Early Jurassic foraminiferal assemblages in platform carbonates of Mt. Krim, central Slovenia Spodnjejurske foraminiferne združbe v plitvomorskih karbonatih na območju Krima, osrednja Slovenija Luka GALE1,2 & Matej KELEMEN3 1University of Ljubljana, Faculty of Natural Sciences and Engineering, Department for Geology, Privoz 11, SI-1000 Ljubljana, Slovenia; e-mail: luka.gale@ntf.uni-lj.si 2Geological Survey of Slovenia, Dimičeva ul. 14, SI-1000 Ljubljana, Slovenia; e-mail: luka.gale@geo-zs.si 3Ulica Štefana Kovača 9, SI-9000 Murska Sobota, Slovenia Prejeto / Received 23. 2. 2017; Sprejeto / Accepted 7. 4. 2017; Objavljeno na spletu / Published online 9.6.2017 Key words: External Dinarides, Adriatic Carbonate Platform, biostratigraphy, post-extinction recovery, Triassic- Jurassic boundary, diversity Ključne besede: Zunanji Dinaridi, Jadranska karbonatna platforma, biostratigrafija, okrevanje po izumrtju, meja trias-jura, diverziteta Abstract During the Early Jurassic, the subtropical carbonate platforms of the peri-Tethys Ocean experienced significant changes in their architectures, as well as in their biota compositions. Shallow-water carbonates from the northern part of the ancient Adriatic Carbonate Platform (External Dinarides) were investigated in six sections, which taken together cover the development of the platform from deposition of the uppermost Triassic Main Dolomite to the middle Lower Jurassic, lithiotid limestone. Our aim was to establish a detailed foraminiferal biostratigraphy and to observe the changes in size, abundance and diversity of foraminifera in different types of facies. As a result, the succession was successfully divided into stage or substage levels. Foraminiferal assemblages were shown to experience a gradual change in taxonomic composition (including an increase in the proportion of complex agglutinated forms), a general increase in abundance of specimens, and greater diversity in each facies type, except in bindstone and mudstone. Notable is the difference between Hettangian assemblages, which display fairly uniform compositions in all facies types and the predominance of opportunists, and the post-Hettangian assemblages, which become progressively more species-rich and where the differences in facies are perhaps more pronounced. Changes in the size of the species Meandrovoluta asiagoensis Fugagnoli & Rettori, and of the largest specimen in the assemblages, however, are less clear, but are arguably present. Faunal changes roughly correspond to the gradual change from the flat-top platform of the upper Triassic – Hettangian, where biota would be repeatedly subjected to stressed peritidal conditions, to a platform differentiated into lagoon, sand bars and ephemeral emergent areas, offering numerous habitats and perhaps more stable living conditions for organisms. Izvleček Karbonatne platforme območja Tetide so v času starejše jure doživljale znatne spremembe v morfologiji in sestavi biote. Plitvomorske karbonate Jadranske karbonatne platforme (Zunanji Dinaridi) smo raziskali v šestih profilih na širšem območju Krima. Profili skupaj zajemajo interval od vrhnjega dela, glavnega dolomita do litiotidnega apnenca. Naš cilj je bil identifikacija foraminifernih biocon. Poleg same taksonomske sestave smo beležili še raznolikost foraminifernih združb, pogostnost (ali gostoto) foraminifer ter spremembo v velikosti vrste Meandrovoluta asiagoensis Fugagnoli & Rettori ter v velikosti največjih primerkov v združbah. Po pričakovanjih rezultati kažejo postopne spremembe v taksonomski sestavi foraminifernih združb, vključno z naraščanjem deleža kompleksnih aglutiniranih vrst ter splošen porast gostote primerkov in raznolikosti v vseh faciesih razen v bindstone in mudstone faciesih. Zanimivo je, da hettangijske združbe izkazujejo precejšnjo podobnost v sestavi in prevlado oportunističnih vrst, medtem ko so razlike med združbami glede na facies v mlajših plasteh bolj izrazite. Sprememba v velikosti vrste M. asiagoensis je znotraj posamičnega faciesa težko dokazljiva, celokupno gledano pa največji osebki te vrste dosegajo večjo velikost v mlajših plasteh. Podobno velja za velikost največjih osebkov v združbi. Favnistične spremembe približno sovpadajo s postopno spremembo v morfologiji platforme, ki se postopno diferencira v laguno, delno omejeno s peščenimi sipinami. GEOLOGIJA 60/1, 99-115, Ljubljana 2017 https://doi.org/10.5474/geologija.2017.008 © Author(s) 2017. CC Atribution 4.0 License 100 Luka GALE & Matej KELEMEN Introduction The end-Triassic biocalcification crisis is gen- erally thought to have had a significant influ- ence on carbonate platforms (Galli et al., 2005; Greene et al., 2012). The acidification of oceanic water greatly influenced carbonate-secreting or- ganisms like corals and calcareous sponges, and many of the marine groups experienced elevated extinction rates (hautMann, 2004; KiesslinG et al., 2007, 2009). Among the strongly affected or- ganisms were also foraminifera, microscopical- ly small, mostly marine, unicellular eukaryotes, which by the end of the Triassic formed diverse shallow-water communities composed of Invo- lutinoidea, Duostominidae, Lagenida, Miliolida and Textulariida (Galli et al., 2005; Mancinel- li et al., 2005; Gale, 2012; Gale et al., 2012). The change to Early Jurassic assemblages, almost completely dominated by agglutinated forms, is a striking example of community replacement. The Adriatic (Dinaric sensu Buser, 1989) Car- bonate Platform, the remnants of which are pres- ently incorporated into the structurally deformed margin of the Adriatic tectonic microplate (Plac- er, 1999; tari, 2002; csontos & vörös, 2004), was a platform with a seemingly less dramatic lith- ological change at the Triassic-Jurassic bound- ary, as peritidal deposition continues from the Upper Triassic to the lowermost Jurassic (e.g., Miler & Pavšič, 2008; oGorelec, 2009). After- wards, the succession records