青藏高原中部岩石圈结构、变形及地球动力学模式的天然地震学研究

STUDY ON THE LITHOSPHERE STRUCTURE, DEFORMATION AND GEODYNAMICS WITH NATURAL EARTHQUAKES IN CENTRAL TIBETAN PLATEAU

根据中法合作项目（１９９２～１９９５）取得的新资料，对青藏高原岩石圈结构、变形及地球动力学模式进行了探讨，研究表明：青藏高原是由不同时期从冈瓦纳古陆分离出的微板块拼合而成的．从新生代开始印度板块与欧亚板块发生高角度陆－陆俯冲，青藏高原内部发生以垂直应变为主的缩短变形，中新世以后增厚的岩石圈上地幔发生不均匀剥离，导致高原快速隆升，并使青藏高原以南北挤压为主的变形变为东西拉张为主的变形，部分地区出现火山活动．

Based on the new data acquired from Sino_French seismic experiment in central Tibetan plateau (1992-1995), the lithosphere structure, deformation and geodynamical model of Tibetan Plateau are discussed. The results indicate that the Tibetan Plateau is composed of microplates split from Gondwana land in different ages. At about Cenozoic, Indian plate collided with Euro_Asia and underthrusted beneath its southern part with steep angle, The hinterland of Tibetan Plateau underwent homogeneous deformation dominated by vertical strain, resulting in the double crustal thickness and thickened lithosphere upper mantle. After Miocene, thickened lithosphere upper mantle delaminated due to the convective instability that would rapidly raise the surface elevation, resulting in the change of deformation style from north_south compression to east_west extension, and some volcanic activities in the northern part of Tibetan Plateau.