COBISS: 1.01 HyDROCHEMIC CHARACTERISTICS AND TECTONIC SITUATION Of SELECTED SPRINGS IN CENTRAL AND NW yUNNAN PROVINCE, CHINA HIDROKEMIČNE ZNAČILNOSTI IN TEKTONSKI POLOŽAJ IZBRANIH IZVIROV V OSREDNJEM IN SZ yUNNANU, KITAJSKA Stanka ŠEBELA1 & Janja KOGOVŠEK1 Abstract UDC 556.3:54(510) S. Šebela & J. Kogovšek: Hydrochemic characteristics and tec-tonic situation and ofselected springs in central andNW Yun-nan province, China Te yunnan Province lies on the eastern rim of the collision zone between the Indian plate and Eurasia. Tis region is char-acterized by complex Cenozoic structures and active seismotec-tonics. In the year 2004 the areas north from Kunming and the NW part of yunnan were studied. Te measurements of the temperature, conductivity and the analyses of carbonate, phos-phate and nitrate were performed in Quinglongtan spring and in the accumulation lake that is situated lower than the spring. Te springs are situated in the wider zone of the xiaojiang fault along which lef horizontal movements are taking place. Along the wider zone of the Zhongdian fault between the town of Zhongdian and the yangtze River on the south there are more springs. Tiansheng Qiao (T = 57.5oC) and xiageiwenquan (T = 48,3 - 66.8oC) are thermal springs along which tufa is depos-ited. Te Baishuitai spring has high mineralization and lower temperature (T = 11.1 - 13.3oC) and deposits calcium carbonate in the form of gours. All studied springs are connected with active fault zones. Te studied areas mostly represent the con-tact areas between carbonate and non-carbonate rocks. key words: springs, tectonics, travertine, yunnan, China. Izvleček UDK 556.3:54(510) S. Šebela & J. Kogovšek: Hidrokemične značilnosti in tektonski položaj izbranih izvirov v osrednjem in SZ Yunnanu, Kitajska Provinca yunnan leži na vzhodnem robu kolizijske cone med Indijsko in Evrazijsko ploščo. Za to ozemlje so značilne zapletene kenozojske strukture in aktivna seizmotektonika. V letu 2004 smo proučevali ozemlja severno od Kunminga in SZ del yunnana. Meritve temperature, specifčne električne prevodnosti in analize vsebnosti karbonatov, fosfatov in nitratov smo opravili na izvirih Quinglongtan in v nižje ležečem akumulacijskem jezeru. Izviri se nahajajo v širši prelomni coni xiaojiang, ob kateri se vršijo levi zmiki. V širši prelomni coni Zhongdian preloma med mestom Zhongdian in reko yangtze na jugu se nahaja več izvirov. Tiansheng Qiao (T = 57,5oC) in xiageiwen-quan (T = 48,3 - 66,8oC) sta termalna izvira, ob katerih se odlaga lehnjak, Baishuitai pa je močno mineraliziran izvir z nižjo temperaturo (T = 11,1 - 13,3oC), ki odlaga kalcijev karbonat in gradi ponvice. Vsi ti izviri so vezani na aktivne prelomne cone. Izbrani predeli večinoma predstavljajo kontakt med karbonatnimi in nekarbonatnimi kamninami. ključne besede: izviri, tektonika, lehnjak, yunnan, Kitajska. 1 Inštitut za raziskovanje krasa ZRC SAZU, Titov trg 2, 6230 Postojna, Slovenia, e-mail: sebela@zrc-sazu.si Received / Prejeto: 20.01.2006 ACTA CARSOLOGICA 35/1, 23–33, LJUBLJANA 2006 STANKA ŠEBELA & JANJA KOGOVŠEK INTRODUCTION Exposed karst areas in China comprise about 900.000 km2 and the karst area in yunnan includes 110.900 km2. Te yunnan region in southwest China is located in the boundary area between the active Tibetan Plateau to the west and the stable South China platform to the east. Tis region is characterized by complex Cenozoic structures and active seismotectonics. Te studied area is part of the Tree parallel riv-ers of yunnan Protected Areas, which is inscribed in the UNESCOs World Heritage List. Te area represents geo-logical history of at least 50 million years associated with the collision of the Indian Plate with the Eurasian Plate, the closure of the ancient Tethys Sea, and the uplifing of the Himalayan Range and the Tibetan Plateau. Te site consists of 15 protected areas (in eight geo-graphic clusters) in the mountainous northwest of yun-nan Province and extends over a total area of 1.698.400 ha, encompassing the watershed areas of the yangtze (Jinsha), Mekong (Lacang) and Salween (Nu Jiang) riv-ers. Te rivers pass through steep gorges, in places up to 3.000 m deep. At their closest the three gorges are 18 km and 66 km apart. Our research work in this region was performed within the Slovene-Chinese project with yunnan Institute of Geography from 18-29th October 2004. In the previous years most researches were oriented to the area around Kunming (Lunan) and SE from Kunming (xichou, Qiubei, Guangnan) (figure 1). Shilin, feng-cong, fenglin, karst caves were studied (Knez & Slabe 