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A lot of geological, geophysical geochemical investigations within the continent and finite element modeling indicate that crustal flow layers exist in the continental crust. Channel flow model and laminar flow model have been created to explain flow regularity and flow mechanism. Channel flow reveals that the flow of a low-viscosity middle to lower crust in thick crust and high elevation orogen or plateau flow outward from mountain root in response to topographic loading or denudation. Laminar flow model proposed by Li Dewei (1992) based on investigation of the Qinghai-Tibet plateau involves a circulative movement of the different states of rocks between basin and orogen, lower crust and upper crust driven by thermal energy related to upwelling mantle plume diapir in internal continent or vertical movement of magma upon dehydration subduction plate on active continental margin. Softened or melted substance of the lower crust in a basin flows laterally toward adjacent mountain root driven by gravity, and simultaneously a thin basin crust and a thick orogenic crust are formed. Partial melting magma within the thickened orogenic lower crust drags vertical movement of metamorphic rocks of lower crust and middle crust because of density inversion, and forms metamorphic core complexes and low-angle detachment fault system acted by vertical main stress induced by thermal underplating of lower crust. Lateral spreading of uplifting mountain results in thrust fault system on the border between mountain and basin, and detritus synchronously produced by erosion of uplifting mountain is transported and deposited along the marginal deep depression in the foreland basin dragged by lower crust flow.
Channel flow is similar to laminar flow on the continental intraplate deformation, middle-lower-crust extrusion, detachment fault contemporaneous with thrust fault, and exhumation of deep metamorphic rocks, and partial melting of orogen, but there are radical difference on tectonic setting, flow domain, flow surface, flow scale, flow pattern, flow regime, flow direction, flow substance, flow behavior or flow effects, flow time, and flow mechanism between the two models. Channel flow can be regarded as a part of spatial-temporal structure of laminar flow, but lower crustal laminar flow is driven by thermal energy and gravity and not by surface processes such as denudation or topographic loading. From a global viewpoint, laminar flow is only a small part of multigrade or multiscale circulative flow system of the earth.
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