藏北羌塘南部地区基性岩墙与玄武岩的岩浆同源性  

Magma homology of mafic dyke and basalt in southern Qiangtang, northern Tibet, China

作　　者：王明[1] 李才[1] 翟庆国[2] 解超明[1] 吴彦旺[1] 

机构地区：[1]吉林大学地球科学学院,吉林长春130061 [2]中国地质科学院地质研究所,北京100037

出　　处：《地质通报》2009年第9期1281-1289,共9页Geological Bulletin of China

基　　金：国家自然科学基金项目(编号:40872146;40672147);中国地质调查局项目(编号:1212010818115)资助

摘　　要：青藏高原羌塘南部地区沿龙木错-双湖缝合带南侧成群分布着近东西向的基性岩墙,形成时代为晚石炭世—早二叠世,其围岩是以晚石炭世—早二叠世裂谷型沉积为主并夹有基性火山岩的浅变质岩系。基性火山岩夹层的数量和厚度有由北向南由多变少的趋势。基性岩墙的岩石类型主要为辉绿岩,火山岩以玄武岩为主,玄武安山岩次之。基性岩墙与基性火山岩在空间上密切共生,形成于大致相同的地质时期内。二者均经历了低绿片岩相变质作用,且化学成分相近,稀土元素、微量元素组成均与板内玄武岩具有相似的特点。初步判定羌塘南部地区基性岩墙群与基性火山岩来自同一岩浆源,为晚石炭世—早二叠世冈瓦纳大陆北缘裂解的产物。There is a group of nearly E–W trending mafic dyke of Late Carboniferous–Early Permian along the Longmu Co – Shuanghu suture zone in Qiangtang area, Qinghai–Tibet plateau. The surrounding rocks are mainly slightly-metamorphosed rocks which belong to rift sedimentary type formations of Late Carboniferous–Early Permian with basic volcanic rocks intercepted. From north to south, amount and thickness of these interceptions decreased gradually. The main rock type of the mafic dyke is diabase while for basic volcanic rock is mainly basalt, secondly basalt andesite. The mafic dyke swarm and basalt formed nearly in the same time and both of them experienced greenschist facies metamorphism. There are no significant differences in the concentrations of the major elements, REE elements and the trace elements between the mafic dyke swarm and the basalt. The elements concentrations of the mafic dyke swarm and the basalt have the same feature as the within–plate basalt .On that basis, combined with the regional geological data, the authors think that the mafic dyke and the basalt come from same source magma. They are the products of the breakup of the northern margin of Gondwana during Late Carboniferous to Early Permian.

关 键 词：青藏高原 羌塘南部 基性岩墙 玄武岩 同源岩浆 

分 类 号：P588.124[天文地球—岩石学] P588.145[天文地球—地质学]