LAMINAR FLOW IN THE LOWER CONTINENTAL CRUST AND ITS SIGNIFICANCE FOR CONTINENTAL DYNAMICS
Li Dewei Ji Yunlong (China University of Geosciences, Wuhan 430074)
The geological and geophysical data show that in the lower crust of young continental tectonic units may occur pervasive, non-seismic, subhorizontal and ductile flow related to thermal softening. The laminar flow drives fault-block movement of the upper crust, results in the formation of orogenic belts and sedimentary basins, and causes coupling between ductile lower crust and brittle upper crust/mantle. The low viscous material in the lower crust flows from mantle upwelling area under basin to mantle depression area under orogen driven by shear stress and gravity related to underplating of mantle magmas that provide heat and material to the lower continental crust. During the process of laminar flow, the variation of thermal field and velocity field may occur in the lower crustal flow channel.