a gradual transi- tion from tidal-flat to restricted lagoon setting, where the present “lithiotid limestone” deposit- ed. This change of the platform topography, how- ever, remains poorly researched, especially due to the lack of biostratigraphically well-defined sections. This paper has two main aims. First, we show the stratigraphic distribution of foraminifera in six sections from the broader area of Mt. Krim, south of Ljubljana, from the base of the Hettan- gian Krka Limestone Member to the lower part of the Pliensbachian Lithiotid Limestone Mem- ber. Five of the sections were investigated in de- tail. On the basis of foraminifera, we determine the age of the sections to the stage or substage level. Secondly, we follow changes in terms of taxonomic composition, abundance of foraminif- era, diversity, the size of Meandrovoluta, and the change in the largest specimen among foraminif- era for each of the stages/substages, in order to gain more detailed insight into the origin of the post-extinction community. We do this for each facies type in order to avoid lithologically-in- duced bias. Geological Setting and General Stratigraphy The studied exposures are located in the northern External Dinarides (Fig. 1; Placer, 1999, 2008). The Lower Jurassic succession con- sists of shallow-marine carbonates deposited on the Adriatic Carbonate Platform (AdCP; vla- hOvić et al., 2002, 2005), locally also known as the Fig. 1. Regional schematic structural map. The position of the studied area is marked by the white arrowhead. A: Structural map of the north-eastern corner of the present Adriatic tectonic plate. B: Present position of the Adriatic tectonic plate and position of Slovenia. The studied area is marked with a black dot. Modified after vraBec and FoDor (2006). 101Early Jurassic foraminiferal assemblages in platform carbonates of Mt. Krim, central Slovenia Dinaric Carbonate Platform (Buser, 1989; oGore- lec & rothe, 1993), which was during the Early Jurassic situated at a paleolatitude of approxi- mately 25°N (staMPFli & Mosar, 1999; staMPFli & Kozur, 2006; Bosence et al., 2009; Berra & an- Giolini, 2014). The thick sequence of carbonates, which continued to be deposited up until the up- permost Cretaceous (Buser, 1989), was later tilt- ed and broken into several tectonic blocks, and separated by faults that in the studied area run in approximately N-S and WNW-ESE to NW-SE directions, separating tectonic blocks compris- ing Upper Triassic to Middle Jurassic carbonates (Fig. 2; Buser et al., 1967; Pleničar, 1970; Buser, 1968, 1974). The lithostratigraphic subdivision of Lower Jurassic carbonates in the External Dinarides was recently revised by Dozet and strohMenGer (2000), Miler and Pavšič (2008), and Dozet (2009) (Fig. 3). The Norian-Rhaetian Main Dolomite is typified by medium- to thick-bedded crystalline dolomite, stromatolitic dolomite, and intraclas- tic breccia, indicating cyclically interchang- ing shallow subtidal, intertidal, and supratidal conditions (i.e., Lofer facies in Fischer, 1964) on a flat-topped carbonate platform (oGorelec & rothe, 1993). Peritidal sedimentation continued into the earliest Jurassic (oGorelec, 2009), though the position of the Triassic-Jurassic boundary is merely arbitrary (Miler et al., 2007). The Lower Jurassic Podbukovje Formation (Dozet & stro- hMenGer, 2000; Predole Beds in Dozet, 2009) con- sists of five members. The Hettangian-Sinemuri- an Krka Limestone (i) is composed of crystalline dolomite, laminated (rarely stromatolitic) dolo- mite, mudstone, wackestone, rarely pellet or ooid grainstone, and intraclastic breccia (Dozet, 1993; Dozet & strohMenGer, 2000; Dozet, 2009; oGore- lec, 2009). Miler and Pavšič (2008) also note thick bodies of mud-supported breccia, which could be indicative of Early Jurassic tectonic activity. The following Upper Sinemurian-Pliensbachian Orb- itopsella Limestone (ii), Lithiotid Limestone (iii) and Ooidal Limestone (iv) members mark the es- tablishment of lagoons restricted by oolitic bars (Miler & Pavšič, 2008; Dozet, 2009; Gale, 2014). The Podbukovje Formation ends with the Toar- cian Spotty Limestone Member (v) with nodu- lar mudstone-wackestone and black ooid pack- stone (Dozet & strohMenGer, 2000; Dozet, 2009; KresniK, 2016). Material and methods The Lower Jurassic succession was investi- gated in five detailed sedimentological sections (Preserje, Tomišelj 2, Jezero, Zalopate, Podpeč sections), which structurally belong to the Ex- ternal Dinarides. Together the sections span the interval from the Krka Limestone to the Lithiotid Limestone Member sensu Dozet and strohMenGer (2000). The Preserje section was measured previ- Fig. 2. Simplified geologic map of the studied area and lo- cation of studied sections. Modified after Buser et al. (1967) and Buser (1968). Je: Jezero (45°57´30´´ N, 14°26´00´´ E); Po: Podpeč (45°58´22´´ N, 14°25´16´´ E); Pr: Preserje (45°57´56´´ N, 14°23´47´´ E); T1: Tomišelj 1 (45°57´51´´ N, 14°28´06´´ E); T2: Tomišelj 2 (45°58´00´´ N, 14°28´16´´ E); Za: Zalopate (45°56´09´´ N, 14°27´21´´ E). Fig. 3. Schematic lithostratigraphic column of the studied area. Shading indicates the interval covered by the detailed sections (the schematic Tomišelj 2 sections ranges further down to the Main Dolomite). Adopted after Miler and Pavšič (2008), Dozet (2009). Vertical scale is reconciled to thicknes- ses given in Dozet (2009). Ages for are taken after OGG et al. (2012). 