辽东新岭铅锌银矿床成因:来自锆石U-Pb年龄、闪锌矿Rb-Sr年龄和H-O-S-Pb-He同位素证据  

Genesis of Xinling Pb-Zn-Ag deposit in eastern Liaoning Province:Evidences from zircon U-Pb age,sphalerite Rb-Sr age and H-O-S-Pb-He isotopic compositions

作　　者：何军成 刘军[2] 王晓彤 侯可军[2] HE JunCheng;LIU Jun;WANG XiaoTong;HOU KeJun(School of Earth Sciences and Resources,China University of Geosciences,Beijing 100083,China;MNR Key Laboratory of Metallogeny and Mineral Assessment,Institute of Mineral Resources,Chinese Academy of Geological Sciences,Beijing 100037,China)

机构地区：[1]中国地质大学地球科学与资源学院,北京100083 [2]中国地质科学院矿产资源研究所、自然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》2023年第2期331-346,共16页Mineral Deposits

基　　金：中央级公益性科研院所基本科研业务费项目(编号:KK2106、KK2105);国家自然科学基金项目(编号:41672066、41820104010);中国地质调查局地质调查项目(编号:N2201-6)共同资助。

摘　　要：辽宁新岭铅锌银矿床位于华北克拉通东北缘,矿体赋存于古元古代辽河群变质岩中,受断裂构造控制。为了确定新岭矿床的成岩成矿时代、成矿流体和物质来源及其与中生代岩浆活动的关系,文章对新岭矿床开展了详细的矿床地质特征、年代学及同位素地球化学研究。结果表明,新岭矿床内与成矿有关花岗斑岩的LA-ICP-MS锆石U-Pb年龄为(227.3±1.5)Ma。5件闪锌矿样品的Rb-Sr等时线年龄为(222.9±2.9)Ma,初始Sr同位素比值为0.7104,确认新岭成岩成矿时代为晚三叠世。成矿流体的δ^(18)O_(W)值介于4.7‰~7.6‰,δD_(W)值介于-97.7‰~-82.0‰,指示成矿流体主要为岩浆热液。黄铁矿3He/4He值介于0.15~0.21 Ra,进一步揭示成矿流体具有壳-幔混源特征。黄铁矿样品的LA-ICP-MS原位δ^(34)S值介于+3.9‰~+7.2‰,均值为+5.5‰。6件闪锌矿样品的铅同位素组成为^(206)Pb/^(204)Pb=17.534~17.822,^(207)Pb/^(204)Pb=15.527~15.591,^(208)Pb/^(204)Pb=37.851~38.162。2件花岗斑岩样品的钾长石铅同位素组成为^(206)Pb/^(204)Pb=17.410~17.500,^(207)Pb/^(204)Pb=15.498~15.509,^(208)Pb/204Pb=37.519~37.614。S-Pb同位素组成表明,新岭矿床成矿物质主要来源于晚三叠世岩浆,少量来源于辽河群变质岩地层。The Xinling Pb-Zn-Ag deposit is located in the northeastern North China Craton.The ore bodies are hosted in the Paleoproterozoic Liaohe Group metamorphic rock,and are controlled by faults.In order to obtain diagenetic and metallogenic ages,source of ore-forming fluids and materials of the Xinling deposit and its genetic relationship with Mesozoic magmatic activity,a systematic studies of deposit geology,chronology and isotopic chemistry have been carried out in this paper.We present LA-ICP-MS zircon U-Pb age of(227.3±1.5)Ma for ore-related granite porphyry,Rb-Sr isochron age of(222.9±2.9)Ma for five sphalerite samples with initial Sr isotope ratio of 0.7104,which represent the Late Triassic diagenetic and metallogenic ages for the Xinling deposit.The δ^(18)O_(W) and δD_(W) values of the ore-forming fluids vary from 4.7‰ to 7.6‰,and -97.7‰ to -82.0‰,respectively,indicating that the ore-forming fluid was mainly derived from magmatic fluid.The 3He/4He ratio of fluid inclusions in ore pyrite ranges from 0.15 to 0.21 Ra,further indicates that the ore-forming fluid was a mixing product of crustal and mantle-derived fluids.LA-ICP-MS in-situ δ^(34)S values of pyrite sample range from +3.9‰ to +7.2‰,with an average of +5.5‰.The lead isotopic compositions of the six sphalerite samples are ^(206)Pb/^(204)Pb=17.534~17.822,^(207)Pb/^(204)Pb=15.527~15.591,^(208)Pb/^(204)Pb=37.851~38.162.The K-feldspar Pb isotopic compositions of the two granite porphyry samples are ^(206)Pb/^(204)Pb=17.411~17.500,^(207)Pb/^(204)Pb=15.498~15.509,and ^(208)Pb/^(204)Pb=37.519~37.614.S-Pb isotope composition indicates that the ore-forming material was mainly derived from the Late Triassic magma with minor Liaohe Group metamorphic rock.

关 键 词：地球化学 锆石U-Pb定年 RB-SR定年 同位素地球化学 新岭矿床 辽东 

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