仲巴微地体之定义及构成  

Definition and Composition of the Zhongba Microterrane in Southwest Tibet

作　　者：李祥辉[1] 王成善[2] 李亚林[2] 魏玉帅[2] 陈曦[2] 

机构地区：[1]南京大学地球科学与工程学院,南京210093 [2]中国地质大学北京地球科学与资源学院,青藏高原研究中心,北京100083

出　　处：《地质学报》2014年第8期1372-1381,共10页Acta Geologica Sinica

基　　金：中国地质调查局“西藏1∶5万仲巴县城北地区4幅区调”项目(编号:12112011086037);“西藏1∶5万仲巴县城西地区6幅区调”(编号:1212011121229);国家自然科学基金项目“西藏山南地区上三叠统复理石物源区分析”(编号:41072075)联合资助的成果

摘　　要：根据1∶5万西藏仲巴地区区域地质调查工作,结合1∶25万区域地质资料和前人研究成果,对被认为属于雅鲁藏布江缝合带西段夹持于两套混杂岩之间呈狭长分布的海相古生界为主地质体进行了研究。建议统一使用"仲巴微地体"术语以体现其构造属性,并初步定义为:仲巴微地体是指南东起于萨嘎县北查藏一带向北西到中印边界附近、被札达—仲巴—查藏和穷果—门士两条主断裂限制、一套以海相地层为主的地质体,它是由海相(震旦系/)奥陶系—三叠系组成的地层地体。进一步对比研究提出,仲巴微地体大致以巴噶—马攸木为界可分为幕霞和霍尔巴—仲巴两个地层分区,前者岩性未变质—弱变质,地层单斜、褶皱开缓;后者前石炭系以中低级绿岩相—片岩相为主,发育紧闭和同斜倒转褶皱;该地体可以划分为震旦系—寒武系、奥陶系—泥盆系、石炭系—二叠系、三叠系四个构造层,大致反映了其构造和沉积演化。On the bases of newly 1∶50,000 regional geological investigation and achievements of 1∶250,000 regional geological reports as well as former studies in Zhongba area,a terrane with strata dominated by the marine Paleozoic-Triassic was nominated and classified in this paper,which are narrowly pinched out between the so-called two series of melanges within the western Yarlung Zangbo suture.The Zhongba microterrane,as suggested herein, is defined as a stratigraphical terrane composed of the marine （Sinian-/）Ordovician through the Triassic and confined between two faults：Zanda-Zhongba-Chacang fault in NE,Qonggo-Munse fault in SW.Two stratigraphical subzonations of the Muxia and Horba-Zhongba can be distinguished by a rough Barga-Mayom boundary.In the Muxia subzonation,the Ordovician-Triassic is sedimentary and/or slightly metamorphosed with single dip and/or open fold,but in the Horba-Zhongba subzonation the pre-Carboniferous is mainly medium-lowly grade metamorphosed with tight and congruous fold. Four tectonic layers are classified as the Sinian-Cambrian, Ordovician-Devonian, Carboniferous-Permian,and Triassic by nonconformity respectively, approximately representing four periods of sedimentary and tectonic evolution for the microterrane.

关 键 词：地层分区 构造层 区域地质调查 仲巴微地体 雅鲁藏布江缝合带 

分 类 号：P535[天文地球—古生物学与地层学]