102 Luka GALE & Matej KELEMEN ously by oGorelec (2009) and is reproduced here- in. Although the succession of this section was originally placed near or at the Triassic-Jurassic boundary, we suggest a slightly younger age for these rocks on the basis of lithostratigraphic cor- relation and foraminiferal biozonation. The sixth, Tomišelj 1 section was measured schematically and reaches to the underlying Main Dolomite. Fig. 4. Early Jurassic foraminifera and algae from the investigated sections. A: Amijiella amiji (Henson). Thin section 535. Section Podpeč. Early Pliensbachian. B: Bosniella oenensis Gušić. Thin secti- on 510. Section Podpeč. Early Pliensbachian. C: ?Coronipora sp. Thin section 528. Section Podpeč. Early Pliensbachian. D: Duotaxis metula Kristan. Thin section 418. Section Zalopate. Late Sinemurian-earliest Pliensbachian. E: Everticyclammina praevirguliana Fugagnoli (white arrowhead). Black arrowhead points at Meandrovoluta asiagoensis, whereas the section in the upper left corner belongs to Duotaxis metula. Thin section 328. Section Zalopate. Late Sinemurian-earliest Pliensbachian. F: Involutina sp. Thin section 528. Section Podpeč. Early Pliensbachian. G: Lituolipora termieri (Hottinger). Thin secti- on 536. Section Podpeč. Early Pliensbachian. H: Lituosepta recoarensis Cati. Thin section 329. Section Zalopate. Late Sinemurian-earliest Pliensbachian. I: Meandrovoluta asiagoensis Fugagnoli & Rettori. Thin section 535b. Section Podpeč. Early Pliensbachian. J: Mesoendothyra? sp. Thin section 515. Section Podpeč. Early Pliensbachian. K: Ophthalmidium sp. Thin section 522. Section Podpeč. Early Pliensbachian. L: Orbitopsella praecursor (Gümbel). Thin section 529. Section Podpeč. Early Pliensbachian. M: Orbitopsella primaeva Henson. Thin section 535b. Section Podpeč. Early Pliensbachian. N: Pseudopfenderina butterlini (Brun). Thin section 510. Section Podpeč. Early Pliensbachian. O: Siphovalvulina gibralta- rensis BouDagher-Fadel, Rose, Bosence & Lord. Thin section 328. Section Zalopate. Late Sinemurian-earliest Pliensbachian. P: Siphovalvulina variabilis Septfontaine. Thin section 412. Section Zalopate. Late Sinemurian-earliest Pliensbachian. R: Siphovalvulina variabilis Septfontaine. Thin section 329b. Section Zalopate. Late Sinemurian-earliest Pliensbachian. S: “Trochammina” almtalensis Koehn-Zaninetti. Thin section Jezero. Early - Middle Sinemurian. T: Trocholina sp. Thin secti- on 325. Section Zalopate. Late Sinemurian-earliest Pliensbachian. U: Palaeodasycladus mediterraneus (Pia). Thin section 34. Section Preserje. Early - Middle Sinemurian. 103Early Jurassic foraminiferal assemblages in platform carbonates of Mt. Krim, central Slovenia The lower part of the Krka Limestone Mem- ber is to a large extent dolomitized. Medium- to very thick-bedded dolomite is coarsely crystal- line, or exhibits planar laminae measuring a few millimetres in thickness. Fine-scale wrinkles, typical of stromatolites of the underlying Main Dolomite, are extremely rare. Tee-pee struc- tures, black pebbles, and birds’ eyes, however, are still common, as well as occasional irregu- lar and clayey bedding planes. After approxi- mately 70 m, medium- to thick-bedded micritic limestone with mudstone to wackestone texture dominates for 15 m, followed again by crystal- line dolomite. Upwards, limestone (mudstone, and rarely wackestone) starts to gradually pre- dominate over dolomite. Laminae, desiccation cracks, and birds’ eyes structures are occasion- ally present. Approximately 100 m from the base of the Krka Limestone Member, the foraminife- ral assemblage with Duotaxis metula, small No- dosariidae, Reophax sp., ?Siphovalvulina colo- mi, Siphovalvulina variabilis, ?”Trochammina” almtalensis and Textularia sp. were found. Ac- cording to velić (2007), S. variabilis first appears in the latest Hettangian. Approximately 130 m from the base of the Krka Limestone, packstone and grainstone with bioclasts, intraclasts, and peloids are encoun- tered. Leached-out clasts may be abundant. Packstone and grainstone are more common as we move to the uppermost part of the section, al- though mudstone still predominates. Red and/or irregular clayey bedding-planes and bird’s eye vugs are occasionally present. The foraminiferal assemblage is notably more diversified and in- cludes: Amijiella amiji, D. metula, Everticyclam- mina praevirguliana, Nodosariidae, Meandrovo- luta asiagoensis, ?Pseudopfenderina butterlini, Reophax sp., Siphovalvulina gibraltarensis, Siphovalvulina sp., Textularia sp., Trocholina sp., and Valvulina sp. According to BouDaGh- er-FaDel and Bosence (2007), E. praevirguli- ana first appears in the Middle Sinemurian, but velić (2007) sets its first appearance already in the Late Hettangian. Furthermore, velić (2007) sets the first appearance of S. gibraltarensis at the beginning of the Sinemurian. This part of the section is thus dated as Early Sinemurian. In the uppermost part of the Tomišelj 2 section, M. asiagoensis and ?Lituosepta recoarensis were also recorded. Lituosepta recoarensis first ap- pears in the Late Sinemurian (BouDaGher-FaDel & Bosence, 2007; velić, 2007). Approximately 200 thin sections 47×28 mm and 75×49 mm in size from 184 beds were investigated for foraminifera (Fig. 4), and assemblages from different facies types were distinguished. Sparse and dense wackestones were distinguished by a borderline value of 30 % of grains. The number of foraminifera in thin sections varies from 0 to 60 per cm2, with up to 434 specimens counted in a single thin section. Changes in abundance (num- ber of specimens per cm2), species richness and diversity for each facies type were investigated on the basis of approximately 150 thin sections. When generic or species determination was not possible, open nomenclature was used instead (e.g. Foraminifera indet. sp. A). Aeolissacus/Ear- landia specimens were not counted due to their indistinct character. Some Nodosariidae were likewise difficult to separate into distinct spe- cies. As a result, biodiversity indices do not rep- resent absolute values that could be directly com- pared to present-day values. The total number of foraminifera in each thin section was divided by the surface area of the investigated area in order to normalize the resulting values. The biodiver- sity of each sample was estimated on the basis of the Shannon-Wiener diversity index H´ (haM- Mer & harPer, 2006). In addition to