矿床地质2009，Vol.28Issue(5)：558-568,11.
新疆西天山查汗萨拉金矿地质、金赋存状态及同位素地球化学研究
Geology, mode of occurrence of gold and isotopic geochemistry of Chahansala gold deposit in West Tianshan, Xinjiang
摘要
Abstract
The Chahansala gold deposit, a newly discovered gold deposit in West Tianshan, is located at the west edge of the Late Paleozoic Yilianhabi'erga arc-trench belt. Ore bodies are in the form of irregular veins and mainly occur in the shatter zone of fine-grained diorite that has intruded in the Upper Carboniferous tuffaceous siltstone and subordinately exist in the contact zone, with weak wall rock alteration. The sulfide minerals are mainly pyrite and subordinately pyrrhotite, chalcopyrite and galena, assuming euhedral and subhedral crystals in the ore and displaying taxitic structure in the structural alteration rock. Gold is most commonly present as native gold and electrum, with gold-bearing sulfides, gold-sulfides (Te) and Au-U minerals also observed. The distribution of gold in ores is uneven: gold mainly assumes relatively fine grains occurring as fracture gold and encapsulated gold in pyrite, and less commonly exists as intergranular gold between pyrite and vein mineral or as encapsulated gold in pyrrhotite, constituting fine-grained dissemination (within 10 μm). Gold minerals have varied shapes, mosdy assuming granular and long angular forms. Studies of fluid inclusions in some gangue minerals show that temperatures of the ore-forming fluids are 220～340℃, δD values of the hydrothermal gangue min-eral quartz are - 92‰～ - 74‰, the δ~(18)O_(V-SMOW) are 11.8‰～12.6‰, suggesting that ore-forming fluids are made up of magmatic water and formational water. δ~(13)C_(V-PDB) values of the hydrothermal gangue mineral calcite are - 8.92‰～ - 8.06‰, and δ~(18)O_(V-SMOW)values are 13.45‰～17.18‰, implying that CO_2 in the ore-forming fluids was mainly derived from the mande-derived carbon. The ~(206)Pb/~(204)Pb of ore sulfides are 18.035～18.173, ~(207)Pb/~(204)Pb are 15.536～15,612, and ~(208)Pb/~(204)Pb are 37.940～38.097, indicat-ing that the ore metals were derived from the magma. The δ~(34)S_(V-CDT) of sulfides are - 9.8‰～ 7.39‰, suggesting that the mineral-ization H_2S resulted from the crust. The Chahansala gold deposit is a tensile structural alteration type deposit formed by the structure-rnagma-hydrothermal process during the extension at the and of the orogenic movement. The Chahansala gold deposit is genetically different from the A' xi gold deposit in the same area, and this new type of gold deposit in West Tianshan should deserve much atten-tion.关键词
地质学/金赋存状态/同位素地球化学/查汗萨拉金矿/新疆西天山Key words
geology/mode of occurrence of gold/isotopic geochemistry/Chahansala gold deposit/West Tianshan Mountain分类
天文与地球科学引用本文复制引用
罗小平,薛春纪,李怀祥,冯京,张兵..新疆西天山查汗萨拉金矿地质、金赋存状态及同位素地球化学研究[J].矿床地质,2009,28(5):558-568,11.基金项目
本文得到国家科技支撑计划(2006BAB07B01-02)、高等学校学科创新引智计划(B07011)及长江学者和创新团队计划(IRT0755)的联合资助 （2006BAB07B01-02）
