of the group is the same as overall average Calculated averages show big differences between various groups of waters. This can be seen from the general characteristics such as pH and electrical conductivity (Table 2). Soft drinks have relatively low average pH, much lower than other groups. This fact is the consequence of added organic acids, mainly citron acid that should act as refresher. Carbonated waters have much higher electrical conductivity than other waters. To define the differences among groups of waters and soft drinks comparison between average value for all samples and averages for particular group was made. The comparison was made numerically without statistical testing and the results are presented in Table 4 and Figure I. When the group average in the Table 4 is higher than overall average (+) is given, otherwise (-) is presented. It can be clearly seen that in all cases the average value of element or anion is higher for carbonated waters then for non-carbonated waters. Only in the case of uranium the average is higher for non-carbonated waters. Nevertheless the differences for all elements and anions are small and the average values are very similar. The comparison between soft drinks and waters is not so straightforward as it is in the case of gaseous COP, however it shows that waters have in general higher averages than soft drinks. Sampled soft drinks are waters without gaseous COp. Therefore, we can expect that the pattern in Table 4 should be similar as is in the case of the comparison between carbonated and non-carbonated samples. But higher concentrations of some elements in soft drinks direct to the interpretation that some flavours change original chemistry of water that represent the base for soft drinks and therefore they have higher average concentrations. Differentiation between carbonated and non-carbonated samples is mainly a consequence of the presence of highly mineralized waters in samples that have their source from deep groundwater in east and northeast Slovenia. These waters are carbonated and have high mineral content. Those samples with high total dissolved solids are usually without flavours and they contribute to higher averages of waters. It is not intention of the present study to deeply analyze the isotopic content of the sampled waters and soft drinks. Better interpretation of the results is possible with the data reduction based on particular samples. However, according to the isotopie composition different groups of waters and soft drinks are very similar (Table 2). Differences in calculated averages are characteristic between particular groups for 513Cdic, while for 5180 only carbonated waters differ considerably. Carbonated waters have slightly lower 613Cdic. This result is not in agreement with belief that C0P in these waters is geogenic. Conclusions The present study shows that chemical composition of waters and soft drinks similar to water available on the Slovene market is very wide. Nearly all elements that are possible to detect with ICP-MS are present but only few elements and anions are detected in all samples. The general 1000000 -100000 -10000 -1000 -100 -10 -1 -0,1 - Figure I. Comparison of different groups averages of waters and soft drinks similar to water. Slika I. Primerjava povprečij različnih skupin vod in pijač podobnih vodam. ■All samples □ Waters withouth aditlves H Waters with aditlves □ Waters without C02 □ Waters with C02 О to О 0 1 characteristics such as pH and conductivity show that the composition of samples differs according to the type of water and soft drinks. In general we can differentiate within samples with gaseous C02 or without it and between water with or flavours additives. The C02 differentiation is mainly a consequence of the presence of highly mineralized waters originating from east and northeast Slovenia. They are carbonated and those with high total dissolved solids are usually without flavours. Average isotopic composition of hydrogen, oxygen and DIC for different groups of waters and soft drinks is very similar. From the calculated averages difference are seen mainly in 813Cdic and in waters with C02 in 5180. However, more detailed analyses of obtained isotopic results will show big differentiation among various types of waters and soft drinks. The aim of the present study was to give a geochemical overview of bottled waters and soft drinks similar to water available on the market in Slovenia. Adopted approach was used to establish the procedure for sampling and analyses, to expose open questions related to bottled waters and present exploration of groundwater for bottling of water. However, further work is needed on the statistical analyses and more rigorous statistical testing should be applied. Several multivariate statistics could be performed; among them analysis of variance, multi-variate regression analysis, discriminant analysis, cluster analysis and factor analysis of R and Q type. Waters must be classified according to the hydrogeochemical classifications and more interpretation is needed in connection with the origin of waters. Further research will be directed also in more differentiate classification of samples based on cross-tabulation. Acknowledgement The results were obtained through the research program "Groundwaters and geochemistry" financially supported by the Ministry of high school, science and technology. The help of Nina Rman is greatly acknowledged during the collection and preparation of samples. The discussion with Simon Pirc was invaluable during the preparation of sampling plan. Povzetek Splošne kemijske karakteristike ustekleničenih vod na slovenskem tržišču Potrošnja ustekleničenih vod in pijač, ki so podobne vodam, narašča iz dneva v dan. Že bežen pregled tržišča pokaže, da se te pijače med seboj zelo razlikujejo. Na tržišču bomo našli vode, ki so opredeljene kot mineralne vode, kot izvirske vode ali pa kot vode z dodatki. Takšne razmere na tržišču so posledica dejanskega slabšanja nekaterih vodnih virov, naraščujoče zavesti potrošnikov, še bolj kot to pa zakonitosti tržišča in proizvajalcev, ki skušajo čimbolj povečevati prodajo. Pri potrošnji teh pijač se pogosto zastavljajo številna vprašanja o kvaliteti, njihovem izvoru in kemizmu. V članku so predstavljeni rezultati raziskav 58 ustekleničenih voda in pijač podobnih vodi, kupljenih na slovenskem tržišču septembra 2004. Vzorčenje je potekalo po shemi neuravnotežene analize variance. Analiza vzorcev je zajemala določitev koncentracije 67 elementov z ICP-MS, anionov z ionsko kromatografijo in izotopske sestave vodika, kisika in raztopljenega anorganskega ogljika z masno spektro-metrijo. Vzorce smo razdelili v štiri skupine (vode in pijače ter gazirane in negazirane vode). Rezultati analiz kažejo, da so v analiziranih pijačah prisotni skoraj vsi elementi, ki jih lahko določimo z metodo ICP-MS (tabela I). Toda le nekateri elementi so prisotni v vseh analiziranih vzorcih (tabela 3). Takšne razlike nas privedejo do sklepa, da je kemijska sestava analiziranih vzorcev posledica različnega izvora in geokemičnih procesov. Razlike v kemijski sestavi so tudi posledica različnih postopkov polnjenja in črpanja podzemne vode, ki predstavlja osnovo za izdelavo teh pijač. Pri pijačah, ki so podobne vodam, pa na kemizem vplivajo tudi različni dodatki. Izračunana povprečja kažejo na zelo velike razlike med pijačami (tabeli I in 2). Te razlike zlahka opazimo že, če med seboj primerjamo splošne karakteristike skupin, kot sta pH in elektroprevodnost (tabela 2). Vode z dodatki imajo relativno nizek pH, mnogo nižji kot ostale skupine. To je posledica različnih dodatkov, predvsem organskih kislin in še posebaj citronske kisline, ki naj bi delovala kot osvežilo. Vode s prostim plinskim C02 pa imajo dosti višjo električno prevodnost kot pijače iz ostalih skupin. Primerjava med povprečji posameznih skupin je bila izvedena le numerično, brez statističnih testiranj. Rezultati primerjave so predstavljeni v tabeli 4 in na sliki I. Ce je povprečje skupine višje kot povprečje celotnega niza vzorcev je ta razlika predstavljena s +, če je nižja pa z -. Iz primerjave v tabela 4 sledi, da je pri gaziranih pijačah v vseh primerih koncentracija elementov in anionov višja od koncentracije v negaziranih vodah. Le v primeru koncentracije urana je povprečna koncentracija višja pri negaziranih kot pri gaziranih pijačah. Razlika med gaziranimi in negaziranimi pijačami je posledica prisotnosti visoko mineraliziranih vod, ki imajo svoj izvor v globoki podzemni vodi severovzhodne in vzhodne Slovenije. Kljub temu pa so razlike majhne in izračunana povprečja zelo podobna. Primerjava med skupinama vod in vod z dodatki pa ni tako premočrtna, kot je to v primeru gaziranih in negaziranih vod. Kljub temu primerjava pokaže, da imajo vode brez dodatkov pravilom višje koncentracije kot vode z dodatki. Analizirane vode z dodatki so negazirane, kar bi lahko pojasnilo razliko, saj imajo gazirane vode višjo mineralizacijo. Na podlagi tega bi lahko pričakovali, da bo primerjava med vodami in vodami z dodatki v tabeli 4 podobna primerjavi med gaziranimi in negaziranimi pijačami. Toda višje koncentracije nekaterih elementov v vodah z dodatki nas napeljujejo na interpretacijo, da nekateri dodatki spremenijo kemizem vode, ki predstavlja osnovo za izdelavo pijače. Rezultati izotopskih analiz kažejo, da so si analizirane skupine med seboj dokaj podobne (tabela 2). Razlike v izračunanih povprečjih so med skupinami opazne predvsem pri 513Cdic, medtem ko pri 5180 znatno odstopajo le gazirane vode. Gazirane vode imajo nekoliko nižjo vrednost 613Cdic, kar nakazuje, da izvor C02 v nekaterih vodah ni geogenega izvora. Namen članka je predstaviti osnovne geo-kemijske značilnosti ustekleničenih voda in vod z dodatki, ki jih je mogoče kupiti na slovenskem tržišču. V okviru opravljene raziskave smo poizkušali vzpostaviti postopek za vzorčenje in odpreti nekatera vprašanja, ki se navezujejo na polnjenje ustekleničenih voda ter na izkoriščanje podzemne vode za potrebe ustekleničenja. Predstavljeni rezultati so le prvi korak k iskanju odgovorov na ta vprašanja. V nadaljnjih koraki bo potrebno izvesti podrobnejšo statistično analizo z rigoroznejšimi statističnimi testi. Statistične analize bodo usmerjene v multivariatne statistike kot so multipla analiza variance, multivariatna regresijska analiza, diskriminantna naliza, clusterska analiza ter faktorska analiza tipa Q in R. Pri nadaljnji analizi bo potrebno izvesti tudi nekatere fizikalno kemijske izračune in hidrogeokemijske klasifikacije ter jih navezati na hidrogeološki izvor vode. Nadaljnje raziskave bodo usmerjene tudi v podrobnejšo klasifikacijo vzorcev. References Gider, N. (2005): Slovenes have drank S8 liters of bottled water (Slovenci popijemo letno 58 litrov ustekleničene vode). Večer 27. maj, 15. Hribar, N. (2000): Opinion poll about housekeeping consumption in Slovenia (Anketa o porabi v gospodinjstvih, Slovenija), 1998. Statistične informacije št.16; Zivljenska raven št.1, Ljubljana. Miesch, A.T. (1976): Geochemical survey of Missouri; methods of sampling, laboratory analyzing, and statistical reduction of data. US Geological Survey Professional Paper 954 - a, 39 p., Washington. Rowlands, R. (2001): Massage in the bottle. Soft Drinks International, July 26-27. Razširjenost onesnaženja s cinkom in kadmijem v Celjski kotlini Distribution of zinc and cadmium pollution in Celje basin Gorazd Žibret, Robert Šajn Geološki zavod Slovenije, Dimiceva 14, 1000 Ljubljana; E-mail: gorazd.zibret@geo-zs.si; robert.sajn@geo-zs.si Received: June 7, 2005 Accepted: October 28, 200S Izvleček: V raziskavi smo proučevali upadanje vsebnosti cinka in kadmija v odvisnosti od razdalje od vira onesnaženja. Vir onesnaženja v Celju je Cinkarna celje, ki je v 100 letnem obdobju proizvedla približno S80.000 ton surovega rafiniranega cinka. Vzorci tal (0-S cm) in podstrešnega prahu so bili odvzeti do oddaljenosti 12 km od obrata. Vzorčne točke smo postavili po dolinah Savinje, Voglajne in Hudinje in se na ta način izognili hribovitemu svetu, ki predstavlja naravno pregrado za širjenje onesnaženega zraka. Rezultati so pokazali, da se vsebnosti Zn in Cd nižajo po potenčni funkciji. Koeficienti determinacije s teoretično potenčno krivuljo so v obsegu od 0,7S do 0,98. Vplivno območje onesnaževalca smo ocenili med IS in 60 km za podstrešni prah ter med 7 in 20 km za tla in je odvisno od tega, proti kateri strani neba se od topilnice oddaljujemo. Najbolj je obremenjena vzhodna dolina, najmanj pa severna. Abstract: In this research we have examined the decreasing of the concentrations of pollutants in the attic dust and topsoil with increasing distance from the source of pollution, which is in this case zinc smelter plant Cinkarna in Celje town. In the 100-year period Cinkarna has produced around S80,000 tonns of raw zinc. The samples of topsoil (0-S cm) and attic dust have been taken up to 12 kilometers distance from the plant. The sampling plan based on the sampling in the river valleys: Savinja on the W and S, Voglajna at the E and Hudinja valley at the N side from the polluter. In that way we have avoided the uplands, which represents the natural barrier for the polluted air. The research has shown that lowering of zinc and cadmium concentrations can be described by power equation with high determination coefficients between hypothetical power curve and measured values, which varies between 0.7S and 0.98. The influence area is between IS and 60 kilometers in attic dust and between 7 and 20 km for topsoil. It depends on the orientation of the valley. The most polluted is east valley and the least polluted the north valley. Ključne besede: onesnaženje, težke kovine, podstrešni prah, tla, Celje, Slovenija. Key words: pollution, heavy metals, attic dust, topsoil, Celje, Slovenia. Uvod V Številnih dosedanjih raziskavah je ugotovljeno, da je stopnja onesnaženosti mesta Celje zelo visoka (Batič, 1984; Domitrovič-Uranjek, 1990; Lobnik et al., 1989). Viri onesnaženja so predvsem celjska industrija, promet ter drobna kurišča. Vsak vir pa ima svoje značilne geokemične karakteristike. Tako Železarna Store izpušča siderofilne prvine, kot so železo, krom, mangan, nikeli in kobalt, individualna kurišča so pomemben vir kalcija, magnezija ter stronCiia, obrati Cinkarne Celie pa so bili močan vir cinka, kadmija, svinca in arzena ter v zadnjih 30 letih tudi titana (Sajn, 2001; Sajn, 2005; Zibret, 2002a). Ker je Cinkarna Celie močan vir cinka in kadmiia v okolici, je mogoče določiti, do kam sega vpliv onesnaževalca oziroma kako daleč ie opazen vpliv nekdanje topilnice. Celjska kotlina se razteza v smeri vzhod-zahod. Od zahoda priteče reka Savinja, ki prav v Celju naredi oster ovinek proti jugu v Posavske gube, ki predstavljajo ostro geografsko meio. V Savinio se od vzhoda izliva reka Voglaina, od severa pa priteče reka Hudinja. V neposredni bližini sotočja treh rek so se nahajale topilnice cinka. V 100 letnem obratovalnem obdobju je po ocenah, dobljenih iz statističnih letopisov SR Slovenije ter posameznih poročil (Felicijan, 1993), bilo pridobljenih 580.000 ton surovega rafiniranega cinka. Postopek predelave ie bil taksen, da ie vsai 3% celotne produkcije Zn bilo emitiranih v okolje v obliki prasnih delcev. Posledica ie ta, da tla na vzorčni točki v bližini Cinkarne vsebuieio 0,86 % cinka in 60 mg/kg kadmija (Zibret, 2002a). Se višje vsebnosti zasledimo v podstrešnem prahu, ki je po ekonomsko- geoloških karakterizacijah kvalitetna cinkova ruda, saj vsebuje 5,6 % Zn in 456 mg/kg kadmija. Emisije v okolje ocenjujemo na približno 1700 ton cinka in 9 ton kadmija (Zibret, 2002b). Geokemično ozadje Slovenije za tla (0-5 cm) znaša 124 mg/kg Zn in 0,5 mg/kg Cd, za podstrešni prah pa 327 mg/kg Zn in 1,2 mg/kg Cd (Sajn, 2003). Približno 7 km severozahodno od Celja je hidrotermalno polimetalno svinčevo-cinkovo rudišče Zavrh (Drovenik et al., 1981), ki na porazdelitev Zn in Cd v okolju verjetno nima večjega vpliva. N NW- ■ ' - ■. .a -.. '••■.NE t \ 0 ; \ :• ; E S ...■■'SE Slika I. Roža vetrov za mesto Celje. Figure I. The wind rose for the town of Celje. Na razširjanje onesnaženosti na celjskem območju najbolj vplivajo podnebni dejavniki, kot so veter, njegova smer in hitrost ter pojav temperaturne inverzije predvsem v zimskem obdobju. Ker leži Celje v kotlini, je zanj roža vetrov (slika 1) neznačilna in zelo lokalno pogojena. Na splošno pa prevladujeta severovzhodnik (12 %) in jugozahodnik (15 %) s povprečno hitrostjo vetra okoli 2 m/s. Brezvetrje traja v povprečju 32,1 % celotnega časa. Pojav temperaturne inverzije traja povprečno 95,2 dni v letu in je prisoten predvsem od septembra do februarja. Materiali in metode Za določitev vplivnega območja topilnic cinkove rude v Celju smo vzorčili podstrešni prah in tla po rečnih dolinah v smereh vzhod, zahod, sever in jug. Vzorčni načrt je predvideval vzorčenje glede na oddaljenost od topilnic Cinkarne Celje, in sicer v bližini cinkarne na vsakih 500 m, potem pa na vsaka 2 km (slika 2). Največja oddaljenost odvzetega vzorca od Cinkarne je po zračni črti znašala 11,9 km proti severu, južno 11,2 km, zahodno 13,7 km in vzhodno 12,9 kilometrov. Podstrešni prah smo vzorčili tako, da smo zbirali prah z lesene konstrukcije podstrešja, ki ni bila v neposrednem stiku s strešniki ali tlemi. Na ta način smo se izognili pobiranju delcev strešnikov, ostankov lesa in malte. Pri vzorčenju podstrešnega prahu smo izbirali starejše objekte, po možnosti z zapuščenim podstrešjem (Šajn, 1999). Tla so bila vzorčena do globine 5 cm. Izven naselij smo vzorčili travniška tla, v naseljih pa vrtna tla ali tla zelenic. Posamezni vzorec je sestavljen iz najmanj 7 podvzorcev, odvzetih v teoretično šesterokotnem načrtu na razdaljah 25 m od središčne točke. Celotni zbrani vzorec tal je tehtal približno 1 kg. Vzorce smo pripravili po postopkih, ki so priporočeni v sklepih UNESCO-vega projekta IGCP 259 (Darnley et al., 1995). Zbrani vzorčni material smo sušili v ventilatorski omari pri 40° C. Vzorce tal smo potem 0 I * Merilo (km) Slika 2. Položaj vzorčnih točk glede na vir onesnaženja. Figure 2. Locations of sampling points with regard to source of pollution. narahlo pretrli ter presejali skozi sito na zrnavost pod 2 mm. Presevke smo po četrtinjenju mleli v keramični terilnici ter sejali na analizno zrnatost pod 0,125 mm. Vzorce podstrešnega prahu smo presejali na posamezne razrede zrnatosti: od 1 do 0,5 mm, od 0,5 do 0,25 mm, od 0,25 do 0,125 mm in manjši od 0,125 mm. Presevek, manjši od 0,125 mm, je predstavljal material za kemijsko analizo po metodi plazemske emisijske spektrometrije (ICP) po štiri-kislinskem razklopu (HCl04, HN03, HCl in HF), ki je potekal pri temperaturi 200°C. Vzorce so analizirali na 42 prvin (Al, Ca, Fe, K, Mg, Na, P, S, Ti, Ag, As, Au, Ba, Be, Bi, Cd, Ce, Co, Cr, Cu, Hf, La, Li, Mn, Mo, Nb, Ni, Pb, Rb, Sb, Sc, Sn, Sr, Ta, Th, U, V, W, Y, Zn in Zr) v laboratoriju družbe ACME v Kanadi. Vsebnosti Hg so bile po razklopu z zlatotopko določene z atomsko absorpcijsko spektrometrijo (AAS), po postopku hladnega izparevanja. Zmanjševanje vsebnosti Zn in Cd v prahu in tleh z oddaljenostjo od vira onesnaženja v Celju lahko opišemo s potenčno krivuljo z asimptotičnim približevanjem ničli v neskončnosti. Enačba 1 opisuje potenčno krivuljo, tabela 1 pa njene posamezne koeficiente glede na prvino, material in smer vzorčenja. X v enačbi 1 pomeni oddaljenost opazovane točke od vira onesnaženja, izraženo v kilometrih, C pa vsebnost v mg/kg. Linearni faktor a in eksponentni faktor ß opisujeta hitrost padanja vsebnosti cinka in kadmija glede na oddaljenost od vira onesnaženja. Oba faktorja sta navedena v tabeli 1. D2 v tabeli 1 pomeni moč povezave med empirično in teoretično krivuljo zmanjševanja vsebnosti prvine. Slaba stran potenčne krivulje je ta, da zadovoljivo opisuje padanje vsebnosti polutantov le na določenem intervalu, izven tega intervala pa vrne nerealne vrednosti. Največje pomanjkljivosti so: • potenčna krivulja predpostavlja neskončen doseg onesnaževalca; • potenčna krivulja predpostavlja neskončne vsebnosti polutanta na mestu onesnaževalca (če za razdaljo vnesemo vrednost 0, dobimo vsebnost neskončno); • vsebnosti se asimptotično približujejo ničli, namesto, da bi se približevale vrednosti geokemičnega ozadja. C = ozadje+a -X (2) Asimptotično približevanje geokemičnemu ozadju se da enostavno korigirati (enačba 2), vendar slednji model slabše opisuje obnašanje vsebnosti cinka in kadmija glede na oddaljenost od vira, saj so vrednosti determinacijskih koeficientov nižje (od 1 do 12 odstotnih točk). Zato je tudi bil uporabljen model po enačbi 1. Vplivno območje topilniških obratov je razdalja, na kateri je vpliv topilnic že tako majhen, da naravna prisotnost cinka in kadmija preseže ocenjeni antropogeni vnos. Takrat ni več možna ločitev med naravno prisotnim cinkom in kadmijem ter med antropogenim vnosom teh dveh prvin. Ta podatek je izračunan po enačbi 3, ki predstavlja rešitev enačbe 1 po X-u v kilometrih. Za koncentracijo (C .. ) ie bila upoštevana vrednost v ozadja' J r geokemičnega ozadia za posamezno prvino in material v mg/kg. Linearni faktor a in potenčni faktor ß sta za posamezno prvino, smer in material enaka, kot pri enačbi 1. Nl/ß C = aX -ß (1) ozadja a у ^ozadja J (3) Tabela I. Parametri potenčnih krivulj. Table I. Parameters of power curves ("ne doseže" means "does not reach"). Cink (prah) / Zinc (dust) a 3 D2 ozadje (km)/ background teoretično / theoretical ozadje (km)/ background izmerjeno / measured sever(N) 9193,9 1,2497 0,98 14,44 ne doseže jug (S) 7741,8 1,0251 0,91 21,91 ne doseže zahod (W) 18907 1,1771 0,97 31,40 ne doseže vzhod (E) 25545 1,1020 0,88 52,19 ne doseže vse točke / all points together 13026 1,0908 0,80 29,31 Cink (tla) / Zinc (soil) sever(N) 1522,9 1,0596 0,88 10,67 8 jug (S) 1082,1 0,9744 0,81 9,24 10 zahod (W) 3357,5 1,2448 0,87 14,15 ne doseže vzhod (E) 4567,5 1,3872 0,95 13,46 ne doseže vse točke / all points together 2056,9 1,0828 0,79 13,38 Kadmij (prah) Cadmium (dust) sever(N) 52,207 1,1413 0,94 27,27 ne doseže jug (S) 39,237 1,0410 0,85 28,50 ne doseže zahod (W) 114,68 1,0322 0,89 82,90 ne doseže vzhod (E) 124,25 1,0703 0,96 76,34 ne doseže vse točke / all points together 71,135 1,0251 0,75 53,64 Kadmij (tla) Cadmium (soil) sever(N) 4,6098 1,2238 0,90 5,95 7 jug (S) 39,237 1,0410 0,85 63,64 8 zahod (W) 114,68 1,0322 0,89 186,37 ne doseže vzhod (E) 124,25 1,0703 0,96 166,76 ne doseže vse točke / all points together 9,6470 1,0276 0,65 17,15 Rezultati Analizne rezultate kažejo slike od 3 do 6. Slika 3 prikazuje upadanje vsebnosti cinka v podstrešnem prahu glede na oddaljenost od vira onesnaženja. Najmanjši koeficient a je v dolini reke Savinje na jugu, kar pomeni manjšo splošno onesnaženost, kot v ostalih treh dolinah. Najvišji koeficient ß pa je v dolini reke Hudinje na severu, kar pomeni, da vsebnosti cinka v podstrešnem prahu najhitreje upadajo v tej smeri. Vrednosti geokemičnega ozadja nismo ugotovili niti na oddaljenosti več kot 13 km od topilnic cinkove rude. Najbolj so se vsebnosti približale ozadju v dolini reke Hudinje proti severu in sicer v vzorcu, odvzetem v Socki. Glede na izračun vplivnega območja ocenjujemo, da se vrednosti cinka v podstrešnem prahu spustijo na raven geokemičnega ozadja med 15 km (N dolina) in 60 km (E dolina) od vira. Če upoštevamo vse opazovane točke, znaša vplivno območje topilnic približno 30 km za cink v podstrešnem prahu. Podobne karakteristike kaže tudi vedenje kadmija v podstrešnem prahu (slika 4). Spet se najvišje vrednosti linearnega faktorja a pojavijo v vzhodni dolini, kar pomeni najvišjo stopnjo onesnaženja, najvišje vrednosti potenčnega koeficienta ß pa v severni dolini, kar nakazuje na najhitrejše padanje vsebnosti glede na oddaljenost od vira. Tudi v tem primeru nismo zaznali upadanja vsebnosti do geokemičnega ozadja. Najnižje vsebnosti kadmija smo zaznali v Laškem, torej v južni dolini. Izračunano vplivno območje znaša približno 30 km proti severu in jugu ter približno 80 km proti vzhodu in zahodu. Ob upoštevanju vseh meritev skupaj znaša vplivno območje približno 50 km. Slika 3. Porazdelitev Zn v podstrešnem prahu glede na oddaljenost. Figure 3. Distribution of Zn in attic dust versus distance. Slika 4. Porazdelitev Cd v podstrešnem prahu glede na oddaljenost. Figure 4. Distribution of Cd in attic dust versus distance. Sliki 5 in 6 prikazujeta upadanje vsebnosti cinka in kadmija v tleh. Ob tem lahko potegnemo analogijo s podstrešnim prahom. Najbolj obremenjeni sta vzhodna (najvišje vrednosti linearnega koeficienta a) in zahodna dolina, najmanj pa severna in južna. Za razliko od podstrešnega prahu smo v tleh zaznali vsebnosti cinka in kadmija, ki so 4,000 6,000 8,000 10,000 12,000 oddaljenost od vira onesnaženja / distance from source of pollution (km) 4,000 6,000 8,000 10,000 oddaljenost od vira onesnaženja / distance from source of pollution (km) Slika 6. Porazdelitev Cd v tleh (0-S cm) glede na oddaljenost. Figure 6. Distribution of Cd in topsoil versus distance. Slika S. Porazdelitev Zn v tleh (0-S cm) glede na oddaljenost. Figure S. Distribution of Zn in topsoil versus distance. upadle na raven geokemičnega naravnega