西藏芒康县西渠河桥铜金矿床黄铁矿原位微量元素和硫同位素组成研究  

In situ trace element and sulfur isotopic compositions of pyrites from the Xiquheqiao copper-gold deposit,Mangkang County,Xizang,China

作　　者：白奥冬 李波[1] 唐果[1,2] 王新富 舒华伟 岳言 李玉彬 BAI Aodong;LI Bo;TANG Guo;WANG Xinfu;SHU Huawei;YUE Yan;LI Yubin(School of Land and Resources Engineering,Kunming University of Technology,Kunming Yunnan 650093,China;Kunming Prospecting Design Institute of China Nonferrous Metals Industry Co.,Ltd,Kunming Yunan 650051,China;School of Earth Science,Yunnan University,Kunming Yunan 650500,China;Sanshan Island Gold Ore Mine,Shandong Gold Group Co.,Ltd.,Laizhou Shandong 261442,China;College of Engineering,Tibet University,Lhasa XiZang 850000,China)

机构地区：[1]昆明理工大学国土资源工程学院,云南昆明650093 [2]中国有色金属工业昆明勘察设计研究院有限公司,云南昆明650051 [3]云南大学地球科学学院,云南昆明650500 [4]山东黄金矿业(莱州)有限公司三山岛金矿,山东莱州261442 [5]西藏大学工学院,西藏拉萨850000

出　　处：《矿物学报》2025年第1期146-159,共14页Acta Mineralogica Sinica

基　　金：云南省基础研究专项-重点项目(202401AS070063);国家自然科学基金项目(编号:42462014);云南省万人计划青年拔尖人才项目(编号:YNWR-QNBJ-2018-093);昆明理工大学重点学科建设项目(编号:14078384)。

摘　　要：西渠河桥铜金矿床位于藏东南芒康县金沙江西侧。黄铁矿作为该矿床主要的载金矿物,对其Au的赋存状态和成矿机制仍不清楚,限制了对区域多金属成矿规律的全面认识。本文运用LA-ICP-MS技术对西渠河桥铜金矿床成矿期黄铁矿开展了原位微量元素和硫同位素组成分析,结果表明,西渠河桥铜金矿床成矿期黄铁矿可分为两种类型,Py I为自形-半自形黄铁矿,以立方体晶形为主,粒径粗大,相对富集Cu、Pb、Bi、Sb等元素;Py II为中-细粒他形晶黄铁矿,粒径0.02~1 mm,相对富集Au、As、Ag等元素。Co、Ni、As在两种类型黄铁矿中以类质同象形式存在,而Cu、Pb、Bi、Sb以纳米、微米级颗粒矿物的形式分布于Py I和Py II晶体中。西渠河桥矿床Au主要以晶格金的形式赋存在Py II中,As在Au的迁移、富集和沉淀等过程中具有重要作用。Py I、Py II的微量元素二元图解和Co-Ni-As图解表明,Py I为岩浆成因,Py II为热液成因。两种类型黄铁矿的δ~(34)S值非常相似(Py I:+2.17‰~+3.79‰,Py II:+0.64‰~+1.02‰),均为典型岩浆硫,指示硫来自于岩浆岩(花岗闪长岩)。The Xiquheqiao copper-gold deposit is located on the west side of the Jinshajiang River in Mangkang County of the southeastern Xizang.Pyrite is the main gold-bearing mineral in the deposit.The occurrence status and mineralization mechanism of Au in pyrite are still unclear.It is limited to comprehensively understand the regional polymetallic metallogenic law.In this paper,in situ laser ablation-inductively coupled plasma-mass spectrometry(LA-ICP-MS)was used to analyze trace element and sulfur isotopic compositions of pyrites in the metallogenic stage of the Xiquheqiao copper-gold deposit.The results show that there are two types of pyrites in the metallogenic stage of the Xiquheqiao copper-gold deposit.PyI is the euhedral-subhedral pyrite,mainly in cubic crystal form,with coarse particle size and relatively enriched contents of Cu,Pb,Bi,Sb and other elements.PyII is the medium-fine heteromorphic anhedral pyrite with a particle size of 0.02~1 mm,and is relatively enriched in Au,As,Ag and other elements.Co,Ni,As occurred in form of isomorphism substitution in the two types of pyrites,while Cu,Pb,Bi,and Sb occured in PyI and PyII crystals in the form of very fine granular minerals with sizes varying from nanometer to micronmeter.Au occurred mainly in form of isomorphism substitution in the lattice of PyII in the Xiquheqiao deposit.As played important roles in the migration,enrichment and precipitation of Au in the gold mineralization process.The trace element binary diagrams and Co-Ni-As diagram of PyI and PyII indicate that,PyI is of magmatic origin,PyII is of hydrothermal origin.Theδ34S values of the two types of pyrites are very similar(PyI:+2.17‰~+3.79‰;PyII:+0.64‰~+1.02‰),suggesting that theie sulfurs are both of typical magmatic origin,and were derived from magmatic rocks(granodiorite).

关 键 词：黄铁矿 原位微量元素 原位硫同位素 西渠河桥铜金矿床 西藏 

分 类 号：P595[天文地球—地球化学] P574[天文地球—地质学]