投稿时间：2016-09-27
修订日期：2017-12-26
网络发布日期：2018-02-28
中文摘要:为了示踪德能铜多金属矿床成矿物质来源，本文利用电子探针技术对黄铁矿、黄铜矿、方铅矿和绿泥石进行了矿物化学成分分析，测定了硫化物闪锌矿、方铅矿、黄铁矿的Pb和S同位素组成。结果表明，硫化物中硫含量均低于理论值，其中黄铁矿S/Fe值为1.067~1.094（平均1.083），Co/Ni>1，立方体{100}晶形发育，指示其形成于较高温度、较高氧逸度和低硫逸度环境；绿泥石为富铁蠕绿泥石，形成温度为185℃~266℃，反映中低温、酸性、还原条件环境。硫化物铅同位素组成较稳定，208Pb/204Pb比值为38.937~39.217，207Pb/204Pb为15.640~15.718，206Pb/204Pb为18.521~18.601，μ值9.53~9.68，ω值38.29~39.76，指示其铅可能来源于念青唐古拉群基底变质岩；硫化物δ34S值为6.6‰~9.3‰，反映硫可能来自花岗质岩浆。
Abstract:In order to investigate the source of ore-forming materials of the Deneng copper polymetallic deposit, the authors analyzed pyrite, galena, chalcopyrite and chlorites by electron microprobe analysis and also investigated Pb, S isotope compositions of galena, sphalerite and pyrite. The results of electron microprobe analysis shows that the sulfur content in the sulfides of the Deneng copper polymetallic deposit is lower than the theoretical value. S/Fe ratios of pyrite are from 1.067 to 1.094 (1.083 on average), Co/Ni ratios are more than 1, and cubic crystal{100}pyrite is developed. According to the study, the authors have drawn the conclusion that the sulfide crystallized under the conditions of high temperature and high oxygen fugacity. Chemical analysis of chlorite shows the mineral is rich in Fe and belongs to prochlorite. Calculation yielded the formation temperatures of chlorite in the range of 185℃ and 266℃, with an average of 221℃. This indicates that ore-forming fluids might have evolved to low sulfur fugacity under middle-low temperature, acidic and reduction condition after the metallogenic period. The sphalerite, galena and pyrite have stable Pb isotopic compositions:208Pb/204Pb ratios from 38.937 to 39.217, 207Pb/204Pb ratios from 15.640 to 15.718 of and 206Pb/204Pb ratios from 18.521 to 18.601. The μ values of sulfides are between 9.53 and 9.68 and the ω values are from 38.29 to 39.76. The authors thus infer that the source of Pb might have been mainly derived from the metamorphic rocks of Nyainqentanglha Group. The δ34S values of sulfides vary in the range of +6.6‰~+9.3‰, indicating that the source of S was probably derived from granitic magma.
keywords:geochemistry sulfur and lead isotopes mineralogy ore-forming material Deneng copper polymetallic deposit Coqen Tibet
文章编号：
中图分类号：P618.41
文献标志码：
基金项目:本文得到国家自然科学基金项目"西藏尼雄矽卡岩铁矿成矿流体演化与成矿作用机制"（编号：41503040）和国家重点研发计划"青藏高原大陆碰撞铅锌成矿系统深部结构与成矿过程"课题（编号：2016YFC0600306）联合资助
引用文本：
于玉帅,杨竹森,田世洪,周云,高原.2018.西藏措勤县德能铜多金属矿床成矿物质来源的矿物学和S-Pb同位素证据[J].矿床地质,37(1):37~49YU YuShuai,YANG ZhuSen,TIAN ShiHong,ZHOU Yun,GAO Yuan.2018.Ore-forming materials of Deneng copper polymetallic deposit, Coqen County, Tibet: Evidence from mineralogy, and S and Pb isotopes[J].Mineral Deposits37(1):37~49
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