ozadja na razdalji med 7 in IO km v severni in južni dolini. Izračunano vplivno območje za cink v tleh znaša IO km proti severu in jugu ter 14 km proti vzhodu in zahodu. Izračuni za vplivno območje pri kadmiju v tleh pa dajo nenavadne rezultate, kar lahko pripišemo visokim vsebnostim kadmija v tleh na velikih oddaljenostih od vira onesnaženja v vzhodni in zahodni dolini. Možno je, da je vrednost geokemičnega ozadja na tem območju podcenjena, ali pa je v okolici Celja prisoten regionalni onesnaževalec (TE Šoštanj ali TE Trbovlje npr.). Vseeno lahko ocenimo, da znaša vplivno območje v tleh med 1O in 2O km. Diskusija V raziskavi je ugotovljeno, da vsebnosti cinka in kadmija v prahu in tleh upadajo od vira onesnaženja po hipotetični potenčni krivulji. Iz korelacijskih koeficientov med resničnimi podatki in teoretičnimi krivuljami vidimo, da se podatki izredno dobro ujemajo s potenčnimi krivuljami (najmanjša vrednost D2 za posamezne smeri je 0,81), kar pomeni, da je s teoretično krivuljo pojasnjeno v najslabšem primeru 81 % celotne variance. Vpliv lokalnih vetrov vidimo iz dejstva, da vsebnosti prvin najhitreje padajo v smeri severno od Cinkarne (največji koeficienti ß), najpočasneje pa proti vzhodu (najmanjši koeficienti ß). Na opazen vpliv vetrov lahko sklepamo tudi iz dejstva, da potenčne krivulje za posamezne smeri dosti bolje opišejo padanje vsebnosti kot pa potenčna krivulja za vse vzorce skupaj (tabela 1). Geokemično ozadje za cink v tleh je v splošnem najbližje doseženo v smereh sever-jug od Cinkarne, in sicer v oddaljenosti približno 10 km. V smereh vzhod-zahod geokemično ozadje z raziskavo ni doseženo niti v oddaljenosti več kot 13 km, čeprav so se vrednosti zelo približale ozadju. To kaže bodisi na rahlo podcenjene naravne vrednosti na tem območju, bodisi na izredno velik vpliv Cinkarne ali pa na prisotnost regionalnega onesnaževalca. Skoraj identična situacija je pri kadmiju. Ob tem lahko ocenimo, da je vplivno območje topilnice za Cd in Zn od 7 do 20 km v tleh ter od 15 do 60 km v podstrešnem prahu. Višje vrednosti so v smereh vzhod-zahod, kar je tudi prevladujoča smer vetrov, ki so onesnaženje prenašali. Ne smemo pa tudi zanemariti vpliva 150-letnega železniškega transporta na relaciji Dunaj-Trst, ki poteka od vzhoda skozi Celje ter dalje proti jugu, poleg tega pa je blizu Žalca delovala tudi manjša topilnica, ki je vlivala zvonove. Vendar je njun vpliv glede na Cinkarno najbrž neznaten. Literatura Sajn, R. (1999): Geokemične lastnosti urbanih sedimentov na območju Slovenije. Geološki zavod Slovenije, 136 p., Ljubljana. Sajn, R. (2001): Geochemical research of soil and attic dust in Celje area (Slovenia). Geologija Vol. 44, No. 2, pp. 3S1-362, Ljubljana. Sajn, R. (2003): Distribution of chemical elements in attic dust and soil as reflection of lithology and anthropogenic influence in Slovenia. Journal de Physique Vol. 107, pp.1173-1176, Les Ulis. Sajn, R. (200S): Using attic dust and soil for the separation of anthropogenic and geogenic elemental distributions in an old metallurgic area (Celje, Slovenia). Geochemistry: exploration, environment, analysis Vol. S, No.1, pp. S9-67, London. Zibret, G. (2002a): Geokemične lastnosti tal in podstrešnega prahu na območju Celja. Diplomsko delo. Naravoslovnotehniška fakulteta Univerze v Ljubljani, 78 p., Ljubljana. Zibret, G. (2002b): Masna bilanca težkih kovin na območju Celja. Geologija Vol. 4S, No. 2, pp. 613-618, Ljubljana. Kidrič, 1S9 p., Ljubljana. Batič, F. (1984): Lišajska karta Slovenije. Prirodoslovno društvo Slovenije, Ljubljana. Darnley, A.G., Björklund, A., Bolviken, В., Gustavsson, N., Koval, P.V., Plant, J.A., Steenfelt, A., Tauchid, M., Xuejing, X., Garrett, R.G. & Hall G.E.M. (199S): A global geochemical database for environmental and resource management. Recommendations for international geochemical mapping. Pinal report oflGCP project 259. UNESCO Publishing, 122 p., Paris. Domitrovič-Uranjek, D. (1990): Onesnaženost okolja v Celju. Zveza društev inženirjev in tehnikov, 3S p., Celje. Drovenik, M., Duhovnik, J. & Pezdič, J. (1981): Cinkovo-svinčevo rudišče Zavrh. RMZ-Mat. & Geoenviron. Vol. 28, pp. 1S2-276, Ljubljana. Felicijan, J. (1993): Topilnica - rojstvo Cinkarne. Cinkarnar Vol. 37, No. 3, p. 8, Celje. Lobnik, F., Medved, M., Lapajne, S., Brumen, S., Zerjal, E., Vončina, E., Stajnbaher, D. & Labovič, A. (1989): Tematska karta onesnaženosti zemljišč Celjske občine. Biotehniška fakulteta, VTOZD za agronomijo, Univerza v Ljubljani; Kemijski inštitut Boris Kovinskih rudniki in okolje (nekateri slovenski primeri) Metal mines and environment (some Slovenian case studies) Mateja Gosar, Robert Šajn Geološki zavod Slovenije, Dimičeva 14, 1000 Ljubljana; E mail: mateja.gosar@geo-zs.si; robert.sajn@geo-zs.si Received: June 7, 2005 Accepted: October 28, 200S Izvleček: V prispevku obravnavamo vplive na okolje, ki so posledica pridobivanja kovinskih rud in njihove predelave. Na vplivnem območju opuščenih rudnikov in predelovalnih obratov rude so večkrat posledice rudarjenja zelo pereče. Vsebnosti težkih kovin v tleh, sedimentih in vodi so mnogokrat povišane, iz rudnikov lahko nenadzorovano odtekajo kisle rudniške in odcedne vode. Območje Slovenije je od nekdaj znano po številnih rudnikih in predelavi kovin. Od prazgodovinskih časov pa do danes poznamo v Sloveniji 49 rudnikov barvastih kovin, od katerih so bili štirje večji veliki (Idrija, Mežica-Topla, Litija in Zirovski vrh), in 2S predelovalnih obratov in topilnic, ki so delovale predvsem v okolici večjih rudnikov (Idrija, Zerjav). Ugotovili smo, da rudarstvo in predelava rude v Sloveniji predstavljata enega od glavnih načinov antropogenega vnosa težkih kovin v okolje. Abstract: The impact of mining and processing of metal ores on the environment is described. In the surroundings of abandoned mining and smelting locations environmental problems such as elevated metal concentrations in soils/sediments, dispersion of toxic metals in soil and water and ecological damage are observed. Slovenia has long been known for its numerous mines and ore processing locations. From the prehistoric times to now, 49 mines and open pits were opened, four of them were large (Idrija, Mežica-Topla, Litija and Zirovski vrh). There were also 2S ore processing plants and smelters, which were operating mostly in the vicinity of larger mines (Idrija, Zerjav). It was established that, in Slovenia, mining and ore processing represents one of the major modes for anthropogenic input of heavy metals into the environment. Ključne besede: vplivi rudarjenja, rudniški odpadki, težke kovine, Slovenija. Key words: mining impacts, mining waste, heavy metals, Slovenia. Uvod Rudarstvoje zelo stara človekova dejavnost. Prvi vidni sledovi pridobivanja soli in kresilnega kamna so iz časa okoli 5000 pr.n.š. Ob odkritju prvih kovin (bakra, svinca, železa) se je z rudarstvom zelo povezalo topilništvo. Že v starem Egiptu so poznali in uporabljali železo in zlato, tudi stari Grki in Rimljani so rudarili. Takratne metode pridobivanja rude so zajemale tudi segrevanje in hitro ohlajevanje, kar je povzročilo razpokanost kamnine. Za razsvetljavo so uporabljali oljenke, vodo so iz jam odstranjevali z lesenimi vodnimi kolesi. Prazgodovinski človek je tudi na ozemlju Slovenije že poznal in izkoriščal pohorska rudišča (Tržan, 1989). Za kopanje je uporabljal kamnita orodja (kladivo, klin, dleto, sekiro) pri pridobivanju rude si je pomagal tudi z ognjem, les je bil pri roki v pohorskih gozdovih. Rudo so ročno prebirali in jo talili v bližini rudišč. Dokaz za rudarjenje v prazgodovini na Pohorju je celoten spekter tam najdenega rudarskega kamnitega orodja, kakršnega poznajo tako bližnja kot oddaljena območja rudarjenja (Tržan, 1989). Domnevajo, da se je izkoriščanje sulfidnih rud na Pohorju začelo v začetku bronaste dobe. V pozni bronasti dobi je dosegla produkcija bakra v vzhodnih Alpah svoj višek, pridelovati so začeli tudi svinec in železo. S starejšo železno dobo, ko se je pojavila potreba po novi kovini, sta nastali ob pohorskih nahajališčih dve pomembnejši postojanki. Na lokaciji ene (Poštela) so našli vzhodnonoriški srebrnik, kar kaže na to, da je Pohorje predstavljalo ekonomsko zaledje vzhodnonoriškega območja. Z razpadom rimskega cesarstva je rudarjenje zelo nazadovalo. V 16. stoletju je rudarska tehnika spet napredovala, predvsem pri odvodnjavanju in prezračevanju. Iz tega časa je delo De re metallica (Agricola, 1556), ki podrobno opisuje tudi rudarjenje v idrijskem rudniku. Da so nekatere kovine strupene, so vedeli že stari Rimljani, ki so opazili bolezenske znake pri sužnjih, ki so delali v rudnikih. Tudi iz obdobja srednjega veka imamo že veliko pisanih virov o zastrupitvah rudarjev delavcev v topilnicah. Vplivi kovinskih rudnikov na okolje Pridobivanje in predelava kovinskih rud imata več neželenih vplivov na okolje. Kovine so v rudnih telesih navadno prisotne v nizkih koncentracijah, zato nastaja ob njihovem pridobivanju velika količina odpadkov, ki lahko vsebujejo težke kovine in kemikalije iz predelovalnega postopka. Posledica topilniške in metalurške dejavnosti ob rudnikih so emisije plinov (C02, S02 in ostalih) in trdnih delcev, izcedne vode in rudniški odpadni material. Letno je posledica rudarjenja več milijard ton jalovine in ostalih rudniških odpadkov, ki so pod vplivom oksidacijskih pogojev na zemeljskem površju izpostavljeni preperevanju. To poteka v dveh zaporednih procesih, ki lahko negativno vplivata na okolje. Prvi je nastanek kislih izcednih vod, drugi proces pa je mobilizacija potencialno strupenih kovin na površje kot posledica preperevanja (Siegel, 2002). Dejavnosti, ki so povezane z rudarjenjem lahko razdelimo v šest zaporednih procesov: • Iskanje in raziskovanje nahajališč koristnih rudnin in rudninskih snovi, ki zajema razne geološke, geokemične in geofizikalne metode. Sledijo sledilna dela, ki omogočajo presojo o zalogah in vrednostih nahajališča. • Odpiranje nahajališča z vrtinami, površinskim kopom ali s podzemeljskimi rudarskimi deli ter izdelava potrebne infrastrukture • Pridobivanje rude (odkop materiala, drobljenje ter mletje) • Bogatenje mineralne surovine, da bi ločili del nekoristne izkopanine -jalovine ali posamezne minerale različnih kovin • Metalurški procesi, s katerimi pridobimo različne kovine • Sanacija rudarskih del, ko poidejo zaloge rude Pri vseh naštetih fazah rudarjenja prihaja do neželenih vplivov na okolje. Te lahko delimo na vplive na prostor, onesnaževanje in vplive na zdravje delavcev (Hoskin et al., 2000). Najpomembnejši prostorski vplivi so: • Uničenje naravnih habitatov na območjih rudarjenja in odlagališč rudniških odpadkov ter kot posledica zračnih emisij in izpustov odpadnih voda • Spremembe v rečnem režimu kot posledica nasipanja jalovine v rečne tokove • Degradacija površja zaradi neustrezne sanacije rudarskega območja • Geomehanska nestabilnost površja in deponij rudarskih odpadkov • Opuščeni rudarski obrati in oprema Vplivi na onesnaževanje so: • Odvajanje odpadnih voda in (onesnaženih) sedimentov v okolje • Onesnaževanje tal • Izluževanje onesnažil iz rudarskih in metalurških odpadnih deponij ter onesnaženih tal • Zračne emisije iz predelovalnih obratov in prezračevalnih jaškov • Emisije prašnih delcev Pri rudarjenju je še posebej pereče ravnanje z jalovino. Pri pridobivanju mineralnih surovin, še posebno kovin, nastajajo velike količine jalovine, ki vsebujejo težke kovine in kemikalije iz predelovalnega postopka in zato lahko negativno vplivajo na okolje. Velike ekološke nesreče, ki so se zgodile v svetu v zadnjih 10-ih letih in še posebno dve, ki sta se pripetili v Evropi (Aznacollar, Španija, leta 1998 in Baia Mare, Romunija, leta 2000), so opozorile svet na veliko nevarnost ekoloških nesreč zaradi posledic rudarjenja. Evropska direktiva o ravnanju z odpadki, ki nastajajo v rudarstvu Da bi v bodoče varno rudarili in imeli nadzor tudi nad opuščenimi rudarskimi jalovišči, sta Evropski parlament in Svet Evropske unije pripravila osnutek direktive o ravnanju z odpadki, ki nastajajo v rudarstvu (http:// europa.eu.int/comm/environment/waste/ mining/index.htm). Direktiva določa minimalne zahteve, da se v največji možni meri prepreči ali zmanjša škodljive vplive na okolje ali zdravje ljudi, ki jih povzroča ravnanje z odpadki iz rudarskih dejavnosti. O omenjeni direktivi je možno več prebrati v prispevku Kortnika in sod. (2005). Predlog evropske direktive o odpadkih rudarske industrije obravnava odpadke, ki nastanejo pri izkoriščanju mineralnih surovin, tako pri njihovem pridobivanju, predelavi in skladiščenju. Direktiva med drugim predvideva, da upravljavci rudarskih dejavnosti pripravijo ustrezne načrte ravnanja z odpadki za obdelavo, predelavo in odlaganje odpadkov. Odpadke, ki nastajajo pri rudarskih dejavnostih, bo potrebno razvrščati glede na njihovo sestavo iz vidika možnih vplivov na okolje. Tistim, ki vsebujejo velike količine nevarnih snovi (težke kovine, radioaktivne snovi, itd.), pa je potrebno posvetiti posebno pozornost. Še posebej to velja za jalovino nastalo pri fizikalno-kemijskih procesih bogatenja kovinskih mineralnih surovin, ki se hrani na odprtih deponijah ali v bazenih, katerih poškodbe ali porušitve lahko predstavljajo veliko nevarnost za okolje. Ker v Sloveniji ni več aktivnih kovinskih rudnikov, je za nas še posebno zanimiv tisti člen bodoče direktive, ki določa, da bodo morale države članice zagotoviti pripravo in redno posodabljanje inventarja zaprtih in opuščenih objektov z rudarskimi odpadki, ki so nameščeni na njihovem ozemlju in povzročajo resne negativne vplive na okolje ali utegnejo srednjeročno ali kratkoročno postati resna grožnja za zdravje ljudi ali okolje. Inventar bo moral vsebovati osnovne podatke o površini in prostornini odloženih rudarskih odpadkov, fizikalno-kemijsko karakterizacijo odloženih snovi in oceno tveganosti. Takšen inventar, ki bo moral biti dosegljiv javnosti, bo potrebno pripraviti v štirih letih od sprejetja direktive. Direktiva predvideva tudi izmenjavo znanstvenih in tehničnih informacij o načinu izvajanja tega inventarja in opredelitev potrebnih raziskav na njihovem območju ter o razvoju metodologij morebitnih potrebnih sanacij zaprtih jalovišč (http://europa.eu.int/comm/ environment/waste /mining/index.htm). Kovinski rudniki v Sloveniji Slovenija je območje zgodovinske rudarske in metalurške dejavnosti, ki sta trajali več stoletij. Rudo so začeli v večjem obsegu topiti že v srednjem veku. Največ je bilo železarstva, čeprav so rudo zbirali na površini ali kopali v manjših rudnikih. Izkoriščali so tudi velika kovinska rudišča, kot so Idrija, Mežica in Litija. V sredini 19. stoletja sta rudarstvo in topilništvo v Sloveniji doživela razcvet. Poleg že prej omenjenih velikih rudnikov je delovalo tudi veliko manjših. Razen železa so začeli v večjih količinah pridobivati barvne kovine -predvsem svinec, cink, živo srebro, baker in antimon. Na prehodu v 20. stoletje so se obdržali le največji rudniki (Cešmiga, 1959; Budkovič et al., 2003). Ti so večinoma z manjšimi prekinitvami delovali do začetka osemdesetih let prejšnjega stoletja, ko je bila sprejeta odločitev o postopnem zapiranju vseh kovinskih rudnikov in večine premogovnikov v Sloveniji. Sprejeti so bili programi zapiralnih del za vsak rudnik (Bajželj, 2001). Tako so v preteklem desetletju vsi kovinski rudniki v Sloveniji prenehali s pridobivanjem kovin, zapiralna dela v nekaterih rudnikih pa še potekajo. Glede na naravo predelovalnih postopkov so za njimi ostale številne anomalije težkih kovin, katerih razsežnosti raziskujemo. V preteklih letih smo na podlagi raznih virov locirali rudarske in topilniške obrate, ugotovili obdobje njihovega delovanja in ocenili količine pridobljenih kovin (Budkovič et al., 2003). Poleg tega smo naredili nekaj raziskav o vsebnostih težkih kovin v tleh in sedimentih v okolici nekaterih največjih kovinskih rudnikov, katerih povzetek bo predstavljen v nadaljevanju. Na nekaterih drugih lokacijah pa so raziskave še v teku. Idrijsko ozemlje Petstoletna proizvodnja živega srebra v Idriji se odraža v povečanih vsebnostih živega srebra v okolju. V celotni zgodovini rudnika se je okoli 37.500 t živega srebra med procesom pridobivanja izgubilo v okolju (Dizdarević, 2001). V času delovanja topilnice so bile najpomembnejši dejavnik širjenja živega srebra v okolje atmosferske emisije, ki so povzročile povišane vsebnosti živega srebra v tleh na širšem območju Idrije. Na podlagi podatkov raziskave porazdelitve živega srebra v tleh (Gosar & Šajn, 2001; 2003), smo določili ozemlja, kjer vsebnosti živega srebra presegajo zakonsko določene normative (Uradni list, 1996, tabela 1) (slika 1). Z odvzemom 118 vzorcev tal smo zajeli 160 km2 ozemlja Idrije in njene okolice ter ugotovili, da na ozemlju, velikem 112 km2, vsebnosti težkih kovin v tleh presegajo mejne oz. opozorilne vrednosti za tla (Uradni list, 1996). 21 km2 ozemlja je kritično onesnaženega (Sajn & Gosar, 2004). Za obremenitev okolja z živim srebrom na idrijskem so pomembni tudi odvali siromašne rude in predvsem odvali žgalniških ostankov, ki vsebujejo še precej živega srebra. Osnovni vzrok za veliko razširjenost in zapleteno prostorsko razporeditev žgalniških ostankov v Idriji in njeni okolici je v načinu žganja rude v preteklosti in uporabi žgalniških ostankov v gradbene namene v povojnem obdobju (Car, 1998). Do srede 17. stoletja so žgali rudo v glinastih posodah na bližnjih gričih Pront, Pringl, pa tudi na bolj oddaljenih krajih v Cekovniku in Kanomlji, o čemer pričajo številni ostanki razbite lončevine. Več lokacij starih žgalnic je našel I. Mlakar pri geološkem kartiranju idrijske okolice, nekaj pa so jih našli tudi kasneje (Car, 1998). Prva trajneje locirana žgalnica v mestu je bila na Lenštatu. Leta 1652 so začeli graditi žgalnico na Prejnuti, ki je delovala vse do 19. stoletja. Tabela I. Mejne, opozorilne in kritične vrednosti težkih kovin v tleh (Ur. list RS 68/96). Table I. Limit, warning and critical emission values of the contents of elements in soils (Ur. list RS 68/96). kovina mejna opozorilna kritična vrednost vrednost vrednost metal limit warning critical value value value (mg/kg) (mg/kg) (mg/kg) As 20 30 55 Cd 1 2 12 Co 20 50 240 Cr 100 150 380 Cu 60 100 300 Hg 0.8 2 10 Mo 10 40 200 Ni 50 70 210 Pb 85 100 530 Zn 200 300 720 Po letu 1868 so postopoma zgradili novo žgalnico na Brusovšu, na Prejnuti pa so žganje opustili. Od takrat pa vse do leta 1977 so večino žgalniških ostankov neposredno vsipavali v Idrijco, ki je material ob visokih vodah odnašala v Sočo in ta naprej v Jadransko morje. Tako so v spodnjem toku Idrijce nastali obsežni rečni nanosi z visokimi vsebnostmi živega srebra (Gosar et al., 1997; Biester et al., 2000), ki so in bodo vir z živim srebrom obremenjenega sedimenta tudi v prihodnosti. Zato vsebnosti živega srebra v aktivnih rečnih sedimentih Idrijce in Soče v zadnjih nekaj letih ne vpadajo. Določali smo jih julija leta 1991, 1995 in 2001 (Gosar, 2003). V zgornjem toku Idrijce vsebuje sediment okoli 2 mg/kg živega srebra. V območju med Idrijo in Spodnjo Idrijo koncentracije zelo nihajo in so ekstremno visoke (od 171 do 4.121, povprečno 735 mg/kg). Od Spodnje Idrije nizvodno vsebuje sediment nekoliko manj živega srebra (od 3,2 do 878, povprečno 218 mg/kg). V soških sedimenti vsebnosti živega srebra nekoliko manj nihajo in so zelo razredčene (od 18 do 183, povprečno 67 mg/kg). Se vedno pa so to visoke vsebnosti. Tako Soča letno prinese velike količine živega srebra v Tržaški zaliv, po oceni Sirce in sod. (1999) kar okoli 1.500 kg na leto. Slika I. Območje kritično onesnaženih tal na idrijskem ozemlju s težkimi kovinami, pretežno s živim srebrom (Ur. list RS 68/96). Figure I. Spatial distribution of critically polluted soil in Idrija area with heavy elements, mainly with mercury (Ur. list RS 68/96). Mežiško ozemlje V Mežiški dolini smo preučevali porazdelitev vsebnosti težkih kovin v tleh, ki so Prvi pisni viri o izkoriščanju svinčeve rude posledica 300 letnega rudarjenja in predelave; na območju Mežice so iz leta 1665. V rude. V letu 2000 smo na območju 101 km2 naslednjih stoletjih so rudarili v predgorju ozemlja, ki se vleče od Čme pa d° Raven na in na pobočjih Pece. Rudnik se je začel Koroškem in zajema skoraj celotno dolino močno razvijati v 20. stoletju in še posebno reke Meže v p—su širokem 6 km, odvzeli 115 po drugi svetovni vojni. V celotnem obdobju vzorcev tal (Sai^ 2°°2). N— raziskanem rudarjenja so pridobili okoli 19 milijonov ton ozemlju živi okrog 23.000 pretw^rey kar svinčeve in cinkove rude. V drugi polovici predstavlja skoraj 907 celotnega 20. stoletja so pridobivali tudi majhne koli- prebivalstva štirih koroških Лйп, ki jih je čine molibdena. raziskava zajela. Slika 2. Območje kritično onesnaženih tal v dolini reke Meže s težkimi kovinami, pretežno s svincem (Ur. list RS 68/96). Figure 2. Spatial distribution of critically polluted soil in Meža valley with heavy elements, mainly with lead (Ur. list RS 68/96). Ugotovili smo, da je večina raziskanega ozemlja obremenjena s težkimi kovinami. Na 74 km2 površine vsebnosti težkih kovin presežejo zakonsko določeno mejno oz. opozorilno vrednost (Uradni list, 1996). Kritično je onesnaženih 24,4 km2 ozemlja (Šajn & Gosar, 2004). To zajema celoten zgornji del Mežiške doline, predvsem okolico Crne na Koroškem in Žerjav. Pas kritično onesnaženih tal se nadalje s prekinitvami vleče vzdolž reke Meže vse do Raven na Koroškem (slika 2). Na kritično onesnaženem območju Mežiške doline izstopajo zlasti visoke vsebnosti svinca (Pb) in kadmija (Cd), povišane pa so tudi vsebnosti cinka, molibdena in arzena. Povprečna vsebnost Pb znaša 878 mg/kg (216 - 27.122 mg/kg) in preseže slovensko povprečje (Šajn, 2003) za več kot 20-krat. Povprečje Cd je 6,2 mg/kg (1,4 - 71 mg/kg) ter preseže slovensko povprečje za skoraj 12-krat. Glavni vzrok onesnaženosti tal sta rudarjenje na območju Mežice in predelava svinčeve rude na Poleni in kasneje v Žerjavu, ki je potekala skoraj 300 let. Ne smemo pa zanemariti vpliva železarske industrije, ki se je prvotno razvila na območju Prevalj in kasneje na Ravnah na Koroškem. Vplivi prometa in drobnih kurišč so na območju Mežiške doline drugotnega pomena. Zaključek Lahko zaključimo, da predstavljajo posledice rudarjenja veliko obremenitev okolja. Na območju Slovenije so dosedanje študije pokazale, da je rudarjenje in z njim povezana predelava rude pustila velike posledice predvsem na območju Idrije in Mežice. Problematiki, vezani na tovrstne vplive, bomo v prihodnosti posvetili posebno pozornost. Literatura Agricola, G. (1SS6): De Re Metallica. Dover Publications, (1986 republication of 1912 edition), 638 p., New York. Bajželj, U. (2001): Okolju prijazno zapiranje rudnikov - slovenske izkušnje. RMZ-mater. geoenviron.; Vol. 48, No. 2, pp. 261-280. Biester, H., Gosar, M., Covelli, S. (2000): Mercury speciation in sediments affected by dumped mining residues in the drainage area of the Idrija mercury mine, Slovenia. Environ. Sci. Technol.; Vol. 34, No.16, pp. 3330-3336. Budkovič, Т., Sajn, Я., Gosar, M. (2003): Vpliv delujočih in opuščenih rudnikov kovin in topilniških obratov na okolje v Sloveniji. Geologija-, Vol. 46, No.1, pp. 13S-140. Car, J. (1998): Mineralized rocks and ore residues in the Idrija region. In: Idrija as a natural and anthropogenic laboratory, Mercury as a global pollutant, Proceedings, pp.10-1S. Cesmiga, I. (19S9): Rudarstvo LR Slovenije. Nova proizvodnja, 267 str., Ljubljana. Dizdarević, Т. (2001): The influence of mercury production in Idrija mine on the environment in the Idrija region and over a broad area. RMZ-mater. geoenviron.-Vol. 48, pp. S6-64. Gosar, M., Sajn, R. (2001): Živo srebro v tleh in podstrešnem prahu v Idriji in okolici kot posledica orudenja in rudarjenja. Geologija; Vol. 44, No. 1, pp. 137-1S9. Gosar, M., Sajn, R. (2003): Geochemical soil and attic dust survey in Idrija, Slovenia. Journal de Physique; Vol. 107, pp. S61-S64. Gosar, M. (2003): Mercury distribution in the Idrijca river sediments in 1991, 199S and 2001. V: 6th International Symposium on Environmental Geochemistry: final programme and book of abstracts, 213 p. Gosar, M., Pirc, S., Bidovec, M. 