胶东辽上金矿床的流体包裹体、氢-氧-碳-硫-铅同位素特征及矿床成因  

The fluid inclusions,H-O-C-S-Pb isotopic characteristics and genesis of the Liaoshang gold deposit in Jiaodong Peninsula

作　　者：梁辉 韩作振 王立功[2] 田瑞聪 王来明[2] 王金辉[2] 智云宝[2] 张文[2] 刘汉栋[2] LIANG Hui;HAN Zuozhen;WANG Ligong;TIAN Ruicong;WANG Laiming;WANG Jinhui;ZHI Yunbao;ZHANG Wen;LIU Handong(College of Earth Science and Engineering,Shandong University of Science and Technology,Qingdao 266590,Shandong,China;Shandong Geological Sciences Institute,Ji’nan 250013,Shandong,China;State Key Laboratory of Geological Process and Mineral Resources,China University of Geosciences,Beijing 100083,China)

机构地区：[1]山东科技大学地球科学与工程学院,山东青岛266590 [2]山东省地质调查院,山东济南250013 [3]中国地质大学(北京)地质过程与矿产资源国家重点实验室,北京100083

出　　处：《地质通报》2022年第6期1053-1067,共15页Geological Bulletin of China

基　　金：国家重点研发计划《胶西北地区三维结构与金矿定位预测》(编号:2016YFC0600107);山东省自然科学基项目《鲁西中生代碱性岩成因及其稀土成矿专属性》(编号:ZR2020MD033);山东省地质勘查项目《山东省海阳市牧牛山成矿带深部金矿资源远景调查》(编号:鲁勘字(2019)1号);《胶西北地区金矿成矿作用研究及深部成矿预测》(编号:鲁勘字(2021)18号);《125万栖霞县、南寨幅区域地质矿产调查》(编号:鲁勘字(2021)2号);《莱州-招远地区构造岩相体系演化与成矿规律研究》(编号:鲁勘字(2012)4号)。

摘　　要：辽上金矿床位于胶莱盆地东北缘,是胶东东部唯一的超大型金矿床。通过流体包裹体和氢-氧-碳-硫-铅同位素地球化学特征研究,探讨辽上金矿的成因。主成矿阶段流体包裹体完全均一温度变化范围为125~345℃,主成矿温度集中于260~320℃,盐度为2.22%~13.87%NaCl_(eqv),流体密度为0.68~1.02 g/cm^(3),成矿流体属于中—低温度、中—低盐度、低密度,为富含CO_(2)的还原性质热液体系。氢、氧同位素(δD=-82.6‰~-68.9‰,δ^(18) O_(W-SMOW)=-0.24‰~+3.33‰)和流体包裹体成分指示,成矿流体为地幔初生水热液及岩浆热液+大气降水的混合流体。碳、氧同位素组成(δ^(13) C PDB=-2.9‰~-4.7‰,δ^(18) O_(SMOW)=6.9‰~9.6‰,)指示成矿流体中碳来源于花岗岩源区。矿石δ^(34) S介于7.6‰~12.6‰之间,206 Pb/204 Pb值为17.202~17.955,^(207)Pb/^(204)Pb值为15.457~15.577,^(208)Pb/^(204)Pb值为37.729~38.341,指示铅源主要来自下地壳的早前寒武纪变质岩系,可能有少量幔源铅的贡献。研究认为,辽上金矿床是与早白垩世伟德山型花岗岩有关的岩浆热液金矿,与壳幔混合花岗岩浆活动有关的岩浆热液、地幔流体在热隆-伸展构造作用下与大气降水混合产生流体不混溶而成矿。The Liaoshang gold deposit is located in the northeastern margin of the Jiaolai Basin.It is the only super-large gold deposit in the eastern part of the Jiaodong Peninsula.This paper discusses the genesis of the Liaoshang gold deposit through fluid inclusions and H-O-C-S-Pb isotopic geochemistry.The fluid inclusions in the main ore-forming stage have a completely uniform temperature range of 125~345℃,the main metallogenic temperature range of 260~320℃,salinity of 2.22%~13.87%NaCl_(eqv),and fluid density of 0.68~1.02 g/cm^(3),indicating that the ore-forming fluid is a reductive hydrothermal system with medium-low temperature,medium-low salinity,low density,and rich in CO_(2).H and O isotopes(δD=-82.6‰~-68.9‰,δ^(18) O_(W-SMOW)=0.24‰~+3.33‰)and fluid inclusion composition indicate that the ore-forming fluid is a mixed fluid of mantle hydrothermal fluid and magmatic hydrothermal fluid+atmospheric precipitation.The carbon and oxygen isotope composition(δ^(13) C PDB=-2.9‰~-4.7‰,andδ^(18) O_(SMOW)=6.9‰~9.6‰,)indicate that C in the ore-forming fluid originated from the granite source area.Theδ^(34) S of the ore ranges from 7.6‰to 12.6‰.^(206)Pb/^(204)Pb ratios ranging from 17.202 to 17.955,^(207)Pb/^(204)Pb ratios ranging from 15.457 to 15.577,and ^(208)Pb/^(204)Pb ratios ranging from 37.729 to 38.341,indicate that the lead source is the Early Cambrian metamorphic rock series mainly from the lower crust,mixed with mantle-derived lead.Studies indicate that the Liaoshang gold deposit is a magmatic hydrothermal gold deposit related to the Early Cretaceous Weideshan-type granite.The mixture of magmatic hydrothermal fluids related to the activity of crust-mantle mixed granite magma,mantle fluids and atmospheric precipitation produced fluid immiscible mineralization under the effect of heat uplift-extension structure.

关 键 词：流体包裹体 成矿流体 氢-氧-碳-硫-铅同位素 矿床成因 辽上金矿 胶东 

分 类 号：P618.51[天文地球—矿床学] P597[天文地球—地质学]