2002; Šebela et al. 2004) and water tracing tests were performed (Kogovšek et al. 1997; Kogovšek & Liu Hong 2000). In the year 2004 it was the frst time that the areas of NW yunnan were visited and some thermal and non-thermal springs with tufa deposits related to active tec-tonics were studied. TUfA DEPOSITS Tufa as a general name covers a wide variety of calcar-eous freshwater deposits, which are particularly com-mon in late Quaternary and Recent successions. Tufa is the product of calcium carbonate precipitation under a cool water regime and typically contains the remains of micro- and macrophytes, invertebrates and bacteria. Te term travertine is restricted to all “freshwater” thermal and hydrothermal calcium carbonate deposits dominat-ed by physico-chemical and microbial precipitates, which invariably lack in situ macrophyte and animal remains. Tufas are usually distinguishable from travertines, even in ancient deposits, by the comparatively high diversity of contained plants, including macrophytes, and animals (ford & Pedley 1996). In Chinas vast karst landscapes there are many tufa deposits. Tey are known in Sichuan, Guizhou, Guangxi and Tibet Provinces. Some of the tufa cascades in Guizhou are broadly comparable with the Plitvice barrages (ford & Pedley 1996). frančišković, Bilinski et al. (2003) analysed the tufa from Guangxi. One tufa sample origi-nated in the Pleistocene, and the others in the Holocene. Te travertines in China are divided into two major geochemical groups: the meteogenes and thermogenes. Te thermogenes are essentially hydrothermal deposits, where CaCO3 is precipitated from high-CO2 groundwa-ters. Most of this CO2 comes from deep within the crust as a result of magmatic degassing or limestone decarbon-ation with DIC (dissolved inorganic carbon) values typi-cally >>10 mM/l. Tey are usually found in tectonically and/or volcanically active regions (Pentecost & Zhang 2001). Tibet, in spite of its cold dry climate and high alti-tude, has a scatter of tufa deposits, mostly either calcare-ous crusts on colluvium or associated with geothermal springs (Waltham 1996). TECTONIC SITUATION Tectonic development of the SE Asia includes the Indian subcontinental collision, which represents the penetra-tion of a rigid block (representing India) into layers of plasticine in a partly confned block (Asia) (Tapponnier 24 ACTA CARSOLOGICA 35/1 – 2006 et al. 1982). Te Red River fault zone (figure 1) is the major geological discontinuity that separates South Chi-na from Indochina. Today it corresponds to a great right-lateral fault, following for over 900 km the edge of four HyDROCHEMIC CHARACTERISTICS AND TECTONIC SITUATION Of SELECTED SPRINGS Fig. 1: tectonic situation of yunnan (afer Burchfeld & Wang 2003). 1 = yulong Snow mountain 5596 m above sea level; lake, 2-ZF = Zhongdian fault, JF = Jianshui fault, QF = Qujiang fault, 3 = studied areas, 1 = tiansheng Qiao and Xiageiwenquan springs, 2 = Baishuitai tufa deposits, 3 = springs north of Kunming 4 = right-lateral slip along the fault, 5 = lef-lateral slip along the fault. Slika 1: tektonske razmere yunnana (po Burchfeld & Wang 2003). 1 = yulong Snow mountain 5596 m nad morjem; jezero, 2-ZF = Zhongdian prelom, JF = Jianshui prelom, QF = Qujiang prelom, 3 = raziskovana mesta, 1= izviri tiansheng Qiao in Xiageiwenquan, 2 = Baishuitai ponvice, 3 = izviri severno od Kunminga, 4 = desni zmik ob prelomu, 5 = levi zmik ob prelomu. narrow (<20 km wide) high-grade gneiss ranges that to-gether form the Ailao Shan-Red River metamorphic belt (Leloup et al. 1995). Te movement along the Red River fault has been dominantly right lateral since the close of the Tertiary. Te best evidence comes from ofsets of tributary streams of up to 5-6 km in the last 2 to 3 Ma (amounting to slip rates of 2-5 mm/yr). No signifcant earthquake has oc-curred along the fault in the last 2000 years (Allen et al. 1984). Tapponnier et al. (1982) surmise reversal of movement on the Red River fault from the initial lef-lateral sense during the frst 20 to 30 Ma following the onset of the Indian collision. A diferent regional stress pattern now favors adjustment by dextral slip. Te orientation of the fault is consistent with N-S shortening and E-W extension. Geological relations near the NW termination of the Ailao Shan suggest the Red River fault had a minimum of 14 - 48 km of right-lateral displacement in pre-Plio-cene (and presumably post -17 Ma) time and only 5-6 km of displacement in Quaternary time (Allen et al, 1984; Wang et al, 1998). Active right-lateral displacement on the eastern part