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(2004): Pregled nekaterih onesnaženih lokacij zaradi nekdanjega rudarjenja in metalurških dejavnosti v Sloveniji. Geologija; Vol. 47, No. 2, pp. 249-2S8. Sirca, A, Horvat, M., Rajar, R., Covelli, S., Žagar, D., Faganeli, J. (1999): Estimation of mercury mass balance in the Gulf of Trieste. Acta Adriat. -Vol. 40, No. 2, pp. 7S-8S. Tržan, B. (1989): Pohorje - prazgodovinski rudarski revir. Časopis za zgodovino in narodopisje; Vol. 2, pp. 238-260. Uradni list RS (1996): Uredba o mejnih, opozorilnih in kritičnih imisijskih vrednostih nevarnih snovi v tleh. Uradni list; Vol. 68, pp. S773-S774. Litofaciesna in konodontna conacija spodnjetriasnih plasti severozahodnega dela Zunanjih Dinaridov (Gorski Kotar, Hrvaška) Lithofacies and Conodont Zonation of Lower Triassic in Northwestern External Dinarides (Gorski Kotar, Croatia) Dunja Aljinović1, Tea Kolar-Jurkovšek2, Bogdan Jurkovšek2 1 Rudarsko-geološki naftni fakultet Sveučilišta u Zagrebu, Pierottijeva 6, HR-10000 Zagreb, Hrvatska; E-mail: daljin@rgn.hr 2 Geološki zavod Slovenije, Dimičeva 14, SI-1000 Ljubljana, Slovenija; E-mail: tea.kolar@geo-zs.si, bogdan.jurkovsek@geo-zs.si Received: July 29, 200S Accepted: October 28, 200S Izvleček: Raziskani spodnjetriasni sedimentni kompleks Gorskega Kotarja predstavlja del Zunanjih Dinaridov. Raziskano je pet profilov, v katerih je bilo mogoče razlikovati več litofaciesov. Prevladujoče karbonatne litofaciese, ki karakterizirajo začetek spodnjetriasne sedimentacije, zaradi vse večjega vpliva terigenega materiala v mlajših delih triasa postopno zamenjajo pretežno klastični sedimenti. Različni faciesi so interpretirani kot sedimenti ooidnih sipin omejenega robnega šelfa, ki se vsled transgresije transformira v prostrano epikontinentalno morje. Natančni podatki kronostratigrafskega položaja raziskanih sedimentov znotraj spodnjetriasnega sedimentnega kompleksa doslej niso bili znani. Zato so bile izvedene obširne dodatne paleontološke raziskave s ciljem definiranja konodontnih con, s katerimi bi lahko podrobneje opredelili starost faciesov raziskanih profilov. Ugotovljene so bile cone parvus-isarcicella in obliqua ter podcona Platyvillosus. Konodontna conacija in litofaciesna definicija prispevata k boljšemu definiranju širšega spodnjetriasnega sedimentacijskega prostora in omogočata korelacijo z drugimi deli zahodne Tetide. Abstract: The investigated area of the Gorski Kotar region (Croatia) is located in the External Dinarides. In the Lower Triassic sedimentary complex several facies were differentiated and interpreted as deposits of a restricted ooid rimmed shelf that transforms to a wide epicontinental sea due to continuous transgression. Predominantly carbonate sedimentation that characterized the beginning of deposition had changed and the increased terrigenuous influx was noticed in the later deposited sediments. Five sections have been sedimentologicaly and palaeontologicaly investigated. The paper aims to present the chronostratigraphic position of the investigated sections based on conodont fauna. The biostratigraphical data allow recognition of the parvus-isarcicella zones, obliqua Zone and Platyvillosus Subzone. The conodont zonation and lithofacial definition contribute to the definition of the Lower Triassic depositional realm of the External Dinarides and prove the correlative elements for comparison with some other parts of the Western Tethys. Ključne besede: spodnji trias, plitvovodni morski litofacies, konodonti, Zunanji Dinaridi, Hrvaška. Key words: Lower Triassic, Shallow marine lithofacies, Conodonts, External Dinarides, Croatia. Uvod Spodnjetriasne plasti Gorskega Kotarja v severozahodnem delu Zunanjih Dinaridov (Hrvaška) so bile dolgo časa predmet različnih nasprotujočih razlag. Na Osnovni geološki karti SFRJ 1:100.000, list Delnice niso izdvojene, temveč so uvrščene v podoben litološki kompleks zgornjetriasnih sedimentov (Savić & Dozet, 1984, 1985). Šćavničar in Šušnjara (1966, 1967), Đurđanović (1967) in Babić (1968) so poleg litoloških značilnosti pri izdvajanju in definiranju spodnjetriasnih plasti upoštevali tudi najdbe foraminifere Meandrospira iulia in značilne makrofavne v osrednjem delu Gorskega Kotarja. Babić (1968) iz plitvomorskih sedimentov vzhodnega dela Gorskega Kotarja navaja vrste Pseudo-monotis (Claraia) cf. orbicularis (Richtofen), Myacites (Anodontophora) fassaensis (Wissmann), Myacites (Anodontophora) cf. canalensis (Catullo), Pseudomonotis (Claraia) cf. inaequicostata (Benecke). Natančnejše litološke raziskave (Šćavničar, 1973) so dale dodatne osnove za razlikovanje spodnje- in zgornjetriasnih plasti, ki temelje na bistvenih razlikah v sestavi težke mineralne frakcije (prisotnost ali odsotnost filosilikatov). Najdbe mikro- in makrofosilov so bili doslej edini kronostratigrafski podatki, na osnovi katerih pa ni bilo mogoče natančneje razčleniti plasti spodnjega triasa. Čeprav sta Palinkaš in S remac (1987) pisala o kontinuirani sedimentaciji iz perma v spodnji trias, do danes P-T meja ni palontološko dokazana. Na področju Gorskega Kotarja je prav tako težko privzeti razčlenitev na starejše "seiske" in mlajše "campilske" plasti kot je mogoče ponekod v drugih delih Zunanjih Dinaridov, n.pr. na območju Knina in Muća v Dalmaciji (Šćavničar in Šušnjara, 1983; Aljinović, 1995; Jelaska et al., 2003), zato je raziskavam spodnjetriasnega kompleksa v Gorskem Kotarju definitivno manjkala kronostratigrafska komponenta. Spodnjetriasni konodonti Hrvaške so bili doslej poznani le iz dveh profilov Dalmacije. V profilu Muć, ki je bil predlagan za tipičen zgornjeskitijski profil v Evropi, so bile opravljene številne geološke raziskave (Herak et al., 1983, Šćavničar in Šušnjara, 1983; Šćavničar et al., 1983; Jelaska et al., 2003). Litostratigrafski profil Muća so Herak et al., (1983) v grobem razdelili v več neformalnih enot (od spodaj navzgor): bazalni karbonatni kompleks ter člene A, B in C. Apneno-laporni kompleks člena B vsebuje pogoste fosile, med drugimi tudi konodonte Ellisonia triassica Müller, Hadrodontina anceps Staesche, Neospatho-dus triangularis (Bender) in Pachycladina tricuspidata Staesche. Na osnovi fosilne vsebine so avtorji ta člen primerjali s členom Val Badia v Dolomitih, vendar dodajajo, da ima verjetno ta enota na Muću (člen B) večji stratigrafski razpon. Dolomitni kompleks člena C je na osnovi litostratigrafskih značilnosti anizijske starosti. Tudi vzhodneje od Muća v profilu ob cesti na Zelovo (planina Svilaja) izdanja velik del spodnjetriasnega zaporedja, vendar sedimenti P-T intervala niso razkriti (Jelaska et al., 2003). Iz najnižjega oolitnega dela profila je bila izdvojena konodontna združba, ki pripada coni obliqua. V njej prevladuje element Pachycladina obliqua Staesche v združbi z redkejšimi predstavniki Hadrodontina sp. (tip biserialis) in Parachirognathus ethingtoni Clark. Novejše sedimentološke raziskave v Gorskem Kotarju (Aljinović, 1997; Aljinović & Tišljar, 2000) so dale rezultate za detajlno interpretacijo litofaciesov, medtem ko podatki o starosti plasti manjkajo, zato je bila korelacija litofaciesov različnih lokalitet negotova, prav tako pa tudi definiranje sedimentacijskega prostora. Sledile so kompleksne raziskave, katerih cilj je kronostratigrafsko definiranje izdvojenih litofaciesov na osnovi konodontnih analiz. Ti ponujajo natančne kronostratigrafske podatke o sedimentih, v katerih drugih fosilov ni ali pa njihova slaba ohranjenost ne omogoča natančne določitve. Vsi raziskani spodnjetriasni profili so dopolnjeni z rezultati mikropaleontoloških analiz. Konodontni elementi Hindeodus parvus, Platyvillosus costatus in PI. hamadai so tokrat prvič najdeni v Zunanjih Dinaridih. Sestav konodontnih združb, kakor tudi natančna litofacialna razčlenitev spodnjetriasnih plasti predstavljajo prispevek k definiranju sedimentacijskega prostora Zunanjih Dinaridov. Na osnovi litologije in konodontne conacije je omogočena primerjava z drugimi prostori Zunanjih Dinaridov, kakor tudi sosednjih prostorov zahodne Tetide (Notranji Dinaridi: Jadarska cona in Južne Alpe: Dolomiti, Karnijske Alpe). Geološke razmere Hribovito območje Gorskega Kotarja se nahaja v severozahodnem delu Zunanjih Dinaridov. Raziskani profili ležijo na prostoru globokih prelomov (Prelogović et al., 2004), širše območje pa tektonsko označujejo narivne strukture (Herak, 1980). Zaradi intenzivne tektonike so izdanki spodnjetriasnih sedimentov redki in prostorsko omejeni (slika 1A), korelacija med posameznimi profili pa razmeroma težka in negotova. Ker so dobri krono-stratigrafski markerji redki, interpetacija sedimentacijskega okolja sloni v glavnem le na interpretaciji pogojev nastanka prisotnih litofaciesov in na predpostavljenem generalnem vertikalnem zaporedju plasti. Na osnovi podatkov dosedanjih raziskav in glavnih značilnosti sedimentov je spodnjetriasni sedimentacijski prostor v generalnem smislu interpretiran kot področje stabilnega kontinentalnega šelfa. Na permskih sedimentih transgresivno ležijo karbonatni in mešani karbonatno-siliciklastični sedimenti spodnjega triasa, ki so raziskani v petih lokalitetah. Raziskani profili: litofacies in konodontna favna Spodnjetriasni sedimenti so raziskani v petih lokalitetah: H-Homer, SB-Skolski Brijeg, ZC-Zelin Crnoluški, KP-Kramarčin Potok in D-Dobra (slika 1B,D,F). Opazne so litofacialne razlike osrednjega dela Gorskega Kotarja (okolica Lokev in Mrzle Vodice) in robnih delov območja - mejno območje s Slovenijo v okolici Cabra in Vrbovsko. Pričetek sedimentacije spodnjega triasa označuje dominantna karbonatna sedi-mentacija z močnejšim terigenim vplivom in povečano vsebnostjo siliciklastične komponente v mlajših nivojih. Litofacialna analiza je dopolnjena z raziskavo kono-dontov v vseh petih profilih. Od skupno petindvajset preiskanih vzorcev jih je trinajst vsebovalo konodontne elemente, vendar je njihova vsebnost večinoma nizka ali zelo nizka. Izjemo KRAMARČIN POTOK ZELIN CRNOLUŠKI Državna me|a State border ŠKOLSKI BRIJEG KP-6A Nadaljnje napredovanje transgresije и и E EPIKDNTINENTALNO MORJE EPICONTINENTAL SEA LAGUNA GLADINA Stabilni MORJA robni Self dotok terlgenegc detritusa dolomikriti predstavljajo elementi konodontnega aparata Pachycladina obliqua, ki so večinoma nepopolno ohranjeni. Barvni indeks kondo-notov (CAI - Color Alteration Index) je višji od 5, kar kaže na temperature po sedimentaciji v območju od 300-480 °C in 490-720 °C (Epstein et al., 1977; Reiebian et al., 1987). Profila Homer in Školski Brijeg Dominantno karbonatni razvoj spodnjega triasa je najbolje viden v osrednjem delu Gorskega Kotarja v starih kopih barita, v lokalitetah Homer, zahodno od Lokev in v lokaliteti Školski Brijeg blizu Mrzle Vodice (slika 1B). V obeh lokalitetah na permskih Slika I. A) Lokacija profilov in geološka karta raziskanega območja (prirejeno po Savić in Dozet, 1984 in Bukovac et. al., (1983)); В) Zaporedje sedimentov v profilu Školski Brijeg; C) sedimentacijski model spodnjetriasnih plasti profila Školski Brijeg: Facies ooidnih sipin (F-1) predstavlja bariero odprto proti morju oziroma z laguno v zaledju (F-2). D) Zaporedje sedimentov v profilu Zelin Crnoluški; E) Sedimentacijski model profila Zelin Crnoluški: Hitra transgresija je povzročila potopitev ooidne bariere in nastanek nove obale z vplivom odprtega morja, ki se manifestira v nizu značilnih nevihtnih sekvenc "shoreface-offshore" faciesa (F-3); CZ -položaj profila Zelin Crnoluški, ŠB - položaj profila Školski Brijeg; F) Zaporedje sedimentov v profilu Kramarčin Potok; G) Sedimentacijski model profila Kramarčin Potok: Napredovanje transgresije je povzročilo nastanek prostranega epikontinentalnega morja, ki se odraža v robnem severo-zahodnem in vzhodnem delu Gorskega Kotarja. Vpliv kopna v prostranih plitvinah je viden v povečani količini peščenega (siliciklastičnega) materiala. Sedimenti so interpretirani kot ooidno-peščeni facies F-4, facies zatišnega zaliva F-S in facies intraformacijskih konglomeratov F-6. DO položaj profila Dobra, KP položaj profila Kramarčin Potok. Legenda: 1-dolomitizirani ooidni grainstone, 2-dolomit, 3-peščeni dolomit in karbonatni peščenjak, 4-navzkrižna slojevitost, S-horizontalna laminacija, 6-valovne sipinice, 7-tokovna laminacija, 8-intraklastični detritus, 9-muljni klasti, 10-žlebaste erozijske teksture, 11-bioturbacija, 12-kopasta navzkrižna laminacija ("hum-mocky-cross lamination"), 13-vzorčevani interval z oznako vzorcev, 14-baritne žile, 1S-sekvence z zmanjševanjem zrn, 16-predpostavljene sekvence z zmanjševanjem zrn, 17-delno pokrit interval, 18-ooidni grainstone, 19-dolomit, 20-peščenjak, 21-laminiran dolomikrit in siltit, 22-rdeč siltit in glinovec, 23-intraformacijski konglomerat, 24- nepravilni vložki glinovca. Velikost zrn: a-glina, b-silt, c-zelo drobnozrnat pesek, d-drobnozrnat pesek, e-srednjezrnat pesek, f-debelozrnat pesek, g-psefit. Figure I. A) Location of sections and geologic map of the investigated area (modified after Savić & Dozet, 1984); В) Školski Brijeg section located in the central part of Gorski Kotar; C) The model of sedimentation proposed for Školski Brijeg section: Shallow shelf with the subtidal ooid bars as a barrier (F-1) and the land laying lagoon (F-2); D) Zelin Crnoluški section located between central and marginal part of the Gorski Kotar region; E) The model of sedimentation proposed for Zelin Crnoluški section: due to rapid transgression the bars drowned and a new coast formed opened to the influences of waves and storms which can be seen in vertical succeeded storm sequences - forming shoreface-offshore facies F-3; proposed position of the sections ŠB -Školski Brijeg and ZC - Zelin Crnoluški; F) Kramarčin Potok section located in the marginal part of Gorski Kotar; G) The model of sedimentation proposed for Kramarčin Potok section: due to the advanced transgression the wide epicontinental sea is established with the deposition in ooid-sandy shoals (F-4) and restricted muddy bays (F-S); proposed position of the sections KP - Kramarčin Potok and DO - Dobra; Legend: 1-dolomitised oolitic grainstone, 2-dolomite, 3-sandy dolomites and calcarenaceous sandstones, 4-cross bedding, S-horizontal lamination, 6-wave ripples, 7-current ripple cross-lamination, 8-intraclastic detritus, 9-mud clasts, 10-gutter cast structure, 11-bioturbation, 12-hummocky cross-lamination, 13-sampled interval, 14-barite veins, 1S-fining upward sequences, 16-uncertain fining upward sequences, 17-partly covered interval, 18-ooid grainstone, 19-dolomite, 20-sandstone, 21-laminated dolomicrite and siltite, 22-red siltite and shale, 23-flat-pebble conglomerate, 24-shale partings. Grain size: a-shale, b-silt, c-very fine sand, d-fine sand, e-medium sand, f-coarse sand, g-pebbles. Slika 2. Zaporedje sedimentov v profilu Školski Brijeg; Hindeodus parvus v spodnjem delu profila (facies F-I) dokazuje najnižji del spodnjega triasa. Figure 2. Školski Brijeg section where in facies F-I Hindeodus parvus has been found (lower part of the section). Slika 3. Mikrofotografija dolomitiziranega ooidnega grainstona z epigenetsko baritno mineralizacijo v medzrnskem prostoru. Figure 3. Photomicrograph of dolomitised oolitic grainstone with relict of ooid detritus and epigenetic barite mineralization in intergranular space (white). Slika 4. Hindeodusparvus (Kozur & Pjatakova, 1976), coni parvus-isarcica, Školski Brijeg, vzorec ŠB-1 (GeoZS 3636). Figure 4. Hindeodus parvus (Kozur & Pjatakova, 1976), parvus-isarcica zones, Školski Brijeg, sample ŠB-1 (GeoZS 3636). sedimentih transgresijsko ležijo ooidni apnenci, ki so izdvojeni kot facies ooidnih sipin (F-I) (slika 2). Prevladujoča značilnost tega faciesa je navzkrižna slojevitost apnenca in baritno-piritna mineralizacija (slika 3). Ooidne sipine faciesa F-I so ustvarjale tipično morfologijo "bariernih sipin", nameščenih med odprtim morjem in obalo (slika 1С). Za njimi, v smeri proti obali se je v lagunah sedimentiral karbonatni mulj, z občasnim dotokom terigenega siliciklasti-čnega detritusa. Ti sedimenti so izdvojeni kot lagunski facies (F-2), ki ga označujejo tankoplastovit dolomikrit, peščen dolomikrit in karbonatni peščenjak. Za konodontne raziskave smo analizirali pet vzorcev iz profila Homer, vendar sta le dva pozitivna (H-1, H-2). Najdeni konodontni elementi so slabo ohranjeni in ne omogočajo določitve. Iz profila Školski Brijeg smo preiskali štiri vzorce, od katerih dva (ŠB-1, ŠB-2) vsebujeta po en element rodu Hindeodus. V vzorcu ŠB-1 je določena vrsta Hindeodus parvus (Kozur & Pjatakova) (slika 4). Profil Zelin Crnoluški Razvoj spodnjetriasnih karbonatnih kamnin tega profila se razlikuj e od razvoj ev v profilih Homer in Školski Brijeg. V krovnini faciesa ooidnih sipin F-1 ni lagunskega faciesa F-2, marveč so sedimenti "shoreface-offshore" faciesa F-3 (slika 1D). Zanj so značilni mikro- do makrokristalasti dolomiti in peščeni dolomiti z redkimi vložki siltita in so organizirani v "fining- upward" sekvencah (slika ID) z značilnostmi nevihtne sedimentacije. Sedimentacija "shoreface-offshore" faciesa je potekala v močno razburkani coni blizu obale odprtega šelfa (slika IE). Iz profila Zelin Crnoluški smo pregledali le vzorec iz njegovega spodnjega dela (ZC-I). Ta vsebuje maloštevilne konodontne elemente Hadrodontina sp., Pachycladina obliqua Staesche in Parachirognathus sp. Tabela I. Shematski prikaz primerjave spodnjetriasnih standardnih konodontnih con po Sweet et al., 1971 s konodontno conacijo Južnih Alp (po Perm, 1991 in Perri & Farabegoli, 2003). Table I. Schematic presentation of standard conodont biozones for the Lower Triassic (after Sweet et al., 1971) correlated with conodont zonation of the Southern Alps, Italy (after Perri, 1991 and Perri & Farabegoli, 2003). SWEET et al. 1971 ш сэ Timorensis Č со z Jubata < X Neosp. n. sp. G. k со Platyvillosus Milleri SMITHIAN STAGE Conservativus Parachirognathus Furnishius Pakistanensis lENERIAN STAGE Crlstagalll Dlenerl о Kummeli i z го < Carlnata Ш X E O O £ o! i — Typicalis — PERRI 1991 PERRI & FARABEGOLI 2003 Triangularis Obliqua Anceps Aequabilis -rf sarcica aeschei - obata Praeparvus U L Profil Kramarčin Potok in profil Dobra V severozahodnem (Čabar) in vzhodnem delu Gorskega Kotarja (Vrbovsko) niso najdeni karbonatni faciesi F-I, F-2 in F-3, kar lahko razložimo s paleogeomorfološkimi razmerami tega področja, to je s postopnim širjenjem morskega sedimentacijskega prostora in napredovanjem transgresije. Bližina in vpliv kopna se izraža v povečanem donosu siliciklastičnega, pretežno peščenega materiala in v visoki vsebnosti rdečega železovega pigmenta. V vertikalnem zaporedju se izmenjujejo ooidno-peščeni facies F-4 (dolomitizirani ooidni grainstone ali peščenjaki), facies plitvin z muljastimi sedimenti (facies zatišnega zaliva) F-S in facies intraformacijskih konglomeratov F-6. Menjavanje teh faciesov je značilno za "seiske" plasti. Profil Kramarčin potok V profilu se izmenjujejo sedimenti faciesa F-4 in F-5, ki so organizirani v sekvencah s zmanjšavanjem zrn (slika IF). Od teh sekvenc vsaka prične z ooidnim apnencem in/ali rdečim peščenjakom (F-4) in konča z laminiranimi dolomiti in muljastimi sedimenti zatišnih zalivov (F-5) (slika IF). Za sedimentacijski prostor sta značilna obilica terigenega materiala in njegovo mešanje z intrabazenskim (ooidnim) detritusom. Prisotnost rdečega železovega pigmenta kaže na dobro prezračno plitvomorsko okolje (slika IG). Facies F-5 označuje menjavanje zelo tankih plasti in lamin dolomikrita in silta. Usedanje delcev različne zrnavosti kaže na različno energijo tokov ali nakazuje na obstoj permskih plimskih tokov. Iz profila Kramarčin Potok smo mikro-paleontološko analizirali skupno devet vzorcev. Določeni so naslednji elementi: Pachycladina obliqua Staesche, Platyvillo-sus costatus Staesche, P hamadai Koike, ? Parachirognathus sp., Hadrodontina sp. (tip biserialis), ? Ellisonia sp. in Foliella gardenae (Staesche). Profil Dobra Značilnosti profila Dobra je prisotnost plasti konglomerata s muljnimi klasti ki so izdvojeni kot facies intraformacijskih konglomeratov (F-6). Facies F-6 se nepravilno izmenjuje s faciesoma F-4 in F-5, podobno kot v profilu Kramarčin Potok. Pojavi nezaobljenih fragmentov (razlom-ljenih muljnih lamin ali plasti) in izsušitvenih razpok kažejo na razmeroma plitvo okolje ter na akumulacijo razlomljenih fragmentov in situ. Vsi vzorci (skupno pet) za konodontne analize so bili vzeti iz faciesa F-4. Združbo sestavljajo odlomki konodontnih elementov Hadrodontina sp., ? Ellisonia sp. in Pachycladina obliqua Staesche. Komentar k spodnjetriasnim konodontom Stratigrafsko pomembne spodnjetriasne vrste pripadajo skupini Hindeodus-Isarcicella. Prvi pojav (FAD-first appearance datum) vrste Hindeodus parvus je bil izbran za definiranje spodnje meje triasnega sistema, kar je potrdila tudi Mednarodna komisija za stratigrafijo in stratotip za permsko-triasno mejo odobrila profil D v Meishanu, Kitajska (Yin, 1993; Yin et al., 1996; 2001). Hindeodus parvus je lahko določljiva vrsta z veliko geografsko razširjenostjo in ima veliko facialno toleranco in je hkrati prva globalno razširjena vrsta, ki se pojavi tik nad minimumom favnistične diverzitete, ki jo nakazuje minimum 513C (Kozur, 1996). Različne spodnjetriasne konodontne biofaciese v odvisnosti od litofaciesa, so najprej prepoznali v Severni Ameriki (Solien, 1979; Clark & Carr, 1984; Paull, 1982; Paull & Paull, 1994). Konodontne conacije spodnjega triasa so slonele na vrstah iz različnih biofaciesov. Šele v letu 1998 sta Orchard in Krystyn uvedla dvojne konodontne cone za najnižji del triasa Spitija (Himalaja), v kateri je vpeljana conacija na osnovi rodu Neogondolella in inter-kalibrirana z vzporedno conacijo na osnovi skupine Hindeodus-Isarcicella. Ločeni conaciji je omogočilo prepoznavanje dveh konodontnih biofaciesov: prevladujoči pelagični biofacies z Neogondolella in manj zastopan biofacies s skupino Hindeodus-Isarcicella. Vpliv faciesa na sestav P-T konodontnih združb so temeljito proučevali Orchard (1996), Kozur (1996) in Orchard & Krystyn (1998). Ugotovljena je različna pogostnost rodov Hindeodus in Neogondolella: gondolellide so bolj pogoste v globljih in /ali hladnejših morskih okoljih, medtem ko je Hindeodus uspeval bližje obali, v plitvejših in/ali toplejših območjih. Kozur (1996) navaja izjemno visoko ekološko toleranco skupine Hindeodus typicalis, ki presega toleranco ostalih konodontov, saj se pojavljajo v številnih plitvovodnih sedi-mentih in so zato najbolj primerni za korelacijo. Prvo popolnejšo konodontno conacijo za spodnji trias je uvedel Sweet (1970), ki je bila razdeljena na 9 konodontnih biocon. Na Simpoziju za konodontno biostratigrafijo so predlagali razdelitev celotnega triasnega sistema v 22 biocon, od tega je bilo 13 biocon v spodnjem triasu in so slonele na podatkih iz Pakistana in zahodnega dela ZDA (Sweet et al. 1971). Zgornjo mejo vsake cone označuje prvi pojav vodilne konodontne vrste za naslednjo biocono. Zaradi povečanega poznavanja biostratigrafie v različnih delih sveta in uvedbo številnih novih vrst ter hkratno dopolnjeno ali popravljeno stratigrafsko in geografsko pojavljanje starejših vrst je botrovalo bolj natančnim biostratigrafskim shemam. Pri primerjavah je potrebno upoštevati razlike v taksonomiji (npr.: H. minutus so številni avtorji vsaj deloma vključili v sinonimiko vrste H. praeparvus), kakor tudi na ostale razlike, na katere je opozoril že Matsuda (1985), predvsem prvi pojav posamezne vrste in sestav združb v različnih območjih/ provincah. Tabela 1 je shematski prikaz primerjave standardnih konodontnih biocon spodnjega triasa po Sweetu et al. (1971) s konodontno conacijo Južnih Alp (Perri, 1991; Perri & Farabegoli, 2003). Natančna razdelitev najnižjega dela spodnjega triasa Južnih Alp je mogoča zaradi srednje do hitre sedimentacije (medium - high sedimentation rate) P-T intervala (Perri & Farabegoli, 2003). Zaključki Na prostoru Gorskega Kotarja smo raziskali pet profilov: Homer, Školski Brijeg, Zelin Crnoluški, Kramarčin Potok in Dobra. Spodnjetriasni sedimentni kompleks Gorskega Kotarja se razlikuje v lateralni in vertikalni porazdelitvi faciesa. V centralnem delu prevladuje sedimentacija stabilnega robnega šelfa ("stable rimmed shelf") in zanj značilni plitvovodni karbonatni faciesi. Bazalni interval ooidnega apnenca z navzkrižno plastovitostjo in debelino ca IO m (Homer, Školski Brijeg) je interpretiran kot ooidna sipina, medtem ko na njem ležijo predvsem tankoploščasti ali laminirani, sivi dolomikriti, peščeni dolomiti ali karbonatni peščenjaki, ki so verjetno bili odloženi v laguni, (slika 1С). Ooidni apnenec verjetno predstavlja bariero odprto proti morju oziroma v laguno v zaledju. Zaradi posledic plime in oseke so nastajale ooidne sipine. Ooidni grainstone je bil kasneje dolo-mitiziran, medtem ko lagunski facies odraža zgodnjediagenetske procese. V profilu Školski Brijeg je določena konodontna vrsta Hindeodusparvus. Ta vrsta je pomembna za določitev P-T intervala in njen prvi pojav (FAD - first appearance datum) dokazuje spodnjo mejo triasnega sistema (Yin et al., 2OO1). Hitra transgresija je povzročila potopitev ooidne bariere in nastanek nove obale, ki jo predstavljajo dolomiti in peščeni dolomiti v tipičnem "shoreface-offshore" faciesu (Zelin Crnoluški) (slika 1E). Nadaljnje napredovanje transgresije je povzročilo nastanek prostranega epikonti-nentalnega morja. To je razvidno v sedi-mentih profilov Kramarčin Potok in Dobra (zahodni in vzhodni del Gorskega Kotarja). Vpliv kopna v prostranih plitvinah je viden v povečani količini peščenega (silici-klastičnega) materiala z bistveno večjim deležem rdečega železovega pigmenta, ki kaže na dobro prezračeno okolje nastanka. Rdeči siliciklastični sedimenti teh dveh profilov odgovarjajo tipičnim "seiskim plastem". Konodontna favna treh profilov, Zelin Crnoluški, Kramarčin Potok in Dobra, označuje prisotnost vrste Pachycladina obliqua v združbi z nekaterimi značilnimi spodnjetriasnimi rodovi (Ellisonia, Hadrodontina, ? Parachirognathus in Platyvillosus). P. obliqua je pomemben biostratigrafski element za lokalno konodontno conacijo, podobno kot drugod v zahodni Tetidi. Konodontne združbe iz petih raziskanih lokalitet Gorskega Kotarja označuje prisotnost rodu Hindeodus v najstarejših plasteh, v mlajših plasteh pa