四川会理拉拉矿田红泥坡铜矿床黑云母矿物化学特征及成矿意义  

CHEMICAL CHARACTERISTICS AND METALLOGENIC SIGNIFICANCE OF BIOTITE IN HONGNIPO COPPER DEPOSIT,LALA ORE CONCENTRATION AREA,HUILI COUNTY,SICHUAN PROVINCE

作　　者：宋明伟 彭义伟[1,2] 丁枫 程文斌 陈曦[3] 李庭学[4] 钱永超[4] 李波 Song Mingwei;Peng Yiwei;Ding Feng;Cheng Wenbin;Chen Xi;Li Tingxue;Qian Yongchao;Li Bo(College of Earth Sciences,Chengdu University of Technology,Chengdu 610000,Sichuan,China;College of Earth Science and MLR Key Laboratory of Tectonic Controls on Mineralization and Hydrocarbon Accumulation,Chengdu University of Technology,Chengdu 610059,China;School of Geosciences and Technology,Southwest Petroleum University,Chengdu 610500,China;Liangshan Mining Co,,Ltd.,Huili 615146,Sichuan,China)

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

出　　处：《矿物岩石》2022年第2期33-46,共14页Mineralogy and Petrology

基　　金：国家自然科学基金项目(批准号:42130804,41702081);成都理工大学珠峰研究计划项目(编号:2020ZF11407);油气藏地质及开发工程国家重点实验室开放基金(项目编号:PLC20210208);大学生创新创业训练计划项目(编号:S202110616003)。

摘　　要：红泥坡铜矿床位于扬子地块西南缘康滇地轴中段。矿体赋存于古元古代河口群变质岩中,主要由高品位脉状矿石和低品位纹层状矿石组成。岩相学鉴定和电子探针分析结果显示,该矿床发育两期黑云母。围岩中的黑云母(Ⅰ)FeO^(T)(~20.515%)和TiO_(2)(~2.801%)含量较高,为铁质黑云母;结晶温度为529~550℃(~538℃),与区域变质温度一致;常与磁铁矿等铁氧化物共生,氧逸度介于HM和NNO之间。脉状矿石中黑云母(Ⅱ)的MgO(~14.841%)含量较高,为镁质黑云母;结晶温度为347~436℃(~411℃),具有中—高温特征;Ⅳ(Cl)和Ⅳ(F)值的范围分别为-4.95~-5.13和1.00~1.03,氧逸度介于HM和NNO之间。结合前人发表的热液脉中流体包裹体特征,本次研究认为成矿流体具有高温、高盐度、富含挥发分特征,据此推测Cu呈易溶卤化物络合物形式迁移。脉状矿石中黄铜矿等硫化物形成时间晚于黑云母(Ⅱ),表明成矿过程中温度、氧逸度发生了较大变化。由于成矿流体成分复杂,本次研究推测流体混合伴随的物理化学条件变化(如f_(O_(2))和T降低)是导致成矿元素沉淀的主要机制。Located in the middle of the Kangdian Axis at the southwest margin of the Yangtze Block,the ore bodies of the Hongnipo copper deposit are hosted by the Paleoproterozoic Hekou Group metamorphic rocks and are mainly composed of high-grade veined ore and low-grade lamellar ore.Petrographic identification and electron probe analysis show that there are two stages of biotite development in the deposit.The biotite(Ⅰ)in the surrounding rock has a high content of FeO^(T)(~20.515%)and TiO_(2)(~2.801%),indicative of ferric biotite,and its range of crystallization temperature is from 529 to 550℃(~538℃),consistent with the regional metamorphic temperature.Biotite(Ⅰ)is usually symbiotic with iron oxides such as magnetite,with oxygen fugacity between HM and NNO.The MgO(~14.841%)content of biotite(Ⅱ)in vein-like ores is high,and it belongs to magnesium biotite.The crystallization temperature of biotite(Ⅱ)is 347-436℃(~411℃),characteristic of medium-high temperature.Its Ⅳ(Cl)and Ⅳ(F)value range from -4.95 to -5.13 and 1.00 to 1.03,respectively,and the oxygen fugacity is between HM and NNO.Based on the above studies and the fluid inclusion characteristics of hydrothermal veins published by predecessors,it is concluded that the ore-forming fluids of the deposit are characterized by high temperature,high salinity and rich volatilization,and the Cu migrates in the form of soluble halide complexes.Chalcopyrite and other sulfides in veined ore formed later than biotite(Ⅱ),indicating that temperature and oxygen fugacity changed greatly during the mineralization process.Due to the complex composition of ore-forming fluid in this deposit,it is speculated that the change of physicochemical conditions accompanying fluid mixing(such as the reduction of f_(O_(2))and T)is the main mechanism leading to the precipitation of ore-forming elements.

关 键 词：拉拉矿田 红泥坡铜矿床 黑云母 成矿流体 

分 类 号：P579[天文地球—矿物学]