of the Red River fault zone is interpreted to be caused by a segment of the fault zone being rotated counterclockwise by shear related to the lef-lateral xiao-jiang fault system (Wang et al. 1998). Stating that the Red River fault has been displaced by the xiaojiang fault, it can be concluded that with respect to its present kinematics, the eastern part of the Red River fault does not accommodate large motions nowadays (Michel et al. 2000). Te northwest-striking Jianshui and Qujiang faults (figure 1) and probably the Zhongdian fault show evidence for diferent amounts of middle Ce-nozoic (pre-Pliocene and post-early Paleogene) lef-lateral displacement that range from 6-25 km. Te age and orientation of the lef-lateral faults suggest that the faults are related to a regional deformational event associated with important lef-lateral shear on the Ailao-Shan shear zone (Burchfel & Wang 2003). Te Zhongdian fault (figure 1) appears to have un-dergone only lef-lateral displacement, some of which may be middle Cenozoic in age and some post-Mio-cene in age. Active displacement on the Zhongdian fault is interpreted to mark the eastern boundary for a small crustal fragment that rotates clockwise around the eastern Himalayan syntaxis (Burchfel & Wang 2003). Active right-lateral movement on the Jianshui fault (figure 1) can be documented by numerous geological (ofset structures) and geomorphic (defected rivers and pull-apart basins) features. Active right-lateral displacement of the Quijiang fault is demonstrated by numerous scarps and ofset Holocene feature and seismic activity (Burchfel & Wang 2003). SE of Zhongdian the Zhongdian fault passes through a series of basins flled with Quaternary sediments and the analysis suggests lef-lateral stream defections in-dicating the fault is active. Te fault bends south at the Jinsha River and merges with the active lef-lateral Jian-chuan fault (Burchfel & Wang 2003). Quaternary basins and lakes north of Dali and with-in the southern part of the xiaojiang fault zone are areas of local active extension (Wang & Burchfel 2000). Only the Jianshui fault and possibly the Quijiang fault contain evidence for right-lateral reactivation of older lef-lateral faults (Burchfel & Wang 2003). Te xiaojiang fault system is at least 2-4 m.y old, and possibly as old as 6-8 m.y, which suggests rapid right-slip did not begin on the ACTA CARSOLOGICA 35/1 – 2006 25 STANKA ŠEBELA & JANJA KOGOVŠEK Quaternary Jianshui and Quijang faults until lef-lateral shear within xiaojiang fault system was well underway (Burchfel & Wang 2003). Te Pliocene-Quaternary sedimentary fll in pull-apart basins associated with lef-lateral xianshuihe-xiao-jiang fault system indicated that this fault system was ini-tiated by at least 2-4 Ma (Wang et al. 1998). Kunming is moving due south with respect to Sun-daland-South China indicating sinistral movement along the xiaojiang fault system with a rate of 11 ±4 mm/yr. Te xianshuihe-xianjiang fault system sufers pure sinistral strike slip faulting in its central part with respect to South China (Michel et al. 2000). SEISMICITy In the broad sense, strike-slip faults and earthquakes in SW China result from the eastward motion of the Earths crust that is driven by the collision of the Indian and Eur-asian continental plates beneath the Himalaya Mountains and the Tibetan Plateau to the west. Tere is an obvious diference between the southern segment and northern segment of the Red River fault from the viewpoint of modern seismicity Te most di-sastrous earthquakes occurred in the northern segment. feigl et al. (2003) report that the Red River fault did not slip faster than 1 or 2 mm/yr between 1994-2001 near Tác Ba, Vietnam. A strong earthquake occurred in Lijiang area in yunnan Province on february 3, 1996 (M = 7.0). Te epicenter was determined to be in the seismically active region of the Hengduan mountains, which belong to the Alpine-Himalaya seismic belt. Kunming is situated in the middle and southern part of seismically active xiaojiang-fault. In the year 1833 earthquakes (M = 8.0) were located in the area of Songmin (figure 1). Te focal mechanisms of the 1966 earthquakes on the N-S-striking xiaojiang fault imply lef-lateral slip along it. A normal component of slip on the roughly N-S faults south from Kunming has created several Quater-nary half-grabens, some of them flled by lakes (Tappon-nier & Molnar 1977). An earthquake of M = 7.7 occurred on the Quijiang fault in 1970 (Tunghai earthquake). Te event produced a 60-km-long surface break and with a maximum right-lateral displacement of 