se večinoma pojavlja združba Pachycladina - Hadrodontina ter ponekod tudi Ellisonia. Redki predstavniki rodov Foliella in Platyvillosus se pojavljajo v dveh nivojih. Za vse najdene konodontne rodove menimo, da kažejo na plitvovodno okolje, le Hindeodus parvus je ubikvitarna vrsta, saj je navzoča v plitvih in bazenskih okoljih. Na osnovi konodontne združbe je bilo mogoče izdvojiti naslednje cone in podcono (od najstarejše k najmlajši): • coni parvus-isarcica. Združbo predstavlja le rod Hindeodus. Določena vrsta H. parvus je ekološko zelo tolerantna, saj se pojavlja v plitvejših in globjih okoljih. H. parvus je stratigrafsko pomembna spodnjetriasna vrsta in je globalno prepoznaven marker permsko-triasne meje. Njegov stratigrafski razpon poleg cone parvus sega še v naslednjo cono isarcica (sensu Kozur 1996, 2003); • cona obliqua. To cono označuje prevladujoči element Pachycladina obliqua Staesche. Ponekod se ta pojavlja kot monospecifična favna (profil Dobra), drugod (Kramarčin Potok, Zelin Crnoluški) pa jo spremljajo še predstavniki rodov Hadrodontina in ? Parachirognathus, redkeje tudi Ellisonia in Foliella. Vsi omenjeni rodovi so značilni za plitvovodna okolja spodnjega triasa. P. obliqua je geografsko razširjena vrsta, njen razpon sega od smithija do spathija (Perri & Andraghetti, 1987). V Severni Ameriki združbo Pachy-cladina-Hadrodontina primerjajo s cono 7 (cona Parachirognathus-Furnishius) sensu Sweet et al. (1971) in jo tako uvrščajo v smithijsko stopnjo (Solien, 1979). Ta vrsta ima velik biostratigrafski pomen v zahodni Tetidi in jo zato upoštevamo tudi pri konodontni conaciji Slovenije (Kolar-Jurkovšek & Jurkovšek, 1996); • podcona Platyvillosus. V profilu Kramarčin Potok smo ugotovili nivo s Platyvillosus. To je redko zastopan spodnjetriasni rod, ki je v združbi predstavljen z dvema vrstama: P. costatus (Staesche) in P hamadai Koike. V biozonaciji Sweeta in sod. (1971) je cona 10 (cona Platyvillosus) izdvojena v najnižjem delu spathija na osnovi pojava tega rodu. Vrsta P. costatus je bila prvič opisana iz campilskih plasti Južnih Alp (Staesche, 1964). Kasneje so bile opisane še nekatere maloštevilne vrste tega rodu. Najstarejši pojavi rodu iz dienerijskih plasti so zabeleženi samo v nekaterih lokalitetah Azije (Goel, 1977; Koike, 1988), zato je povsem verjetno, da je pojavljanje rodu zaradi ekoloških faktorjev geografsko in stratigrafsko omejeno. Izdvojitev nivoja s Platyvillosus (podcona Platyvillosus znotraj cone obliqua) temelji tudi na podatkih o njegovem pojavljanju drugod v zahodni Tetidi in je poznana iz campilskih plasti Južnih Alp in zahodne Srbije. Vrsti Foliella gardenae in Platyvillosus costatus, se pojavljata v campilskih plasteh, vendar nikoli hkrati (Staesche, 1964) in glede na njuno različno vertikalno pojavljanje sta bili izdvojeni cona costatus v spodnjem delu, in cona gardenae v njenem zgornjem delu (Budurov & Pantić, 1974). Summary Lithofacies and Conodont Zonation of Lower Triassic in Northwestern External Dinarides (Gorski Kotar, Croatia) The investigated area of the Lower Triassic sedimentary complex in the Gorski Kotar region - Croatia, is located in the External Dinarides between the Alps and the Velebit Mt. The Lower Triassic depositional environment is envisaged as shallow marine realm of a passive continental margin (Jelaska et al., 2003). Sedimentary complex differentiates in predominantly carbonate sedimentation that characterise the beginning of deposition with upward increasing trend of terrigeneous influx. Five Lower Triassic sections (Homer, Školski Brijeg, Zelin Crnoluški, Kramarčin Potok and Dobra) have been investigated (Aljinović, 1997) (Fig. 1A), but their chronostratigraphical position was uncertain due to lack of fossils or their inadequate preservation. A facial assemblage investigated in central part of Gorski Kotar region (Homer, Školski Brijeg and Zelin Crnoluški sections) differs from those appeared in marginal parts (Kramarčin Potok and Dobra sections). In central part the shallow water carbonate facies predominate. Basal cca. IO m thick cross-bedded interval of ooid grainstones (Homer and Školski Brijeg sections) was interpreted as dolomitised ooid bar facies (F-I) (Fig. IB, Fig. 2) that possibly formed subaqueous oolithic barrier with the landward laying lagoon. The overlaying thin or medium-bedded grey dolomicrites, sandy dolomites and calcarenaceous sandstones were interpreted as lagoonal facies (F-2). Storms and post-storm tidal reworked processes influenced the deposition of ooid bars. Ooid grainstones were late diagenetically dolomitised (Fig. 3), while the lagoonal facies (F-2) reflects the early diagenetic processes. The widening of the lagoon has been conceived through overall transgressive trend (Fig. IC). The rapid transgression caused in-place drowning of the ooid bars and formation of a new seaward oriented coast that is represented by sediments organized in typical storm sequences of Crnoluški Zelin section and defined as shoreface-offshore facies (F-3) (Fig. 1D,E). Deposition occurred near fair weather wave base of unrestricted shelf. The intense influx of a dominantly red siliciclastic terrigenous material has been recorded in the Lower Triassic sediments of the marginal, north-western and eastern parts of Gorski Kotar region (Kramarčin Potok and Dobra sections). The thick-bedded ooid bar facies as well as overlaying lagoonal facies are missing in those sections. Vertical successions are characterised by the interbedded ooid-sandy shoal facies (F-4) (oolithic limestone/dolostone and sandstone beds) and carbonate silicilastic mudstone or red siltite of restricted bay facies (F-S) (Fig. IF). Flat pebble conglomerates appear occasionally and are defined as F-6. Beds vary in thickness from few decimetres up to 1 m and are organised in fining upward sequences that represent shifting of a laterally existed ooid/sandy shoals and restricted muddy bays (Fig. 1F,G). The lithofacies present in Kramarčin Potok and Dobra sections resemble red clastic sediments i. e. Siusi Beds of the Southern Alps that make them compatible to the wide area of the External Dinarides. The different lateral facies distribution was interpreted as the result of transgression that transformed narrow rimmed shelf with ooid bars and lagoon facies to unrestricted shelf and finally to the wide epicontinental sea (Fig. 1C,E,G). This interpretation has never been proved while the precise chronostratigraphic dating of the investigated sections were missing in previous investigations. Therefore the lithofacial investigations were supplemented by conodont studies at each of five localities. The oldest investigated strata are marked by the presence of Hindeodus parvus in the Školski Brijeg section (Fig. 4). The first appearance datum (FAD) of this taxon has been approved to define the base of the Triassic system (Yin et al., 2OO1). The biostratigraphical data obtained from the five studied sections in Gorski Kotar allow recognition of the parvus-isarcicella zones, obliqua Zone and Platyvillosus Subzone (Table 1). The conodont zonation and lithofacial definition contribute to the definition of the Lower Triassic depositional realm of the External Dinarides and prove the correlative elements for comparison with some other parts of the Western Tethys. Zahvala Raziskavo sta finančno omogočila Hrvaško ministrstvo za znanost, izobraževanje in šport ter Agencija za raziskovalno dejavnost Republike Slovenije (program PI-OOII and projekt Jl-6665). Laboratorijske analize so bile opravljene na Rudarsko-geološki naftni fakuteti, Zagreb in na Geološkem zavodu Slovenije, Ljubljana. Posnetki z elektronskim mikroskopom so bili narejeni na Pale-ontološkem inštitutu ZRC-SAZU, Ljubljana. Avtorji se zahvaljujejo doc. dr. Bojanu Ogorelcu (Ljubljana) za kritični pregled članka. Delo je prispevek projekta IGCP 467. 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(1983): The geologic column of the Lower Triassic at Muć (Southern Croatia). -Acta Geologica 13, 1-25, Zagreb Sćavničar, B., Šušnjara, A. & Prohić, E. (1983): The geologic column of the Lower Triassic in the Zmijavac Valley (Muć, Southern Croatia). In: Babić, Lj. & Jelaska, V. (eds): Contribution to Sedimentology of Some Carbonate and Clastic Units of the Coastal Dinarides. Excursion Guidebook, 4th I.A.S. Regional Meeting, Split, Yugoslavia, 87-97, PMF, Zagreb Yin, H. (1993): A proposal for the global stratotype section and point (GSSP) of the Permian - Triassic boundary. Albertiana 11: 4-30, Utrecht. Yin, H., Sweet, W.C., Glenister, B.F., Kotlyar, G., Kozur, H., Newell, N.D., Sheng, J., Yang, Z. & Zakharov, Y.D. (1996): Recommendation of the Meishan section as Global Stratotype Section and Point for basal boundary of Triassic System. Newsl. Stratigr. 34/2, 81-108, Stuttgart. Yin, H., Zhang, K., Tong, J., Yang, Z. & Wu, S. (2001): The Global Stratotype Section and Point (GSSP) of the Permian-Triassic Boundary. Episodes 24, 102-114, Ottawa. Numulitine iz Lokavca v Vipavski dolini Nummulitins from Lokavec in Vipava valley (Vipavska dolina, SW Slovenia) Rajko Pavlovec Naravoslovnotehniška fakulteta, Katedra za geologijo in paleontologijo, Univerza v Ljubljani, Privoz II, SI-1000 Ljubljana Received: July 29, 200S Accepted: October 28, 200S Izvleček: Opisane so numulitine iz flišnih olistostrom v Lokavcu pri Ajdovščini. Starost je srednji cuisij. Abstract: Described are nummulitins from flysch olistostroms in Lokavec near Ajdovščina. The age is Middle Cuisian. Ključne besede: numulitine, spodnji eocen, fliš, Slovenija. Key words: nummulitins, Lower Eocene, flysch, Slovenia. Uvod V flišnih plasteh Vipavske doline je veliko nahajališč numulitin. Marsikatero še ni podrobneje obdelano, mnoga pa brez dvoma še niso odkrita. Numulitine so predvsem v olistostromnih plasteh, čeprav tako bogatih njihovih nahajališč, kot so recimo v Istri (cf. Hagn et al., 1979; Pavlovec, 2003b), doslej v Vipavski dolini ne poznamo. Numulitine v olistostromah so na sekundarnem nahajališču in so bile zanešene v flišno morje iz karbonatnih platform. Na ta način lahko sklepamo na favno, ki je takrat živela v plitvejših delih morja (Pavlovec, 1988). V olistostromah so tudi olistoliti, ki izhajajo iz različno starih plasti od krede do paleogena, morda tudi jure. Lokavec je vas severno od Ajdovščine v Vipavski dolini. Tam je v olistostromnih plasteh iskal fosile neumorni zbiralec Stanislav Bačar iz Ajdovščine. V njegovi zbirki so tudi opisani primerki. Poleg numulitin so korale, mehkužci, morski ježki in alge. Zanimivo je, da je v Vipavski dolini in Brkinih v flišu precej numulitov z gostimi septami in ne posebno visokimi zavoji. To so med drugim Nummulites ustjensis De Zanche & Pavlovec, N. vipavensis De Zanche & Pavlovec, N. brkiniensis Khan & Pavlovec, iz Lokavca doslej še nedoločena vrsta Nummulites sp., številni primerki, označeni kot N. aff. aquitanicus sensu Schaub (1981), in najbrž še nekateri. Takšni numuliti so bili očividno na spodnjeeocenski karbonatni platformi dosti pogosti in morda kažejo celo na določeno specifično okolje. Ponovno se odpira vprašanje, zakaj najdemo nekatere numulitinske vrste dokaj pogosto v flišu, v apnencih pa mnogo redkeje ali sploh ne. Numulitine pri Lokavcu so iz manjše olistostrome ali morda iz roba večjega podmorskega plazu. So dobro ohranjene. Nahajališče je bilo odkrito ob zidavi in bilo kasneje uničeno ali vsaj povsem spremenjeno, plasti pa so bile uničene med gradnjo. Na žalost nimamo nobenih podatkov o plasteh nad in pod sedimenti s preiskanimi numulitinami, tako da nahajališče pri Lokavcu nima drugega pomena, kot da je droben prispevek k poznavanju numulitin iz fliša pri nas. Numulitinske hišice niso vedno najbolje preparirane, tako da je pri nekaterih težko videti podrobno površinsko strukturo, kar ovira lažjo in zanesljivo determinacijo. Nabrani so samo primerki mikrosferičnih oblik. Najbrž je vzrok za to zbiralec negeo-log, ki nabira le vidnejše večje primerke. Numulitine iz Vipavske doline Doslej je bilo opisanih nekaj nahajališč numulitin v Vipavski dolini. Prve numulitine iz tega prostora, poznane od novejših raziskav (Pavlovec, 1963), so srednje-cuisijska podvrsta Nummulites burdigalensis cantabricus Schaub, najdena južno od Lozic in pri Vipavskem Križu. Najbolj znano nahajališče je pri Ustjah nedaleč od Ajdovščine (De Zanche et al.,1967). Ugotovljeni sta bili novi vrsti Nummulites vipavensis De Zanche & Pavlovec, N. ustjensis De Zanche & Pavlovec, nadalje N. rotularius Deshayes, N. cf. inkermanensis Schaub, N. partschi De la Harpe, N. praelucasi Douvillé, N. ornatus Schaub in N. jacquoti De la Harpe. Flišne plasti z numulitinami pri Ustjah so iz prehoda med spodnjim in srednjim cuisijem, kar je potrjeno tudi z nanoplanktonom. Pri Dolnjem mlinu ob Vipavi južno od Ajdovščine so bile v olistolitu ugotovljene vrste (Pavlovec & Bačar, 2004) Nummulites ornatus Schaub, N. bombitus Hottinger, N. haymanensis Schaub in N. subdistans De la Harpe. Kos v flišnih olistostromah je spodnjecuisijske starosti, medtem ko so flišne plasti mlajše. Opisi vrst Assilina escheri (Hottinger, 1977) (tabla I, si. I, 2) 1977. Operculina escheri n.sp. - Hottinger, 76-78, si. 27 A-E, tab. 33, si. 1, 2, tab. 34, 35, Material: Najdena sta bila dva dobro ohranjena primerka z oznako LO 6. Mikrosferična generacija. Primerka sta v drobnozrnatem peščenjaku, torej v olistolitu iz olistostrome. Hišica je tanka. Zavoji se hitro višajo. Septa so močno upognjena, velikokrat srpasto. Zlasti vrhnji del sept je odebeljen in na njih so nežne granule. Premera hišic iz Lokavca sta 12,6 in 16,5 mm. Hottinger (1977) navaja med besedilom velikost mikrosferične generacije 25 mm, na slikah pa so tudi manjši primerki z velikostmi med 10 in 20 mm. Vrsto escheri so prvotno uvrščali v rod Operculina, danes je to Assilina escheri (Serra-Kiel et al., 1998) Ta vrsta je živela v spodnjem in srednjem cuisiju. Znana je iz Švice, avstrijske Koroške (Sonnenberg, Guttaring = Kotarče) in Furlanije (Buttrio). V Vipavski dolini je ugotovljena prvič. Assilina marinellii marinellii (Dainelli, 191S) (tabla I, si. 3) 1915. Operculina Marinellii n.sp. - Dainelli, 170-171, tab. 18, si. 27-28 1977. Operculina marinellii Dainelli, 1915 - Hottinger, 68-69, tab. 27-29 2003-a. Assilina marinellii marinellii (Dainelli) - Pavlovec, 234, tab. 1, sl. 2 Material: Najdenih je bilo več večinoma dobro ohranjenih primerkov, ki imajo oznake LO 1,2,3,4,5,7,9. Tabla I - Plate I: i и % >ЙЬ - Sliki I in 2 - Figures I and 2. Assilina escheri (Hottinger), ekvatorialni prerez - equatorial section. Slika 3 - Figure 3. Assilina marinellii marinellii (Dainelli), površina hišice - surface of the shell. Mikrosferična generacija. Zavojni rob je močan. Zavoji se precej enakomerno in hitro višajo. Septa so ponekod skoraj ravna in upognjena samo v vrhnjem delu, drugod so nekoliko bolj usločena. Na površini hišice so v srednjem delu nežne granule, medtem ko jih v ostalih delih ni videti. Premeri hišic so I0,l mm, 10,9 mm, Il,l mm, 11,6 mm, 11,8 mm in 12,8 mm. Po velikosti ustrezajo omenjeni podvrsti. Nekateri primerki imajo nekoliko gostejša septa, vendar ta oblika precej variira. Podvrsta Assilina marinellii similis (Khan & Pavlovec, 1975) je nekoliko manjša, vendar je vprašljivo, če je ne bi bilo treba uvrstiti v variacijsko širino podvrste Ass. marinellii marinellii (Pavlovec, 2003a). Assilina marinellii marinellii je živela v spodnjem in srednjem cuisiju. Nummulites tauricus (tab. 2, sl. 1 in 2) non 1963. Nummulites partschi tauricus (de la Harpe) - Pavlovec, 452-453, sl. 11 1973. Nummulites partschi tauricus De la Harpe - Kapellos, 86, tab. 43, sl. 1, tab. 46, sl. 2, tab. 49, sl. 2-3 1981. Nummulites tauricus De la Harpe, 1926 - Schaub, 109-110, tab. 29, sl. 15-33, tab. 31, sl. 1-9, 16, 18, 19, 22, 23, 25, 27 Material: Najdena sta bila dva primerka z oznakama L 11 in 30. Mikrosferična generacija. Premera hišic sta 18,5 mm s 15 zavoji in 14,7 mm s 13 zavoji, medtem ko Schaub (1981) navaja velikosti 10 do 19 mm in pri polmeru 9 mm 15,5 zavojev. Zavoji se zlasti v srednjem delu precej hitro dvigajo, proti zunanjemu robu so nižji in tanjši. Septa so močno nagnjena in upognjena zlasti v zgornji polovici. Zavojni rob je močan in obsega okrog 1/3 zavoja. Hišica je tanka in ima na površini nežne septalne podaljške. Drobni trni so na primerkih iz Lokavca slabo vidni, deloma pa je zgornja plast hišice odstranjena. Podobna vrsta Nummulites praelorioli Herb & Schaub ima nižje zavoje in gostejša septa. Nummulites tauricus je bil omenjen iz Goriških brd (Pavlovec, 1963), vendar je bilo pozneje ugotovljeno, da determinacija ni bila pravilna (Cimerman et al.,1974). Nummulites tauricus je živel v srednjem in zgornjem cuisiju. Nummulites sp. Material: Trije primerki z dobrim ekvatorialnim presekom in žal slabo preparirano površino. Oznake so L 3, 5, IO. Mikrosferična generacija. Za omenjene tri primerke nismo mogli ugotoviti, kateri vrsti pripadajo. Hišice so precej tanke. Zavoji se počasi višajo, zavojni rob je precej enakomerno debel in obsega okrog ^zavoja. Septa so gosta, rahlo ukrivljena in nagnjena. Velikosti hišic so Il,2, I2,l in 12,4 mm s številom zavojev od 13 do 15. Na površini hišic so radialni, nekoliko ukrivljeni septalni podaljški. Numulitom iz Lokavca je podobna srednje in zgornjecuisijska vrsta Nummulites gracilis Schaub, ki pa je manjša in tanjša. Po Schaubu (1981) so velikosti hišic te oblike med 5 in 9,5 mm. Tudi zavoje imajo nekoliko višje, septa pa v zgornjem delu bolj ukrivljena. Nekoliko podobna je tudi vrsta Nummulites discorbinus (Schlotheim), ki je živela v srednjem in zgornjem luteciju, torej je mlajša od nahajališča pri Lokavcu. Kamrice in septa so precej podobna našim primerkom. Vendar je Nummulites discorbinus bistveno manjši, po Schaubu (1981) med 4 in 8,4 mm. Vsekakor so numuliti iz Lokavca zanimiva vrsta, ki jo bo ob boljšem in številčnejšem materialu tudi megalosferične generacije potrebno morda opisati kot novo vrsto. Nummulites pavloveci (tab. 2, sl. 3) 1981. Nummulites pavloveci nov.sp. -Schaub, 12O-121, tab. 27, sl. 26-52, tab. 5, sl.m,n Material: Primerek iz Lokavca ima oznako L 58. Mikrosferična generacija. Hišica se proti sredini počasi debeli. Na površini ima tanke radialne septalne linije. Velikost hišice je 11,2 mm, debelina 4,8 mm. Schaub (1981) navaja velikosti med 8 in 15 mm, debeline pa med 3,2 in 5,8 mm. Zavoji se v notranjem delu hitro višajo, zunanja dva se znižata. Zavojni rob je močan in obsega tretjino do polovice višine zavoja. Septa so nagnjena, upognjena, pogosto srpasta. Kamrice so večinoma izometrične, le v zunanjih zavojih se podaljšajo, tako da pri nekaterih dolžina presega višino. Nummulites pavloveci je živel od spodnjega do zgornjega cuisija. Tabla 2 - Plate 2: Sliki I in 2 - Figures I and 2. Nummulites tauricus De la Harpe, ekvatorialni prerez - equatorial section. Slika 3 - Figure 3. Nummulites pavloveci Schaub, ekvatorialni prerez - equatorial section. Nummulites aff. rotularius (tab. 3, si. I) Material: Najdeni so primerki z oznakami L 25, C, D. Mikrosferična generacija. Hišica je ploščata, na površini ima rahlo ukrivljene in ne posebno goste septalne linije. Pri najbolje ohranjenem primerku z oznako L 25 je velikost hišice 12 mm, debelina okrog 6,3 mm. Zavoji se hitro in enakomerno višajo, v zunanji polovici hišice nekoliko hitreje. Zunanja dva zavoja se malo znižata. Zavojni rob je močan in obsega približno tretjino zavoja. Septa so nagnjena in precej upognjena, najmočneje v zgornjem delu. Kamrice imajo v notranjih zavojih večjo višino od dolžine, v zunanjih se podaljšujejo in so včasih izometrične, včasih pa celo z večjo dolžino od višine. Ta oblika iz Lokavca je zelo podobna vrsti Nummulites rotularius Deshayes, vendar je večja od nje. Schaub (1981) navaja velikosti hišic med 6 in 10 mm, najpogosteje med 5,7 in 7 mm. Pri polmeru 5,3 mm omenja 14 zavojev, medtem ko je pri našem primerku pri polmeru 6 mm 15 zavojev. Res pa je, da so tudi primerki iz Ustij v Vipavski dolini (De Zanche et al., 1967) veliki med 9 in 11 mm, vendar so v ekvatorialnem prerezu zelo podobni tipičnim predstavnikom te vrste. Morda je numulit iz Lokavca eden od naslednikov vrste Nummulites rotularius, katerih v smeri proti N. perplexus Schaub in N. praediscorbinus Schaub avtor obeh vrst ni ugotovil (glej Schaub, 1981, slika 25). Žal po naših primerkih tega problema ni mogoče rešiti. Poleg tega še ni zadovoljivo rešena variacijska širina posameznih elementov te vrste, ki je glede na višino zavojev, debelino zavojnega roba in oblike kamric zelo različna (primerjaj Schaub, 1981, tabla 26). Zaradi vsega tega označujemo primerek 25 iz Lokavca kot Nummulites aff. rotularius. Iz Lokavca sta primerka z oznakama L C in L D s premeroma hišic 8,8 in 7 mm in sta po tem bližja tipičnim primerkom. Imata pa zelo debel in nekoliko nepravilno potekajoč zavojni rob zlasti v srednjem delu hišice. Kamrice imajo ponekod precej večjo dolžino od višine in to bolj od primerka L 25 ali numulitov na tablah pri Schaubu (1981). Vrsta Nummulites rotularius je znana iz spodnjega in srednjega, morda še iz zgornjega cuisija. Nummulites äff, aquitanicus sensu Schaub (tab. 3, sl. 2 in 3) 1981. Nummulites aff. aquitanicus - Schaub, 161, tab. 7, sl. i Material: Ta oblika numulitov je najpogostejša v Lokavcu. Oznake primerkov so L 15-18, 20, 21-24, 26-29, 31-45, 47-50. Mikrosferična generacija. Hišice se proti sredini enakomerno debelijo, njihove velikosti so med 9,7 in 13,1 mm, po Schaubu (1981) med 5,5 in 15 mm. Na površini so tanke, goste in zavite septalne linije. Izrazite granulacije ni, le ponekod so redke nežne granule. Zavoji se počasi in enakomerno višajo. Zavojni rob je precej močan. Septa so nagnjena, rahlo upognjena, v zgornjem delu so močneje nagnjena nazaj. Kamrice imajo večjo višino kot dolžino. Ta oblika se loči od tipičnega Nummulites aquitanicus po površini, ker nima izrazitih granul. Zavoji so pri večini primerkov nižji kot pri tipičnih primerkih te vrste. Podobnega numulita označuje Schaub (1981) kot Nummulites aff. aquitanicus iz srednjecuisijskih plasti v nahajališču Colombres (Oviedo) v Španiji. Med sorodnimi vrstami je še nekaj prehodnih oblik. Tudi iz Campa v Španiji opisuje Schaub (1966) Nummulites aff. aquitanicus, ki ima višje zavoje od naših primerkov. Tega numulita postavlja med vrsti Nummulites aquitanicus in N. man/redi, najden pa je bil v srednjecuisijskih plasteh. Te in druge podobne numulite bo potrebno revidirati in najbrž opisati kako novo vrsto ali podvrsto ali celo več nekoliko različnih oblik. Vsekakor pri teh numulitih zelo variirajo višine zavojev in debeline zavojnega roba. Nekateri primerki iz Lokavca so po velikosti hišic, obliki sept in kamric podobni vrsti Nummulites praecursor De la Harpe, ki pa je starejša, ilerdijska. Tabla 3 - Plate 3: Slika I - Figure I. Nummulites aff. rotularius Deshayes, ekvatorialni prerez - equatorial section. Sliki 2 in 3 - Figures 2 and 3. Nummulites aff. aquitanicus sensu Schaub, 1981, ekvatorialni prerez -equatorial section. Nummulites aquitanicus je živel v spodnjem in srednjem cuisiju, N. aff. aquitanicus sensu Schaub 1981 je znan iz srednjega cuisija. Nummulites brkiniensis (tabla 4, sl. 1 in 2) 1975. Nummulites brkiniensis n.sp. - Khan et al., 35-37, tab. 6, sl. 4-6, tab. 7, sl. 1-2 1981. Nummulites brkiniensis Khan et Pavlovec - Pavlovec, 295-298, tab. 1, sl. 6 Material: Najdenih je bilo šest dobro ohranjenih primerkov. Imajo oznake L 6,7,8,9,12,14 in številne druge. Za nekatere primerke ni zanesljivo, ali sodijo v variacijsko širino te vrste. Mikrosferična generacija. Zavoji se precej enakomerno višajo. Zavojni rob je močan. Septa so rahlo usločena, najbolj pri vrhu. Kamrice imajo večjo višino kot dolžino, le redke so izometrične. Pri premeru 12 mm je 15 zavojev, pri 14 mm 14 in pri 13 mm 13 zavojev. Velikosti hišic so v variacijski širini te vrste, ki je med 11,4 in 17 mm (Khan et al., 1975). Nummulites brkiniensis je v južnozahodni Sloveniji dokaj pogost. Poleg uničene tiplokalitete pri Podgradu na južnem robu Brkinov smo ga ugotovili še v nekaj nahajališčih, ki niso dokončno preučena. Pogosta je ta vrsta ali njej zelo podobne oblike tudi pri Lokavcu. Čeprav je bilo pri tej vrsti že doslej znano precejšnje variiranje, je vendar vprašljivo, če ne bi bilo potrebno ločiti kako novo vrsto ali podvrsto. Razlike so v višini zavojev in ponekod v nepravilnem poteku zavojev. Nekateri primerki so precej podobni obliki, označeni kot Nummulites aff. aquitanicus sensu Schaub (1981). Nummulits brkiniensis je znan iz srednjega cuisija. Nummulites praelaevigatus (tab. 4, sl. 3) 1951. Nummulites praelaevigatus nov.sp. -Schaub, 188, sl. 257, 273-275, tab. 8, sl. 1,2 1981. Nummulites praelaevigatus Schaub, 1951 - Schaub, 170-171, sl. 104, tab. 60, sl. 1-3,5, tab. 7, sl. u Material: Primerek iz Lokavca ima oznako L 19. Mikrosferična generacija. Tanka hišica ima na površini nežne, nekoliko vijugaste septalne linije. Velikost je 13,8 mm, in debelina okrog 4,4 mm. Po Schaubu (1981) so hišice velike med 4,7 in 11 mm, vendar precej variirajo in nekateri navajajo hišice celo 4,1 mm (cf. Kapellos, 1973). Zavoji se hitro višajo, le zunanja dva sta nižja. Pri polmeru hišice 6,5 mm je 15 zavojev. Zavojni rob