Abstract: 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.

Key words: Lower continental crust, Laminar model, Continental dynamics, Coupling between ductile layer and brittle layer, Ductile flow

摘要： 大量的地质和地球物理资料表明,年轻的大陆构造活动区的下地壳可能因热软化而出现透入性非地震式顺层韧性流动,这种下地壳层流作用驱动大陆上地壳发生地震式脆性断块运动,形成盆山格局,发生圈层耦合。大陆下地壳低粘度物质顺层流动可能是在地幔岩浆底侵作用为下地壳提供热能和添加幔源物质的基础上,并在地幔上升派生的重力和剪切力作用下,造成大陆下地壳热软化物质从盆地下部的幔隆区顺层流向相邻造山带之下的幔拗区。在下地壳层流过程中,地温场和速度场发生变化。

关键词: 大陆下地壳, 层流模式, 大陆动力学, 圈层耦合, 韧性流动