Copper isotopic signature of the Tiegelongnan high-sulfidation copper deposit, Tibet: implications for its origin and mineral exploration
Copper isotopic signature of the Tiegelongnan high-sulfidation copper deposit, Tibet: implications for its origin and mineral exploration
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西藏铁格隆南高硫化铜矿床的铜同位素特征：对其成因和找矿的启示
DOI：
10.1007/s00126-015-0624-x
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发表时间：
2016-06-01
影响因子：
4.8
通讯作者：
Wang, Yiyun
中科院分区：
文献类型：
--
作者：
Duan, Jilin;Tang, Juxing;Wang, Yiyun
本文报道了西藏铁格隆南高硫化型铜存款矿床中铜硫化物的铜同位素组成，探讨了铜同位素在找矿中的应用。4个钻孔样品的铜同位素值显示出一致的递增趋势，从深度到地表以下400 m，δ 65 Cu的总体变化高达7.60‰（-4.76至2.84‰）。这一大范围与斑岩铜矿中所观察到的δ 65 Cu值有很大的不同，后者通常表现出较小的δ 65 Cu值范围（<1‰），且随深度增加而减小。δ 65 Cu的大变化可能是表生成因，反映了氧化条件下强烈的淋滤作用。δ 65 Cu随深度的系统性增加可以通过同位素重Cu在顶部的释放和向下的迁移来解释，这一点得到了δ 65 Cu正值与高Cu品位的耦合以及两个钻孔中δ 65 Cu负值和正值的出现的支持。基于Cu同位素的质量平衡考虑可以指示已被侵蚀或尚未发现的矿化带。这种矿化目标，如果埋在深处，可以使用铜同位素定位。
We report the copper isotopic composition of Cu sulfides in the Tiegelongnan high-sulfidation (HS) copper deposit, Tibet, and investigate the possible application of Cu isotopes to mineral exploration. The copper isotopic values of samples from four drill holes display consistent progressive increase with depth to 400 m below surface, with an overall variation of δ65Cu of up to 7.60‰ (−4.76 to 2.84‰). Such a large range is very different from that observed in Cu porphyry deposits which commonly exhibit a small δ65Cu range (<1‰), with decreasing values with depth. The large δ65Cu variation is likely of supergene origin and reflects strong leaching under oxidized conditions. The systematic increase of δ65Cu with depth can be explained by the release of isotopically heavy Cu at the top and its transport downward, which is supported by the coupling of positive δ65Cu values with high Cu grade and the occurrence of both negative and positive δ65Cu values in two drill holes. Mass-balance consideration on the basis of Cu isotopes can indicate mineralized zones which have been eroded or have not been found yet. Such mineralized targets, if buried at depth, could be located using Cu isotopes.