calculating diversity, the maximum specimen size from each biozone was measured (see Payne et al., 2011). We also measured the largest specimen of the most common and widespread species, Meandrovoluta asiagoensis, in different facies types. Description of sections and biostratigraphy Tomišelj 2 This section serves as a reference section for the easier lithostratigraphic positioning of oth- er sections. Due to the patchy exposure of beds (up the forested slope), no detailed sampling was possible. The section comprises the upper 18 m of the Rhaetian Main Dolomite and almost 300 m of the Lower Jurassic Krka Limestone Member (Fig. 5). The Main Dolomite consists of medium thick beds of dolomitized bindstone with stromatolites and crystalline dolomite. Birds’ eyes, tee-pee structures, desiccation cracks, black pebbles, and irregular bedding surfaces filled with lithified clasts in a clayey matrix are common. Only rare, small agglutinated forms and small Nodosarii- dae (Lagenida) were found in the uppermost part of the Main Dolomite. 104 Luka GALE & Matej KELEMEN Fig. 5. Schematic stratigraphic log of the Tomišelj 2 section. The section is exposed along the slo- pe from Tomišelj towards Mt. Krim and is partly covered. 105Early Jurassic foraminiferal assemblages in platform carbonates of Mt. Krim, central Slovenia Preserje Medium to thick beds predominate. The low- ermost part of the section is strongly dolomitized. Mudstone, bioclast and peloid wackestone pre- dominate throughout the section (Fig. 6). Frag- mented thin-shelled bivalves, foraminifera, os- tracods, gastropods, echinoderms, green algae (Palaeodasycladus mediterraneus), and micro- problematica Thaumatoporella parvovesiculif- era are present among bioclasts. Horizons and beds of laminated dolomite, very rarely stroma- tolites, and intraclastic breccias are subordinate, as well as oolite with micritized grain-centres. Desiccation cracks and pores are present (oGore- lec, 2009). The lowermost part of the section contains few foraminifera. Only Nodosariidae, small Tex- tularia and ?“T.”almtalensis were determined. The rest of the section contains Ammobaculites sp., D. metula, Involutina sp., Nodosariidae, M. asiagoensis, P. butterlini, Reophax sp., ?S. co- lomi, S. gibraltarensis, S. variabilis, Siphoval- vulina sp., Textularia sp., ?“T.” almtalensis, and Trocholina sp. Whereas the previous assemblage could possibly belong to the Hettangian, this as- semblage is placed in the Early to Middle Sine- murian according to the stratigraphic chart for the Dinarides in velić (2007). Additionally, ac- cording to BouDaGher-FaDel and Bosence (2007), P. butterlini first appears in the Early to Middle Sinemurian Siphovalvulina colomi zone. Jezero Beds vary in thickness from thin, rarely even platy, to very thick. Grey and black mudstone and wackestone predominate (Fig. 7). Ooidal limestone is subordinate, sometimes presenting only horizons or lenses. Floatstone with bivalve and gastropod shells is likewise rare, whereas bioclast rudstone is slightly more abundant in the uppermost part of the section. Peloids pre- dominate among clasts. Horizontal lamination in mudstone and gently dipping cross lamination are rare. Small-scale erosion relief, reworked mud chips, shell lags, red clayey bed surfaces, boring and burrowing structures are present. The foraminiferal assemblage is identical to the one in the Tomišelj 1 section. Mesoendothyra sp. first occurs 13 m from the base of the section, and L. recoarensis 47 m from its base. Thus, it is possible that the section spans the successive Me- soendothyra sp. partial-range zone between the Early and Late Sinemurian, and the L. recoaren- sis partial-range zone of the early Late Sinemu- rian (velić, 2007). Tomišelj 1 Beds are medium- and occasionally very thick (Fig. 8). Mudstone and wackestone with rare intraclasts, peloids, ooids, thin-shelled bi- Fig. 6. The Preserje section. Redrawn and simplified after oGorelec (2009). For the legend see Fig. 5. Fig. 7. Jezero section. For the legend see Fig. 5. 106 Luka GALE & Matej KELEMEN valves, and small gastropods predominate. Ooid and bioclast-ooid packstone and grainstone are also common. Intraclast rudstone is rare and bivalve floatstone is present only in single hori- zons. Bioturbation is common in mudstone and wackestone, whereas normal and inverse grad- ings were rarely noted in ooid grainstone. The foraminiferal assemblage consists of A. amiji, Ammobaculites spp., ?Bosniella oenensis, Coronipora sp., D. metula, E. praevirguliana, In- volutina sp., Nodosariidae, ?Lituolipora termieri, ?L. recoarensis, M. asiagoensis, Mesoendothyra sp., Ophthalmidium sp., P. butterlini, Reoph- ax spp., ? S. colomi, S. gibraltarensis, S. varia- bilis, Siphovalvulina sp., Textulariidae, ?“T.” almtalensis, Trocholina spp., and Valvulina sp.. According to the presence of ?L. recoarensis and the absence of Orbitopsella sp., this section belongs to the L. recoarensis partial-range zone of the early Late Sinemurian. Alternatively, because determination of Lituosepta is here questiona- ble, it could belong to the older, Mesoendothyra sp. partial-range zone, spanning the transition from the Early to Late Sinemurian (velić, 2007). According to Bassoullet (1997), this assemblage would be of Late Sinemurian age. Due to the early occurrence of A. amiji, the stratigraphic scheme of BouDaGher-FaDel and Bosence (2007) seems less appropriate for this assemblage. Zalopate The predominant lithology in the Zalopate section is ooid grainstone in mostly medium thick beds (Fig. 9). Bivalve fragments, brachi- opods, intraclasts, and oncoids are sometimes accumulated at the base of the oolite, and may be common enough to constitute a bioclast-ooid grainstone. Mudstone, lithiotid rudstone, peloid wackestone with T. parvovesiculifera, bivalve floatstone to rudstone with a bioclast-peloid wackestone-packstone matrix, and peloid grain- stone are subordinate