湖北郧西地区锑矿床成矿机制研究:流体包裹体和原位硫同位素证据  

Metallogenic mechanism of antimony deposit in Yunxi,Hubei Province:Evidence from fluid inclusion and in-situ S isotope studies

作　　者：王希君 段登飞 周豹 孙峰 吴越 朱金 刘文文 WANG XiJun;DUAN DengFei;ZHOU Bao;SUN Feng;WU Yue;ZHU Jin;LIU WenWen(College of Resources and Environment,Cooperative Innovation Center of Unconventional Oil and Gas,Yangtze University,Wuhan 430100,Hubei,China;Hubei Geological Survey,Wuhan 430100,Hubei,China;Geological Exploration Institute of Shandong Zhengyuan,China Metallurgical Geology Bureau,Jinan 250013,Shandong,China)

机构地区：[1]长江大学资源与环境学院,非常规油气省部共建协同创新中心,湖北武汉430100 [2]湖北省地质调查院,湖北武汉430100 [3]中国冶金地质总局山东正元地质勘查院,山东济南250013

出　　处：《矿床地质》2022年第4期823-838,共16页Mineral Deposits

基　　金：湖北省地质局2020年度科技项目(项目编号:KJ2020-59);长江大学科研启动基金(编号:9621000801);湖北省博士后创新研究岗位项目(编号:9621000814)联合资助。

摘　　要：湖北郧西地区(鄂西北)发育有一系列锑矿床,但这些锑矿床的成因仍存在较大争议。为了准确限定该区域锑矿床的成因类型,本次研究以高桥坡和王家沟锑矿床为研究对象,在详细的野外地质调查和室内显微镜观察基础上,开展了系统的流体包裹体和原位S同位素研究。研究表明高桥坡锑矿床的成矿阶段可划分为:Ⅰ石英-硫化物阶段,此阶段为主成矿阶段,硫化物以黄铁矿和辉锑矿为主;Ⅱ石英-方解石-硫化物阶段;Ⅲ方解石-硫化物阶段。王家沟锑矿床的成矿阶段可划分为:Ⅰ石英-黄铁矿-闪锌矿阶段;Ⅱ石英-辉锑矿阶段,此阶段为主成矿阶段;Ⅲ石英-黄铁矿阶段。两个矿床各期次包裹体均以富液的气液两相包裹体为主。高桥坡矿床从早到晚,成矿流体温度逐渐降低,主成矿阶段成矿流体温度为160~260℃,流体盐度一般较低(w(NaCl_(eq))为2%~4%)。王家沟锑矿床主成矿阶段成矿流体温度为170~310℃,流体盐度较低,w(NaCl_(eq))约为0.35%~4.8%。高桥坡锑矿床的δ^(34)S值从Ⅰ阶段(7.2‰~12.4‰)到Ⅱ阶段(-3.4‰~2.5‰),再到Ⅲ阶段(-1.9‰~2.5‰)逐渐降低;王家沟锑矿床的δ^(34)S值变化趋势与高桥坡相似,由Ⅰ阶段(7.4‰~10.5‰),到Ⅱ阶段(2.5‰~10.4‰),再到Ⅲ阶段(-3.7‰~0.8‰)逐渐降低。结合区域内矿床地质、地球化学特征,笔者认为高桥坡和王家沟锑矿可能为浅成热液矿床。浅部流体循环到深部并富集成矿物质,随后循环至浅部,随着成矿流体温度下降,辉锑矿沉淀,形成了高桥坡和王家沟锑矿床。A number of Sb deposits have developed in the Yunxi area of Hubei(northwestern Hubei),the genesis of these Sb deposits are still controversial.In order to accurately define the genetic type of Sb deposits in this area,systematic fluid inclusions and in-situ S isotope analysis were carried out on the Gaoqiaopo and Wangjiagou antimony deposits.The metallogenic stages of the Gaoqiaopo antimony deposit can be divided into:Ⅰquartz-sulfide stage,this stage is the main mineralization stage,in which pyrite and stibnite are the main sulfides;Ⅱquartz-calcite-sulfide stage;Ⅲcalcite-sulfide stage.The metallogenic stages of the Wangjiagou antimony deposit can be divided into:Ⅰquartz-pyrite-sphalerite stage;Ⅱquartz-stibnite stage,which is the main metallogenic stage;Ⅲquartz pyrite stage.The fluid inclusions in two deposits are mainly liquid-rich two phase fluid inclusion.From stageⅠto stageⅢ,the temperature of ore-forming fluid in the Gaoqiaopo deposit decreases gradually.The temperature of the main ore-forming stage was 160~260℃,and the fluid salinity w(NaCl_(eq))was generally low with 2%~4%.The temperature of the main ore-forming stage is 170~310℃in the Wangjiagou deposit,and it also has low fluid salinity(w(NaCl_(eq))=0.35%~4.8%).Theδ^(34)S value of the Gaoqiaopo deposit decreased gradually from stageⅠ(7.2‰~12.4‰),through stageⅡ(-3.4‰~2.5‰),to stageⅢ(-1.9‰~2.5‰).The Wangjiagou deposit has similar S isotope as Gaoqiaopo,δ^(34)S gradually decreases from stageⅠ(7.4‰~10.5‰),through stageⅡ(2.5‰~10.4‰),to stageⅢ(-3.7‰~0.8‰).Combined with the geological and geochemical characters of regional deposits,we propose that the Gaoqiaopo and Wangjiagou deposits are epithermal deposits.The fluid in shallow place,circulated to the deep site,leaching and enriching ore forming elements.The enriched ore-forming fluid then migrate to the shallow place.As the temperature of the ore-forming fluid decreases,the stibnite precipitates,forming the Gaoqiaopo and Wangjiagou antimony deposits.

关 键 词：地球化学 高桥坡锑矿 王家沟锑矿 浅成热液 鄂西北地区 

分 类 号：P618.66[天文地球—矿床学]