The system of crust-mantle ductile shear zones in China continental lithosphere.
Cai Xuelin, Cao Jiamin, Zhu Jieshou, Cheng XianqiongChengdu University of Technology, Chengdu 610059,China
The structural analyses of many seismic sounding profiles indicate that there are two fault systems in China continental lithosphere, which are different obviously and correlative closely: one is the shallow fault system composed of ductile-brittle shear zones mainly in surface crust, and the other is deep fault system mainly composed of crust-mantle ductile shear zones, which cuts the Moho. Based on the characteristic of seismic wave velocity and the result of petrology and geochemistry of deep structure, we divide the system of crust-mantle ductile shear zones in China continental lithosphere into three classes and five types: (1) trench subduction zones in marginal sea of continental lithosphere; (2) collision suture belts in continental lithosphere; (3) compressive ductile shear zones for crust-mantle; (4) expanded ductile shear zones for crust-mantle; (5) strike-slip ductile shear zones for crust-mantle. Then we construct a model of tectonic deformation of China continental lithosphere, which expands from the surface to the deep and from the crust-mantle transition zone to the upper and middle crusts. As the crust-mantle ductile shear zone is both a channel for inorganic origin gas and one of the earthquake-generating structures in the seismic activity area, the research of crust-mantle ductile shear zone is of great academic value and of practical significance.