2,7 m (Liu et al. 1988; Ma, 1989). SPRINGS NORTH fROM KUNMING Upper Devonian, Carboniferous and Permian shallow-water carbonates build the south China tower karst, south from Kunming. Near Kunming basalt rock is inter-bedded with the Upper Permian limestones. Within the frame of the feldwork the accumula-tion lake and Quinglongtan spring (figure 2) north from Kunming were studied on 21st October 2004. Te water from several springs is lead to a common channel that runs into the accumulation lake that was made for irriga-tion and water supply of Kunming. Te springs are located in the wider zone of xaojiang fault (figure 1), which is still tectonically active. Te measured temperature and conductivity (SEC) of the three main springs showed that the water from the springs belong to the same source (temperature 14.7oC and SEC 277 µS/cm). Te water in the accumulation lake was warmer (19.4oC), while the SEC measurement was within the values of the Quinglongtan spring. Te carbonate concentration in accumulation lake and in the springs was low; just 135 mg CaCO3/l (2.7 mekv/l) what means it was a little bit lower than total hardness (146 mg CaCO3/l or 2.92 mekv/l, figure 3). In Tianshen-gan area we measured such low values of hardnesses in karst springs at high hydrological conditions (Kogovšek 1998). Te phosphate concentration in accumulation lake and in the spring was under the detection limit of the method (<0,01 mg PO43-/l), the nitrate concentration was 4,6 or 4,4 mg NO3-/l, what shows good water quality 26 ACTA CARSOLOGICA 35/1 – 2006 HyDROCHEMIC CHARACTERISTICS AND TECTONIC SITUATION Of SELECTED SPRINGS • Ca+Mg-96-97 • Ca+Mg-04 Fig. 2: Qinglongtan spring (one of the several springs) north from Kunming (photo by J. Kogovšek). Slika 2: Qinglongtan izvir severno od Kunminga (foto J. Kogovšek). I 8 6 4 2 O ..* 2 4 6 8 10 12 Karbonati - Carbonates (mekv/l) Fig. 3: total and carbonate hardness of sampled springs in year 2004 and sampled karst waters in tianshengan area in the years 1996 – 97 at diferent hydrological conditions. Slika 3: Celokupna in karbonatna trdota vzorčevanih izvirov v letu 2004 in vzorčevane kraške vode na področju tianshengan v letih 1996-97 v različnih hidroloških pogojih. SPRINGS NORTH fROM LIJIANG Te water supply for the Lijiang derives from the near-er Zhenzhuquan spring (figure 4), where the water is cached in a smaller lake that is regulated for tourism. Part of the water is accumulated into the channels that run through the Lijiang town. On the principal spring Fig. 4: Zhenzhuquan spring near lijiang (photo by J. Kogovšek). Slika 4: Izvir Zhenzhuquan pri lijiangu (foto J. Kogovšek). there is a pumping area (figure 5) that is still used for water supply of the Lijiang. During our visit on the 24th October 2004 we met many natives who come to take the water from the spring. Te water temperature was 14.8oC, SEC 370 µS/cm, carbonate hardnesses 158 mg CaCO3/l (3,16 mekv/l), and the total hardness 162 mg CaCO3/l (3,24 mekv/l). Tese measurements fall well with characteristics of groundwater and karst springs in Tianshengan area near Stone forest (Kogovšek et al. 1997, Kogovšek 1998). Te water had good quality re-garding the low chloride concentration (1 mg Cl-/l), the nitrate concentration (1,3 mg NO3-/l), and the o-phos-phates (< 0.01 mgPO43-/l). yulong Snow Mountain (5596 m) consists of Pa-leozoic carbonate rocks and in the eastern area of Ter-tiary clastic rocks with marlites and calcareous rocks (Huang Chuxing 2004). Bai Shui He river that runs on the northern slope of the mountain showed the temperature of 9,6oC (23rd October 2004), low SEC (196 µS/ cm), low carbonate hardness (109 mg CaCO3/l or 2.17 mekv/l) and just 1 mg NO3-/l. Te pH measurement showed value 8.2. ACTA CARSOLOGICA 35/1 – 2006 27 STANKA ŠEBELA & JANJA KOGOVŠEK Fig. 5: Te pumping area at Zhenzhuquan spring (photo by J. Kogovšek). Slika 5: črpališče na izviru Zhenzhuquan (foto J. Kogovšek). Fig. 6: Xiageiwenquan thermal spring (photo by J. Kogovšek). Slika 6: termalni izvir Xiageiwenquan (foto J. Kogovšek). SPRINGS SOUTH fROM ZHONGDIAN About 42,2% of the Zhongdian County represents car-bonate surface. Most of the carbonate rocks are from Devonian and Cretaceous. Some are from lower Per-mian and the middle and lower Triassic (Huang Chux-ing 2004). In the wider zone of the Zhongdian fault near the town of Zhongdian and yangtze river there are more tectonic depressions that are developed inside carbonate rocks but border also to other rocks as magmatic, sand-stones and marbles. In such cases we don’t deal with the true karst