LITHOSPHERIC THERMAL-RHEOLOGICAL STRUCTURE AND DEEP GEODYNAMICS IN THE YANGTZE RIVER ECONOMIC BELT

Constructing the finite three-dimensional numerical model through Crust 2.0, under constraints of the surface temperature, deep inversion temperature and surface heat flow, we have calculated the thermal structure of the continental lithosphere beneath Yangtze River Economic Belt and adjacent regions. On the basis of 3D thermal structure, deriving surface strain rates from GPS observation, and selecting representative rock physical properties, we have calculated the strength and effective viscosity of the continental lithosphere. The results show that there is obvious lateral heterogeneity in the Yangtze River Economic Belt. The Sichuan basin has low temperature, high strength and high viscosity. In the same depth, temperature beneath the Sichuan basin is lower than ambient region for 100~300℃. Strength and viscosity is lower for 1~2 orders of magnitude. The transition zone of temperature, strength and viscosity has strong active tectonics. Combining with deep geophysical observation, the study proposed that the Pacific Plate subduction and India-Eurasia Plate collision played important roles in the deep dynamic process respectively in the eastern and western parts of the Yangtze River Economic Belt. The effective sphere reach the eastern and western boundaries of Sichuan basin, deep dynamic process may lead to the horizontal heterpgeneity of the lithosphere.