to grainstone. Normal and inverse grading, red clay partings, scour struc- tures and flow-ripples are occasionally present. The foraminiferal assemblage comprises A. amiji, Ammobaculites spp, B. oenensis, Coroni- pora sp., D. metula, E. praevirguliana, Involutina sp., Nodosariidae, L. recoarensis, M. asiagoen- sis, Ophthalmidium sp., Orbitopsella primaeva, Orbitopsella sp., P. butterlini, Reophax spp., ?S. colomi, S. gibraltarensis, S. variabilis, Siphoval- vulina sp., Textularia spp., Trocholina spp., and Valvulina sp. According to the presence of Orbi- topsella sp. and O. primaeva, this section repre- sents the O. primaeva partial-range zone of Late Sinemurian to earliest Pliensbachian age (velić, 2007). Podpeč The dominant lithology of the Podpeč section (Fig. 10) is medium to massive bedded grey ooid grainstone and bioclast-ooid grainstone. Also common are peloid wackestone to packstone, and oncoid and bioclast floatstone. Fragments of bi- valves are the most frequent bioclasts; terebrat- ulid brachiopods, foraminifera, gastropods and Fig. 8. Tomišelj 1 section. For the legend see Fig. 5. Fig. 9. Zalopate section. For the legend see Fig. 5. 107Early Jurassic foraminiferal assemblages in platform carbonates of Mt. Krim, central Slovenia green algae are other common bioclasts. Lithi- otid bivalves are mostly accumulated inside red claystone beds, rarely at the bases of limestone beds. Thin to medium thick beds of wackestone and mudstone are subordinate. Irregular bed- ding planes, red clayey surfaces, parallel lam- ination and grading are common. Cross-lami- nation in ooid grainstone was found outside the quarry. The foraminiferal assemblage consists of A. amiji, Ammobaculites spp., B. oenensis, Coroni- pora sp., D. metula, E. praevirguliana, Involuti- na sp., Lagenida, L. termieri, M. asiagoensis, Mesoendothyra sp., Ophthalmidium sp., Orbi- topsella praecursor, O. primaeva, Orbitopsella sp., P. butterlini, Reophax spp., ?S. colomi, S. gibraltarensis, S. variabilis, Siphovalvulina sp., Textularidae, Trocholina spp., and Valvulina sp. This assemblage belongs to the O. praecur- sor taxon-range zone of Early Pliensbachian age (velić, 2007). Trends in foraminiferal assemblages Stratigraphic distribution of foraminifera is shown in Figures 5-10. Table 1 summarizes the composition of assemblages of successive time intervals and is divided according to facies. The highest abundance of specimens per cm2 of thin section, the highest number of species and the highest calculated diversity are also given. These parameters, together with corresponding propor- tions of complex agglutinated foraminifera, are graphically shown in Figure 11. Figure 12 shows the change in size of M. asiagoensis and of the absolute largest specimen for each time interval. Discussion Facies changes Lithological succession in the measured sec- tions is summarized as follows: i) Lofer cycles are typical for the Hettangian part of the succession (Dozet, 1993; oGorelec, 2009). Irregular surfaces, clay infillings, and black pebbles point to occasional subaerial ex- posure (haas et al., 2007), which together with birds’ eyes, tee-pee structures, and desiccation cracks indicate intertidal sedimentation on a platform with a flat top. ii) Mudstone, bioclast and peloid wackestone gradually start to become more common during the Late Hettangian, indicating longer-lasting subtidal conditions and/or the gradual recovery of invertebrates after the end-Triassic mass ex- tinction, while stromatolites and subaerial expo- sures become less frequent. Transgression may be partly related to the global rise in sea level (haq et al., 1988; hallaM, 2001) and/or the tec- tonic subsidence of the AdCP northern margin (bucKOvić et al., 2001). iii) During the Early - Middle Sinemuri- an and in the early Late Sinemurian, bioclastic limestone gradually becomes more common. Red clayey bed surfaces indicate short periods of ex- posure (Martinuš et al., 2012). iv) Ooid and bioclast-ooid packstone and well-sorted ooid grainstone with mature ooids become common during the early Late Sinemu- rian, and predominate in the Late Sinemurian and the Early Pliensbachian. Accumulations of bioclasts and scour structures indicate the in- fluence of occasional storms (see FlüGel, 2004: 714). Well-preserved and paired shells of lithiot- id bivalves suggest the presence of bivalve bio- herms in the vicinity (Fraser et al., 2004; Posena- to & avanzini, 2006; Posenato & Masetti, 2012). Short-lasting emersions are still evident as occa- sional red and clayey bedding planes. This type of platform was no longer dominated by peritid- al conditions, but probably resembled internally differentiated lagoon with accumulations and/ or buildups of lithiotid bivalves and oolitic sand shoals (Gale, 2015). Fig. 10. Podpeč section. For the legend see Fig. 5. 108 Luka GALE & Matej KELEMEN M ic ro fa ci es A ge M ax H ‘ M ax ab un da nc e pe r cm 2 *M ax N o. sp ec ie s A ss em bl ag e (d et er m in ed ta xa o nl y, w ith ou t s pe ci es h el d in o pe n no m en cl at ur e) B in ds to ne R ha et ia n – M id dl e H et ta ng ia n 1. 00 0. 42 3 N od os ar iid ae , T ex tu la rii da La te H et ta ng ia n 0. 56 1. 06 2 M ea nd ro vo lu ta a si ag oe ns is , N od os ar iid ae Ea rly – m id dl e Si ne m ur ia n 0. 75 5. 87 6 M ea nd ro vo lu ta a si ag oe ns is , N od os ar iid ae , P se ud op fe nd er in a bu tte rl in i, Te xt ul ar iid a, “ Tr oc ha m m in a” a lm ta le ns is , T ro ch ol in a sp . ea rly L at e Si ne m ur ia n 0 0 0 / M ud st on e La te H et ta ng ia n 0 0. 29 1 »T ro ch am m in a« a lm ta le ns is Ea rly - M id dl e Si ne m ur ia n 1. 31 2. 26 5 M ea nd ro vo lu ta a si ag oe ns is , N od os ar iid ae , P se ud op fe nd er in a bu tte rl in i, Re op ha x sp ., Si ph ov al vu lin a sp ., Te xt ul ar iid a ea rly L at e Si ne m ur ia n 0. 8 0. 