poljes. All depressions are related to active tectonic faults that are NW-SE oriented with active sinistral horizontal movements. In the area of the active Zhongdian fault there are more springs (figure 1). Some are thermal springs oth-ers have lower temperature and many of them precipitate tufa deposits. Te spring waters are supposed to come from the depths. During our feld studies we visited the xiageiwenquan thermal springs, Tiansheng Qiao thermal spring, and Baishuitai tufa deposits. All three loca-tions are tourist attractions. Xiageiwenquan (figure 6) is situated about 10 km east from the Zhongdian town and represents about 10 smaller and bigger thermal springs in the distance of 300 m. In the area there are older and younger still active travertine deposits. Te area is built of Triassic limestones, sandstones and mudstones. yuan Daoxian (2002) mentioned 9 springs with discharges between 0,5 to 1 l/s and temperature between 36,6 and 67,4oC. Te SEC values of the springs were between 1676 and 2660 µS/cm. Our measurements taken on the 26th October 2004 detected the temperature being between 48,3 and 66,8oC, 28 ACTA CARSOLOGICA 35/1 - 2006 and minimal discharges. Te SEC values were from 1260 to 1510 µS/cm (measurements were performed with WTW instrument Lf 90 at ref temperature 20oC). Tiansheng Qiao is situated some km south from xiageiwenquan, along the active sinistral horizontal Su-oge-xuejiping fault on the western side of the Jinsha river. Te fault is a deep and wide fault formed in the early stage of Permian but still active today. A hot liquid of the gabbro plasma efuses up through this fault. And it is the precondition to form tufa landscapes (Huang Chuxing 2004). Te attraction of the Tiansheng Qiao is the natural bridge with Shuodugang river running below it (figure 7). Te limestone natural bridge is 40 m high, 10 m wide and 15 m long. In the area there is also the Tiansheng Qiao thermal spring with travertine deposits. Huang Fig. 7: Natural bridge of tiansheng Qiao (photo by J. Kogovšek). Slika 7: Naravni most tiansheng Qiao (foto J. Kogovšek). HyDROCHEMIC CHARACTERISTICS AND TECTONIC SITUATION Of SELECTED SPRINGS Chuxing (2004) speaks about sulphur springs, formed in diferent stages. Te east side is from the earlier stage and the west side from the later stage. Travertine deposits at a relatively high speed with the estimated sedimentation 1-5 cm/year. By comparison with other in the surround-ing areas the travertine of Tiansheng Qiao did not form earlier than 5000 years ago. Te thermal water of the Tiansheng Qiao spring is accumulated into the thermal pools (figure 8) used by Fig. 8: Termal spring of tiansheng Qiao is accumulated into the pools (photo by J. Kogovšek). Slika 8: termalni izvir tiansheng Qiao je speljan v bazene (foto J. Kogovšek). tourists. Te Shuodugang river had (25th October 2004) the temperature of 10oC and low SEC (115 µS/cm). Te water of the thermal spring had the temperature of 57,5oC and high SEC (1805 µS/cm), high carbonate concentra-tion (20 mekv/l) higher chloride values (27 mg Cl-/l) and the sulphate values of 26 mg SO42-/l. High SEC value means high concentration of dissolved substances. Te water probably contains other substances but our analy-ses were limited to the analyses mentioned above. Te scenic spot is the gathering place between the surface and underground water, and also the converging place of the N-S trending Suoge-xuejiping fault and an-other E-W trending fault (Huang Chuxing 2004). baishuitai spring contain high mineralizated waters with regular temperatures. Baishuitai is situated about 20-30 km north from the yangtze river. Te area is built of Triassic rocks (limestones and sandstones) as well as of Permian rocks and Quaternary (delluvium) rocks. Because the spring water is oversaturated it deposits dissolved mineral substances. In this sense the slopes are covered by mostly white tufa. Te tufa dams and gours (figure 9) are covering the areas of Lower and Middle Triassic limestones. Te water resurges from diferent springs. Te spring area is covered by deciduous trees, which are the source for pollution and also the food for Fig. 9: tufa gours of Baishuitai (photo by J. Kogovšek). Slika 9: Baishuitai ponvice (foto J. Kogovšek). algae growth. Te springs are decorated with Buddhist symbols. Many people visit the spring area and walk over the tufa deposits what causes dams’ destruction. Te park administration is trying to protect the area. Te springs’ temperature is between 11,1 and 13,3oC Te SEC measurements showed a little bit over 1000 µS/ cm what means