新疆坡北基性-超基性岩带Ⅰ号岩体Sm-Nd和SHRI MP U-Pb同位素年龄及其地质意义  

Isotopic ages of No.1 intrusive body in Pobei mafic-ultramafic belt of Xinjiang and their geological significance

作　　者：李华芹[1] 陈富文[1] 梅玉萍[1] 吴华[2] 程松林[2] 杨甲全[2] 代玉财[2] 

机构地区：[1]中国地质调查局宜昌地质矿产研究所,湖北宜昌443003 [2]新疆维吾尔自治区地质矿产勘查开发局第六地质大队,新疆哈密839000

出　　处：《矿床地质》2006年第4期463-469,共7页Mineral Deposits

基　　金：国家重点基础研究发展规划项目(2001CB409810)资助成果

摘　　要：坡北基性_超基性岩带Ⅰ号岩体位于塔里木板块东北部北山裂谷带内,侵位于下石炭统红柳园组。该岩体规模较大、分异良好,是坡北岩带中寻找铜镍硫化物矿床最具代表性岩体之一。前人根据侵位地层的时代,间接推断该岩体形成于中、晚石炭世。笔者首次对该岩体不同岩相进行了同位素年代学研究,获得岩体Sm_Nd等时线年龄为(307±32)Ma(95%可信度,MSWD=0.12),辉长岩锆石SHRIMPU_Pb年龄为(278±2)Ma(95%可信度,MSWD=1.17)。鉴于铜镍矿化无论从时间上和空间上都与岩体的侵位密切相关,矿床成因类型为岩浆熔离型,说明坡北Ⅰ号铜镍矿区的成岩成矿作用发生于晚石炭世—早二叠世,是后碰撞构造背景下幔源岩浆上侵的产物。Located in Beishan rift in the northeastern part of Tarim plate, the Pobei No. 1 mafic-ultramafic body intruded into Early Carboniferous Hongliuyuan Formation. It is large in size and well differentiated, being one of the most important intrusive bodies in search for copper-nickel-sulfide orebodies. According to its emplacement strata, it was previously thought that this intrusive body was formed in Middle-Late Carboniferous. The authors dated for the first time different lithofacies of the Pobei No. 1 mafic-ultramafic intrusive body, obtained a whole-rock Sm-Nd isochron age of （307 ± 32） Ma（95% confidence, MSWD= 0.12） and a zircon SHRIMP U-Pb age of （278 ± 2） Ma（95 % confidence, MSWD = 1.17）. Cu-Ni mineralization shows a close time-space relationship with the mafic-ultrarnafic intrusive body, being a product of magmatic liquation. It is therefore concluded that the intrusion of the Pobei No. 1 mafic-ultramafic rock body and the related mineralization occurred in a post-orogenic dynamic setting in Late Carboniferous-Early Permian.

关 键 词：地球化学 基性-超基性岩 坡北Ⅰ号岩体 SM-ND年龄 锆石SHRIMP U-Pb年龄 新疆 

分 类 号：P597.3[天文地球—地球化学]