投稿时间：2021-08-15
修订日期：2022-04-20
网络发布日期：2022-07-07
中文摘要:广西贵港新民铜多金属矿床位于大平天山岩体的南东边缘，是大平天山岩浆热液成矿系统的重要组成部分。矿床以切层产出的热液脉型矿体为主，顺层的层状矽卡岩型矿体为辅。系统的野外测量和研究表明，脉状矿体形态简单，主要受控于近直立的北北西向断层；层状矽卡岩型矿体主要受围岩地层中的灰岩夹层控制。为查明成矿流体的类型、性质、演化特征及成矿物质来源，文章对石英流体包裹体进行了系统的显微测温、成分及HO-S同位素测试分析，在此基础上，探讨了矿床成矿机制，并进一步完善了大平天山岩浆热液成矿系统。研究结果表明，新民铜多金属矿床可以分为以下4个成矿阶段：矽卡岩阶段、早期金属硫化物阶段、晚期金属硫化物阶段、方解石-石英脉阶段。矽卡岩阶段均一温度为398~286℃，盐度w （NaCleq）=13.0%~6.2%；早期金属硫化物阶段均一温度为374~163℃，盐度w （NaCleq）=9.3~4.3%；晚期金属硫化物阶段均一温度为340~151℃，盐度w （NaCleq）=8.0%~2.6%；方解石-石英脉阶段均一温度为298~150℃，盐度w （NaCleq）=5.4%~1.6%。主成矿阶段（早期和晚期金属硫化物阶段）成矿流体以高中温、中盐度的NaCl-H2O-CO2±N2体系为主，流体沸腾和流体混合是矿质沉淀的主要原因。H-O同位素组成（δD值介于－86‰~－64‰，δ18OH2O值介于0.33‰~7.47‰）显示成矿流体与岩浆热液有关，且后期有大气降水混入。硫化物的δ34S值介于－1.4‰~2.6‰，推测硫源与晚白垩世岩浆-热液系统有关。新民铜多金属矿床为晚白垩世区域岩石圈减薄、伸展环境下形成的岩浆热液充填交代矿床，并与邻区的Au-Cu-Pb-Zn-Ag矿床共同构成了大平天山岩浆热液成矿系统。
Abstract:The Xinmin copper-polymetallic deposit in Guigang of Guangxi is located on the southeastern edge of the Dapingtianshan pluton. The deposit is mainly composed of hydrothermal vein-type orebodies produced by cutting layers, supplemented by stratabound skarn-type orebodies. Systematic field observations and studies have shown that the vein-like orebodies have a simple shape and are mainly controlled by suberect NWW-trending faults. Stratabound skarn-type orebodies are mainly controlled by limestone interlayers in the surrounding rock strata. In order to find out the types, properties, evolution characteristics and source of ore-forming fluids, this paper conducted systematic micro-temperature measurement, composition and H-O-S isotope analysis of quartz fluid inclusions. The results show that the Xinmin copper-polymetallic deposit can be divided into the following four mineralization stages:skarn stage, early metal sulfide stage, late metal sulfide stage and calcite-quartz vein stage. The fluid inclusion in the skarn stage have homogenization temperatures of 398℃~286℃, with salinities (w(NaCleq)) of 13.0%~6.2%. The fluid inclusion in the early metal sulfide stage have homogenization temperatures of 374℃~163℃, with salinities (w(NaCleq)) of 9.3%~4.3%. The fluid inclusion in the late metal sulfide stage have homogenization temperatures of 340℃~151℃, with salinities (w(NaCleq)) of 8.0%~2.6%. The fluid inclusion in the calcite-quartz vein stage have homogenization temperatures of 298℃~150℃, with salinities (w(NaCleq)) of 5.4%~1.6%. The ore-forming fluids in the main mineralization stage (early and late metal sulfide stages) are dominated by the NaCl-H2O-CO2±N2 system of high to medium temperature and salinity. Fluid boiling and mixing are the main reasons for ore precipitation. The oxygen and hydrogen isotopic compositions(δ D=-86‰~-64‰, δ18H2O=0.33‰~7.47‰) show that the ore-forming fluid is related to magmatic hydrothermal fluid, and was mixed with atmospheric precipitation in the later period. The δ34S values of sulfide are between -1.4‰ and 2.6‰, suggesting that sulfur source was related to the Late Cretaceous magmatic-hydrothermal system. The Xinmin copper-polymetallic deposit is a magmatic-hydrothermal filling-replacement deposit formed in the Late Cretaceous regional lithosphere thinning and extensional environment. Together with the Au-Cu-Pb-Zn-Ag deposits in the neighboring area, the Xinmin deposit constitutes the Dapingtianshan magmatic-hydrothermal mineralization system.
keywords:geochemistry magmatic-hydrothermal metallogenic system genesis of deposit Xinmin copper deposit Guangxi of Guigang
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基金项目:本文得到国家重点基础研究发展计划（973计划）课题《改造型花岗岩钨锡稀有金属成矿作用》（编号：2012CB416704）和广西壮族自治区部门前期地质勘查项目《广西大瑶山地区多期次岩浆活动及成矿作用研究》（编号：桂地矿地[2014]17号）共同资助
引用文本：
陈港,陈懋弘,李杨林,王昱,吴启强.2022.广西贵港新民铜多金属矿床成矿机制研究[J].矿床地质,41(3):506~526CHEN Gang,CHEN MaoHong,LI YangLin,WANG Yu,WU QiQiang.2022.Study on metallogenic mechanism of Xinmin copper polymetallic deposit in Guigang, Guangxi[J].Mineral Deposits41(3):506~526
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