豫西老里湾银铅锌矿床流体包裹体和同位素特征及其地质意义  

Fluid inclusion study and isotopic characteristics of Laoliwan Ag-Pb-Zn deposit in western Henan Province

作　　者：常云真 裴海洋 范海洋 赵康 王中杰 CHANG YunZhen;PEI HaiYang;FAN HaiYang;ZHAO Kang;WANG ZhongJie(No.1 Institute of Geological and Mineral Resources Survey,Henan Bureau of Geoexploration and Mineral Development,Luoyang 471000,Henan,China;Key Laboratory of Au-Ag-Polymetallic Deposit Series and Deep-seated Metallogenic Prognosis of Henan Province,Luoyang 471000,Henan,China;MLR Key Laboratory of Metallogeny and Mineral Assessment,Institute of Mineral Resources,Chinese Academy of Geological Sciences,Beijing 100037,China)

机构地区：[1]河南省地质矿产勘查开发局第一地质矿产调查院,河南洛阳471000 [2]河南省金银多金属成矿系列与深部预测重点实验室,河南洛阳471000 [3]中国地质科学院矿产资源研究所国土资源部成矿作用与资源评价重点实验室,北京100037

出　　处：《矿床地质》2018年第2期246-268,共23页Mineral Deposits

基　　金：河南省国土资源厅省"两权价款"地质科研项目(编号:豫国土资函[2016]106号-01);中国地质调查局中国矿产地质与成矿规律综合集成和服务(矿产地质志)项目(编号:DD20160346)资助

摘　　要：河南省老里湾银铅锌矿床位于华北克拉通南缘华熊地块崤山断隆区,是近年来在崤山东部浅覆盖区新发现的一处大型矿床。老里湾矿床的矿体受断裂构造控制,主要呈浸染状、细脉浸染状和脉状赋存于早白垩世花岗斑岩体内的NW向和NNW向断裂破碎带中,亦有少量的矿体产于中元古界熊耳群火山岩内的断裂中。根据矿物共生组合、矿石组构及脉体穿插关系,将老里湾银铅锌矿床的成矿过程划分为3个成矿阶段,即:(1)绢云母+闪锌矿+方铅矿+黄铁矿阶段(早阶段);(2)重晶石+闪锌矿+方铅矿+银矿物±碳酸盐±石英阶段(中阶段);(3)闪锌矿+方铅矿+银矿物阶段(晚阶段)。文章对花岗斑岩的石英斑晶和热液阶段重晶石流体包裹体的研究表明,石英斑晶中主要发育含子矿物多相包裹体(S型)、富液两相水溶液包裹体(WL型)及少量的富气两相水溶液包裹体(WG型);重晶石中主要发育WL型包裹体。花岗斑岩的石英斑晶中包裹体完全均一温度介于338~586℃,平均494℃;盐度w(Na Cleq)介于11.0%~70.2%,密度为0.87~1.27 g/cm^3,属于高温、高盐度的H_2O-Na Cl体系。成矿中阶段的重晶石中包裹体均一温度为128~401℃,平均254℃;盐度w(Na Cleq)为1.6%~8.1%,密度0.59~0.95g/cm^3,属于中温、低盐度的H_2O-Na Cl体系。成矿中阶段重晶石中流体的δ^(18)O水值介于5.9‰~8.4‰,δDV-SMOW值介于-89.7‰^-65.5‰,表明成矿流体为岩浆水。重晶石的δ^(13)CPDB变化于-22.9‰^-12.5‰,具有花岗质岩浆演化形成的流体特征。矿石金属硫化物的δ^(34)S值介于1.9‰~5.9‰,平均3.5‰,具有深源硫的特征;成矿阶段重晶石的δ^(34)S值介于9.2‰~11.1‰,平均10.2‰。重晶石的δ34S值大于硫化物的δ^(34)S值,是同位素分馏造成的。矿床金属硫化物的Pb同位素组成较为集中,^(206)Pb/^(204)Pb介于17.262~17.430;^(207)Pb/^(204)Pb介于15.444~15.501;^(208)Pb/^(204)Pb介于37.774~38.050。S-Pb同位素组成�The Laoliwan deposit,located in western Henan Province,is a newly discovered large silver-lead-zinc deposit in the Xiaoshan uplift of the Huaxiong block on the southern margin of the North China craton.Orebodies of the deposit are composed of disseminated,veinlet disseminated,and vein-type ores.Most of the orebodies are hosted in NW-and NNW-extending faults developed in the Early Cretaceous granite porphyry,with a small amount of orebodies occurring within NW-and NNW-extending faults developed in the Xiong'er Group.The ore-forming process in the deposit can be divided into three stages according to the mineral association,ore fabric,and vein body interpenetration:①sericite+sphalerite+galena+pyrite stage(early stage);②barite+sphalerite+galena+silver mineral±carbonate±quartz stage(middle stage);and③sphalerite+galena+silver mineral stage(late stage).Three types of fluid inclusions(FIs)have been distinguished in quartz phenocryst of granite porphyry and barite of hydrothermal stage,i.e.,liquid-rich(WL type),gas-rich(WG type),and daughter mineral-bearing(S type)inclusions.The FIs in quartz phenocrysts of the granite porphyry are composed of WL-,WG-,and S-types,their homogenization temperature,w(NaCleq),and density vary from 338℃to 586℃(494℃on average),11.0%to 70.2%,and 0.87 g/cm3 to 1.27 g/cm3,respectively,and fluid in this stage generally belongs to the H2O-NaCl system with high temperature and high salinity.The FIs in barite of the middle stage only consist of WL-type,their homogenization temperature,w(NaCleq),and density vary from 128℃to 401℃(254℃on average),1.6%to 8.1%,and 0.59 g/cm3 to 0.95 g/cm3,respectively,and the fluid in this stage generally belongs to the H2O-NaCl system with medium temperature and low salinity.The ore-forming fluid of the Laoliwan deposit is a medium temperature and low salinity fluid,which belongs to the H2O-NaCl system.Theδ18OH2O andδDH2O values of ore-forming fluids in the middle stage vary from 5.9‰to 8.4‰and-89.7‰to-65.5‰,respectively,indicating that the

关 键 词：地质学 流体包裹体 H-O-C-S-Pb同位素 斑岩型成矿系统 热液脉型银铅锌矿床 老里湾 豫西 

分 类 号：P618.42[天文地球—矿床学] P618.43[天文地球—地质学]