扬子地块西南缘红泥坡铜矿床成矿流体特征与铜矿化机制——来自流体包裹体和原位S同位素的证据  

Ore-forming fluid characteristics and copper mineralization mechanism in the Hongnipo copper deposit,southwestern margin of Yangtze Block:Evidence from in-situ S isotopes and fluid inclusions

作　　者：宋明伟 彭义伟[1,2] 陈翠华[1] 丁枫 程文斌[1] 李葆华[1] 杨玉龙 陈良 吴锦 陈曦[4] SONG Ming-wei;PENG Yi-wei;CHEN Cui-hua;DING Feng;CHENG Wen-bin;LI Bao-hua;YANG Yu-long;CHEN Liang;WU Jin;CHEN Xi(College of Earth Sciences,Chendu University of Technology,Chengdu 610059,China;MLR Key Laboratory of Tectonic Controls on Mineralization and Hydrocarbon Accumulation,College of Earth Science,Chengdu University of Technology,Chengdu 610059,China;Liangshan Mining Co.,Ltd.,Huili 615146,China;School of Geoscience and Technology,Southwest Petroleum University,Chengdu 610500,China)

机构地区：[1]成都理工大学地球科学学院,四川成都610059 [2]自然资源部构造成矿成藏重点实验室,成都理工大学地球科学学院,四川成都3610059 [3]凉山矿业股份有限公司,四川会理615146 [4]西南石油大学地球科学与技术学院,四川成都610500

出　　处：《岩石矿物学杂志》2023年第5期629-651,共23页Acta Petrologica et Mineralogica

基　　金：国家自然科学基金项目(42130804,41702081);国家重点研发计划项目(2018YFC0604003);大学生创新创业训练计划项目(S202110616003)。

摘　　要：扬子地块西南缘红泥坡矿床是近年来新发现的大型铜矿床。本文通过流体包裹体岩相学、显微测温、激光拉曼成分分析和硫化物原位S同位素分析,揭示了红泥坡铜矿床的成矿物质来源、成矿流体来源及矿质沉淀机制。该矿床成矿过程分为火山-沉积期和热液成矿期。热液成矿期石英+方解石+硫化物阶段(Ⅰ)的石英中发育纯CO_(2)包裹体、水溶液-CO_(2)包裹体、含固相的水溶液-CO_(2)包裹体、含固相的水溶液包裹体以及富液相两相水溶液包裹体。各类包裹体成群分布,均一温度(106~500℃)和盐度(8.8%~59.8%)变化大。激光拉曼分析表明成矿流体中挥发分成分为H_(2)O、CO_(2)和少量CH_(4)。火山-沉积期黄铁矿原位δ^(34)S值为9.18‰~9.34‰,为海水硫和岩浆硫的混合硫;热液成矿期硫化物的原位δ^(34)S值为4.42‰~5.26‰,为岩浆硫和少量地层硫的混合硫。综合矿床成矿时代、流体包裹体及S同位素组成特征,认为古元古代火山-沉积作用形成含Fe和Cu的矿源层;新元古代随着罗迪尼亚超大陆的裂解,来自深部的岩浆流体携带的大量成矿物质在向上运移过程中与中低盐度、富CO_(2)的变质流体发生混合,触发了成矿物质的饱和沉淀,形成了红泥坡矿床的工业铜矿体。The Hongnipo deposit is a large Cu deposit newly discovered in southwestern margin of Yangtze Block.In this study,fluid inclusion petrography,microthermometry,laser Raman and in-situ S isotope analysis of sulfide were carried out aiming to reveal the source of metallogenic materials,ore-forming fluid and mineral precipitation mechanism.The mineralization process includes volcano-sedimentary and hydrothermal stages.The fluid inclusions in the quartz from the quartz-calcite-polymetallic sulfide stage(I)include pure CO_(2),aqueous-CO_(2),aqueous-CO_(2)with crystals,liquid-vapor aqueous with crystals and liquid-vapor.These inclusions are usually densely distributed,with a wide range of homogenization temperature(106~500℃)and salinity(8.8%~59.8%).The results of laser Raman spectrum analysis show the volatiles of ore-forming fluid are mainly H_(2)O,CO_(2)and a little CH_(4).Sulfides from the volcano-sedimentary stage haveδ^(34)S values ranging from 9.18‰to 9.34‰,suggesting the mixed derivation of sulfur from seawater sulfates and magmatic fluids.Sulfides from the hydrothermal stage haveδ^(34)S values that range from 4.42‰to 5.26‰,which implies a significant contribution of magmatic-sourced sulfur with minor stratal sulfur.Based on the geochronology,fluid inclusions and in-situ S isotopic composition of sulfides,it is considered that Paleoproterozoic volcano-sedimentary processes formed Fe and Cu containing source beds.In the Neoproterozoic,with the breakup of the Rodinia supercontinent,the magmatic hydrothermal fluid from the deep carrying a large number of ore-forming materials mixed with the metamorphic fluid of medium and low salinity and rich CO_(2),which triggered the saturated precipitation of ore-forming materials and formed the industrial copper body of Hongnipo deposit.

关 键 词：扬子地块西南缘 红泥坡铜矿床 拉拉矿田 流体包裹体 原位S同位素 

分 类 号：P618.41[天文地球—矿床学] P597[天文地球—地质学]