内蒙古白乃庙铜矿床辉钼矿铼锇同位素定年及其地质意义  

Re-Os isotopic dating of molybdenite separated from the Bainaimiao copper deposit,Inner Mongolia and its geological significance

作　　者：赵云[1,2] 王建平[1,2] 杨增海[1,2] 张捷先[1,2] 王守光[3] 尚恒胜[3] 左海洋 杨光 张彩霞 

机构地区：[1]中国地质大学地质过程与矿产资源国家重点实验室,北京100083 [2]中国地质大学(北京)地球科学与资源学院,北京100083 [3]内蒙古自治区地质调查院,内蒙古呼和浩特010020 [4]内蒙古有色地质矿业(集团)地博矿业有限责任公司,内蒙古呼和浩特010020 [5]青海省第三地质矿产勘查院,青海西宁810029

出　　处：《地学前缘》2013年第4期361-368,共8页Earth Science Frontiers

基　　金：国家重点基础研究发展计划"973"项目(2012CB416600);中国地质调查局地质矿产资源调查评价专项(1212011220923)

摘　　要：内蒙古白乃庙铜矿床位于兴蒙造山带温都尔庙加里东增生带铜多金属成矿带。矿床包括南北两个矿带,南矿带矿体产于白乃庙组绿片岩中;北矿带矿体主要产于花岗闪长斑岩体内,其成矿作用复杂,矿床成因争议较大。采用铼锇同位素定年法对矿区的7件辉钼矿单矿物样品进行分析,所获铼锇同位素模式年龄变化范围为(439.6±6.4)～(450.0±6.6)Ma,加权平均值为(446.5±3.5)Ma,获得等时线年龄为(451.2±3.5)Ma,MSWD值为1.3。结合矿床地质特征分析,认为白乃庙铜矿床是在原始喷流沉积作用形成矿源层基础上,经加里东期岛弧花岗闪长斑岩成矿作用形成,矿床成因应属多期叠加成矿。The Bainaimiao copper deposit of Inner Mongolia is located in the copper polymetallic belt of the Ondor Sum Caledonian accretion zone in Xing’an-Mongolia orogenic belt.The deposit is comprised of the northern and the southern ore belts.The host rock of the southern ore belt is greenschist,whereas the orebodies in the northern belt mainly occurred in the Caledonian granodiorite porphyry.Because of its complicated process of mineralization,the metallogenesis of this deposit is rather debatable and the study of this deposit is of great significance.The present paper is the first time to report accurate Re-Os isotopic data acquired from 7 crystals of molybdenite separated from this deposit.The Re-Os isotopic model age ranges from（439.6±6.4） Ma to（450.0±6.6） Ma and weighted average age is（446.5±3.5） Ma.The Re-Os isotope analysis also gives an isochronal age of（451.2±3.5） Ma and the MSWD is 1.3.Combined with the geological features of the deposit,it is concluded that the deposit is a porphyry copper deposit produced by island arc granodioritic porphyry on the basis of the primitive exhalative sedimentary mineralization under a subduction environment.Therefore,the metallogenesis of the deposit should belong to the multiple superimposed mineralizations.

关 键 词：内蒙古 白乃庙铜矿 RE-OS同位素定年 

分 类 号：P618.41[天文地球—矿床学] P597.3[天文地球—地质学]