| 西藏甲玛铜多金属矿床角岩中黑云母矿物化学特征及地质意义 |
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| 关键词:hornfels primary biotite hydrothermal biotite magnesian biotite chemical characteristics Cu and Mo ore-forming indicator SEM EMPA |
| 基金项目:国家973项目(编号: 2011CB403103);危机矿山接替资源找矿专项典型矿床及成矿规律总结研究项目(编号: 20089932);青藏专项(编号: 1212010012005) |
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| Mineral Chemical Characteristics of Biotites from Hornfels in the Jiama(Gyama) Polymetallic Copper Deposit of Tibet and Their Geological Significance |
| Biotite from hornfels in the Jiama(Gyama) polymetallic copper deposit can be classified into primary biotite and hydrothermal one. Two sorts of biotite were observed by SEM and measured by EMPA. The authors calculated the chemical formula of biotite on the basis of EMPA data. Both primary and hydrothermal biotites are magnesian biotites and have experienced hydrothermal alterations. Magma-hydrothermal fluids were gradually converted into oxidation state, as evidenced by the increase of Fe3+ and decrease of Fe2+, the increasing differentiation between Fe3+ and Fe2+, and the decrease of K, Na and Ca content from primary biotite to hydrothermal one. Compared with things of primary biotite, more Cu was likely to be concentrated in hydrothermal biotite. The Cu content of rocks has positive correlation with Fe2+/(Fe2++Mg2+) of biotite, and negative correlation with Fe3+/Fe2+ in hydrothermal biotites, which suggests that the mineralization intensity of hornfels-type ores containing hydrothermal biotites might be judged by Fe2+/(Fe2++Mg2+) ratio of hydrothermal biotites; nevertheless, Mo is spread in two sorts of biotite diffusely, and doesn’t have characteristics of selective occurrence. |
| WANG Wei-ping,TANG Ju-xing,YING Li-juan.2012.Mineral Chemical Characteristics of Biotites from Hornfels in the Jiama(Gyama) Polymetallic Copper Deposit of Tibet and Their Geological Significance[J].Acta Geoscientica Sinica,33(4):444-458. |
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