摘要
本文利用中法合作研究获得的定日—格尔木天然地震记录资料所揭示的青藏岩石圈存在的各向异性变化，讨论了雅鲁藏布江缝合带南北地幔物质运动方向的差异。结合区域重力场、地热和大量地质资料，提出了解释青藏高原形成和隆升的新模式。青藏高原是在印度板块和欧亚板块强烈碰撞挤压下，地壳缩短变形增厚，碰撞挤压达于极限，地幔内物质产生热熔变，导致了受热幔壳的急剧膨胀，托浮起上覆地壳整体，形成了巨大高耸而且地形平坦的高原。喜马拉雅造山带则是印度板块北缘俯冲受阻，逆冲叠覆堆积变形的结果。
ased on the data of digital seismic recocdings of SKS and PKS velocities from Tingri to Goimud, by Sino - French joint project, and the anisotropy expressed by SKS and PKS waves in Qinghai - Xizang(Tibet) plateau, the paper shows a comparison on the different behavior of mantle mass between the sides of Yarlung zangbu suture. New model is proposed according to the Seismic recordings and the information of gravities, geothermals and geology.We put up a new model integrating several existing models. It can be espressed by the analysis on the tectonic development stages: - 60 - 40Ma, Continent - continent collision between northern indian plate and southern Eurasian plate. The Himalayan Terrane was accomplished through the accumulation of underthrusting, folding and layer inwolution. The Himalayan is uplifting continually in company with the ongoing collision. At last it becomes the highest mountain in the world. - 40-10Ma, Eurasian plate was passived in the collision and indian plate with Himalayas Terrane as the foreland dirfted northward for 1500-2500km (ZHu zhiwen, 1980, Achacbe, at, al, 1984), Causing the coalescing continent terrane to be greatly shortened and thickened. - Later, Qilian, Altyn and Kunlun mountains at the northern QXP folded and thrusted as the response to the S - N going pressure. - In early Pleistocene epoch the mantle materal melted due to the continuous S - N pressure. The heat source may be radioactive decay. The crust floated on the hot expanded mantle smoothly uplifting just as the rising muchroom cloud by unciear explosion. The smooth morphologic reigion of main part of the plateau appeared, supported by the beat mantle plume convection, inclulling Banggong- Nujiang Suture and Kunlun mountain. Tarim Basin underthrusted beneath Kulllun mauntain (about 80km?) Qilian fold system thrusted northward on Jiuquan Basin and southward on Qaidam Basin.The generation of super giant laleral shp fault system of Altyn mountain allowed stress field to go to balance.
关键词
青藏高原
各向异性
热熔变
地幔对流
隆升
Qinghai- Xizang (Tibet) plateau anisotropy tomography heat melting mantle convection