97 3 Am m ob ac ul ite s s p. , N od os ar iid ae , P se ud op fe nd er in a bu tte rl in i La te S in em ur ia n – ea rli es t P lie ns ba ch ia n / 0 0 / Sp ar se w ac ke st on e La te H et ta ng ia n / 0 0 / Ea rly - M id dl e Si ne m ur ia n 2. 48 10 .7 7 9 Am iji el la a m iji , A m m ob ac ul ite s s p. , ? C or on ip or a sp ., D uo ta xi s m et ul a, In vo lu tin a sp ., M ea nd ro vo lu ta a si ag oe ns is , N od os ar iid ae , O ph - th al m id iu m sp ., Ps eu do pf en de ri na b ut te rl in i, Re op ha x sp ., Si ph ov al vu lin a sp ., Te xt ul ar iid a, “ Tr oc ha m m in a” a lm ta le ns is , ? Tr oc ho lin a sp . ea rly L at e Si ne m ur ia n 1. 98 8. 55 11 Am iji el la a m iji , E ve rt ic yc la m m in a pr ae vi rg ul ia na , M ea nd ro vo lu ta a si ag oe ns is , N od os ar iid ae , R eo ph ax sp ., Si ph ov al vu lin a sp ., Te xt ul ar iid a D en se w ac ke st on e La te H et ta ng ia n 0. 72 10 .1 2 4 D uo ta xi s m et ul a, M ea nd ro vo lu ta a si ag oe ns is , N od os ar iid ae , T ex tu la rii da Ea rly - M id dl e Si ne m ur ia n 1. 56 36 .1 3 16 Am iji el la a m iji , A m m ob ac ul ite s s p. , D uo ta xi s m et ul a, L itu ol ip or a te rm ie ri , M ea nd ro vo lu ta a si ag oe ns is , N od os ar iid ae , P se ud op fe nd er in a bu tte rl in i, Re op ha x sp ., Si ph ov al vu lin a gi br al ta re ns is , S ip ho va lv ul in a va ri ab ili s, Te xt ul ar iid a, “ Tr oc ha m m in a” a lm ta le ns is , T ro ch ol in a sp . ea rly L at e Si ne m ur ia n 2. 06 11 .5 8 13 Am m ob ac ul ite s s p. , D uo ta xi s m et ul a, E ve rt ic yc la m m in a pr ae vi rg ul ia na , M ea nd ro vo lu ta a si ag oe ns is , N od os ar iid ae , P se ud op fe nd er in a bu tte rl in i, Re op ha x sp ., Si ph ov al vu lin a sp ., Te xt ul ar iid a, “ Tr oc ha m m in a” a lm ta le ns is La te S in em ur ia n – ea rli es t P lie ns ba ch ia n 1. 83 1. 69 7 Si ph ov al vu lin a gi br al ta re ns is Ea rly P lie ns ba ch ia n 1. 94 28 .6 7 20 Am m ob ac ul ite s s p. , I nv ol ut in a fa ri nn ac ia e, M ea nd ro vo lu ta a si ag oe ns is , M es oe nd ot hy ra sp ., N od os ar iid ae , O ph th al m id iu m sp ., Re op ha x sp ., Te xt ul ar iid a, T ro ch ol in a sp . T ab le 1 . T h e la rg es t va lu es f or d iv er si ty ( H ), a b u n d a n ce a n d n u m b er o f sp ec ie s p er t h in s ec ti on a n d t h e li st o f d et er m in ed f or a m in if er a. 109Early Jurassic foraminiferal assemblages in platform carbonates of Mt. Krim, central Slovenia Pa ck st on e La te H et ta ng ia n 1. 64 2. 94 6 D uo ta xi s m et ul a, R eo ph ax sp ., Si ph ov al vu lin a va ri ab ili s, Te xt ul ar iid a Ea rly – M id dl e Si ne m ur ia n 3. 18 14 .6 2 24 Am iji el la a m iji , A m m ob ac ul ite s s p. , ? C or on ip or a sp ., D uo ta xi s m et ul a, E ve rt ic yc la m m in a pr ae vi rg ul ia na , I nv ol ut in a sp ., L itu ol ip or a te r- m ie ri , M ea nd ro vo lu ta a si ag oe ns is , M es oe nd ot hy ra sp ., N od os ar iid ae , O ph th al m id iu m sp ., Ps eu do pf en de ri na b ut te rl in i, Re op ha x sp ., ?S i- ph ov al vu lin a co lo m i, Si ph ov al vu lin a gi br al ta re ns is , S ip ho va lv ul in a sp ., Si ph ov al vu lin a va ri ab ili s, Te xt ul ar iid a, “ Tr oc ha m m in a” a lm ta le ns is , Tr oc ho lin a sp . ea rly L at e Si ne m ur ia n 2. 38 24 .2 8 15 Am iji el la a m iji , A m m ob ac ul ite s s p. , ? C or on ip or a sp ., D uo ta xi s m et ul a, E ve rt ic yc la m m in a pr ae vi rg ul ia na , I nv ol ut in a sp ., M ea nd ro vo lu ta as ia go en si s, N od os ar iid ae , O ph th al m id iu m sp ., Ps eu do pf en de ri na b ut te rl in i, Re op ha x sp ., Si ph ov al vu lin a gi br al ta re ns is , S ip ho va lv ul in a sp ., Si ph ov al vu lin a va ri ab ili s, Te xt ul ar iid a, “ Tr oc ha m m in a” a lm ta le ns is , T ro ch ol in a sp . La te S in em ur ia n – ea rli es t P lie ns ba ch ia n 2. 38 29 .8 2 30 Am iji el la a m iji , A m m ob ac ul ite s s p. , ? C or on ip or a sp ., D uo ta xi s m et ul a, E ve rt ic yc la m m in a pr ae vi rg ul ia na , I nv ol ut in a sp ., Li tu os ep ta re - co ar en si s, M ea nd ro vo lu ta a si ag oe ns is , M es oe nd ot hy ra sp ., N od os ar iid ae , O ph th al m id iu m sp ., O rb ito ps el la p ri m ae va , O rb ito ps el la sp ., Ps eu do pf en de ri na b ut te rl in i, Re op ha x sp ., Si ph ov al vu lin a gi br al ta re ns is , S ip ho va lv ul in a va ri ab ili s, ?S ip ho va lv ul in a co lo m i, Te xt ul ar iid a, Tr oc ho lin a sp ., Ea rly P lie ns ba ch ia n 2. 21 59 .8 6 18 Am iji el la a m iji , B os ni el la o en en si s, ?C or on ip or a sp ., D uo ta xi s m et ul a, E ve rt ic yc la m m in a pr ae vi rg ul ia na , I nv ol ut in a sp ., M ea nd ro vo lu ta as ia go en si s, M es oe nd ot hy ra sp ., N od os ar iid ae , O ph th al m id iu m sp ., O rb ito ps el la p ra ec ur so r, O rb ito ps el la p ri m ae va , O rb ito ps el la sp ., Si ph ov al vu lin a gi br al ta re ns is , S ip ho va lv ul in a va ri ab ili s, Te xt ul ar iid a, T ro ch ol in a sp . G ra in st on e La te H et ta ng ia n 1. 63 4. 83 6 D uo ta xi s m et ul a, N od os ar iid ae , R eo ph ax sp ., Si ph ov al vu lin a va ri ab ili s, Te xt ul ar iid a Ea rly – M id dl e Si ne m ur ia n 2. 31 18 .8 9 16 Am iji el la a m iji , A m m ob ac ul ite s s p. , D uo ta xi s m et ul a, E ve rt ic yc la m m in a pr ae vi rg ul ia na , I nv ol ut in a sp ., Li tu ol ip or a te rm ie ri , M ea nd ro vo lu ta as ia go en si s, M es oe nd ot hy ra sp ., N od os ar iid ae , P la ni in vo lu ta sp ., Ps eu do pf en de ri na b ut te rl in i, Re op ha x sp ., Si ph ov al vu lin a gi br al ta re ns is , Si ph ov al vu lin a va ri ab ili s, Si ph ov al vu lin a sp ., Te xt ul ar iid a, “ Tr oc ha m m in a” a lm ta le ns is , T ro ch ol in a sp . ea rly L at e Si ne m ur ia n 2. 