东昆仑南缘布青山构造混杂岩带的地质特征及大地构造意义  

Geological characteristics of the Buqingshan tectonic melange belt in the southern margin of East Kunlun and its tectonic implications

作　　者：刘战庆[1] 裴先治[1] 李瑞保[1] 李佐臣[1] 陈有炘[1] 高景民[1] 刘成军[1] 王学良[1] 魏方辉[1] 张刚[1] 杨忠智[1] 

机构地区：[1]长安大学地球科学与资源学院/西部矿产资源与地质工程教育部重点实验室,陕西西安710054

出　　处：《地质通报》2011年第8期1182-1195,共14页Geological Bulletin of China

基　　金：国家自然科学基金项目<西秦岭北缘变形构造解析及其祁连-秦岭构造交接关系研究>(批准号:40972136);国家自然科学基金项目<扬子地块西北缘后龙门东段变质核杂岩形成机制和区域构造背景>(编号:40572121);中央高校基本科研业务费专项资金项目<东昆仑南布青山蛇绿混杂岩带物质组成研究>(编号:CHD2009JC053);中央高校基本科研业务费专项资金项目<扬子地块西北缘后龙门山造山带新元古代构造岩浆事件研究>(编号:CHD2009JC046);中央高校基本科研业务费专项资金项目<东昆仑造山带东段阿拉克湖-西里克特一带晚古生代构造-岩浆事件研究>(编号:CHD2009JC070);青海省国土资源厅-中国铝业公司公益性区域地质矿产调查基金项目<青海省都兰县阿拉克湖-红水川地区7幅1:5万区域地质矿产调查>(编号:中铝基金200801)

摘　　要：在1∶50000地质填图的基础上,运用详细的野外剖面测制、岩石组合分析、LA-ICP-MS锆石U-Pb同位素定年等研究手段,将东昆仑南缘布青山构造混杂岩划分为基质和构造混杂岩块。构造混杂岩块包括变质基底岩块、洋壳型岩块和岛弧型岩块。其中,洋壳型混杂岩块又细分为早古生代蛇绿岩(516.4Ma±6.3Ma)、晚古生代蛇绿岩(332.8Ma±3.1Ma)和海山/洋岛玄武岩;岛弧型混杂岩块细分为加里东期中酸性侵入岩岩块(441.1Ma±6.3Ma)和火山熔岩岩块。建立了东昆仑南缘布青山构造混杂岩带2套典型的古洋盆扩张、俯冲消减的物质组合,分别代表东原特提斯洋和东古特提斯洋的形成与演化,从而为研究东特提斯洋演化的进程提供了新证据。On the basis of geological mapping on the scale of 1∶50000 in the Buqingshan area on the southern margin of the East Kunlun Mountains and by means of detailed field section measurement and rock assemblage analysis as well as LA-ICP-MS zircon U-Pb dating,the authors have divided the melange into two parts,i.e.,matrix and tectonic melange rock blocks.The includes metamorphic basement rock block,oceanic crust type rock block and island-arc type rock block,in which the ocean-crust type rock block can be further divided into Early Paleozoic ophiolite（516.4±6.3Ma）,Late Paleozoic ophiolite（332.8±3.1Ma）and seamount or island basalt,whereas the island-arc type rock block is composed of Caledonian island-arc type granodiorite（441.1±6.3Ma）and middle-acid volcanic rocks.It is thus concluded that there are two typical rock assemblages of paleo-ocean basin＇s spread and subduction in Buqingshan ophiolite complex belt,which represent the formation and evolution of eastern Proto-Tethys and eastern Paleo-Tethys respectively.The results provide new evidence for the study of evolution process of East Tethys.

关 键 词：东昆仑南缘 布青山构造混杂岩带 东特提斯洋 构造演化 

分 类 号：P542.4[天文地球—构造地质学]