Study on crustal,lithospheric and asthenospheric thickness beneath the Qinghai-Tibet Plateau and its adjacent areas

【作者】 张雪梅；

【Author】 ZHANG XueMei~(1+),SUN RuoMei~1 &TENG JiWen~(1,2) 1 Institute of Geology and Geophysics,Chinese Academy of Sciences,Beijing 100029,China; 2 College of Geo-exploration Science and Technology,Jilin University,Changchun 130026,China

【机构】 Institute of Geology and Geophysics,Chinese Academy of Sciences；

【摘要】 <正>Based on the results of pure dispersions of Rayleigh wave tomography in the Qinghai-Tibet Plateau and its adjacent areas,taking S wave velocities from previous linear inversion as the initial model,using the simulated annealing algorithm,a nonlinear simultaneous inversion has been carried out for S wave velocity and thickness of different layers,including the crust,the lithosphere and the asthenosphere. The results indicate:The crustal thickness shows strong correlation with geology structures sketched by the sutures and major faults.The crust is very thick in the Qinghai-Tibet Plateau,varying from 60 km to 80 km.The lithospheric thickness in the Qinghai-Tibet Plateau is thinner(130-160 km) than its adjacent areas.And two blocks can be recognized,divided by an NNE strike boundary running between 90°E-92°E Inside the plateau.Its asthenosphere is relatively thick,varies from 150 km to 230 km,and the thickest area is located in the western Qiangtang.India has a thinner crust(32-38 km),a thicker lithosphere of 190 km and a rather thin asthenosphere of only 60 km.Sichuan and Tarim basins have the crust thickness less than 50 km.Their lithospheres are thicker than the Qinghai-Tibet Plateau, and their asthenospheres are thinner.A discussion has been made on the character and formation mechanism of the typical crust-mantle transition zone in the western Qiangtang block.更多还原

【Abstract】 Based on the results of pure dispersions of Rayleigh wave tomography in the Qinghai-Tibet Plateau and its adjacent areas,taking S wave velocities from previous linear inversion as the initial model,using the simulated annealing algorithm,a nonlinear simultaneous inversion has been carried out for S wave velocity and thickness of different layers,including the crust,the lithosphere and the asthenosphere. The results indicate:The crustal thickness shows strong correlation with geology structures sketched by the sutures and major faults.The crust is very thick in the Qinghai-Tibet Plateau,varying from 60 km to 80 km.The lithospheric thickness in the Qinghai-Tibet Plateau is thinner(130-160 km) than its adjacent areas.And two blocks can be recognized,divided by an NNE strike boundary running between 90°E-92°E Inside the plateau.Its asthenosphere is relatively thick,varies from 150 km to 230 km,and the thickest area is located in the western Qiangtang.India has a thinner crust(32-38 km),a thicker lithosphere of 190 km and a rather thin asthenosphere of only 60 km.Sichuan and Tarim basins have the crust thickness less than 50 km.Their lithospheres are thicker than the Qinghai-Tibet Plateau, and their asthenospheres are thinner.A discussion has been made on the character and formation mechanism of the typical crust-mantle transition zone in the western Qiangtang block.更多还原