CO2-Rich Fluid Inclusions and Ore Genesis of Qiaxia Copper Deposit in Altay Area
详细信息
- 责任者：Yang Rui (Resource Engineering Department ; University of Science and Technology Beijing ; Beijing 100083 ; China) ; Xu Jiuhua
- 刊名：Mineral Deposits
- 出版年：2013
- 卷期：32(2)
- 关键词：铜矿 ; copper ores ; 流体包裹体 ; fluid inclusions ; 新疆 ; Xinjiang
- 页码：p.323-336
- 图表：illus., 3 tables, 41 refs.
- 分类号：1001
- issnNo：ISSN0258-7106
- isbnNo：CN11-1965/P
摘要
Located in Kelan volcanic-sedimentary basin on the southern margin of the Altay Mountains in Xinjiang,the Qiaxia copper deposit occurs in Lower Devonian Kangbutiebao Formation.Veined copper mineralization is characterized by two types of quartz veins:① the early quartz veins(Q1)occurring in lenticular or streaked form parallel to the foliation of the meta-crystal tuff and meta-basic volcanic rocks;② copper-bearing pyrite-quartz veins(Q2)with disseminated chalcopyrite cutting meta-mafic volcanic rocks and magnetite quartzite.Fluid inclusions are abundant in various quartz veins,especially CO2-rich inclusions(LH2O-LCO2),with lots of aqueous inclusions and very little carbonic fluid inclusions.Microthermometric studies show that solid CO2 melting temperatures(tm,CO2)of early stage quartz(Q1)are concentrated in the range of-61.5~-57.5℃,and partial homogenization temperatures(th,CO2)vary from 25℃ to 27℃,with the densities being 0.82~0.90 g/cm3.The total homogenization temperatures(th,tot)for these inclusions range from 223℃ to 280℃.Copper-bearing pyrite-quartz veins(Q2)have tm,CO2 of-61.5~-58.7℃ and th,CO2 of 23.5~28.7℃,with densities being 0.81~0.86 g/cm3.The homogenization temperatures(th,tot)for Q2 range from 230℃ to 310℃.The ore-forming fluids of the Qiaxia copper deposit are similar to those of orogenic gold deposits,and are characterized by a CO2-rich,low salinity,and CO2-H2O-NaCl±CH4±N2 system.According to the geological setting,ore-controlling structures,and fluid inclusion characteristics,the veined copper mineralization in the Qiaxia copper deposit should be genetically related to orogenic and metamorphic hydrothermal fluids.The Qiaxia copper deposit was formed during orogeny and regional metamorphism in Late Devonian and Permian.The SRXRF tests indicate that the minor elements are rich in Au,suggesting that the CO2-rich fluid might have had some relationship with gold enrichment.
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