je zlasti v notranjih zavojih močan. Septa so nagnjena in rahlo ukrivljena, najbolj zgoraj. Kamrice imajo v večini zavojev večjo višino od dolžine, le v zunanjih zavojih se podaljšajo in so nekatere izometrične ali celo bolj dolge kot visoke. Po ekvatorialnem prerezu se numulit iz Lokavca ujema s tipičnimi primerki te vrste (cf. Schaub, 1966, sl. 6 h), vendar je nekoliko večji. Numulita z oznako Nummulites aff. praelaevigatus iz fliša v Postojni (Pavlovec, 1981) in iz apnenca pri Ivartniku v severni Sloveniji (Drobne et al.,1977) imata nekoliko višje zavoje in sta manjša od numulita iz Lokavca. Nummulites praelaevigatus je živel v zgornjem delu spodnjega in v srednjem cuisiju. Nummulites vipavensis (tab. 4, sl. 4) 1967. Nummulites vipavensis n.sp. oblika В - De Zanche et al., 228-230, tab. 6, sl. 1-2, tab.8, sl. 1 1981. Nummulites vipavensis De Zanche et Pavlovec - Pavlovec, 295, tab. 1, sl. 5 Material. Ta vrsta v Lokavcu ni pogosta, saj je bil doslej najden en sam primerek z oznako L 51. Mikrosferična generacija. Vrsta Nummulites vipavensis je bila prvič opisana iz Ustij v Vipavski dolini, torej ne daleč od Lokavca. Hišica je tanka in ima na površini goste, nekoliko zavijajoče septalne linije z manj izrazitimi »trabécules transverses«. Velikost hišice je 11,6 mm, debelina okrog 5 mm. Pri dosedanjih opisih so omenjene velikosti med 11 in 12 mm, debeline pa med 5,5 in 6,5 mm (De Zanche et al., 1967; Pavlovec, 1981). Najhitreje se višajo zavoji v srednjem delu hišice, medtem ko so zunanji zavoji malo nižji. Potekajo nekoliko nepravilno. Zavojni rob je močan. Septa so nagnjena, usločena in najbolj upognjena v zgornjem delu. Kamrice imajo v notranjih zavojih večjo višino od dolžine. Proti zunanjim zavojem se daljšajo, tako da so nekatere skoraj izometrične. Na splošno oblike kamric in sept precej variirajo. Vrsta Nummulites vipavensis je znana iz srednjega cuisija. Megalosferične oblike še vedno ne poznamo. V nahajališču holotipa pri Ustjah smo pregledovali celoten material in lahko sklepamo, da so v flišu oblike A zelo redke. Tabla 4 - Plate 4: Sliki I in 2 - Figures I and 2. Nummulites brkiniensis Khan & Pavlovec, ekvatorialni prerez - equatorial section. Slika 3 - Figure 3. Nummulites praelaevigatus Schaub, ekvatorialni prerez - equatorial section. Slika 4 - Figure 4. Nummulites vipavensis De Zanche & Pavlovec, ekvatorialni prerez - equatorial section. Zaključek Lokavec je novo nahajališče numulitin v Vipavski dolini. Vrsta Assilina escheri je nova za to področje, najbližje doslej znana nahajališča so v Furlaniji. Dokaj pogosta je v flišnih plasteh pri nas Assilina marinellii marinellii in vse bolj se kaže tudi Nummulites brkiniensis. Zanimivo je, da marsikatere v flišu ugotovljene pogoste vrste ne najdemo tako številčne v apnencih iz istočasne karbonatne platforme. Assilina escheri in Ass. marineHii marineHii sta znani iz spodnjega in srednjega cuisija, vendar je prva v olistolitu, ki je najbrž starejši od flišnih plasti pri Lokavcu. Nummulites pavloveci je živel od spodnjega do zgornjega cuisija, enako vrsta N. rotularius, ki pa pri Lokavcu ni zanesljivo določena. Nummulites aquitanicus sensu Schaub (1981) je doslej znan v srednjem cuisiju. Nummulites praelaevigatus je živel od zgornjega dela spodnjega in v srednjem cuisiju, N. vipavensis in N. brkiniensis sta znana iz srednjega cuisija, N. tauricus pa iz srednjega in zgornjega cuisija. Po tem lahko sklepamo na srednjecuisijsko favno iz olistostrom v Lokavcu. Možno pa je, da je favna iz Lokavca nekoliko mlajša od one pri Ustjah, ki jo postavljajo na prehod med spodnji in srednji cuisij (De Zanche et al., 1967). Glede na klasifikacijo numulitinskih nahajališč (Pavlovec, 2003-b) uvrščamo favno pri Lokavcu med prestransportirano s karbonatne platforme. Večina oblik je sinhronih s flišnimi plastmi, tiste v olistolitu pa so lahko starejše. Summary Nummulitins from Lokavec in Vipava valley (Vipavska dolina, SW Slovenia) In the flysch beds from Vipava valley (SW Slovenia) are more localities with nummulitins. Partly they are not researched, in future we expect to find new localities. The new finding place is in the olistostrom flysch sediments in Lokavec near Ajdovščina. Nummulitins, anthozoans, molluscs, echinoids and algae are discovered there. Determined species and subspecies are Assilina escheri (Hottinger), Assilina marinellii marinellii (Dainelli), Nummulites tauricus De la Harpe, N. pavloveci Schaub, N. aff. rotularius, N. aff. aquitanicus sensu Schaub 1981, N. praelaevigatus Schaub, N. vipavensis De Zanche & Pavlovec, N. brkiniensis Khan & Pavlovec, and Nummulites sp., that could be the new species, but we do not have enough good preserved samples. The flysch sediments in Lokavec are from Middle Cuisian. Literatura Cimerman, F., Pavlovec, Я., Pavšič, J. & Todesco, L. (1974): Biostratigrafija paleogenskih plasti v Goriških Brdih (Biostratigraphy of the Paleogene Beds of Goriška Brda). Geologija 17, Ljubljana, 7-130. Dainelli, G. (191S): L'Eocene Friulano. Mem. geograph, Firenze, 1-721, tab. 1-S6. De Zanche, V., Pavlovec, R. & Proto Decima, F. (1967): Mikrofavna in mikrofacies iz eocenskih flišnih plasti pri Ustju v Vipavski dolini, JZ Slovenija (Microfauna and microfacies of the Eocenic flysch series near Ustje in the Vipava Valley). Razprave 4. razr. SAZU,10, Ljubljana, 20S-263, tab. 1-17. Drobne, K., Pavlovec, R. & Drobne, F. (1977): Paleogenske velike foraminifere s področja med Mežico in Slovenj Gradcem (Paleogene larger foraminifera from the area between Mežica and Slovenj Gradec, NW Yugoslavia). Razprave 4. razr. SAZU, 20/1, Ljubljana, 1-88, tab. 1- 23. Hagn, H., Pavlovec, R. & Pavšič, J. (1979): Excursion G, Gračišće near Pićan, Istria - Eocene. 16th Europ. Micropal. Colloquium, Ljubljana, 18S-190. Hottinger, L. (1977): Foraminifčres operculiniformes. Mém. Mus. Hist. Nat., n.s., C/40, Paris, 1-1S9, pl. 1-66. Khan, M.R., Pavlovec, R. & Pavšič, J. (197S): Eocenski mikrofosili iz okolice Podgrada (Eocene microfossils from Podgrad). Geologija 18, Ljubljana, 9-60. Kapellos, C. (1973): Biostratigraphie des Gurnigelflysches. - Schweiz. Paläontol. Abh. 96, Basel, 1-128, Taf. 1-49. Pavlovec, R. (1963): Stratigrafski razvoj starejšega paleogena v južnozahodni Sloveniji (Die stratigraphische Entwicklung des älteren Palaeogens im südwestlichen Teil Sloweniens). Razprave 4. razr. SAZU, 7, Ljubljana, 419-SS6. Pavlovec, R. (1981): Fliš v Postojni (Flysch from Postojna). Geologija 24/2,Ljubljana, 28S-301. Pavlovec, R. (1988): Savremeni pogledi na istraživanja numulitina (Contemporary aspects of study of nummulitinae). Radovi Akad. nauka umjet. Bosne i Herceg., odj. teh. nauka 12, Sarajevo, 141-170. Pavlovec, R. (2003-a): Nummulitins from flysch in surroundings of Ilirska Bistrica, southwest Slovenia (Numulitine iz fliša v okolici Ilirske Bistrice). Geologija 46/2, Ljubljana, 231-244. Pavlovec, R. (2003-b): The types of nummulitins localities in the Dinarides (Tipi numulitinskih nahajališč v Dinaridih). RMZ-Materials and Geoenvironment 50/4, Ljubljana, 777-788. Pavlovec, R. & Bačar, S. (2004): Eocenski numuliti pri Dolnjem mlinu v Vipavski dolini, JZ Slovenija (Eocene nummulitins from Dolnji mlin in Vipava valley, Vipavska dolina, SW Slovenia). Annales, ser. hist. nat. 14, Koper, 121-126. Schaub, H. (19S1): Stratigraphie und Paläontologie des Schlierenflysches. Schweiz. Pal. Abh. 68, Basel, 1-222, Taf. 1-9. Schaub, H. (1966): Über die Grossforaminiferen im Untereocaen von Campo (Ober-Aragonien). Eclogaegeol. Helvet. 59/1, Basel, 3SS-377, Taf. 1-6. Schaub, H. (1981): Nummulites et Assilines de la Tèthys paléogène. Taxinomie, phylogenèse et biostratigraphie. Schweiz. Paläontol. Abh. 104106, Bale, 1-236, pl. 1-97. Serra-Kiel, J., Hottinger, L., Caus, E., Drobne, K., Ferrrndez, C., Jauhri, A.K., Less, G., Pavlovec, R., Pignatti, J., Samsó, J.M., Schaub, H., Sirel, E., Strougo, A., Tambarerau, Y., Tosquella, J. & Zakrevskaya, E. (1998): Larger foraminiferal biostratigraphy of the Tethyan Paleocene and Eocene. Bull. Soc. géol. Prance 169/2, Paris, 281-299. Minerals Planning Policies in Europe Razvojne usmeritve planiranja mineralnih surovin v Evropi Horst Wagner1, Günther Tiess1, Slavko Šolar2, Kai Nielsen3 'Department of Mineral Resources and Petroleum Engineering, University of Leoben, Austria; 2Geological Survey of Slovenia, Ljubljana, Slovenia; QDepartment of Geology and Mineral Resources Engineering, Norwegian University of Science and Technology, Trondheim, Norway. Received: June 2, 2005 Accepted: September IS, 200S Abstract: This paper summarizes the main results of a study of minerals planning policies in Europe which objective was to provide information on different approaches to mineral planning policies, to evaluate them and to highlight best practices in the frame of sustainable development. Izvleček: V članku povzemamo temeljne rezultate študije o razvojnih usmeritvah na področju planiranja mineralnih surovin v Evropi. Namen študije je bil predvsem zbrati informacije o različnih pristopih k planiranju mineralnih surovin, te pristope ovrednotiti ter izpostaviti primere dobre prakse, ki temelje na načelih trajnostnega razvoja. Key words: mineral resources, policy, planning, European Union. Ključne besede: mineralne surovine, razvojne usmeritve, planiranje, Evropska Unija. Introduction This paper summarizes the main results of a study of minerals planning policies in Europe. The objective of the study was to provide information on different approaches to mineral planning policies and practices in the Member States. In the course of the study it was found that there are some general issues, which have a major impact on the non-energy extractive industries in Europe. The study has shown that contrary to the public opinion the production of industrial minerals and construction minerals is significant, the former accounting for about 20 percent of global production, the latter amounting to about 3 billion tonnes per annum. In contrast the importance of metal ores has diminished although metal production in some European countries can still be significant. The study revealed that very few Member States have clearly defined mineral policies. Common to most mineral policies is the emphasis on reducing minerals consumption and recycling, whereas the important aspect protecting access to minerals resources is not adequately addressed by most policies. Access to mineral deposits is regulated in most Member States by land use legislation and administration. Information on mineral deposits in land use planning databases tends to be scarce. This together with the absence of formal mineral policies places minerals at a disadvantage in land use decisionmaking. The emergence in the recent past of environmental legislation and in particular environmental impact assessments has had a crucial effect on the duration of the authorization process for new mineral projects. Examples are given how minerals planning is handled in some of the Member States. This paper concentrates on the general issues rather than discussing specific mineral planning policies and practices of the individual Member States. Only where appropriate will examples be given of specific mineral planning policies and practices. All details have been presented in a very comprehensive report, which has been submitted to the European Enterprise Directorate at the end of November 2004. The non-energy extractive INDUSTRY in the eu The non-energy extractive industry is often considered to be made up of three broad sub-sectors'11: • Metalliferous minerals, • Industrial (non-construction) minerals, • Construction minerals. Metalliferous minerals During the past 50 years the structure of the European minerals industry has undergone fundamental changes. The production of metal ores has decreased steadily resulting in a situation where the requirements of the industry have to be met, with a few exceptions, through imports of metal ores. Important metal ores mined in Europe are zinc, lead and copper. Production of all other metal ores is less than 2 % of global production. For most metal ores import dependency is in excess of 50 % and for some even in excess of 80 %. This makes the European metals industry very vulnerable to external developments. Industrial minerals The production of industrial minerals has been growing steadily over the years and this sector of the non-energy extractive industries has increased in importance. In the field of industrial minerals, European producers play a major role and account for about 20 % of total world production. Europe is a major producer of kaolin, bentonite and salt. Construction minerals The third and most important area is that of construction minerals. More than 3 billion tonnes of sand, gravel and crushed stone are produced annually to meet the demands of the European building and construction industries. While most of the construction minerals are produced close to the major development centres, the establishment of mega-quarries next to the sea in Norway and in Great Britain is a new development that could have important consequences for parts of Europe, which can be reached by bulk carriers. Assessment of the actual quantities of construction minerals produced in Europe is difficult because official statistics do not cover small and very small enterprises, which produce significant quantities of construction minerals. Table I. EU 2S: European minerals Production as a Proportion of Total World Production (Source: World Mining Data, 2002). Ores Production t (Metal) % Proportion World Bauxite (Aluminum) 2,467,255 1.8 Copper 715,689 5.2 Lead 271,190 8.8 Zinc 843,810 9.5 Chrome 288,343 5.6 Nickel 22,201 1.9 Iron Ore 11,878,949 1.6 Industrial Minerals Production (t Minerals) % Proportion World Baryte 398,936 5.8 Bentonite 2,586,585 24.7 Diatomite 128,387 12.0 Feldspar 4,684,413 52.1 Fluorspar 314,381 7.1 Graphite 21,479 3.6 Magnesite 2,649,830 19.0 Perlite 1,014,165 46.1 Salt 44,878,991 21.9 Talk 1,274,770 17.2 Agricultural Minerals Production (t K20) % Proportion World Potash 4,936,875 19.9 Annual per capita minerals consumption in Europe Annual per capita consumption of minerals in the European Member States varies considerably, with consumption figures ranging from less than 3 tons per capita and year in some of the new Member States to more than 15 tons per capita and year in some of the other states. Sustainable Development and National Minerals Policy Sustainable Development The European Community has adopted the sustainable development concept as detailed in the Brundtland Report. The Brundtland definition has been incorporated in the EU Strategy for sustainable development, adopted at the Gothenburg Council in 2001. This strategy requires that all policies should be judged by how they contribute to sustainable development'4. The 5th and 6th Community Policy and Action Programmes make direct reference to the concept of sustainable development. As far as the extractive industries are concerned the most relevant document is the Communication on "Promoting sustainable development in the EU non-energy extractive industry" (COM (2000) 265). This was the first document to discuss the problem of sustainable mining. It made important statements such as: • Mining is increasingly influenced by other competing land uses, such as urban development, agriculture, nature conservation; • A balanced consideration of economic, environmental and social aspects to ensure the sustainable development of the industry is needed; • A coherent Community policy is necessary. The Communication raises two kinds of concern from the point of view of sustainable development. These are the use of non-renewable resources themselves, which may mean that these "resources will not be available for future generations"'31 and the quality of the environment, pointing to general and specific risks since mining may affect the quality of the environment. Recent major environmental accidents involving tailing ponds on metal mines have switched the attention at EU level from sustainable development in the minerals industry to the safety and environmental hazards of mineral extraction. An example was the Communication from the Commission on "Safe operation of mining activities: A follow-up of recent mining accidents", COM (2000) 664. From this followed three key follow-up actions, namely the amendment of the Seveso II Directive, an initiative on the management of mining waste, and a best available technology (BAT) reference document under the IPPC Directive. As a consequence of these accidents some of the important points raised in COM (2000) 265 have not been addressed. Most Member States have taken measures to implement the principles of sustainable development. The emphasis has been on environmental protection, promoting reduced use of minerals, and recycling of materials. Examples of this are the policies adopted by the Netherlands and Sweden. The important issue of safeguarding mineral deposits for future generations by protecting them from other land uses has been addressed by only but a few of the Member States. The Swedish landbank system developed by declaring various types of mineral deposits to be of national interest in accordance with the Environmental Code, and protecting the resources from being sterilised by other land use development, must be considered to be successful with regard to the future sustainability of minerals supply in Sweden. Austria is working on a raw materials plan, which as one of its main objectives has the protection of access to mineral deposits. Minerals Policy Closely linked to the issue of sustainability of minerals supply is the question of minerals policies. The survey of EU-policies and Member States has shown that very few have comprehensive and published mineral policies. This is a marked change from the situation some years ago when minerals played a focal role in Europe as reflected by the European Coal and Steel Community, the original predecessor of the European Community. Member States, which have such policies, are amongst others the Czech Republic, the Netherlands and some of the German Federal States. Minerals policies are particularly important in connection with land use planning which is the main instrument for securing access to mineral deposits. As land use planning is about choices between different options minerals tend to be disadvantaged in the absence of clearly defined minerals policies. The need for minerals policies has been stressed by Regueiro from Spain in a recently published paper'4". General Legal and Policy Framework All Member States have some form of hierarchical government structure, with the national government at the apex and legal and administrative structures following the "cascade" principle, i.e. regional, county and local law and practices, which are consistent with national law and practice and, especially European law and practice. Impact of EU-legislation on non-energy extractive industries The emergence of environmental protection legislation/policy at the EU-level has added a number of additional factors that impact the authorisation process for mineral extraction. The influence of EU-legislation and policy on national legislation and practice has grown markedly in recent years, especially regarding environmental matters. Table I at the end of the paper provides an overview of recent EU-legislation impacting on the non-energy extractive industries. Many national laws were/are amended to implement EU-legislation (especially in the new Member States). While this is having a harmonising effect with regard to environmental matters, it has had an impact on the extractive industry due to increasing the number of restrictions on mineral extraction and increasing the time and costs required for approval. Both aspects have adverse effects on available mineral reserves. Reports from various countries show that the impact is more strongly felt by small extraction companies. Considering that the 25- 20 15- ф N M ю- Ш ■ bird protection sites ■ FFH-Directive Figure I. Summary of land areas designated as Natura 2000 and bird protection areas. RMZ-M&G 2005, S2 largest sector of the European non-energy extractive industries, namely the construction minerals sector, consists of predominately small to very small enterprises, this trend could ultimately lead to a change in the structure of the industry with possible consequences for the local supply of construction minerals and increased minerals transport. Extractive activities depend on geology and the particular location of mineral deposits. Access to the deposits is, therefore, of crucial importance for the competitiveness of the extractive industry. This, however, is made difficult by some of the directives. The most important impact results from the so-called Natura 2000 areas, a FFH - Directive. Mineral deposits that can be used for extraction are often found in undeveloped, mostly natural areas, thus the Natura 2000 protection areas can have a serious impact on the raw material industry in the field of land utilization. Areas set aside for nature protection vary considerably throughout Europe (Fig. I). Principal Legislation Controlling Mineral Extraction The principal legislation governing mineral extraction in the Member States trends to be strongly influenced by the mineral rights issue. Historically mineral rights belong either to the state or to the owner of the land. State owned minerals in most countries are metal ores, rare industrial minerals and minerals of high purity. Landowner minerals are the bulk of the industrial minerals and the construction minerals. In most Member States the extraction of state-owned minerals is covered by a specific mining law. In many Member States the extraction of construction and most industrials minerals is covered by some other law, i.e. "Abgrabungsgesetz" in some German Federal States, land use planning laws or environmental laws. There is a trend to regulate minerals extraction through environmental laws, i.e. in Sweden. The mineral rights no longer reflect the changing importance of industrial minerals and construction minerals (aggregates) which together account for more than 95 % of all non-energy minerals mined in Europe. Construction minerals in many parts of Europe are becoming of strategic importance and interstate trade of construction minerals is increasing. In the light of the increased strategic importance of construction minerals in most European states and the difficulties encountered by the construction minerals industries in connection with the issuing of new extraction permits the question has been raised on several occasions whether it is still appropriate to consider landowner minerals as being minerals of low national importance'41. Land Use Planning Short, medium and long-term access to mineral deposits is crucial for the sustainable development of the minerals industry. Two factors play a key role in this regard, namely whether a national minerals policy exists and the legislation and practice of land use planning. Land use planning is an integrative process, in which different claims of utilization are subjected to an evaluation process. For land use planning to be an effective tool it is essential that it is based on a solid and well substantiated database and that it includes all necessary information, including information on mineral deposits. The study has shown that in many Member States information on mineral deposits is not either not available at all or incomplete in land use planning data bases. From a minerals development point of view, it is crucial that the information concerning mineral deposits is entered into the land use databases to ensure that minerals are considered in all land use planning decisions. Geological surveys have to make the data on mineral deposits available. The need for closer involvement of national geological surveys in land use planning has been identified as one of the most important issues by the coordinating committee of the geological surveys of the Federal States in Germany. Similar views have been expressed by Regueiro of Spain[4]. Key factors influencing land use planning are: • Policy and legislation taken at EU-level • Structure of government • Role of national government in the planning process for minerals • Planning framework Policy and legislation taken at EU-level have shown to have a major impact on national land use planning (e.g., European Spatial Development Perspective (ESDP), NATURA 2000, etc.). The structure of government in the Member States is another critical factor in the planning process for mineral extraction (hierarchical planning). The survey of Member States has shown that in most of them land use planning is done at two levels, namely at regional and at district or municipal level. Since mineral deposits are not uniformly spread throughout a country land use planning for minerals at a low tier of government has been found to be not without problems and does not promote sustainable solutions. The view has been expressed by a number of industry representatives that land use planning for