62 26 .6 2 17 Am iji el la a m iji , A m m ob ac ul ite s s p. , B os ni el la o en en si s, ?C or on ip or a sp ., D uo ta xi s m et ul a, E ve rt ic yc la m m in a pr ae vi rg ul ia na , I nv ol ut in a sp ., Li tu ol ip or a te rm ie ri , L itu os ep ta re co ar en si s, M ea nd ro vo lu ta a si ag oe ns is , M es oe nd ot hy ra sp ., N od os ar iid ae , P se ud op fe nd er in a bu tte rl in i, Re op ha x sp ., ?S ip ho va lv ul in a co lo m i, Si ph ov al vu lin a va ri ab ili s, Si ph ov al vu lin a sp ., Te xt ul ar iid a, “ Tr oc ha m m in a” a lm ta le ns is , T ro ch ol in a sp . La te S in em ur ia n – ea rli es t P lie ns ba ch ia n 2. 64 29 .4 8 25 Am iji el la a m iji , A m m ob ac ul ite s s p. , ? C or on ip or a sp ., D uo ta xi s m et ul a, E ve rt ic yc la m m in a pr ae vi rg ul ia na , I nv ol ut in a sp ., L itu os ep ta re co a- re ns is , M ea nd ro vo lu ta a si ag oe ns is , N od os ar iid ae , O ph th al m id iu m sp ., O rb ito ps el la p ri m ae va , O rb ito ps el la sp ., Ps eu do pf en de ri na b ut te rl i- ni , R eo ph ax sp ., Si ph ov al vu lin a gi br al ta re ns is , S ip ho va lv ul in a va ri ab ili s, Te xt ul ar iid a, T ro ch ol in a sp . Ea rly P lie ns ba ch ia n 2. 02 29 .9 4 24 Am iji el la a m iji , A m m ob ac ul ite s s p. , ? C or on ip or a sp ., D uo ta xi s m et ul a, In vo lu tin a sp ., M ea nd ro vo lu ta a si ag oe ns is , M es oe nd ot hy ra sp ., N od os ar iid ae , O ph th al m id iu m sp ., O rb ito ps el la sp ., Re op ha x sp ., Si ph ov al vu lin a sp ., Te xt ul ar iid a, T ro ch ol in a sp . O oi da l gr ai ns to ne Ea rly – M id dl e Si ne m ur ia n 2. 38 3. 35 12 Am iji el la a m iji , A m m ob ac ul ite s s p. , D uo ta xi s m et ul a, In vo lu tin a sp ., M ea nd ro vo lu ta a si ag oe ns is , M es oe nd ot hy ra sp ., N od os ar iid ae , O ph - th al m id iu m sp ., Re op ha x sp ., Si ph ov al vu lin a gi br al ta re ns is , S ip ho va lv ul in a sp ., Si ph ov al vu lin a va ri ab ili s, Te xt ul ar iid a, “ Tr oc ha m m in a” al m ta le ns is , T ro ch ol in a sp . ea rly L at e Si ne m ur ia n 2. 53 11 .0 3 17 Am iji el la a m iji , A m m ob ac ul ite s s p. , B os ni el la o en en si s, D uo ta xi s m et ul a, E ve rt ic yc la m m in a pr ae vi rg ul ia na , I nv ol ut in a sp ., L itu ol ip or a te rm ie ri , L itu os ep ta re co ar en si s, M ea nd ro vo lu ta a si ag oe ns is , M es oe nd ot hy ra sp ., N od os ar iid ae , O ph th al m id iu m sp ., Ps eu do pf en de ri na bu tte rl in i, Re op ha x sp ., ?S ip ho va lv ul in a co lo m i, Si ph ov al vu lin a gi br al ta re ns is , S ip ho va lv ul in a sp ., Si ph ov al vu lin a va ri ab ili s, Te xt ul ar iid a, Tr oc ho lin a sp . La te S in em ur ia n – ea rli es t P lie ns ba ch ia n 2. 21 18 .0 8 18 Am iji el la a m iji , B os ni el la o en en si s, ?C or on ip or a sp ., In vo lu tin a sp ., L itu os ep ta re co ar en si s, M ea nd ro vo lu ta a si ag oe ns is , N od os ar iid ae , O ph th al m id iu m sp ., Pl an iin vo lu ta sp ., Ps eu do pf en de ri na b ut te rl in i, Re op ha x sp ., ?S ip ho va lv ul in a co lo m i, Si ph ov al vu lin a gi br al ta re ns is , Si ph ov al vu lin a sp ., Te xt ul ar iid a, T ro ch ol in a sp . Ea rly P lie ns ba ch ia n 2. 92 43 .3 9 29 Am iji el la a m iji , A m m ob ac ul ite s s p. , B os ni el la o en en si s, ?C or on ip or a sp ., D uo ta xi s m et ul a, E ve rt ic yc la m m in a pr ae vi rg ul ia na , In vo lu tin a sp ., Li tu ol ip or a te rm ie ri , M ea nd ro vo lu ta a si ag oe ns is , M es oe nd ot hy ra sp ., N od os ar iid ae , O ph th al m id iu m sp ., O rb ito ps el la p ri m ae va , O rb i- to ps el la p ra ec ur so r, O rb ito ps el la sp ., Ps eu do pf en de ri na b ut te rl in i, Re op ha x sp ., Si ph ov al vu lin a gi br al ta re ns is , S ip ho va lv ul in a va ri ab ili s, ?S ip ho va lv ul in a co lo m i, Te xt ul ar iid a, T ro ch ol in a sp . * sp ec ie s h el d in o pe n no m en cl at ur e in cl ud ed 110 Luka GALE & Matej KELEMEN Fig. 11. Changes in foraminiferal assemblages according to different facies. A: Maximum abundance (number of speci- mens per cm2 of thin section). B: Maximum number of spe- cies (species richness) per facies type. C: Maximum diversity for different facies types. D: Percent of relatively complex agglutinated foraminifera. Specimens with an advanced en- doskeleton (e.g., axial infill, pillars) and/or with exoskeletal structures (complex outer wall, possibly for hosting endosym- bionts) were counted, and include the genera: Bosniella, Lituolipora, Pseudopfenderina, Amijiella, Mesoendothyra, Lituosepta, Orbitopsella, Everticyclammina, Cymbriaella. Fig. 12. Trends in sizes of foraminifera. A: A within-genus change of size for Meandrovoluta per facies type. Vertical bars indicate variability within distinct facies types, and the symbol the mean size. The oblique solid line represents a ge- neral increase in size. B: The among-genus change in size. The largest specimens encountered in different time-slices were measured, regardless of facies type. 111Early Jurassic foraminiferal assemblages in platform carbonates of Mt. Krim, central Slovenia Diversification in foraminifera Foraminiferal assemblages from Hettangian to Pliensbachian undergo significant changes in composition, diversity and abundance, which take place cotemporaneous with a facies change from restricted tidal-flat to predominantly sub- tidal and normal marine conditions: i) Until the Late Hettangian, the taxonom- ic composition is virtually the same in all facies types of the peritidal environment. The assem- blage consists of species, that may be considered opportunists (see FuGaGnoli, 2004; BouDaGh- er-FaDel, 2008), e.g. M. asiagoensis, Siphoval- vulina spp., and Triassic survivors, e.g. D. metu- la, “T.” almtalensis. ii) A strong increase in abundance, species richness, diversity of foraminifera and number of complex agglutinated forms is common to all facies types, except mudstone and bindstone in the Early - Middle Sinemurian. There is a strong possibility of a continued increase in the abun- dance of foraminifera until the Early