Abstract:

Abstract:  There are very close relationship between orogenic belts and sedimentary basins, which show some features including interdependence of their spatial structures, mutual compensation of their materials, interaction of their tectonics, and simultaneity of their tectonic evolutions. A unified formation mechanism of continental orogenic belts and sedimentary basins is presented as follows: The lower crustal ductile flow from basin to orogen driven by thermal energy related to upwelling mantle plume in continental intraplate or vertical diaper movement of dehydration and magma of subduction plate on active continental margin, resulted in the denudation of upper crust and surface in orogenic belt and sediment in basin, and led to a circulative movement of different states of rocks between basin and orogen, and between lower crust and upper crust. The typical coupling between the QinghaiTibet Plateau and adjacent basins occurred in the intraplate tectonic setting. The formation of the QinghaiTibet Plateau was not caused by the collision between India Plate and Eurasia Plate, but by intraplate basinmountain coupling driven by lower crustal flow. The intraplate basinmountain coupling process of the QinghaiTibet Plateau can be divided into two stages: (1)Intraplate orogeny and basinforming stage; (2)Isostatic mountain building and basin margin subsiding stage. The spatialtemporal evolution of the intraplate orogeny and basinforming of the QinghaiTibet Plateau and related basins was shown by the evolution sequence proceeding from the north and east, to the middle, and finally to the south of the QinghaiTibet Plateau in the corresponding periods from 180120 Ma, 6530 Ma, to 237 Ma, and was represented by extensive intraplate faulting, folding, block movement, magmatism and metallogeny.  Rapid uplift and strong erosion of the QinghaiTibet Plateau as a whole and rapid settlement and molasse formation of the depressions on the margins of the peripheral basins resulting from gravity isostasy since 3.6 Ma, characterized by pulsative uplift and settlement, crustscale vertical movement, integral rapid uplift of the plateau, local subsiding of basin margin, and considerable variations in topography and environment occurring in 3.6 Ma B.P., 2.5 Ma B.P., 1.81.2 Ma B.P., 0.8 Ma B.P., 0.15 Ma B.P., etc. Synchronous evolution of continental intraplate basinorogeny system underwent tectonic transformation from extension to compression, with the transformation from active movement of basin to active movement of orogeny. NonAnderson lowangle detachment, wavy thrust fault and abnormal conjugate strikeslip fault were formed by lower crustal flow and intraplate basinorogen coupling.

Key words: Key words: lower crustal flow; basinorogen coupling; intraplate tectonics; nonAnderson fault;  QinghaiTibet Plateau