Abstract:Modern continental dynamics and structure geology have determined that shell with control weak interaction between crust and mantle not only restricts the coupling relationships between the spheres of rock, but also affects the interaction plots. The coupling effect can compare the different depth of the deformation and stress characteristics analysis. The widespread low velocity zones at the depth of 20-35 km in the southeastern margin of the Qinghai-Tibetan plateau may have potential decoupling functions in the present seismic and tectonic activities due to melting from the inner part of the crust. This paper, based on the 2015-1999 GPS coordinate time series data to obtain the velocity field, combined with the previous SKS given shear wave data, analyzes the horizontal deformation coupling characteristics; further it collects the Moho and lithosphere bottom deformation data, showing that the deformation characteristics are vertical upward. The use of EGM2008 gravity model 11-36 order spherical harmonic coefficients are calculated in the Sichuan-Yunnan region under the lithosphere mantle convection stress field, collecting and sorting the 1 131 focal mechanism solutions of the data since 2000, the regional stress tensor inversion method of damping the seismogenic layer stress field of the region; and further analysis of the two kinds of stress field correlation. In the ABAQUS software, the 3D lithospheric viscoelastic finite element model of Sichuan-Yunnan region is established, while adding the upper crust boundary displacement constraints and the bottom surface of the mantle convection drag loading conditions. The stress and strain in horizontal and vertical directions are analyzed respectively, and the results of strong earthquake profile are given. The seismogenic mechanism of crust mantle coupling is discussed, and the seismic risk of faults in Sichuan-Yunnan region is analyzed. Through the above research, the dissertation infers that the uneven development of stress is the key of strain energy accumulation, and vertical coupling relationship between the spheres has greatly influenced the block effect. Further, the shell weak zone blocks the extensive development of stress stratification, the edge area of transverse and longitudinal stress changes high volt, crustal seismic hazard and contact.
HOU Qiang,ZOU Wenyuan,OU Minglin et al. Mechanical Coupling in Southeastern Qinghai-Tibetan Plateau and Its Geodynamic Implications[J]. jgg, 2018, 38(10): 991-1000.