ISOTOPIC GEOLOGY OF THE DASHUIGOU TE-DEPOSIT,SHIMIAN COUNTY, SICHUAN PROVINCE
Wang Ruchecg;Shen Weizhou;Xu Shijin;Lu Jianjun;Chen Xiaoming;Lou Yaonan;Chao Zhimin(1)Department of Earth Scjences,Naming Naniversity,210093,Nanhng,PRC;2)Sichuan bureau of Geology and Mineral Resources, 610000,Chendu,PRC;a)Chengdu University of Technology
Dashuigou Tedepesit,Shhoinn County,Sichuan Prohoce is located in thewestern part of the Yangtze platform,and belongs to the tecto-metallogenetic province of ing It is the first independent Te-multhoetth deposit reported up to date in the world. Theore body is found spatal in metamorphic rocks and temporally contemporary with the regional dynamiothermai metamorphism of the wallrocks,It is compared of four principal ore belts,each of them consisting of 1￣4 veins of a few to several centimeters, even up to 70￣80 cm inwidth.The ores are massif, brecciform,net-veined or disseminated.The Te minerals are0prepaily tetrodymite,tsumoite,pdsenite,joseite,teliurobismutnite,and secondly calaveriteac nativebismuth.The main associated metal mineral are pWrhotite,pyrite,chalcopyrite,sphaierite 4 the gangues are dolomite,calcite,quartz,sericite and muscovite.The ore-formingtemperature varies between 120℃ and 350℃,corresponding to the medium temperature conditiollS of formation.The hydrbthermat oreforming solutions have hasher salinity (7.2 wt%￣3.5 wt % NaCl),lower Oxygen fugacity (fO2=-42. 26￣-45. 49) with pH=6. 32￣6.39,δD=-68.7%￣41. 6% and δ18O=2. 61‰￣11.93‰.It originates probably from themetamorphic rocks due to a devoprboion of metamorphic water during the regionat dynamicthermal metamorpliism. Ph isotopic compositions of ore minerals are varhole, 208 Pb/204 Pb=18. 33￣19. 28, 207Pb/204 Pb=15.49￣15. 62,208Pb/204 Pb=38.00￣38. 52. In the 207Pb/206 Pb-208 Pb/206 Pb diagram, ore minerall display linear correlation with the wallrwts,indiCated their parental relationship. 87 Sr/86 Sr of dolomite in ore Veins varies between 0.71009￣0. 71030.δ34S of ore minerals is in average 1. 37‰,indicatin.g deeper source, possiblymetabaSic volcanites δ13C of dOlOmite the ￣e,in average of-5. 60hi, is sAnfor to that ofthe wedlOCks (-5. 90th). Ph, Sr, S, C isotOPiC studied Of ore and glue m￣ show thatore-forming elements are Of mwtisources, but Prinmpaily of orthometamorphite ac metasedimentS.LeaChed form the wdeocks by the metamorpthe so1Otion, the ore-forming components(Te, An, Fe, ...) are enriched the formation of the speCall Te-mult￣ deposit under the￣allle COnditions of the regional dynamic-thermal metamorphism.