minerals should be done at high level -national or regional level - and should consider long time periods, which depending on the mineral could be 20 to more than 50 years. A principal distinction between Member States is the degree to which land use plans provide detailed prescriptive information on where mineral extraction might be acceptable and where it is not acceptable. Some Member States have identified areas for minerals extraction, areas where minerals extraction may be possible subject to certain criteria and areas where minerals extraction is not allowed. Examples are the Scandinavian countries, Denmark, Belgium, certain Federal States of Germany and some provinces in Austria as well some regions in France. Experiences in some of these states have shown that the time required for the authorization process tends to be significantly shorter for projects situated in declared extraction areas. Some Member States provide rather policy guidance and contrast the above-mentioned approach; for example the procedure adopted in England and Wales is that at ministerial level regional demand forecasts for aggregates are made for periods of 7 to 10 years. It is then up to the local authorities to ensure that sufficient extraction sites are available at local level to meet the demand. Authorization of mineral development The issue of permits and authorisation depends to some extend on the mineral rights. For minerals permits to conduct mineral exploration work and to exploit minerals are required in all Member States for minerals that are important to the state or belong to the state. In the case of landowner minerals the situation differs. The permits fall into the following areas: mining rights, mining licences (exploration, mining), permits according land use plan, other permits, especially health and safety, environmental permits. The procedures for granting mining licences have been updated in most Member States in recent years to incorporate more fully environmental impacts of minerals extraction in the approval procedures. Applications The authorisation process for mineral extraction defines the details required by the applicant and the public bodies involved in the process. To assist the applicant with the preparation of application some of the Member States (Belgium, Denmark, England and Wales) have standard application forms. An important aspect of the authorisation process is which public body is the lead authority and the relationship between the various public bodies involved in the process. In some Member States, five or six public bodies take part in the process, i.e. the mining authority, the environmental agency, the nature conservation agency, the water authority, and the health and safety agency. This tends to prolong 'the authorisation process. Critical for the time required to complete the authorisation process is whether the various investigations that are requested by public bodies participating in the process can be carried out in parallel or have to be performed in sequence. Significant timesavings can be expected if the processes run in parallel as for example in the Netherlands. Environmental impact assessments A key element of the authorisation process is whether or not a project application requires an environmental assessment (EA). The survey of Member States has shown that there exists no common pattern as far as environmental assessments are concerned. The span of threshold values ranges from 5 hectares in Ireland and Portugal up to 500 hectares in the case of state owned minerals in the Netherlands. With regard to marine aggregates, Ireland and the Netherlands make an EA compulsory for all project applications. Irrespective of defined threshold values it has become practice in some Member States to subject all applications for extraction licences to an EA. Examples are Greece, Norway, Portugal and all quarrying operations in France. Right to appeal The study has shown that appeals are one of the major causes for delays in the authorisation process. Most Member States have the right of appeal by the applicant and by third parties as part of their authorisation process. As far as the applicant is concerned this right is confined in Denmark and Finland to strictly legal matters and not to the outcome of the application. All Member States except Great Britain have the right for appeal by third parties in their authorisation process. In Finland, Greece and Sweden this right is however confined to local residents. In Denmark appeals by third parties are uncommon. This can be attributed to dealing with contentious issues at the planning stage. Funding of restoration work An issue, which is of concern to most Member States, is the funding of restoration work. For this reason, most of the Member States provide in their minerals legislation for mechanisms to secure the funding of restoration work. This is being done through provisions for the establishment of closure funds, bank guaranties or other forms of security. These arrangements are part of the extraction permissions. At this stage there is insufficient information to assess which arrangements are best. Monitoring Monitoring is a central element of the authorisation process. Its objective is to ensure adherence to regulations and good mining and environmental practices. In most Member States the staff of the mining authorities is qualified mining personnel having been trained on mines and/or at appropriate universities. The situation is different when the supervising and monitoring authority comes from lower tiers of government, as is the case with most landowner minerals. In these cases the inspection personnel tends to have a much broader background in the fields of works inspection and health and safety, but is often lacking in specific mining skills. Evaluation of the Impact of Mineral Policies/Systems Minerals Policy Minerals Policy in many Member States is a low-key issue and few Member States have specific and clearly defined and published mineral policies. A number of Member States have a minerals legislation which dates back to a time when minerals were considered as one of the pillars of economic development and for this reason minerals were given a high legal status as reflected by the category of "free minerals", i.e. Austria, Germany, Finland, Norway, and Sweden. Some of the Member States have a principal minerals legislation that is based on the concept of sustainable development. Most Member States delegate implementation of minerals policy issues to lower tiers of government. At this level the instrument to implement the policy is land use planning. Access to and protection of mineral deposits is an important aspect of mineral planning policies, particularly as far as construction minerals are concerned which constitute the bulk of non-energy minerals extracted in Europe. However, in countries, which do not have clearly defined mineral policies, minerals issues are often allocated lower priority in land use planning compared to other issues such as environment protection, nature conservation and water protection. In very few Member States reference is made to minerals being an important consideration in land use planning, e.g. identifying areas which have been set aside for minerals extraction. One of the critical issues is that in most Member States construction minerals are not considered to be of national or high importance. This is despite the fact that the European society is strongly dependent on a sustainable supply of construction minerals, which as far as the interior of Europe is concerned should, for environmental reasons, involve short transport distances'51. Legislation All Member States have legislation governing mineral rights, licensing of minerals exploration and exploitation, monitoring and supervising of mining activities and mine closure. In most Member States several categories of minerals are defined. Usually a distinction is made between more common minerals with an intrinsically lower value (construction minerals and some of the industrial minerals) with the mineral right belonging to the landowner and minerals of higher intrinsic value or of national importance (e.g. metallic ores) with the mineral right belonging to the state. With regard to the principal legislation controlling mineral extraction there, exists - in addition to the specific minerals legislation (i.e. mining act) other legislation, such as an excavation act, planning act or other laws that impact mineral extraction. In some Member States the specific minerals legislation no longer applies (e.g. Belgium) or only applies to minerals that do not belong to the landowner. As a result minerals of low value (mostly construction minerals) are legislated by other laws, which are either a general land use planning law or an environmental law (e.g. Belgium, France, Germany). In addition to the specific minerals or raw materials legislation, there are a number of other laws, which are of direct or indirect relevance to minerals extraction in the Member States (e.g. environmental aspects). There is an increasing tendency in Europe to regulate minerals extraction through provisions in other legislations, i.e. environmental protection, forestry and water legislation. As most of these provisions are of a prohibitive nature, minerals extraction is adversely affected. Administration The study has shown that a number of different laws, such as for mining law, nature conservation law, water law, waste law apply to mineral exploitation and that these laws are administered by different government, provincial and local authorities. This raises the issue of the effectiveness and efficiency of the administrative processes governing mineral extraction. The various country reports have shown that different approaches have been adopted by Member States and that the situation can be quite complex with the potential for inefficiencies, time delays and increased cost. The analysis of the various procedures adopted in the different Member States shows that in all instances the authorisation process is such that it is unavoidable for local and regional authorities to become involved in the final decision making step. The main difference between the Member States is the role of the national level in the process. In some Member States and for some categories of minerals, the national authority becomes involved in the authorisation process in an operational manner. An example is the applications for the exploitation of state owned minerals and free minerals in Austria. The other extreme are states where the role of national authorities is to define policies and to provide guidance but not to become operationally involved in the process. Examples of this approach are England and Wales. In addition, in these countries the lower level authority is charged with the responsibility to ensure that adequate mineral reserves are available for extraction (landbanks). In all other Member States the issue of mineral reserves is controlled by private interests and initiatives. The authorities in these cases act as permitting agencies. Between those extremes falls France where the national authority has delegated the responsibility for the administration of minerals applications to its regional directorates, but in the case of state owned minerals has reserved the final decision to the national level. The difference between France and Austria is that in France the role of provincial and local authorities in the authorisation process is restricted. The role of central government in the issue of permits for landowner minerals tends to be limited. In the majority of Member States, decisions concerning this category of minerals are taken at the regional and sometimes even local level. Finally, it should be noted that in a number of Member States minerals are not very well covered and considered in the land use planning process. The time required for extraction permission varies considerably. It ranges from a few months to several years and usually exceeds the time specified. Reports from Member States indicate that the time required for an extraction permission is significantly shorter if the application concerns a mineral deposit that is situated in a designated mineral extraction area. The main reasons for time delays are the involvement of many different authorities in the licensing procedure and the involvement of the public in certain elements of the approval process. Experience shows that especially the preparation of Environmental Impact Assessments (EIA's) is a complex issue and tends to take up much of the time. Minerals planning The level at which planning for minerals is done is crucial. At the national level regional demands for minerals can be considered and included in overall mineral development plans taking into consideration the distribution of mineral resources in the country. However, at this level it is impossible to include all detailed site-specific considerations. This is the responsibility of lower level planning. Lower level planning on the other hand lacks the broader background and the long-term vision. It appears therefore that minerals planning has to be done at two levels, namely long-term strategic planning at the national or at least regional level and detailed planning at the lower level. Models for such an approach are for instance England and France. Social Benefit Societal benefits can be measured in the most direct way by the number of persons directly and indirectly involved in the non-energy extractive industries. Directly involved are persons working on the extraction and processing of minerals and the production of mineral based products such as cement, bricks, tiles and other mineral based building materials and ready made concrete. Indirectly involved are persons manufacturing goods and materials used by the non-energy extractive industry, those that provide services to it, and also the municipalities involved. One of the fundamental problems encountered in assessing the importance of the non-energy extractive industries is the incomplete statistical information. As far as the traditional mineral commodities such as metal ores and the more important industrial minerals are concerned there exist relatively reliable statistical data. The same cannot be said for the bulk of minerals produced in Europe, namely construction minerals. For example in Germany and Austria the production of construction minerals is underestimated by the official statistics by as much as 50%. This is seen as a serious shortcoming as it does not reflect the true importance of the sector. In the case of construction minerals another difficulty is that many of the companies are also involved in downstream activities, which add value. Typical examples are ready-mixed concrete or manufacturing of bricks or cement production. In the case of many industrial minerals producers the mineral extraction is only a minor aspect of the business. The difficult question is where to draw the line. According to figures published by UEPG (Union Europeenne des Producteurs des Granulats), which represents 17,000 companies employing 250,000 persons producing 2.6 billion construction minerals, the annual turnover of the construction minerals industry amounts to 18.5 billion Euros. To this have to be added the production values of companies not belonging to UEPG and the production from the New Member States. Comparing the employment figures quoted by UEPG, which do not include companies from the New Member States, with the EU-15 figures and considering that the EU-15 figures are not confined to construction minerals but include all non-energy extractive industries, it is apparent that the official EU figures on the non-energy extractive industries are a serious underestimation of the economic importance of the sector. A socio-economic study of the finish mineral industries indicate that job creation in downstream industries using mineral raw materials is 35-40 times the number of people working directly in the mineral sector. Environmental Performance Environmental considerations are an important aspect of the planning and operation of minerals extraction sites in all Member States. In most member States the larger producing companies have established environmental quality management systems and report on their environmental performance. Many of the smaller mineral producers in Europe do not have the resources to implement such systems. One of the recommendations for overcoming this was that small enterprises should be supported with the implementation of new regulations'61. No standardised approach to environmental performance reporting exists in the Member States. Most of the large mineral producing companies in Europe do however report on environmental performance in their Annual Reports. In some Member States the polarisation between environmental groupings and mineral producers no longer exists and meaningful ways of collaboration have been found to mutually benefit both sides'71. A matter of concern to the European minerals producers is the continuing shifting of goalposts as far as environmental standards are concerned. This has adverse effects on investments in mineral development, which is long term in nature. Another concern is that environmental standards increase continuously. This trend has to be seen against the life span of mineral production projects, which ranges from 20 to 100 years. Conclusions Minerals and in particular construction minerals are crucial for the long-term development of Europe. In the case of construction minerals the consumption patterns and logistics are such that most European states will have to rely on local supply of such minerals. The absence of clearly defined minerals policies, incomplete official statistical data on minerals production and consumption as well as the contribution of minerals to the European and national economies, and the lack of information on mineral resources in land use data banks indicate that minerals are a low priority issue in Europe. In many Member States construction minerals and in particular aggregates are still considered as minerals that occur in abundance and require little protection. This can have long-term consequences for the sustainable supply with construction minerals. As part of the concept of sustainability mineral resources should be considered as an integral part of the land use planning system and process. Environmental legislation at the EU-level has a major influence on minerals extraction in Europe, both in terms of access to mineral deposits as well as in terms of cost of production. Environmental legislation has not been balanced by initiatives, which recognise the importance of minerals for the long-term development of Europe. Minerals planning has to be done at two levels, namely long-term strategic planning at the national or at least regional level and detailed planning at the lower level. Experiences from the different Member States show that there is potential for improving administrative procedures for the minerals industries. Acknowledgements This work, presented at SDIMI 2005, was commissioned by the European Enterprise Directorate. Within the framework of the study a country report was made for each EU member state. Markus Ramler (University of Leoben), Slavko Solar (Geological Survey of Slovenia) and Simon Friškovec (Ministry for Economy, Directorate for Energy, Mining sector; Slovenia) wrote the Country report for Slovenia. The country report of Slovenia and the complete Study of minerals planning policies in Europe were not yet broadly discussed in Slovenia. References [1] European Commission (2004): DG Enterprise work- ing paper, preparatory work on the assessment of the competitiveness in the EU-Non-Energy Extractive Industries, pp. S-8. [2] European Commission (2001): Communication of the Commission 264: A sustainable Europe for a better world: a European Union strategy for sustainable development. [3] EU (2000): Promoting sustainable development in the EU non-energy extractive industry" (COM (2000) 26S, Section 2...3 "Environmental Impact"). [4] Regueiro, M., Martins, L., Feraud, J. & Arvidsson, S. (2002): Aggregate Extraction in Europe: The Role of the Geological Surveys. Raw materials planning in Europe. Change of conditions! New perspectives: Conference transcript and field trip guide: Tagungsband und Ekskursionsführer. Krefeld: Geologischer Dienst NordrheinWestfalen, pp. 187-198. (2002) [5] Quarry Association of Switzerland (2002): Kurze Transportdistanzen begrenzen schädliche Umweltauswirkungen. Sand und Kies, Januar/ Februar 2002, pp. 4-7. [6] H ägele, H. (1988): Sicherheit und Gesundheitsschutz im Bergbau: Auswirkungen von EU-Regelungen auf das Arbeitsumfeld und die wirtschaftliche Situation der Unternehmen. In Studien der ISG Sozialforschung und Gesellschaftspolitik. Band 23 Köln 1998. [7] The Forum Rohstoffe, WWF (2003): Forum Rohstoffe und WWF vergeben den Naturschutzpreis 2003. Stein&Kies, NovemberDezember 2003, p.1. Thermodynamic Analysis of AlSilOMg Alloy Termodinamična analiza zlitine AlSilOMg Maja Vončina, Primož Mrvar, Jožef Medved Faculty of material science and engineering, Department of materials and metallurgy, University of Ljubljana, Aškerčeva 12, 1000 Ljubljana, Slovenija; E-mail: jozef.medved@ntf.uni-lj.si Received: July 2S, 200S Accepted: October 28, 200S Abstract: The AlSilOMg alloy is one of the most frequently used alloys for different purposes because of its suitable mechanical properties. The alloy was examined with chemical analyses, with the triple simple thermal analysis (TSTA), the simultaneous thermal analysis (STA), the computer simulation using Thermo-Calc program and with the metallographic analyses. The triple simple thermal analysis has been performed in three measuring cells simultaneously, with different cooling rates. High cooling rates simulated the actual cooling rate in the die casting process. Chemical analyses were used to verify whether the concentration of alloying elements is in suitable limits. Metallographic analyses enabled us to define phases in the microstructure at different cooling rates and they were verified with the Thermo-Calc computer simulation method. Research showed that the alloy should contain the amount of silicon near to the highest limit and a suitable concentration of manganese, which prevents the formation of needle ß-AlSFeSi phase and enables formation less harmful a-AlI5(MnFe)3Si2 phase. The triple simple thermal analysis showed that higher cooling rate has beneficial influence on the development of microstructure. Key words: Al-alloy, thermodynamics, solidification, triple simple thermal analysis. Introduction The AlSilOMg alloy is used for making complicated, heavy-duty castings with thick walls for aircraft, vehicle, chemical and food industry. It is suitable for sand casting, mould casting, and die casting. At casting of Al alloys often defects appear which cause that the casting is unsuitable. Reasons for casting defects and defects in the structure of the material can be found in the melt preparation technology and in the casting procedure itself. Technically significant aluminium casting alloys are developed from the Al-Si binary system being extended with some other alloying elements to improve mechanical and other properties where it becomes important the process of precipitation. Excellent castability of aluminium casting alloys enables to produce castings of complicated shapes. Alloying the magnesium to the binary Al-Si alloys enables precipitation of alloy and attainment of prescribed mechanical properties. For a reliable production of castings with prescribed properties we have to get insight into the course of solidification, development of microstructure and the structure of the alloy, which in practice represents bigger or smaller difficulties. To accomplish this purpose we have laboratorically examined AlSilOMg alloys of three different manufacturers (ZI, Z2 and Z3). Foundries usually use chemical analyses for control of the melt, and optical and electron microscopy for control of the final castings. We have examined our alloys with chemical analyses, with the TSTA, the STA, with the computer simulation using the Thermo-Calc program, and with the metallographic analyses. The minimum and maximum liquidus temperatures - T,, . and T,, , minimum and r L/min L/max^ maximum eutectic temperatures - T„, . and r E/min TE/max, temperatures of completed solidification - TK, and the temperatures of precipitation of the Mg2Si phase were determined. Crystallography of AlSilOMg alloy Aluminium and silicon are showing limited mutual melting and they form a eutectic system with the eutectic point at 12.6 mass % Si and at temperature 577 °C. Silicon as an alloying element causes small contractions during the cooling and solidification'1!. Concentration of silicon in aluminium alloys is 5 to 25 %'1]. With alloying magnesium to the binary alloys Al-Si the heat precipitation of the alloy is enabled. It is necessary to prepare the melt before