Abstract:

The Late Cenozoic and present-day deformation of the Asian continent is characterized by rigid motions of active blocks with different motion patterns and velocities. To research different structural deformation and interaction among these active-blocks, we establish four different finite element numerical models based on the tectonic framework of the Asian continent. By comparing the modeling result with the GPS data, focal mechanism solution and geological survey, we quantitatively explain the distribution characteristics of the principal stresses. Then, the major factors influencing the present-day deformation of the Asian continent are discussed accordingly. The results are summarized as followings. Velocity of active blocks movements in the Western China mainland was influenced by the continuous northward compression of the Indian plate gradually decreasing from south to north across a series of lithospheric-scale active tectonic zones. This kind of variety can change stress environment from compressional-tensional area in the central Tibet to completely compressional area in the Tarim basin and the Tianshan Mountain. In the model, the calculated stress of the North China block displays very weak compressional environment, but the seismicity and extensional structures extensively developed in the inner North China block. This puzzle probably means that deep dynamics cause the North China block reactive. Because of the compression between the India plate and the Philippines plate, the motion senses of the South China block and the Taiwan orogenic belt are opposite, resulting in the formation of strong compressional-tensional domain south of the Qinling-Dabie orogenic belt. As “extrusion window” of the South China and the Indochina block, the Sunda block shows particular stress distribution, which has an arc-shaped weak compressional area centered by the South China Sea and there is a relatively strong compressional-tensional area around it.

Key words: Asian continent, active block, structural stress, finite element method