北祁连山石居里铜矿硅、铅、硫同位素组成特征
Silicon-lead-sulfur isotopic constitution of Shijuli copper deposits of North Qilian Mountains
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摘要: 石居里铜矿是北祁连山典型的塞浦路斯型铜矿,通过对矿石和围岩的硅、铅和硫同位素研究,作者认为,硅同位素组成δ30Si(-0.9‰～-0.2‰)与火山岩的δ30Si范围一致(落在火山岩范围内),由此可知是火山成因的产物。矿石中黄铁矿、黄铜矿的铅同位素组成同各矿区范围玄武岩的铅同位素组成相近,以此为线索结合Rona(1983)的试验规律,推断本区成矿金属主要来源于蚀变玄武岩。硫同位素δ34S值变化于1.5‰～8.88‰,矿化剂硫来源于火山岩源与海水源的不同比例混合。Abstract: Shijuli copper deposits are typical Cyprus-type ones in the western part of North Qilian Mountains.On the basis of the silicon-lead-sulfur isotope constitution of the ores and wall rocks in Shijuli ore area, the author thinks that it is volcanic genesis.The δ30Si(-0.9‰～-0.2‰) from jaspilite and quartz of ores show that they are consistent with ones of basaltic rocks.Lead isotope compositions of pyrites and chlcopy rites are similar to those of basalts in the area.Thus, it is considered that the lead from ores comes mainly from altered basalts.However, sulfur in the deposits may be the results of reactions to different degrees between sea-water and basaltic rocks, because δ34S in pyrites and chlcopyrites varies between 1.5‰～8.88‰
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Keywords:
- Shijuli /
- Cyprus-type deposits /
- stable isotope
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