that the water has a lot of dissolved car-bonates. Total hardness was 600 mg CaCO3/l (12 mekv/l) and carbonate concentration 560 mg CaCO3/l (11,2 mekv/l). Te ratio Ca/Mg of the water was equal to 4,4, what shows that the Mg values are 4,4-times lower then the Ca and that the water is coming from the hinterland. Te water had low nitrate and phosphate concentrations and 40 mg SO42-/l of sulphates. Te temperature and conductivity measurements of the water in the gours along the water fow showed the 14 12 • 10 v. .v *» . V«' J" S" • Ca+Mg-02 ¦ Ca+Mg-99 Ca*Mg-98 • Ca+Mg-96-97 • Ca+Mg-04 200 400 600 80C 1000 1200 SEC (pS/cm) Fig. 10: SEC and total hardness of karst waters from diferent parts of yunnan (Kogovšek 1998) and in the article mentioned springs. Slika 10: Specifčna električna prevodnost in celokupna trdota kraških voda iz različnih delov yunnana (Kogovšek 1998) in v članku omenjenih izvirov. ACTA CARSOLOGICA 35/1 – 2006 29 STANKA ŠEBELA & JANJA KOGOVŠEK increase of temperature and lowering of the SEC values, what is typical of intensive carbonate precipitation. At the bottom of the slope the water is led into the chan-nel that runs to the nearest village where it is used for water supply and irrigation. Total hardness of this wa-ter was only 240 mg CaCO3/l (4,8 mekv/l), with 210 mg CaCO3/l belonging to carbonates (4,2 mekv/l). Te ratio Ca/Mg was 3, suggesting mainly the calcium carbonate precipitation (from 1 liter of water up to 360 mg CaCO3 was deposited) while magnesium remains in the solu-tion. Te same results were obtained in tufa precipitation at Podstenjšek spring in Slovenia (Kogovšek 2006). Te Te yunnan Province lies on the eastern rim of the col-lision zone between the Indian plate and Eurasia. Tis region is characterized by complex Cenozoic structures and active seismotectonics. Te Quinglongtan spring (T = 14,7oC and low values of SEC, carbonate and total hardnesses) are situated north from Kunming. Similar values were detected in the area of Tianshengan, yunnan at high hydrological conditions. Te Zhenzhuquan spring near Lijiang had the same temperature but higher values of the SEC and hardnesses. Quinglongtan and Zhenzhuquan springs and ac-cumulation lake had low leve ls of phosphate (under 0,01 mg PO43-/l) and low nitrate concentrations (from 1,3 to 4,6 mg NO 3-/l) and are showing good water quality. Te springs are situated inside the xiaojiang fault zone along which sinistral horizontal movements are still active (figure 1). Most probably they are karst springs. In the wider zone of the Zhongdian fault between Zhongdian town and the yangtze river there are more tectonic depressions, which are developed inside carbonate and non-carbonate rocks. In this sense they are not lower concentration of sulphates (5 mg/l) compared with the values of the higher spring shows partial sulphate precipitation only Tese are our frst results, which should be expanded, as the nice and attractive gours need to be protected from numerous visitors. Liu Zai-Hua et al. (2004) reported about researches of geochemical indica-tors (saturation index, pH, CO2 partial pressure) in cal-cite-precipitating stream and channel at Baishuitai. Baishuitai tufa deposits in yunnan are comparable with the Plitvice travertine dams in Croatia. Tey are probably thermogene (Pentecost & Zhang 2001). the true karst poljes. All depressions are developed inside NW-SE and N-S oriented active fault zone with sinistral horizontal movements. In the wider zone of the Zhongdian fault there are more springs related to active tectonics. Tiansheng Qiao (T = 57,5oC) and xiageiwenquan springs (T = 48,3 -66,8oC) are thermal springs with tufa deposits. Baishuitai is very mineralized spring with lower temperature (T = 11,1 - 13,3oC), which deposits mostly calcium carbonate. Te ratio of Ca/Mg decreases along the precipitation path, what means that Mg remains in solution. Also the sulphates are partly precipitating. Baishuitai travertines are probably thermogene (Pentecost & Zhang 2001). Because carbonate tufas are very sensitive to water and climate Huang Chuxing (2004) performed the geo-morphological investigations to provide scientifc basis for the protection of tourist tufa resources of Tiansh-engqiao. Te study was performed within the Slovene-Chi-nese project with yunnan Institute of Geography be-tween 18-29th October 2004 and supported by Agencija za raziskovalno dejavnost RS. 30 ACTA CARSOLOGICA 35/1 – 2006 HyDROCHEMIC CHARACTERISTICS AND TECTONIC SITUATION Of SELECTED SPRINGS REfERENCES Allen, C.R., Gillespie, A.R., Han, y, Sieh, K.E., Zhang, B. & Zhu, C, 1984: Red River and associated yunnan province, China; Quaternary geology, slip rates, and seismic hazard.