the casting process, because of its influence on the quality of final castings. Preparation of the melt before the alloying mainly consists of cleaning the melt to remove impurities, to degas and modify the melt in order to obtain the required shape, size and distribution of microstructure components and phases'1,21 The chemical composition of the casting alloy is presented in Table 1'1]. The alloy Table I. Chemical composition of alloy AlSilOMg ISO (3522 AlSilOMg (R164)) m. Tabela I. Kemijska sestava zlitine AlSilOMg po ISO 3522 AlSilOMg (R164). Si Fe Cu Mn Mg Zn Other elements Difference 9.0-10.0 06 (П ÖÖ5 0.45-0.6 ÖÖ5 0Л5 Al Table 2. Possible reactions during solidification of Al-Si-Mg alloy[I]. Tabela 2. Reakcije, ki lahko potekajo med strjevanjem zlitine Al-Si-Mg. Reaction_Temp. [°C] ej l»(Al) + Mg2Si 593 e2 1» Al3Mg2 + Mg2Si e3 1 <=> Ali2Mgi7 + Mg2Si E! L<=> (Al) + Mg2Si + (Si) 550 E2 L » (Al) + Al3Mg2 + Mg2Si 444 E3 L <=> Al3Mg2 + Al30Mg23(HT) + Mg2Si 445 E4 L » Al12Mg17 + (Mg) + Mg2Si 434 U! L + Al i2Mgi7 » Al5Mg4 + Mg2Si 452 U2 L + Al5Mg4 <=> Al30Mg23(HT) + Mg2Si_448 belongs to the Al corner of the ternary system Al-Si-Mg, where the following equilibria occur: L> aA1, L > aA1 + ßsi and ternary eutectic L > aA1 + Mg2Si + ßsi'(Figure I)[2]. In alloys of Al-Si-Mg system the process of solidification can be performed over the reactions that are shown in Table 2. Depending on the cooling rate, especially for in practice typical larger cooling rates, dendritic shape primary crystals multi-component solid solution aA1 can be obtained in the microstructure in the first stage of solidification (Figure 2a)[1], because of alloying elements like iron and manganese, we can trace in the microstructure labyrinthine phase aA1-Al15(MnFe)3Si2 (Figure 2b)[1'2]. Figure I. Liquid surface of the ternary system Al-Si-Mg[7]. Slika I. Likvidus ploskev ternarnega sistema Al-Si-Mg. Figure 2. Microstructure of AlSilOMg alloy: a) Primary crystal of solid solution aA1dendritic shape and eutectic (aA1 + bsj), b) Dendritic phase of aA1 and a-AlI5(MnFe)QSi2 phase (labyrinthine) and MgpSi (black)[7]. Slika 2. Mikrostruktura zlitine AlSilOMg: a) Primarni kristali trdne raztopine aA1 v obliki dendritov ter evtektik (aA1 + bsj), b) Dendriti faze aA1 ter faza a-AlI5(MnFe)QSi2 (labirintasto) in MgpSi (črno). Experimental In the present research we used standard blocks of AlSilOMg alloy of three different manufacturers with composition, shown in Table 3. TSTA measurements were carried out in three different cells simultaneously. Each measurement was performed three times. Figure 3 shows the measuring cells used in TSTA. We used two measuring cells made of gray cast iron with lamellar graphite, while the third cell was made by the Croning process. The first measuring cell, made of gray cast iron with lamellar graphite, had a diameter of 3O mm and volume of 33.8O7 mmQ, the second one, made of the same materials, had a diameter of 15 mm and volume of 8.O62 mmQ, while the third cell, made of sand, had the same dimensions as the first one. We have put the K-type thermocouples in the center and at the same height of each measuring cell, as shown in Figure 3. The prepared alloys were melted in graphite crucibles in an induction furnace. As the temperature 75O °C was reached, the melt was poured from the graphite crucible into the three measuring cells. The thermocouples were connected to the National Instruments DAQPad-MIO-16XE-5O measuring card, and this to the personal computer, where the measured values were collected with the LabVIEW 5.O program. Cooling curves were plotted using the Origin 6.O program. Different geometries and materials of the measuring cells caused various heat transfers, and, consequentially, different cooling rates. Simultaneous thermal analysis of specimens of starting materials was performed on the STA 449 NETZSCH machine. We put together two equal cups made of corundum to the platinum sensor. In one cup there was the examined material, in the other one the reference material. The measurements were carried out in a protective atmosphere of inert gas 99.999 % pure nitrogen. The specimens were heated up to 72O °C with heating rate of 1O K/min and cooled with the same cooling rate to the room temperature. Thermodynamic equilibrium of the alloys ZI, Z2 and Z3 of three different manufacturers were simulated with the computer Thermo-Calc application. A suitable database in the program and the elements that composed our alloy were chosen. Our next step was to determine the amount of elements and to define the temperatures and pressures of the simulated equilibrium. The program has recorded all the thermodynamically possible phases that were present at defined conditions, and it constructed the equilibrium binary phase diagram. For all the alloys, the phases of completed solidification were simulated. The chemical analyses of starting materials made by the Z1, Z2 and Z3 manufacturers and of the specimens after the TSTA were made. The specimens for the metallographic Table 3. Chemical composition of alloy from three different manufacturers; mass %. Tabela 3. Kemijska sestava zlitin treh različnih proizvajalcev; mas. %. _Al Cri Mg Mnl Си Zn Ti Ni3 Fe2 Si2 Pb z1 88.4888 0.0484 0.2999 0.1198 0.0815 0.0415 0.0092 0.0249 0.6504 10.2216 0.0067 z2 87.5246 0.0018 0.3458 0.0209 0.0239 0.0175 0.0137 0.0035 0.4593 9.9959 0.0086 z3 88.0195 0.0034 0.3631 0.0176 0.0728 0.0626 0.0065 0.0221 0.4556 10.9168 0.0503 а) Ъ) с) Figure 3. Measuring cells: a) made Ъу Croning sand, Ъ) made Ъу cast iron 30 mm diameter and c) made Ъу cast iron IS mm diameter; I - cast iron, 2 - thermocouples and 3 - coated. Slika 3. Merilni lončki: a) iz Croning peska, Ъ) iz sive litine premera 30 mm ter c) iz sive litine premera IS mm; I - siva litina, 2 - termoelementi in 3 - s premazom. analyses were cut from the specimens after the completed TSTA. The samples for the optical microscopy were prepared by the standard metallographic procedure. Prepared samples were observed and photographed in the Nikon Microphot FXA optical microscope that was equipped with the 3CCD-videocamera Hitachi HV-C20A and the analySIS computer program to analyze metallographic pictures. Results And Discussion Cooling curves and suitable microstructures of alloys from three different manufacturers are shown in Figures 4 - 6. Table 4 presents average temperatures of the TSTA. Table 4 reveals that the temperatures of the starting solidification, the minimum and maximum liquidus temperatures, and the minimum and maximum eutectic temperatures are Table 4. Characteristic temperatures from triple simple thermal analyses; °C. Tabela 4. Značilne temperature trojne enostavne termične analize; °C. Alloy ZI Z2 Z3 а b с а b с а В С TN 640.5 633.0 647.5 639.3 631.0 629.8 626.3 633.5 TL 588.0 578.5 575.5 Tb/min 582.3 581.8 576.5 584.5 582.3 577.3 575.3 575.2 571.5 Tb/max 586.5 584.0 579.8 589.0 584.5 579.5 579.8 581.7 575.8 dTL 4.2 2.2 2.2 4.5 2.2 1.5 4.5 6.5 2.8 TE 556.0 567.0 567.0 566.5 ТЕ/шш 563.5 556.8 553.3 558.8 554.0 551.3 566.8 567.3 565.8 t E/m ах 566.3 559.4 557.0 562.3 556.2 552.5 569.0 569.0 567.0 dTE 2.8 2.6 2.5 3.5 2.2 1.2 1.5 1.2 0.8 Тк 542.8 550.2 531.0 548.8 545.0 531.0 542.8 550.8 533.0 decreasing with the increasing cooling rate. The highest liquidus undercooling was observed at the alloy Z3, the highest eutectic crystallizations undercooling at the alloy Z2. With the STA, where the cooling rate was IO K/min, temperatures of the starting solidification or liquidus temperature at cooling, and the temperatures of the initial melting or solidus temperature, at heating were determined. During cooling, the first to begin to solidify was the alloy ZI (585.3 °C), then the alloy Z2 (585 °C), and the lowest liquidus temperature corresponded to the alloy Z3 (581.3 °C) (Figure 7a). Heating curves showed that the alloy Z3 had the lowest solidus temperature (543 °C), the alloy Z2 had a little higher solidus temperature (55O °C), and the highest solidus temperature belonged to the alloy Z1 (557 °C) (Figure 7b). @ DO 750 700 5 50 6 DO SSO son 450 ET 400 350 (300 200 150 too 50 1 Icooling rale: 5,1 °C/s \ 4 rate: 27,2 "Cls ■ ■ 3. cooling rate: 100 "C/s О 50 100 150 200 250 300 350 400 450 500 550 000 t[s] Figure 4. Cooling curves of AlSilOMg alloy ZI at three different cooling rates and their corresponding micro-structure; l. sand mould, Ф 3O mm; 2. cast iron mould, Ф 3O mm; 3. cast iron mould, Ф IS mm. Slika 4. Ohlajevalne krivulje zlitin AlSilOMg ZI pri treh ohlajevalnih hitrostih ter njihove ustrezne mikrostrukture; l. peščena kokila, Ф 3O mm; 2. jeklena kokila, Ф 3O mm; 3. jeklena kokila, Ф IS mm. Using the Thermo-Cale program, the course of equilibrium solidification of the AlSil OMg alloy was determined. The SipTi phase started to solidify the first, followed by the aA1 phase (primary mixture crystals of solid solution based on aluminium). We can define the temperature of solidification of aA1 crystals as liquidus temperature of the alloy. From the melt, the Si and Al13Fe4 phases began to precipitate. When the eutectic temperature was reached, the remaining melt solidified as eutectic (aA1+ ßsi). At the end, the MgpSi phase and Al1pMn and AlpCu phases precipitated from the solid solution. Figure 8 shows characteristic temperatures at different cooling rates. Cooling rate of O.Ol°C/s represented the equilibrium solidification that was achieved with the Thermo-Calc program. With STA the cooling l. 3. Figure S. Cooling curves of AlSilOMg alloy Z2 at three different cooling rates and their corresponding micro-structure; l. sand mould, Ф 3O mm; 2. cast iron mould, Ф 3O mm; 3. cast iron mould, Ф IS mm. Slika S. Ohlajevalne krivulje zlitine AlSilOMg Z2 pri treh ohlajevalnih hitrostih ter njihove ustrezne mikrostrukture; l. peščena kokila, Ф 3O mm; 2. jeklena kokila, Ф 3O mm; 3. jeklena kokila, Ф IS mm. Figure 6. Cooling curves of AlSilOMg alloy Z3 at three different cooling rates and their corresponding micro-structure; l. sand mould, Ф 3O mm; 2. cast iron mould, Ф 3O mm; 3. cast iron mould, Ф IS mm. Slika 6. Ohlajevalne krivulje zlitine AlSilOMg Z3 pri treh ohlajevalnih hitrostih ter njihove ustrezne mikrostrukture; l. peščena kokila, Ф 3O mm; 2. jeklena kokila, Ф 3O mm; 3. jeklena kokila, Ф IS mm. rate of 0.17 °C/s was achieved. Cooling rates of approximately 5 °C/s, 40 °C/s, and 100 °C/s were achieved with the TSTA. At equilibrium cooling rate, only liquidus temperature TL and the temperature of completed solidification TE (the lowest temperature where the melt still exists or solidus temperature) were determined. The differences in TL and at TE appeared because of different chemical compositions of alloys of researched alloys. The tendency is indicated that characteristic temperatures of solidification are dropping with the increasing cooling rate. If all three materials are compared, it can be noticed that the greatest deviation appeared at the alloy Z3. The solidification of eutectic took always place the first with the alloy Z3, followed by the alloy Z1, the last was the alloy Z2. The widest solidification range had the alloy Z2 and the narrowest the alloy Z3. The level of Figure 7. Cooling (a) and warming (b) curves of specimens from the simultaneous thermal analysis taken from the block. Slika 7. Ohlajevalne (a) in ogrevne (b) krivulje simultane termične analize vzorcev vzetih iz blokov zlitin ZI, Z2 in Z3. ZI ■ TL dT, Figure 8. Graphic review of the main temperatures during solidification of alloy at triple simple thermal analyses (S °C/s, 40 °C/s in 100 °C/s), simultaneous thermal analysis (0.17 °C/s) and at Thermo-Calc (0.01 °C/s) and their corresponding microstructures. Slika 8. Grafični prikaz značilnih temperatur pri strjevanju zlitine iz trojne enostavne termične analize (S °C/s, 40 °C/s in 100 °C/s), simultane termične analize (0,17 °C/s) ter Thermo-Calca (0,01 °C/s) in ustreznih mikrostruktur. undercooling at liquidus temperatures and at eutectic temperature increased with the increasing cooling rates. The alloy Z2 had the highest liquidus and the smallest eutectic undercooling. Conclusions Examinations of three commercial AlSilOMg alloys with the TSTA, STA, computer Thermo-Calc program, chemical analyses and metallographic analyses enabled several conclusions. The variation in chemical composition of three commercial alloys has been reflected on the characteristic temperatures of the TSTA. Silicon and magnesium reduced not only liquidus temperatures, but also the temperatures of eutectic solidification (aA1+ ßsi). Among the metal inclusions, the most frequent in the AlSilOMg alloy is iron that precipitates in a shape of needles, which represents intermetallic ß-Al5FeSi phase that worsen the properties of the alloy[10]. The manganese present in the alloy prevents formation of ß-Al5FeSi phase and forms less harmful labyrinthine, a-Al15(MnFeMe)3Si2 (Me=Cr,Cu), phase[10]. The alloy ZI contained more a suitable amount of manganese with regard to iron; therefore the smallest amount of the harmful ß-Al5FeSi phase was found in alloy ZI, while the amount of a-Al15(MnFeMe)3Si2 phase was the highest. In the alloys Z2 and Z3 with less manganese it had to be alloyed. Solidification in usual practice takes place under non-equilibrium conditions, mainly because of high cooling rates. The development of microstructure depends on the chemical composition, the cooling rate and the addition of modifying elements. Highest cooling rate causes reduction of the liquidus temperatures and the temperatures of binary eutectic solidification. Small primary crystals of multicomponent solid solution based on aluminium, aA1 dendritic shape, and equable distribution of eutectic are formed at higher cooling rates, which improves the mechanical properties of the castings, and conditions closer to the die-casting conditions are achieved. The alloy Z2 had a larger amount of silicon, and thus the microstructure primary phase aA1 and binary eutectic is equally distributed, but during the solidification it formed primary silicon crystals, which is caused by the fluctuations in the melt. The best results with the TSTA were obtained with the alloy Z3, but the microstructure was the most favorable with the alloy ZI, due to small primary crystals. Binary eutectic end a-Al15(MnFeMe)3Si2 (Me=Cr,Cu) and ß-Al5FeSi phases were equally distributed among the interdendritic spaces of primary crystals aA1. There was less ß-Al5FeSi phase because of the suitable amount of manganese. For use in the casting production the alloy ZI can be recommended. Povzetek Termodinamična analiza zlitine AlSilOMg Pri ulivanju pogosto prihaja do napak, ki povzročijo, da je ulitek neuporaben. Vzroke za livarske napake in napake v zgradbi materiala lahko iščemo v tehnologiji priprave taline na litje in v postopku litja ali pa že v samem vhodnem materialu. Preiskovali smo zlitino AlSilOMg proizvajalcev Zl, Z2 in Z3 in sicer s trojno enostavno termično analizo, simultano termično analizo, z računalniško simulacijo Thermo-Calc ter metalografsko analizo. Za vsako zlitino različnih proizvajalcev smo preizkus trojne enostavne termične analize ponovili trikrat. Glede na hitrost ohlajanja smo oznakam pripisali končnico a za ohlajanje v peščeni kokili, b za ohlajanje v veliki jekleni kokili ter c za ohlajanje v mali jekleni kokili. Kemijsko analizo smo opravljali na vhodnih materialih Zl, Z2 in Z3 ter na vzorcih po končani trojni enostavni termični analizi. Meritve trojne enostavne termične analize so potekale v treh različnih lončkih hkrati. Uporabili smo dva merilna lončka (kokili) iz sive litine z notranjim premerom 3O mm in z notranji premer 15 mm, tretji merilni lonček pa je bil izdelan po postopku Croning premera 30 mm. V vsak merilni lonček smo v isti višini namestili na sredino termo-element tipa K (Ni-CrNi) ter jih priključili na merilno kartico National Instruments DAQPad-MI0-16XE-50, le-to pa na osebni računalnik na katerem smo s pomočjo programskega paketa LabVIEW 5.0 zajemali merilne vrednosti ter jih sproti grafično in tabelarično beležili. Pripravljene zlitine, mase približno od 230 g do 250 g, smo stalili v grafitnem lončku s pomočjo indukcijske peči. Ko je talina dosegla temperaturo 750 °C, smo odkrili lonček, odstranili oksidno plast in vlili talino v vse tri merilne lončke. Z računalniško aplikacijo Thermo-Calc smo izdelali simulacijo termodinamičnih ravnotežij zlitine ZI, Z2 in Z3. V programu smo izbrali ustrezno bazo podatkov, iz periodnega sistema pa izbrali elemente, ki so sestavljali našo zlitino. Program nam je izpisal vse termodinamično možne faze, ki so prisotne pri določenih pogojih in skonstruiral binarni ravnotežni fazni diagram. Vzorci zlitin Z1, Z2 in Z3 so bili preiskani s simultano termično analizo. Na platinasti senzor aparature STA 449 firme NETZSCH smo vstavili dva enaka lončka. V en lonček smo dali preiskovani material, v drugega pa primerjalni (inertni) vzorec. Meritve smo opravljali v zaščitni atmosferi zaščitnega plina 99,999 % N2. Vzorce smo segrevali do temperature 720 °C s hitrostjo 0,17 °C/s in jih ohlajali z enako hitrostjo do sobne temperature. Vzorce za metalografske preiskave smo pripravili iz vzorcev od trojne enostavne termične analize. Ustrezno razrezane vzorce smo vroče vložili v umetno maso ter jih nato mehansko pripravili (brusili in polirali). Pripravljene vzorce smo nato opazovali in slikali z optičnim mikroskopom Nikon Microphot FXA, ki je opremljen s 3CCD-videokamero Hitachi HV-C20A in računalniškim programom analySIS za analizo metalografskih slik. S termično analizo določene povprečne vrednosti hitrosti ohlajanja znašajo v peščenem lončku izdelanem po postopku Croning v območju med 4 in 6 °C/s, v jeklenem lončku premera 30 mm v območju med 30 in 45 °C/s in v jeklenem lončku premera 15 mm v območju med 90 in 110 °C/s. Ugotovili smo, da z naraščajočo ohlajevalno hitrostjo karakteriastične temperature trojne enostavne termične analize padajo, podhladitve pa se večajo. Pri ohlajanju zasledimo s pomočjo diferenciranih ohlajevalnih krivulj izločanje faze Mg2Si, ki se začne pri temperaturi 537 °C. Računalniška simulacija s programom Thermo-Calc nam potrdi nastajanje te faze pri temperaturi 535 °C pri Z1, pri 549 °C pri Z2 ter pri 556 °C pri Z3. Literaturni viri navajajo izločanje faze Mg2Si pri temperaturi 554 °C. Literaturni vir navaja možnost nastanka faze a-Al15(Fe,Mn,Me)3Si2 (Me=Cr,Cu), ki jo zasledimo v mikrostrukturi kot labirintasti heterogeni zlog, z naraščajočo temperaturo litja pa je te faze manj. Z metalografsko analizo ugotovimo, da se mikrostrukture glede na proizvajalca razlikujejo med seboj. V vzorcu iz zlitine Z2 je mikrostruktura izločenega evtektika bistveno enakomerneje razporejena v primerjavi z vzorcem iz zlitine ZI. Z naraščajočo hitrostjo ohlajanja dosežemo manjše izoblikovane primarne zmesne kristale aA1, izognemo pa se nastanku iglic faze ß-Al5FeSi, ki neugodno vplivajo na mehanske lastnosti končnih ulitkov. References И Mrvar, P., Trbižan, M., Medved, J. (2001): Preiskava dimenzijskih sprememb ulitka in forme med strjevanjem modificiranih in nemodificiranih aluminijevih zlitin z dilatometrom. Livarski vestnik, Vol. 48, No. S-6, pp. 131-140. [2] Mondolfo, L. F. (1976): Aluminum Alloys: Struc- ture and Properties. London, Boston, Butterworths. [3] Tomović. M. N. (1990): Livenje lakih i obojenih metala. Beograd: Tehnološko-metalurški fakultet. [4] Rosina, A. (1994): Teorija metalurških procesov. Ljubljana: Naravoslovnotehniška fakulteta, Oddelek za materiale in metalurgijo. [5] Aluminium-Taschenbuch, 14. Auflage, Aluminium- Verlag Düsseldorf, 1993. l6ìASM Specialty handbook, Aluminium and Aluminum Alloys, 1993. m Villars, P., Prince, A., Okamoto, H. (199S): Handbook of Ternary Alloy Phase Diagram, ASM International. [8] Hanemann and Schräder (19S2): Ternäre legirungen des aluminiums, Beispiele für die kristallisation ternärer systeme, Atlas metallographicus III, 2, Verlag stahleisen M.B.H., Düsseldorf. Pi Bäckerud, L., Chäi, G., Tamminen, J. (1990): Solidification Characteristics of Aluminum Alloys. Volume 2, Poundry Alloys. AFS/ SKANALUMINIUM. Department of Structural Chemistry - Arrhenius Laboratory, University of Stockholm. [I0] Markoli, B., Spaić, S. and Zupanic, F. Maribor. The intermetallic phases containing transition elements in common Al-Si cast alloys, ALUMINIUM 80. Jahrgang 2004 ", pp. 84-88. Plinsko in ionsko nitriranje orodij iz AISI HIO in H13 za toplo ekstruzijo aluminija ter njihova stabilnost kakovosti Gas and ion nitriding of dies for aluminium hot extrusion made from AISI HIO and H13 steels and their stability of quality Milan Terčelj, Anton Smolej, Rado Turk Oddelek za materialein metalurgijo, Univerza v Ljubljani, Aškerčeva cesta 12, 1000 Ljubljana, Slovenija; E-mail: Milan.Tercelj@ntf.uni-lj.si Received: June I, 2005 Accepted: October 28, 200S Izvleček: Orodja z ozkimi in globokimi režami, izdelana iz jekla AISI HIO in H13, so bila nitrirana pri različnih proizvajalcih naprav za ionsko in plinsko nitriranje, pri čemer so proizvajalci sami izbrali parametre nitriranja. Dobljene mikrostrukture kažejo na razlike glede na prisotnost ali odsotnost spojinske plasti (bele plasti), njene debeline in variiranja faznega razmerja е/у v tej plasti ter glede na globino nitriranja (difuzijsko cono) in trdotni profil. Dobljene globine nitriranja, maksimalne vrednosti za trdote in е/Y fazno razmerje so ponavadi podobni za orodja nitrirana pri istem proizvajalcu, medtem ko za različne proizvajalce naprav te vrednosti variirajo. Ugotovljene so bile manjše razlike med mikrostrukturami v I mm in 4 mm reži, ki so tudi posledica različnega strujanja plinske mešanice. Nitrirani vzorci so bili testirani na obrabo z "blok na cilinder" testno napravo. Strukture spojinskih plasti, ki so bližje monofazni, ob dovolj veliki trdoti in globini nitriranja, izkazujejo njeno poznejše luščenje. To rezultira v daljši življenski dobi orodja, saj spojinska plast ščiti površino orodja pred kemičnim reagiranjem z vročim Al. Abstract: A specially shaped die (AISI HIO and H13) with I and 4 mm narrow gap was developed to analyse the efficiency of nitriding process in narrow gaps. The dies were gas or ionic nitrided at various manufacturers of nitriding equipments. The manufacturers themselves, based on their experience with extrusion dies, chose the optimal nitriding parameters. The microstructure obtained showed differences with regard to the presence or abesence of a compound layer, its thickness and £// phase ratio (XRD), nitriding depth and microhardness values. The nitriding depths obtained, the maximum microhardness of the nitrided surfaces and £// phase ratio are usualy similar on dies of the same manufacturer, while for different manufacturers these values differ. The different characteristics of the nitrided microstructures resulted in various times of compound layer spalling (removal) during testing for wear resistance. On the sites of compound layer removal accelerated chemical attack took place that increased wear on the die surface. The compound layer is chemically more resistant to hot aluminium in comparison to nitrided base material. Earlier removal of the compound layer consequently results in decreased die life and later removal leads to prolongation of die life. Ključne besede: Topla ekstruzija Al, AISI HIO, AISI H13, nitriranje, spojinska plast, obraba. Key words: Al hot extrusion, AISI HIO, AISI H13, nitriding, compound layer, wear. I. Uvod Toplo stiskanje aluminija (slika I) je postopek, pri katerem se na cca. 450-500°C ogreta okroglica iztiskuje skozi odprtino na orodju, ki daje profilu želeno obliko. Potrebne sile stiskanja so v območju med 1055 MN, izstopne hitrosti profila pa do 100 m/min. Poškodbe in tribološke razmere na drsni površini omenjene odprtine orodja vplivajo na kakovost površine ekstrudiranca. Kontaktni pritiski na drsni površini orodij dosegajo vrednosti do 100 MPa, temperature pa lahko lokalno porastejo celo nad 600°C, saj se med procesom ekstruzije generira veliko toplote, ki je posledica volumskega stiskanja okroglice in trenja na kontaktu iztiskovanega profila in površine orodja. Najpogosteje uporabljeno orodno jeklo za izdelavo matrice je AISI H13, pa tudi H11 in H10. Življenjska doba orodja je determinirana z dopustnimi tolerancami prečnega preseka, kot tudi z lepim izgledom površine extrudiranca [1_4]. Od orodij za toplo ekstruzijo aluminija zahtevamo, da imajo čim večjo odpornost proti abraziji, adheziji in mehanskemu utrujanju ter kemično obstojnost. Več o kemičnih reakcijah med vročim Al in orodjem si bralec lahko prebere v literaturi [14_15]. Boljšo obrabno obstojnost in s tem daljšo življenjsko dobo orodij dosegamo z dodatnim oplemenitenjem površine orodja in sicer s plinskim nitriranjem, ionskim nitriranjem, nitriranjem v kopeli, s CVD ali PVD prevlekami, dupleks postopki, itd [5_12]. Slabost nitriranja v kopeli je predvsem škodljiv vplivu tega postopka na okolje, omejitev PVD postopka pa je vezana na težave učinkovitega oplaščevanja površin, ki ležijo v ozkih in dolgih režah. Na orodjih so omenjene ozke in globoke reže zelo pogosto prisotne; ekstrudirani profili so namreč zaradi težnje po čim večjem vztraj-nostnem momentu in tankih stenah posledično tudi zelo kompleksnih oblik (slika 2). Zaradi slednjega je plinsko nitriranje še vedno aktualno, saj je učinkovito tudi v ozkih in dolgih režah orodij. Pri nitriranju orodnih jekel (AISI H13, H11 in H10) pogosto nastaja spojinska plast (bela plast). Kemična sestava orodij in stanje površine, ki jo želimo nitrirati, kot tudi pravilna nastavitev parametrov žarjenja in nitriranja (plinska mešanica in njen pretok, temperatura, čas, itd.), vplivajo na nastanek in rast spojinske plasti (bele plasti), na razmerje faz (e in Y) v njej ter na difuzijo dušika v jekleno matico i5"8-12!. Mnenja Iztiskanj profil Slika I. Princip tople ekstruzije aluminija in drsna površina na orodju. Slika 2. Raznolikost extrudiranih profilov z ozkimi režami. v literaturi o tem, ali spojinska plast pozitivno oz. negativno vpliva na obrabno obstojnost površine orodij so zelo deljena. Tudi proizvajalci naprav za ionsko in plinsko nitriranje niso enotnega mnenja o tem, katera mikrostruktura jekla nastala pri nitriranju je obrabno najbolj obstojna. Tako nekateri belo plast odklanjajo, nasprotno pa drugi želijo nitrirane plasti s tankimi (3-5 ^m) belimi plastmi [1]. Iz prakse je tudi znano, da življenjska doba nitriranih orodij, celo pri ekstrudiranju enakega profila, zelo niha. V prispevku so podane in analizirane mikrostrukture površin v zato posebej izdelanih ozkih in globokih režah orodij iz jekel AISI HIO in H13, ki so bila nitrirana pri različnih proizvajalcih naprav za ionsko in plinsko nitriranje, nadalje je podana njihova fazna analiza (XRD), trdote, itd. Opravljeni preizkusi obrabe na nitriranih površinah so fokusirani na pojasnjevanje vloge spojinske plasti glede njene kemične odpornosti v kontaktu z vročim aluminijem. 