| 黔东南平秋金矿成因研究:来自氢、氧、硫同位素的制约 |
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| 引用本文： | 陈祎,陈葛成,王中群,肖旭东.黔东南平秋金矿成因研究:来自氢、氧、硫同位素的制约[J].矿物岩石地球化学通报,2021,40(2):448-457. |
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| 作者姓名： | 陈祎 陈葛成 王中群 肖旭东 |
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| 作者单位： | 贵州省油气勘查开发工程研究院,贵阳550004;湖北省煤炭地质勘查院,武汉430061;江苏南京地质工程勘察院贵州分院,贵阳550008 |
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| 摘 要： | 黔东南地处江南造山带西南段雪峰隆起西南端,区内金矿床(点)广布,是湘黔金矿集中区的重要组成部分。平秋金矿是该区金矿床的典型代表,其矿体产于下江群番召组浅变质火山-沉积岩,严格受北东向断裂褶皱控制。为理清其成因,对平秋金矿床含矿石英脉中的石英包裹体进行了氢、氧同位素测试。结果显示,其δD为-51.3‰~-59‰,δ18OH2O-SMOW为4.46‰~8.16‰,表明平秋金矿成矿期流体以变质水为主。对成矿期黄铁矿的硫同位素分析结果表明,其δ34S值为-1.86‰~4.55‰,而围岩下江群浅变质岩中黄铁矿的δ34S值为9.63‰~13.56‰,二者相差巨大,表明矿床中硫不是直接来自于赋矿围岩。根据上述氢、氧、硫同位素测定结果并结合区域地质背景,本文认为平秋金矿的成矿流体和成矿物质源自下伏地层的变质脱水作用,成矿作用与加里东运动造成的变质变形有关。
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| 关 键 词： | 氢、氧、硫同位素 变质脱水作用 黔东南 平秋金矿 |
Ore Genesis of the Pingqiu Gold Deposit in the Southeastern Guizhou:Constraints from Oxygen,Hydrogen and Sulfur Isotopes |
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| CHEN Yi,CHEN Ge-cheng,WANG Zhong-qun,XIAO Xu-dong.Ore Genesis of the Pingqiu Gold Deposit in the Southeastern Guizhou:Constraints from Oxygen,Hydrogen and Sulfur Isotopes[J].Bulletin of Mineralogy Petrology and Geochemistry,2021,40(2):448-457. |
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| Authors: | CHEN Yi CHEN Ge-cheng WANG Zhong-qun XIAO Xu-dong |
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| Institution: | (Guizhou Research Institute of Petroleum E.xploration&Development,Guiyang 550004,China;Hubei Coal Geological Exploration Institute,Wuhan 430061,China;Guizhou Branch of Jiangsu Nanjing Geo-engineering Surtey Institute,Guiyang 550008,China) |
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| Abstract: | The southeastern Guizhou district is located on the southwestern margin of the Xuefeng uplift. It is an important part of the Xiang-Qian gold metallogenic belt in South China due to the distribution of a lot of gold deposits and occurrences there. The Pingqiu gold deposit is a typical example in this area. Its ore bodies are distributed in the volcanic sedimentary rocks of the Neoproterozoic Fanzhao Formation, and are strictly controlled by the NE-trending faults and folds. In order to explore metallogenesis of the Pingqiu deposit, we have carried out hydrogen and oxygen isotope analysis of fluid inclusions in its quartz veins. Results of hydrogen and oxygen isotope studies show that the δD and δ18OH2O-SMOW values vary from-51.3‰ to-59‰ and from 4.46‰ to 8.16‰, respectively, suggesting that its ore-forming fluid was mainly sourced from the metamorphic fluid. Sulfur isotope study demonstrates that pyrites in auriferous quartz veins have δ34S values ranging from-1.86‰ to 4.55‰ which are quite different from those of pyrites(9.63‰-13.56‰) in metamorphic rocks of the Fanzhao Formation. Thus it is believed that sulfur in the ore-forming fluid was not directly derived from the host rocks. Combined with the geological background and H-O-S stable isotope study, it is inferred that the gold mineralization was related to the metamorphism and deformation resulted from the Caledonian orogeny and the ore-forming fluids and materials could be sourced from the underlying Mesoproterozoic units during the metamorphic dehydration. |
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| Keywords: | oxygen hydrogen and sulfur isotopes metamorphic dehydration southeastern Guizhou Pingqiu gold deposit |
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