| 湖南古台山金锑矿床成矿流体He-Ar、Sr同位素地球化学及深部找矿意义 |
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| 关键词:deep prospecting He-Ar isotope Sr isotope source of ore-forming fluid Gutaishan Au-Sb deposit Xuefeng arc structure belt |
| 基金项目:国家重点研发计划“深地资源勘查开采”重点专项课题(编号: 2017YFC0601506);湖南省自然资源厅科研项目(编号: 2017-03; 2019-02);湖南省地质院科研项目(编号: 201701; 2017-01-01; 201902-01; 201912) |
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| He-Ar-Sr Isotope Geochemistry of Ore-forming Fluids in the Gutaishan Au-Sb Deposit in Hunan Province and Its Significance for Deep Prospecting |
| The Gutaishan quartz vein type gold-antimony deposit is a representative deposit in the middle of Xuefeng arc structure belt. The deposit, located in the external contact zone of Baimashan composite granite mass, is hosted within Nanhua Changan Formation and Qingbaikouan Wuqiangxi Formation. This paper reports He-Ar and Sr isotopic data of fluid inclusions trapped by arsenopyrite and quartz, respectively. It is shown that the 3He/4He ratios are in the range of 0.011~0.038 Ra, and 40Ar/36Ar ratios vary from 414.4 to 732.6. The results suggest that the ore-forming fluids were dominated by continental crust fluids and some meteoric water in the metallogenic process. 87Rb/86Sr ratios are in the range of 0.013~0.956, and 87Sr/86Sr ratios are in the range of 0.725 29 ~ 0.732 45. Calculation shows that the initial 87Rb/86Sr ratio was 223.6 Ma (i.e. ISr-223.6) when the deposit was formed. The ISr-223.6 values range from 0.723 60 to 0.731 67, with an average of 0.727 44. A comparison with the associated lithologies of Baimashan granite mass, Banxi Group and Lengjiaxi Group shows that the ore-forming fluids could not merely sourced from the Indosinian granitoids. Instead, it is shown that Indosinian granitoids provided ore fluids which upwardly moved and interacted with the underlying sedimentary rocks to form the Gutaishan Au-Sb deposit. The isotope geochemical characteristics of He-Ar reveal that, in prospecting for resources in Banxi Group, the underlying strata of the Chang’an Formation have better potential than the upper strata. |
| SUN Ji,ZHOU Chao,LU Wen,GUO Ai-min,XIAO Rong,WEI Han-tao,TAN Shi-min,JIA Peng-yuan.2020.He-Ar-Sr Isotope Geochemistry of Ore-forming Fluids in the Gutaishan Au-Sb Deposit in Hunan Province and Its Significance for Deep Prospecting[J].Acta Geoscientica Sinica,41(2):267-279. |
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