2. Potek (analiza) obrabe NITRIRANE drsne POVRŠINE NA realnem orodju Na drsni površini orodja (slika 3a) nastopajo tri različne cone in sicer cona lepljenja, prehodna (tranzicijska) cona in cona Slika 3. Faze napredovanja obrabe na nitrirani drsni površini orodja (a.) za toplo ekstruzijo okroglega profila, kemično reagiranje (luknjičavost) v coni tranzicije in formiranje kraterjev (b.) ter širitev (podaljševanje) kraterjev proti izstopnemu robu drsne površine (c.) - (d.). drsenja [13]. Obrabi je najbolj izpostavljena prehodna cona, saj prav na tem mestu pride do občasnega sprijemanja (lepljenja) ekstrudiranega materiala s površno orodja in s tem tudi do kemičnih reakcij (aktivnosti) ter do ločitve omenjene zveze. Posledica tega je tvorba luknjičavosti (eng. pitting), ki pozneje vodi do tvorbe majhnih kraterjev (slika 3b), kateri se med nadaljnj im procesom ekstruzije počasi razširijo (podaljšajo) v smeri drsenja Al profila na celotno drsno cono vse do izstopnega roba drsne površine (slika 3c-d). Pri tem so prisotni obrabni mehanizmi kot kemično reagiranje aluminija s površino orodja, abrazija in adhezija. 3. Ionsko in plinsko nitriranje orodij z ozkimi in globokimi režami Naša študija temelji na analizi nitriranih mikrostruktur orodij z I mm in 4 mm režo (slika 4). Kemična sestava uporabljenih orodnih jekel iz AISI HIO in H13, ki so bila nitrirana pri osmih različnih proizvajalcih naprav za ionsko (proizvajalec I-II) in plinsko nitriranje (proizvajalec IV-VIII), je podana v tabeli 1. Od proizvajalcev naprav (tabela 2) se je zahtevala izpolnitev dveh pogojev in sicer: • celoten čas postopka nitriranja ne sme presegati 12 ur, • minimalna globina nitriranja lahko znaša 12O p.m. Proizvajalci so sami izbrali parametre nitriranja (vrednosti parametrov ne želijo posredovati) t.j. optimalno plinsko mešanico in pritisk, temperaturo, čas nitriranja, ohlajanje, itd. Iz nitriranega orodja smo potem s pomočjo elektroerozije izrezali manjše bloke za analizo mikrostrukturne in meritve trdote difuzijske plasti, opravili fazno analizo in izmerili debelino spojinske plasti ter eksperimentalno indentificirali obrabo. Orodje z ozkimi in globokimi režami je bilo izbrano za primerjavo učinkovitosti plinskega z ionskim nitriranjem; namreč, ozke reže so na orodjih za ekstruzijo preje omenjenih kompliciranih oblik profilov pogosto prisotne in predstavljajo omejitev pri uporabi ionskega nitriranja. Ionsko nitriranje je namreč relativno neučinkovito v omenjenih ozkih in globokih režah orodij. Tako za plinsko, kot tudi za ionsko nitrirana orodja, je značilna možnost nastanka spojinske plasti, na kar pri plinskemu nitriranju vplivajo sledeči parametri: temperatura in čas nitriranja, vrsta orodnega jekla, kemična sestava plinske mešanice in strujanje plina v peči (parcialni tlak dušika), čas nitriranja, itd. Dostopna literatura še ne poroča o učinkovitosti plinskega nitriranja v ozkih in globokih režah oz. kako na to vpliva intenziteta lokalnega strujanja plinske mešanice. Pri vplivu spojinske plasti na obrabno obstojnost je potrebno upoštevati, da ta nima enotne debeline, ampak se le-ta spreminja. To ima za posledico povečanje hrapavosti na mestu njenega luščenja in s tem tudi površine za cca. 1OO% [12]. I mm i j mm 12 mm Slika 4. Orodje z I in 4 mm režo ter prečnim presekom A-A. Tabela I. Kemcna sestava uporabljenih orodnih jekel, (AISI, METAL Ravne), [mas.%]. Metal Ravne AISI C Si Mn Cr Mo V Fe Utop 33 HIO 0.30 0.30 0.38 3.0 2.80 0.45 Ost. Utop Mo2 H13 0.40 1.0 0.40 5.05 1.28 0.95 Ost. Tabela 2. Seznam proizvajalcev za ionsko (ION) in plinsko (GSN) nitriranje orodij, debeline spojinske plasti (DSP), globine difuzijske plasti (GDP), in maksimalne vrednosti trdote (MHRD) v I mm in 4 mm visoki reži na orodjih iz jekel HIO in H13. Proizvajalec I. II. HI. IV. V. VI. VII. VIII. Način nitriranja ION ION PLN PLN PLN PLN PLN PLN Reža Glavni parametri - HIO DSP[|un] lmm / / 4-12 4-12 8-14 8-12 4-10 5-10 4mm / 0-5 4-8 6-13 8-14 8-12 6-12 6-12 GDP [pm] lmm 170-30 150-70 120 160 180 120 160 150 4mm 150-70 340-100 110 180 180 130 170 150 MHRĐ [Hv] lmm 1200-700 934-819 1135 1120 1130 1020 1092 1120 4mm 1185-1065 1054-945 1146 1130 1130 1035 1100 1146 Reža Glavni parametri - H13 DSP[|im] lmm / / 4-12 4-12 5-8 8-12 4-10 3-7 4mm / / 8-16 6-13 8-12 8-12 6-12 5-8 GDP [|im] lmm 170-30 150-70 120 130 150 120 140 130 4mm 150-70 340-100 110 140 150 120 150 140 MHRD[Hv] lmm 1200-500 850-790 1050 1100 1150 1020 1090 1080 4mm 1185-700 1054-900 1070 1100 1150 1035 1100 1080 4. MlKROSTRUKTURA, FAZNA SESTAVA IN TRDOTA JEKLA NA POVRŠINI 4.1 Ionsko nitriranje Na orodjih iz obeh uporabljenih jekel in nitriranih pri proizvajalcih I in II, smo ugotovili (izmerili) razlike tako v globini nitriranja (difUzijska cona) v I mm in 4 mm reži, kot tudi v zvezi s spojinsko plastjo (prisotnost oz. neprisotnost). Globina nitriranja je bila določena na osnovi merjenega profila trdot. Boljša učinkovitost nitriranja v 4 mm reži, v primerjavi z I mm režo, je značilna za oba proizvajalca. Proizvajalec II je bil uspešnejši v obeh primerih, čeprav uspešnost nitriranja v lmm reži ne zadošča postavljenim pogojem. Na sliki 5 je prikazan profil trdote (globina nitriranja) za proizvajalca št. II v 4 mm reži in orodje iz jekla HIO. Vidimo lahko, da je globina nitriranja med cca. 34O p,m na začetku, in cca. lOO p,m na koncu 12 mm reže. V lmm reži pa dobimo 15O p,m na začetku, in 7O p,m na koncu reže, kar so prenizke vrednosti za orodja za toplo ekstruzijo Al. Za proizvajalca I velja, da so mikrostrukture v l in 4 mm reži brez spojinske plasti. Enako velja za 1 mm režo pri proizvajalcu II medtem ko smo v 4 mm reži dobili O-5 p,m debelo belo plast. Dejstvo, da smo v 4 mm reži dobili spojinsko plast, v lmm reži pa ne, lahko pripišemo različnemu strujanju (histrosti) plinske mešanice znotraj 1 in 4 mm reže in temu posledično tudi različnemu gradientu vplivnih parametrov Slika S. Potek trdotne pod površino ionsko nitriranega jekla HIO v štiri milimetrski reži, proizvajalec II. (tlak, temperatura, itd). Tudi pri drugem orodju obeh proizvajalcev smo dobili podobne rezultate za globino nitriranja in maksimalne trdote na površini. Proizvajalec II bi torej lahko zadovoljivo nitriral v 4 mm režah le v primeru, če so te krajše (cca. 5 mm). Iz prakse je znano, da je dolžina drsnih površin ponavadi v območju med 3,5 mm do 12 mm. Za orodje iz jekla H13 so bili dobljeni podobni mikrotrdotni profili, le da so bile vrednosti za trdote še nekoliko nižje. 4.2 Plinsko nitriranje Orodja iz jekel HIO in H13 so bila nitrirana pri šestih različnih proizvajalcih naprav za plinsko nitriranje. Dobili smo precej podobne vrednosti tako za maksimalne trdote, kot tudi za globine nitriranja na orodjih nitriranih pri istem proizvajalcu. To velja za obe orodni jekli, pri čemer smo za jeklo iz HIO dobili nekoliko višje globine nitriranja in maksimalne vrednosti za trdote (tabela 2). Naslednja značilnost je, da večina orodji za jeklo iz HIO posedujejo belo plast, katere debelina pa se ponavadi malo razlikuje glede na 1 mm in 4 mm režo (tabela 2). V 1 mm reži smo dobili manjše trdote. V isti tabeli so podane še globine nitriranja za 1 in 4 mm režo. Pri orodjih iz jekla H13 je bilo opaziti večjo variabilnost glede prisotnosti oz. neprisotnosti spojinske plasti saj je bila na nekaterih orodjih prisotna na drugih pa ne. Na slikah 6a-l so podane tipične mikrostrukture tako brez spojinske plasti, kot tudi z spojinsko plastjo na površini orodja iz jekla H13, katere debelina se rahlo spreminja od orodja do orodja, še bolj pa od proizvajalca do proizvajalca. V nekaterih primerih ni spojinske plasti. To nas napeljuje na sklep, da je proces nitriranja zelo občutljiv; strujanje plinske mešanice namreč ni konstantno po celotnem volumnu peči kar pomeni, da so relevantni parametri za nitriranje odvisni od pozicije orodja v peči oz. od razmer na lokalnem nivoju, kar rezultira v različnih dobljenih mikro-strukurah nitriranih plasti. Debeline spojinske plasti, maksimalne trdote in globine nitriranja so za orodno jeklo H13 prav tako podane v tabeli 2. Tudi fazna analiza nitriranih površin kaže na podobno razmerje faz l/a' med orodji nitriranih pri istih proizvajalcih in sicer tako za orodja iz jekla H1O (slika 7) kot tudi za orodja iz jekla H13. Orodja iz jekla HIO: Kot je bilo že omenjeno, smo pri jeklu H1O skoraj pri vseh nitriranih orodjih dobili spojinsko plast na površini. Proizvajalec III je v 1 mm reži dosegel relativno majhno globino nitriranja, ki znaša cca. 12O pm, maksimalna vrednost trdote pa cca 1146 HV, debelina spojinske plasti pa 4-12 p.m. V 4mm reži je bila dosežena globina nitriranja cca. 110 pm, debelina spojinske plasti cca. 4-8 pm, maksimalna trdota je cca. 1135 HV. Fazna analiza (XRD) na nitrirani površini (slika 7) razkriva precej večji delež faze e kot faze Y ter železove okside. Ocenjeno e/Y fazno razmerje znaša cca. 6, kar pomeni, da je sestava spojinske plasti relativno blizu e monofazni mikrostrukturi. Proizvajalec IV je v 1 mm reži dosegel relativno veliko globino nitriranja, t.j. cca. 160 pm, maksimalna trdota je cca. 1120 HV, debelina spojinske plasti pa cca. 4-12 p.m. V 4 mm reži je bila namerjena globina nitriranja cca. 180 pm, malenkostno večja debelina spojinske plasti, t.j. cca. 6-13 pm, in maksimalna trdota cca. 1130 HV. XRD (slika 7) nam razkriva velik delež 1 in nekoliko več faze Y glede na orodja pri proizvajalcu III. Ocenjeno fazno razmerje e/Y znaša cca. 3 (slika 7), kar je manj kot v pri proizvajalcu III. Za proizvajalca V je značilna velika globina nitriranja cca 180 mm za obe reži, debelina spojinske plasti cca. 8-14 mm ter maksimalna trdota cca 1130 HV. Ocenjeno fazno razmerje e/Y znaša cca. 0,7 (slika 7), kar pomeni, da je v spojinski plasti več faze Y ■ Za proizvajalca VI je značilna relativno majhna globina nitriranja cca 120-130 pm, Slika 6. Variabilnost mikrostruktur iz jekla H13 med orodji in različnimi proizvajalci: (a-c) -proizvajalec III, (d) - proizvajalec IV, (e-g) - proizvajalec V, (h) - proizvajalec VI, (i-j) -proizvajalec VII, (k-l) - proizvajalec VIII, OM, jedkano z nitalom. debelina spojinske plasti cca. 8-12 p,m, ter maksimalna trdota cca 1030 HV. XRD nam pokaže veliko faze Y (ocenjeno fazno razmerje e/Y znaša cca. 0,8) ter tudi vrh a(Fe) kar pomeni, da spojinska plast verjetno ni prekrila celotne nitrirane površine ali pa je ta pretanka. To posledično odpira vprašanje o učinkovitosti plinskega nitriranja v ozkih in globokih režah tega proizvajalca. Za proizvajalca VII je značilna relativno velika globina nitrirane plasti in sicer v 1 mm reži znaša cca. 160 p,m, debelina spojinske plasti pa cca. 4-10 p,m ter 170 p,m oz. 6-12 p,m v 4 mm reži. Maksimalne trdote so cca. 1100 HV. XRD nitrirane plasti pokaže na veliko faze e ter malo faze Y. Ocenjeno fazno razmerje e/Y znaša cca. 4. Za proizvajalca VIII je značilna nekoliko nižja globina nitriranja v obeh režah t.j. cca. 150 mm, debelina spojinske plasti pa znaša 5-10 p,m v 1 mm reži in 6-12 p,m v 4 mm reži. Maksimalne trdote so cca. 1120-1150 HV. XRD analiza razkrije skoraj monofazno mikrostrukturo spojinske plasti, saj ima ocenjeno fazno razmerje e/Y znaša cca. 10. Vzroke za prisotnost oz. neprisotnost spojinske plasti in ponavadi malenkostno večjo globino nitriranja in debelino spojinske plasti v 4 mm reži je treba iskati v že omenjenem različnem strujanju plinske mešanice tako v peči za nitriranje, kot tudi v 1 in 4 mm reži. Na sliki 8 so prikazani površinski izgledi nitriranih površin nekaterih blokov, kjer je jasno viden prehod iz 9 mm reže na 1 oz. 4 mm režo, kar nakazuje na vpliv lokalnega strujanja (hitrost, pritisk, itn.) plinske mešanice na nitriranje. Slika 7. Fazna analiza (XRD) nitriranih površin orodij iz jekla HIO pri proizvajalcih III-VIII. Slika 8. Izgled nekaterih plinsko nitriranih površin z jasnim prehodom iz 9 mm reže v I oz. 4 mm režo. 5. Individualno testiranje OBRABE NITRIRANIH mikrostruktur Posebna izvedba "blok na cilinder" naprave za študij obrabe (slika 9) je omogočilo testiranje pri povišanih temperaturah in visokih kontaktnih pritiskih, ki so značilni za toplo ekstruzijo Al; testni pogoji so podani v tabeli 3. Dimenzije ogretih cilindrov iz zlitine AA 6063 (0.5 Mg, 0.5 Si, 0.19 Fe, 0.05 Mn), ki predstavljajo ogreti extru-diranec, so bile premera Ф146 mm x 35 mm, dimenzije testiranih blokov pa so bile 30 mm x 30 mm x 20 mm. Ogrevanje Al cilindrov je induktivno s pomočjo tuljave s samo polovico ovoja. Na obeh straneh Al cilindra sta nameščena bakrena diska, preko katerih je tudi posredno kontrolirana temperatura Al (sevalni koeficient bakra znaša cca. 0,8); namreč, sevalni koeficient Al je zelo nizek in napake meritev na Al cilindru bi posledično lahko bile zelo velike. Nadalje, omenjeni bakreni diski omogočajo testiranje pri visokih kontaktnih pritiskih, kar ima za posledico krajše potrebne čase testiranja, sočasno pa onemogočajo plastično defor- macijo Al cilindrov. V realnem procesu tople ekstruzije drsenje med površino orodja in extrudirancem poteka v skoraj neoksida-tivnih pogojih, zato med testiranjem v komoro dovajamo argon (kemična sestava v volumskih ppm: O2 max 5 ppm, H20 max 10 ppm, CO2max 0,5 ppm, Np max 20 ppm). Testiranje obrabe z vročim Al sodijo med najbolj zahtevna tribološka testiranja, zato so objave s tega področja v literaturi tudi zelo redke. Pri topli ekstruziji so eksperimentalni podatki o vlogi spojinske plasti pri življenski dobi orodja še posebej zaželeni, saj je študij v industrijskih pogojih zelo otežen. Pri laboratorijskem testiranju (testni pogoji 1, tabela 3) nas je zanimal predvsem vpliv spojinske plasti na obrabno obstojnost: in sicer njena odpornost proti kemičnemu reagiranju z vročim aluminijem, način njene odstranitve z nitrirane površine ter odziv tako nanovo nastale površine na kontakt z vročim Al. Začetno stanje površine je podano na slika 10a. Opazili smo, da je za odstranitev spojinske plasti bistven proces nastanka razpok na njeni površini (slika 10b) kar vodi do njenega postopnega (delnega) luščenja (40-60 %), kot je prikazano na slika I0c. To nas tudi napeljuje na dejstvo, da je duktilnost spojinske plasti zelo pomembna karakteristika, ki bo vplivala na čas njene odstranitve. Nadalje, na mestu odstranitve spojinske plasti začne vroč aluminij (cca. 570 °C, relativno blizu tališča) pospešeno reagirati z novo nastalo površino (slika I0c). Vzrok za to lahko pripišemo povečanju hrapavosti na mestu odstranitve spojinske plasti, kar ima za posledico povečanje (cca. 100 % [12]) površine, potencialno primerne za kemično reagiranje s toplim Al; spojinska plast namreč ni enakomerne debeline, kot je to vidno iz slik 6a-f ter iz tabele 2. Proces delnega luščenja spojinske plasti in pospešenega kemičnega reagiranja smo opazili na vseh testiranih blokih, razlikoval se je le čas, ko je prišlo do pojava luščenja (tabela 4). Iz slike 10c je tudi razvidno, da je spojinska plast kemično bolj obstojna proti vročemu Al kot osnovni material, saj so ta mesta (Ang. pitting) na spojinski plasti komaj opazna. Poslabšanje kvalitete površine v poznejši fazi testiranja je verjetno posledica intenzivnega kemičnega reagiranja z razkrito površino, pa tudi adhezije (slika 10d). V tabeli 4 so podani približni časi delnega luščenja (cca. 40-60 %) spojinske plasti za nekatere proizvajalce oz. za nekatere tipične lastnosti nitriranih mikrostruktur in sicer za H10 in H13. Manj krhke so monofazne spojinskih plasti, pri čemer pa je vsekakor bolj zaželjena Y, ki je manj krhka kot £. S tega vidika je bila dobljena spojinska plast proizvajalca III relativno ugodna, vendar je Tabela 3. Testni pogoji. zaradi manjše globine nitriranja in manjših maksimalnih trdot prišlo do delnega luščenja (cca. 40-60 %) že po eni uri testiranja (tabela 4). Isto je bilo opaženo tudi pri proizvajalcu V, z relativno neugodno fazno sestavo spojinske plasti, kljub relativno veliki globini nitriranja in visokih maksimalnih vrednosti trdote. Delno luščenja spojinske plasti po dveh urah (tabela 4) pa je bilo opaženo pri proizvajalcu VII. Omenjena mikrostruktura namreč poseduje strukturo spojinske plasti, ki vsebuje malo Y faza in relativno zelo globoko difuzijsko plast. Spojinska plast proizvajalca VIII je skoraj monofazna (e), poleg tega pa ima še relativno veliko globino difuziske plasti (150 p,m), kar je rezultiralo z delnim luščenja po 2 dveh urah testiranja (slika 10c). Kot je bilo že omenjeno so rezultati delnega luščenja spojinske plasti za obe nitrirani jekli podani v tabeli 4. Potek obrabe površin, kot je prikazan na slika 10a-d, je značilen za vse testirane mikrostrukture. Karakteristike spojinske plasti in difuzijske cone pa pogojujejo dinamiko obrabnih procesov na testirani površini oz., kdaj bo nastopilo določeno stanje na površini, kot je prikazano na prej omenjeni sliki. Kdaj bo prišlo do luščenja spojinske plasti je odvisno od predvsem od njene mikrostrukture (zaželena monofazna mikrostruktura) in nosilnosti difuzijske plasti (zaželena čim večja nosilnost). Orodno jeklo Cas lh 2h H10 Proizvajalec III, V, VI IV,vìi, vin H13 Proizvajalec III, VI V,VII, Vili Tabela 4. Približni časi delnega (40-60 %) luščenja spojinske plasti, testni pogoji I. Testni pogoji 1 Testni pogoji 2 Normalna sila [N] 2200 1920 Naležna površina [mm x mm] 30x10 30x5 Povprečni kontaktni pritisk [MPa] 7,5 15 Relativna hitrost zdrsa [m/min] 25 25 Temperatura Al cilindra [°C] 510 510 Slika 9. Shema naprave "blok na cilinder" Slika IO. Časovni potek obrabe nitriranih površin: začetno stanje, SEI (a.), pokanje spojinske plasti, SEI (b.), delna odstranitev spojinske plasti in pospešena obraba (najverjetneje zaradi kemične reagiranjem z vročim Al) na mestu njene odstranitve, BEC (c.) in kemično reagiranje in adhezija na mestih brez spojinske plasti, SEI (d.), (testni pogoji I). Slika II. Primerjalno testiranje (t=3h) vzorcev z različnima mikrostrukturama: vzorec 2 (a.), vzorec I (b.), toplotno obdelani blok z vstavljenima vzorcema in makro posnetek obrabljenih površin (c.), začetno sanje površine (d.), površina vzorca 2 posneta v SEI (e.), površina vzorca I posneta v SEI (f.), (testni pogoji 2), smer drsenja označena s puščico. Debelina spojinske plasti pri različnih proizvajalcih in orodjih ni nihala v takem obsegu, da bi iz tega lahko izpeljevali enolične zaključke. V povprečju je znašala okrog 4-15 p.m. 6. Primerjalno testiranje obrabe Na osnovi individualnega testiranja smo ugotovili, da ohranjanje spojinske plasti na drsni površini podaljšuje življenjsko dobo orodja. Znano je tudi, da večja trdota in globlja difuzijska cona povečuje obrabno obstojnost orodij. Za pojasnjevanje dileme, kaj bolj povečuje obrabno obstojnost, ali srednje debela spojinska plast z ugodno fazno sestavo (proizvajalec IV, H13, vzorec 2, slika 11a,c) ob zadostni globini difuzijske cone in velikosti trdot ali tanka spojinska plast z manj ugodno sestavo ob večji trdoti (proizvajalec V, H13, vzorec 1, slika llb-c) in globini difuzijske cone, smo izvedli primerjalno (t=3h) testiranje obrabe omenjenih vzorcev pri večjih kontaktnih pritiskih (testni pogoji 2, tabela 3). Makrografski posnetek površin na sliki 11 c nam kaže, da je drugi vzorec, kljub manj ugodni sestavi spojinske plasti, vendar z njeno tanjšo debelino ter z večjo trdoto in globino difuzijske cone, obrabno bolj obstojen (sliki 11c,f). Daljšo življenjsko dobo orodij lahko torej povečujemo tudi z večjo globino nitriranja; smo pa z globino nitriranja tudi omejeni, saj to lahko privede do prenitriranja, če ta postopek večkrat ponovimo. 7. Zakjučki Izdelana so bila laboratorijska orodja iz jekel H10 in H13 z ozkimi (1 mm oz. 4 mm) in dolgimi (12 mm) režami, ki so bila nitrirana pri različnih proizvajalcih za plinsko in ionsko nitriranje, pri čemer so slednja služila za primerjavo uspešnosti obeh postopkov nitriranja po dolžini različno ozkih rež. Dobljene mikrostrukture jekla plinsko nitriranih površinah se precej razlikujejo, tako glede globine difuzijske cone in maksimalne vrednosti dobljenih trdot, kot tudi glede sestave oz. deleža e ali Y spojinske plasti. Globine difuzijskih plasti nihajo v območju med 110-190 pm, fazno razmerje e/Y pa se spreminjal od proizvajalca do proizvajalca od skoraj monofazne e sestave do e/Y razmerja cca. 0,7. Pri nobenem od proizvajalcev ni bila dobljena čista monofazna Y sestava spojinske plasti. Debeline spojinskih plasti so se gibale v območju cca. 4-16 p.m. V 1 in 4 mm reži istega orodja so bile opažene manjše razlike, tako v globini nitriranja, kot tudi v debelini spojinske plasti. Te razlike bi lahko pripisali različnemu strujanju plinske mešanice v 1 mm in 4 mm reži. Različne, zgoraj karakterizirane mikrostrukture so rezultirale tudi v različnih časih luščenja spojinske plasti med tribološkim simuliranjem vroče ekstruzije aluminija. Spojinska plast je kemično bolj obstojna proti vročemu aluminiju. Na mestih njenega luščenja zaradi povečanja hrapavosti pride najverjetneje do pospešenega kemičnega reagiranja z vročim aluminijem, kar pospeši obrabo. Zato v primeru, ko se spojinska plast odlušči v zelo zgodnji fazi procesa tople ekstruzije, to luščenje negativno vpliva na življenjsko dobo orodja. V primeru kasnejšega luščenja spojinske plasti, pa zaradi njene večje kemične stabilnosti do vročega Al, to rezultira v daljši življenjski dobi orodja. Sestava spojinske plasti, ki se približuje enofazni, je bolj odporna proti luščenju. Fazna razmerja cca. 1:1 povečujejo krhkost spojinske plasti in s tem zmanjšujejo življenjsko dobo orodja. Orodja z relativno neugodno sestavo spojinske plasti ter večjo difuzijsko cono in trdoto so v primerjalnem testiranju izkazale boljšo obrabno obstojnost v primerjavi z orodjem z ugodno sestavo spojinske plasti, vendar manjšo difuzijsko cono in manjšo trdoto. Pri ionskem nitriranju so bile dobljene večje razlike v učinkovitosti nitriranja, tako glede na geometrijo rež I in 4 mm, kot tudi glede na proizvajalca. V I mm reži nihče od proizvajalcev ni bil uspešen. V primeru, da ima orodje z 4 mm ozko režo krajšo drsno površino (do cca. 5 mm), bi bila učinkovitost drugega proizvajalca lahko zadovoljiva. Literatura И Björk, Т., Westeg&d, Я., Hogmark, S. (2001): Wear of surface treated dies for aluminium extrusion-a case stadij, Wear 249/2, 316-323. [2] Björk, Т., Berger, M., Westerglrd, S., Hogmark, R., Bergström, J. (2001): New physical vapour deposition coatings applied to extrusion dies, Surface & Coatings Technology 146-147, 3341. 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Autor's Index Aljinović Dunja daljin@rgn.hr 581 Brenčič Mihael mihael.brencic@geo-zs.si 549 Dolenec Tadej tadej.dolenec@ntfgeo.uni-lj.si 523,523 Gosar Mateja gosar@geo-zs.si 571 Jurkovšek Bogdan bogdan.jurkovsek@geo-zs.si 581 Kolar-Jurkovšek Tea tea.kolar@geo-zs.si 581 Nielsen Kai Kai.Nielsen@geo.ntnu.nu 607 Medved Jožef jozefmedved@ntf.uni-lj.si 621 Mrvar Primož primoz.mrvar@ntf.uni-lj.si 621 Pavlovec Rajko rajko.pavlovec@ntf.uni-lj.si 597 Serafimovski Todor seraft@rgf.ukim.edu.mk 523, 523 Smolej Anton smolej@ntf.uni-lj.si 635 Sajn Robert robert.sajn@geo-zs.si 561, 571 Šolar Slavko slavko.solar@geo-zs.si 607 Tasev Goran tasevg@rgf.ukim.edu.mk 523, 523 Terčelj Milan Milan.Tercelj@ntf.uni-lj.si 635 Tiess Günther guenther.tiess@notes.uniloeben.ac.at 607 Turk Rado rado.turk@ntf.uni-lj.si 635 Vončina Maja maja.voncina@ntf.uni-lj.si 621 Vreča Polona polona.vreca@ijs.si 549 Wagner Horst horst.wagner@notes.uniloeben.ac.at 607 Zibret Gorazd gorazd.zibret@geo-zs.si 561