- Geological Society of America Bul-letin 95, 686-700. Burchfeld, B.C. & Erchie, Wang, 2003: Northwest-trend-ing, middle Cenozoic, lef-lateral faults in southern yunnan, China, and their tectonic signifcance.-Journal of Structural Geology 25, 781-792. feigl, K. 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Pentecost, A. & Zhang, Z., 2001: A review of Chinese travertines.- Cave and Karst Science Volume 28, number 1, 15-28. Šebela, S., Slabe, T, Liu, Hong & Pruner, P, 2004: Speleo-genesis of selected caves beneath the Lunan Shilin and caves of fenglin karst in Qiubei, yunnan.- Acta Geologica Sinica, vol. 78, no. 6, 1289-1298. Tapponier, P. & Molnar, P, 1977: Active faulting and tec-tonics of China.- J. Geophys. Res., 82, 2905-2930. Tapponnier, P, Peltzer, G., Le, Dain, A.y. & Armijo, R., 1982: Propagating extrusion tectonics in Asia: new insights from simple experiments with plasticine.-Geology 10, 611-616. yuan Daoxian, 2002: Karst Dynamic Systems of China. IGCP 299. Geological press, Beijing. Waltham, A.C., 1996: Limestone karst geomorphology in the Himalayas of Nepal and Tibet- Z. Geomorphol. N. f., 40 (1), 1-22. Wang, E., Burchfel, B.C, Royden, L.H., Chen, L., Chen, J. & Li, W., 1998: Te late Cenozoic xianshuihe-xiao-jiang, Red River, and Dali fault systems of south-western Sichuan and Central yunnan, China.- Geological Society of America Special Paper 327, 108. Wang, E. & Burchfel, B.C, 2000: Late Cenozoic to Ho-locene deformation in southwestern Sichuan and adjacent yunnan, China, and its role in formation of the Southwestern part of the Tibetan Plateau.- Geological Society of America Bulletin, vol. 112, number 3, 413-423. ACTA CARSOLOGICA 35/1 - 2006 31 STANKA ŠEBELA & JANJA KOGOVŠEK HIDROKEMIČNE ZNAČILNOSTI IN TEKTONSKI POLOŽAJ IZBRANIH IZVIROV V OSREDNJEM IN SZ yUNNANU, KITAJSKA POVZETEK Kitajska provinca yunnan je tektonsko zelo zanimiva, še vedno je tudi tektonsko zelo aktivna, kar dokazujejo močni potresi. Leži na stičišču dveh velikih tektonskih plošč Azijske na severu in Indijske na jugu, ki se podri-vata ena pod drugo. Prelom Ailao Shan - Red River je eden najbolj izrazitih prelomov na Kitajskem. Današnje gibanje ob prelomu je desnozmično za 2-8 mm na leto. Prelom najprej sledimo zahodno od mesta Dali, potem pa se nadaljuje proti JV yunnana po dolini Rdeče reke (Slika 1). Sledimo ga vse do obale vietnamskega morskega zaliva Tonkin v Južnokitajskem morju. Kunming se nahaja v xiaojiang prelomni coni, znotraj katere se vršijo levi zmiki. V okviru terenskega dela 18. do 29.10.2004 smo si severno od Kunminga ogledali akumulacijsko jezero in više ležeči izvir Quinglongtan (Slika 1, točka 3), ki prispeva vodo v akumulacijo. To so zgradili za oskrbo Kunminga s pitno vodo in za namakanje. Meritve temperature in specifčne električne prevodnosti (SEP) treh glavnih izvirov Quinglongtan so pokazale, da gre za isto vodo (temperatura 14,8oC in SEP 277 µS/cm). Voda v akumulaciji je bila toplejša (19,4oC), po SEP pa je le minimalno odstopala od vrednosti izvira Quinglongtan. Vsebnost karbonatov je nizka (135 mg CaCO3/l) tako v izvirni vodi kot v akumulaciji in je bila le malo nižja od celokupne trdote (146 mg CaCO3/l). V izviru in v akumulaciji je bila koncentracija fosfatov pod mejo detekcije (<0,01 mg PO43-/l), koncentracija nitratov pa je bila 4,6 oz. 4,4 mg NO3-/l, kar kaže glede na omenjena parametra dobro kakovost vode. SZ del yunnanan je premrežen s številnimi prelomnimi conami. Severno do Dalija se od preloma Red River odcepi še ena močna prelomna cona. V skrajnem SZ delu yunnana se ta prelom imenuje po tibetanskem mestu Zhongdian, ki leži na nadmorski višini nekaj čez 3.000 m. Prelom Zhongdian, ob katerem se vršijo levi zmiki, poteka vzporedno z dolino reke yangtze, nato pa se obrne proti jugu, v smeri mesta Dali, kjer se razširi v širšo prelomno cono. Mesto Lijiang, ki je v UNESCO-vi kulturni dediščini od leta 1997 je 3.februarja 1996 stresel močan potres z magnitudo M = 7.0 po Richterju. Mesto se nahaja v širši prelomni coni generalne smeri sever-jug, ki povezuje Zhongdian prelom z Red River prelomom. Mesto Lijiang se z vodo oskrbuje iz bližnjega izvira Zhenzhuquan (Slika 4), kjer so vodo zajezili v majhno jezerce, ki je turistično zelo obiskano. Del vode je speljan 32 ACTA CARSOLOGICA 35/1 – 2006 po kanalih skozi mesto, pred časom je bil to verjetno način oskrbe mesta z vodo. Na glavnem izviru je črpališče (Slika 5) za oskrbo mesta s pitno vodo. Ob našem obisku smo srečali številne