| 西藏嘎拉勒铜金矿床成矿物质来源探讨——来自硫、铅、碳和氢氧同位素地球化学特征的证据 |
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| 关键词:the west of the Bangong Co–Nujiang metallogenic belt isotope geochemistry mantle material skarn copper-gold ore deposit Galale |
| 基金项目:中国地质调查局基础性公益性地质矿产调查项目(编号: DD20160026);四川省科技计划项目(编号: 2017JY0143);四川省教育厅一般项目(编号: 14ZB0062) |
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| Source of Ore-forming Materials in the Galale Copper-gold Deposit of Tibet: Evidence from Geochemical Characteristics of Sulfur, Lead,Carbon and Hydrogen-Oxygen Isotopes |
| The Galale copper and gold deposit in Tibet is located in the western part of the Bangong Co–Nujiang metallogenic belt. It is a large-sized magnesia skarn type copper gold deposit discovered in recent years. Based on field geological survey, the authors investigated the material source of the Galale gold deposit on the basis of S-Pb-C-H-O isotope analysis. Some conclusions have been reached: ① The δ34SV-CDT values of chalcopyrite in skarn-type ore exhibit tower-type distribution on the sulfur isotope histogram, and the variation range is –4.4‰ ~ 6‰, with a few samples showing rather wide variation range. Isotopes are mainly mantle-derived sulfur, with the mixture of a small amount of crustal source. ② The variation range of 208Pb/204Pb ratios is 38.427‰ ~ 39.008‰,the variation range of 207Pb/204Pb ratios is 15.588‰~15.701‰, and the variation range of 206Pb/204Pb ratios is 18.330‰~18.871‰, which indicates that the lead isotopic source in the mining area was dominated by orogenic lead. The crustal lead is characterized by the combination; the Galale deposit was formed in a collisional orogenic environment; ③ The δ18OV-SMOW range in the quartz vein is 12.2‰~12.8‰, with an average value of 12.5‰, whereas the δDV-SMOW values vary from –103.3‰ to –95.3‰, with an average of –99.3‰; δ18OV-PDB values vary in the range of –18.1‰ ~ –17.6‰, with an average value of –17.85‰, indicating that the precipitation was significant. ④ The isotope analytical results of calcite in skarn are δ13CV-PDB of –2‰, δ18OV-PDB of –15.1‰ andδ18OV-SMOW of 15.4‰, which shows that the carbonate of the Galale copper-gold deposit was marine carbonate and experienced the dissolution. It is shown that the Galale copper-gold deposit was formed by the mantle-derived ore-forming fluid, and the meteorite was added in the mineralization process. The ore-forming fluid interacted with the carbonate rocks to form the skarn-type copper-gold deposit. |
| LI Zhi-jun,ZHAO Run-dong,HE Zi-xuan,ZHANG Zhi,LI Pi-rong,YOU Meng,HE Shan,GUO Qi-qi,OU Jun.2017.Source of Ore-forming Materials in the Galale Copper-gold Deposit of Tibet: Evidence from Geochemical Characteristics of Sulfur, Lead,Carbon and Hydrogen-Oxygen Isotopes[J].Acta Geoscientica Sinica,38(5):651-658. |
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