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地球学报 1996
Uplift of Qinghai - Xizang (Tibet) Plateau and Mantle Deformation due to Patial Melting
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Abstract:
Based 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.