H-O, S and Pb isotope geochemistry of the Awanda gold deposit in southern Tianshan, Central Asian orogenic belt: Implications for fluid regime and metallogeny
H-O, S and Pb isotope geochemistry of the Awanda gold deposit in southern Tianshan, Central Asian orogenic belt: Implications for fluid regime and metallogeny
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中亚造山带南天山阿旺达金矿床H-O、S、Pb同位素地球化学：对流体形态和成矿的启示
DOI：
10.1016/j.oregeorev.2014.02.017
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发表时间：
2014-10
影响因子：
3.3
通讯作者：
Gu, Lian-Xing
中科院分区：
文献类型：
--
作者：
Fu, Yu;Dong, Lian-Hui;Qu, Xun;Gu, Lian-Xing
阿万达金矿床位于中国西北部塔里木地块北缘的晚古生代造山带南天山增生杂岩内。这里的金矿化主要发生在剪切带和次生断层内，以石英云母片岩为主要赋矿岩。硫化物矿物组合以毒黄铁矿和磁黄铁矿为主，少量黄铁矿和硅锰铁矿。蚀变包括硅化、绢云母化和稀有碳酸盐化。测得的含金石英 δ18O 值范围为 15.9 至 20.3‰，估计的 δ18O 流体值范围为 7.8 至 12.2‰。石英流体包裹体的 δD 值范围为 − 116.3 至 − 87.6 ‰。与金伴生的硫化物矿物的δ34S值范围为−3.6至+6.2‰，热液中H2S的计算δ34SH2S值范围为−4.8至+5.8‰，平均值为−0.4‰。含金矿石硫化物的铅同位素组成显示，206Pb/204Pb比值范围分别为17.4625至18.5356、207Pb/204Pb比值范围为15.4943至15.6468、208Pb/204Pb比值范围为37.8825至38.8238。总的来说，同位素（H、O、S、Pb）特征表明，成矿流体是变质成因，是由碳质黑色页岩与地壳成分中的硫脱水形成的，而铅则来自于围岩和成矿变质流体的混合物。该矿床可归类为造山型金矿床，与 Muruntau 型金矿床有许多共同的主要特征。晚古生代，南天山增生杂岩受褶皱逆冲作用强烈变形为造山带，产生不同规模的区域逆冲断层。随后也形成了控矿副断裂，深层碳质黑色页岩脱水产生的成矿流体，矿液进入剪切带导致金沉淀。
The Awanda gold deposit is located within the southern Tianshan Accretionary Complex, a late Paleozoic orogenic belt in the northern margin of Tarim block in NW China. The gold mineralization here occurs in primarily within shear zones and secondary s faults with quartz mica schist as the principal host rock. The sulfide mineral assemblage is dominated by arsenopyrite, and pyrrhotite, with minor pyrite and gudmundite. Alteration includes silicification, sericitization and rare carbonatization. The measured δ18O values for the gold-bearing quartz range from 15.9 to 20.3‰, and the estimated δ18O fluid values range from 7.8 to 12.2‰. The δD values for fluid inclusions from quartz range from − 116.3 to − 87.6‰. The δ34S values of gold-associated sulfide minerals range from − 3.6 to + 6.2‰, and the calculated δ34SH2Svalues of H2S for the hydrothermal fluids range from − 4.8 to + 5.8‰, with an average of − 0.4‰. Lead isotopic compositions of sulfides from gold-bearing ores show206Pb/204Pb ratios ranging from 17.4625 to 18.5356,207Pb/204Pb ratios from 15.4943 to 15.6468, and208Pb/204Pb ratios from 37.8825 to 38.8238, respectively. Collectively, the isotope (H, O, S, Pb) characteristics suggest that the ore-forming fluids were of metamorphic origin derived through dehydration of carbonaceous black shale with the sulfur sourced from crustal components, and the lead from a mixture of host rocks and ore-forming metamorphic fluids. This deposit can be classified as orogenic gold deposit and share many major characteristics with those of Muruntau-type gold deposits. During late Paleozoic, the southern Tianshan Accretionary Complex was intensely deformed into an orogenic belt by folding and thrusting, generating regional thrust faults at different scales. The ore-controlling subsidiary faults also formed subsequently, with the ore-forming fluids derived from dehydration of deeply buried carbonaceous black shale and the ore fluids channeled into shear zones leading to gold precipitation.
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