内蒙古大井铜锡多金属矿床矿石中Cu-S同位素特征及成矿预测  

Cu-S Isotope characteristics and metallogenic prediction of orebodies in the Dajing Sn-Cu polymetallic deposit in Inner Mongolia

作　　者：王跃 苏尚国[1] 张旗[3] 周奇明 张雅南 WANG Yue;SU Shangguo;ZHANG Qi;ZHOU Qiming;ZHANG Yanan(School of Earth Sciences and Resources,China University of Geosciences(Beijing),Beijing 100083,China;China Nonferrous Metals(Guilin)Geology and Mining Co.,Ltd.,Guilin 541004,China;Institute of Geology and Geophysics,Chinese Academy of Sciences,Beijing 100029,China)

机构地区：[1]中国地质大学(北京)地球科学与资源学院,北京100083 [2]中国有色桂林矿产地质研究院有限公司,广西桂林541004 [3]中国科学院地质与地球物理研究所,北京100029

出　　处：《地学前缘》2022年第3期319-328,共10页Earth Science Frontiers

基　　金：国家自然科学基金项目(41773100,41373095)。

摘　　要：内蒙古大井铜锡多金属矿床是大兴安岭成矿带代表性矿床之一,矿区位于内蒙古东部林西县境内,成矿地质条件良好。矿床矿石中同位素特征及与成矿的关系研究薄弱。本文通过对矿体中黄铜矿Cu同位素,黄铜矿、黄铁矿S同位素和Pb同位素的研究表明:黄铜矿δ^(65)Cu值总体范围为-0.46‰~+0.32‰,平均值为0‰,2σ误差平均值约为0.03‰;黄铜矿、黄铁矿δ^(34)S值总体范围为+0.076‰~+3.00‰,平均值为+1.83‰,且δ^(34)S值分散程度也较小,整体较均一,属于岩浆硫的同位素特征;Pb同位素数据整体变化很小,具体为^(206)Pb/^(204)Pb=18.291~18.353,^(207)Pb/^(204)Pb=15.501~15.574,^(208)Pb/^(204)Pb=38.051~38.265。结合区域前人的研究表明,大井矿Cu同位素的变化是由于硫化物岩浆分异过程导致,大井矿矿石黄铜矿δ^(65)Cu的变化可能指示了矿化阶段成矿硫化物的演化方向,δ^(65)Cu逐渐降低的方向可能存在隐伏矿体,研究区域东部生产区域与外围预测未生产区域具有一致的Cu同位素特征,Cu同位素证据表明大井矿外围预测区可能存在深部隐伏矿体。The Dajing Sn-Cu polymetallic deposit in Inner Mongolia represents typical ore deposits in the Daxinganling metallogenic belt.The mining area is located in Linxi County,eastern Inner Mongolia,with geological conditions favorable for ore formation.Here,we studied Cu isotopes in chalcopyrite and S and Pb isotopes in chalcopyrite and pyrite orebodies.The measuredδ^(65)Cu value for chalcopyrite ranged from-0.46‰to+0.32‰overall,averaging at 0‰with an average 2σerror of~0.03‰;theδ^(34)S values for chalcopyrite and pyrite ranged from+0.076‰to+3.00‰overall,averaging at+1.83‰,with relatively high uniformity,showing magma associated S isotopic characteristics.The ranges of Pb isotopic ratios were small overall;specifically,206 Pb/^(204)Pb ranged between 18.291-18.353,207 Pb/^(204)Pb between 15.501-15.574,and 208 Pb/^(204)Pb between 38.051-38.265.Together with previous studies in the region we show that,in the Dejing deposit,Cu isotopic changes occur during the sulfide-magma differentiation process.Theδ^(65)Cu variation pattern in chalcopyrite may indicate the direction of evolution of ore-forming sulfides in the mineralization stage.For instance,the direction of gradualδ^(65)Cu value decreasing may point to concealed orebody.In the study area of the Dejing deposit,the mining district in the east shares similar Cu isotopic characteristics with the non-production target area of its periphery,where,according to Cu isotope evidence,may exist deep concealed orebodies.

关 键 词：大井矿 铜锡多金属矿床 Cu同位素 S同位素 隐伏矿体 

分 类 号：P618.41[天文地球—矿床学] P618.44[天文地球—地质学]