domačine, ki so prišli na izvir po vodo. Dne 24.10.2004 je bila temperatura izvira 14,8oC, SEP 370 µS/cm, karbonatna trdota je bila 158 mg CaCO3/ l, celokupna pa 162 mg CaCO3/l. Voda je imela nizko vsebnost kloridov, nitratov (1,3 mgNO3-/l) in fosfatov in je bila glede na te parametre dobre kakovosti. Bai Shui He reka, ki priteka z območja yulong Snow mountain (5596 m), je imela temperaturo le 9,6oC, nizko SEP (196 µS/cm) in nizko karbonatno trdoto (2,17 mekv/ l), pH = 8,2 in je vsebovala le 1 mg NO3-/l. V širši prelomni coni Zhongdian preloma med mestom Zhongdian in reko yangtze je več tektonskih depresij, ki so razvite v apnencih, mejijo pa tudi na nekraške kamnine, kot so magmatske kamnine, peščenjaki. Tako ne gre vedno za prava kraška polja. Vse depresije so vezane na aktivne prelomne cone, ob katerih se vzdolž prelomov smeri SZ-JV vršijo levi zmiki. V širši prelomni coni Zhongdian preloma se nahaja več izvirov, ki so močno mineralizirani in izločajo del raztopljenih snovi. Nekateri so termalni, drugi pa nimajo povišane temperature. Glede na raziskave kitajskih znanstvenikov gre za izvire, kjer voda prihaja na dan iz velikih globin. Izmed številnih izvirov je potrebno poudariti tri: naravni most s termalnim izvirom Tiansheng Qiao (Slika 1, točka 1), xiageiwenquan (termalni izviri) (Slika 1, točka 1) in Baishuitai (ponvice) (Slika 1, točka 2). Vsa tri mesta so dobro obiskane turistične točke. xiageiwenquan se nahaja 10 km južno od Zhongdia-na in obsega več termalnih izvirov, ob katerih najdemo starejše in mlajše plasti sige. Tudi ti izviri so vezani na aktivne tektonske prelome. Toplo vodo uporabljajo v tera-pevtske namene. Dne 26.10.2004 smo izmerili temperaturo na treh izvirih in ugotovili, da dosega voda od 48,3 do 66,8oC ter da vsebuje obilo raztopljenih snovi, saj je bila izmerjena količina raztopljenih snovi - SEP od 1260 do 1510 µS/cm. Tiansheng Qiao se nahaja ob aktivnem levo zmičnem Suoge-xuejiping prelomu na zahodni strani reke Jinsha. Naravni most (Slika 7), pod katerim teče reka Shuodugang, je zgrajen iz apnenca in je 40 m visok, 10 m širok in 15 m dolg. Neposredno ob naravnem mostu je termalni izvir Tiansheng Qiao, ki izloča travertin. Odlaganje travertina naj ne bi bilo starejše kot 5.000 let. HyDROCHEMIC CHARACTERISTICS AND TECTONIC SITUATION Of SELECTED SPRINGS Voda termalnega izvira Tiansheng Qiao je imela 25.10.2004 temperaturo 57,5oC, zelo visoko SEP (1805 µS/cm), visoko vsebnost karbonatov ter povišane vrednosti kloridov in sulfatov. Verjetno vsebuje še številne druge snovi, vendar so bile naše meritve in analize omejene le na zgoraj omenjene parametre. Topla voda z izvira odteka v bazen v sklopu »toplic« (Slika 8), kjer ponujajo različne terapevtske usluge. Neposredno ob bazenu tekoča reka Shuodugang je imela tedaj temperaturo 10oC in nizko SEP. Tudi baishuitai izvir je vezan na aktivno tektoniko. Ker je voda na izvirih prenasičena, izloča ob polzenju po pobočju raztopljene mineralne snovi. Tako je celotno pobočje pokrito z belo prevleko, ki ga krasijo manjše in tudi zelo velike ponvice (Slika 9). Ponvice so se oblikovale na širšem področju spodnje in srednje triasnega apnenca. Voda izvira v več izvirih, del pa je priteka po manjšem kanalu iz višjega izvira. Izvirno področje je delno poraslo predvsem z listavci, tako da je odpadlo listje vir onesnaževanja oz. vir hrane za različne alge, ki motijo belino pobočja. Svoje dodaja tudi turistični obisk. Očitno se tega do določene mere zavedajo upravljalci, saj so na nekaj mestih napeli vrvi, ob našem obisku pa so se zanimali kaj merimo. Meritve so na več izvirnih točkah pokazale, da je temperatura izvirov med 11,1 in 13,3oC. Meritve SEP, ki so dale vrednosti celo nekoliko nad 1000 µS/cm, so nakazale, da izvirna voda vsebuje veliko raztopljenih karbonatov, kar so potrdile kasnejše analize vode. Celokupna trdota je znašala 600 mg CaCO3/l, od tega je bilo kar 560 mg CaCO3/l karbonatov. Razmerje Ca/Mg vode je bilo enako 4,4. Voda je imela nizke vsebnosti nitratov in fosfatov, vsebnost sulfatov pa je bila 40 mg SO42-/l. Meritve temperature vzdolž pobočja in v ponvicah so pokazale segrevanje vode in upadanje SEP in razmerja Ca/ Mg ter vsebnosti sulfatov, iz česar smo sklepali na intenzivno izločanje kalcijevega karbonata ter delno sulfatov, medtem ko magnezij ostaja v raztopini. Podobno smo ugotavljali tudi za izvir Podstenjšek v Sloveniji. Do dna pobočja se je iz enega litra vode izločalo povprečno 360 mg CaCO3. Voda je speljana nato po kanalu do bližnje vasi, kjer jo uporabljajo kot pitno vodo in vodo za namakanje. ACTA CARSOLOGICA 35/1 – 2006 33