Pliens- bachian, which is the youngest sampled interval. As such increase occurs in all facies types (except in bindstone and mudstone), we can rule out the possibility of simply sampling a more suitable fa- cies type (i.e., more “grainy” limestone opposed to micritic limestone). iii) Bosniella oenensis, L. recoarensis, and Or- bitopsella spp. are restricted to packstone, grain- stone and ooid grainstone since the early Late Sinemurian. These may be more strongly agitat- ed facies types. iv) Although the size of M. asiagoensis varies, there may be a general trend in increase in size; and the size of the largest species in the assem- blage also increases. The recorded succession of faunas parallels the studies of benthic foraminifera elsewhere in the present peri-Mediterranean area (chi- occhini et al., 1994; zaMBetaKis-leKKas et al., 1996; BouDaGher-FaDel et al., 2001; eren et al., 2002; KaBal & tasli, 2003; Barattolo & roMa- no, 2005; Mancinelli et al., 2005; PoMoni-PaPaio- annou & KostoPoulou, 2008; Bosence et al., 2009; tunaBoylu et al., 2014). The contrasting Hettan- gian - Early Sinemurian and Late Sinemurian - Pliensbachian communities are mostly inter- preted as survival and recovery communities of the post-extinction period (Barattolo & roMano, 2005; Mancinelli et al., 2005; BouDaGher-FaDel & Bosence, 2007; BouDaGher-FaDel, 2008; tunaBoy- lu et al., 2014), and could be interpreted as part of the global community maturation process (Hot- tinger, 1996, 2014). However, FuGaGnoli (2004; see also sePtFontaine, 1986) related a low-diversity assemblage dominated by Glomospira/Plani- involuta spp. (i.e., Meandrovoluta sp.), together with Duotaxis, simple textulariids and valvulin- ids, to eutrophic conditions (bioturbated mud- stone-wackestone alternating with black shale), while the diversity and proportion of complex lituolids increase as conditions changed towards meso- and oligotrophic. The change in nutrient supply and oxygen availability from Hettangian to Pliensbachian is not as strongly supported in the present study, as there is no transition from or- ganic-rich facies (although algal mats contained plenty of organic matter, while well-washed sands in the younger part of the succession were well oxygenated). Rather, environmental stabili- ty itself might be more important in establishing more complex associations of foraminifera. Such stability might have been related to stabilization of the physical environment (e.g., ocean chemis- try, sea temperature) after the end-Triassic ex- tinction, or to the increasing interactions among organisms, but it might also have come with the transition from highly fluctuating peritidal con- ditions where there are drastic changes in light intensity, salinity and temperature, to predom- inantly subtidal and thus more physically stable conditions (see hallocK, 1988). Furthermore, al- though a steady increase in the size of foraminif- era has been recorded after the Permian-Triassic boundary extinction and used as an argument for a true (i.e., not facies-change related) recov- ery of foraminifera (Payne et al., 2011; reGo et al., 2012), it is not known whether such an increase in size is possible also during the time of rising sea level (wilMsen & neuweiler, 2008). In other words, the increased complexity of foraminiferal assemblages in transgression-affected succession should not be attributed solely to post-extinction biotic recovery and diversification, but may in- stead reflect a rather local re-establishment of suitable habitat. Conclusions The precise age of Lower Jurassic carbonates from the Mt. Krim area (External Dinarides) was determined on the basis of foraminifera. Such bi- ostratigraphic framework is obligatory for poten- 112 Luka GALE & Matej KELEMEN tial future studies of the northern Adriatic Car- bonate Platform. During the Late Hettangian, sedimentation took place on a relatively flat plat- form with quickly interchanging subtidal and intertidal conditions, as can be concluded from the exchange of micritic limestone/dolomite with laminated (stromatolitic) limestone/dolomite and emersion surfaces. Foraminiferal assemblage, consisting of small opportunists, is identical in all microfacies types, even in rare packstone and grainstone. The low diversity of the assemblage may be attributed to the early stages of recovery after the end-Triassic extinction, or to unstable environmental conditions. Towards the Early – Middle Sinemurian, foraminiferal assemblages of various facies types show an increase in abun- dance, species richness, and diversity. Larger ag- glutinated species appear for the first time. This change in the assemblage corresponds to a shift towards predominantly subtidal and more stable conditions. The younger strata show a continu- ing increase in abundance until the Early Pliens- bachian, but the trend is not so clear as regards species richness and diversity. The facies associ- ation suggests the contemporaneous development of an internally differentiated lagoon, which hin- ders distinguishing between the true speciation and the mere colonisation of suitable habitats. Acknowledgements This study was financially supported by the Slovenian Research Agency (pr. no. P1-0011). Thin sections were prepared by Mladen Štumergar (Geological Survey of Slovenia). We thank students Maša Jamnik and Primož Oprčkal for their help with the field work. We also thank the reviewers for their constructive remarks. References Barattolo, F. & roMano, R. 2005: Shallow car- bonate platform bioevents during the Upper Triassic-Lower Jurassic: an evolutive inter- pretation. Boll. Soc. Geol. It., 124: 123-142. Bassoullet, J.-P. 1997: Large foraminifera. In: cariou, e. & hantzPerGue, P. (eds.): Jurassic biostratigraphy of the western Europe and Mediterranean: microfossil distribution and zonations. Bull. Centre Rech. Explor. Prod- uct. Elf, 17: 293-304. 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