CO₂-rich fluid inclusions with chalcopyrite daughter mineral from the Fenghuangshan Cu¨CFe¨CAu deposit, China: implications for metal transport in vapor

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• 作者：Jianqing Lai and Guoxiang Chi
• 关键词：CO2 ; rich inclusions ; Daughter mineral ; Metal transport ; Vapour
• 刊名：Mineralium Deposita
• 出版年：2007
• 出版时间：February, 2007
• 年：2007
• 卷：42
• 期：3
• 页码：293-299
• 全文大小：256 KB

文摘

CO₂-rich fluid inclusions containing opaque mineral crystals were found in the Fenghuangshan skarn-porphyry Cu–Fe–Au deposit in Tongling, Anhui, China. These inclusions show variable CO₂ contents and are accompanied by aqueous inclusions, both occurring as secondary inclusions in quartz and being locally associated with chalcopyrite mineralization. Laser Raman microspectroscopic analyses confirm the predominance of CO₂ in the vapor and the presence of H₂S as high as 8 mol % , and identify the opaque mineral with yellow reflectance color in the inclusions as chalcopyrite. More than half of the CO₂-bearing inclusions contains chalcopyrite, whereas few of the associated aqueous inclusions do so. The chalcopyrite, occupying less than 1 % (volume) of the inclusions, is interpreted to be a daughter mineral, and calculated Cu concentrations in the inclusions range from 0.1 to 3.4 wt % . Copper is inferred to have been transported in CO₂-dominated fluids as HS− complexes. The occurrence of chalcopyrite daughter crystals in CO₂-rich fluid inclusions indicates that CO₂-rich vapor has the capacity of transporting large amounts of Cu, and possibly Au. This finding has significant implications for metal transport and mineralization in hydrothermal systems enriched in CO₂, such as orogenic-type and granitic intrusion-related gold deposits.