青藏高原隆升动力学与阿尔金断裂  

Uplift dynamics of the Qinghai-Tibet Plateau and Altun fault

作　　者：葛肖虹[1] 刘永江[1] 任收麦[1] 

机构地区：[1]吉林大学地球科学学院,吉林长春130061

出　　处：《中国地质》2002年第4期346-350,共5页Geology in China

基　　金：国家自然科学基金项目(49772157)

摘　　要：青藏高原最晚一期也是最强烈的一期隆升发生在1～0.8Ma,与印度洋中脊三联点附近的“亚澳”陨击事件有关。陨击事件引起印度洋的快速扩张并导致印度板块在锡瓦利克带的强烈(A型)俯冲,正是这次俯冲引起了青藏高原及其外围山脉的快速隆升,中国西北的盆-山地貌因此而形成,其中东昆仑山推覆隆升近3000m,向北推挤近400km,是柴达木盆地、河西走廊新生界构造变形的主因。因此,“亚澳”陨击事件的影响,提供了青藏高原最晚一期隆升和中亚与中国西部大陆构造形成的大陆动力学背景;根据近年对阿尔金断裂带内同变形期新生矿物的激光微区40Ar/39Ar测年结果,阿尔金断裂走滑变形有可能起始于97～89Ma,它与喜马拉雅“西构造结”的形成(102～85Ma)近于同步,其累积错距达350～400km,晚白垩世—新生代同步错移了两侧原有的构造带和原型盆地,这为中国西部找矿、找油气的的战略评估提供了一个新的思路。The last-phase and strongest uplift of the Qinghai-Tibet plateau occurred at1-0.8Ma BP,which was related to the Australasian meteorite impact event in the triple junction of the Indian Ocean ridge.The impact event resulted in rapid spreading of the Indian Ocean ridge and strong A-subduction of the Indian plate beneath the Siwalik.The strong subduction gave rise to the rapid uplift of the Qinghai-Tibet Plateau and its surrounding mountains ,thus forming the basin-range geomorphology in western China.The eastern Kunlun Mountains were elevated approximately3000m by the thrust system and meanwhile moved～400km to the north,which should be responsible for the Cenozoic deformation in the Qaidam basin and Hexi corridor.Therefore,this impact event can interpret the last phase of the uplift of the Qinghai-Tibet Plateau and geodynamic background of the formation of continental tectonics of western China. 40 Ar / 39 Ar dating of neogenic minerals during deformation suggests that the strike-slip movement of the Altun(Altyn)fault may have started at97-89Ma ,occurring nearly synchronously with the formation of the'Western tectonic node'in the Nepal-western Kunlun area.The Altun strike-slip fault has a cu-mulative offset of 350-400km and displaced the original tectonic belts and basins in the Late Cretaceous-Cenozoic,which provides a new idea for mineral,oil and natural gas searching in western China.

关 键 词：青藏高原隆升 隆升动力学 “亚澳”陨击事件 阿尔金断裂 同步错移 

分 类 号：P542.3[天文地球—构造地质学]