青藏高原中部非均匀地壳变形演化及其大型断裂带的控制作用OA

The Cenozoic crustal deformation and evolution of the Qiangtang block in the central Tibetan Plateau gradually drove the migration and extrusion of plateau materials eastward,but its mechanism has always been one of the difficulties in geological research worldwide.Based on detailed field geological surveys and interdisciplinary studies,this study innovatively proposes several important results:(1)The strike-slip faulting at the lithospheric scale in the southern part of the Qiangtang block began around 35 Ma,together with the Ailaoshan-Red River and Jiali shear zones in the eastern region,forming a giant strike-slip boundary fault belt with a length of 2 500-3 000 km,which drives significant uplift of the central valley.(2)The material in the western segment began to migrate eastward diffusely and inhomogeneously at approximately 15 Ma,in association with the formation of a series of nearly north-south trending grabens.Among the grabens,the extension rate of～2.3 mm/a in the western margin is much higher than that in the central segment.In combination with elastic flexure modelling,the results reveal that the eastward migration of crustal material in the western and middle segment is limited to the upper crust,but is incompletely decoupled due to the influence of rising heat flow from the middle and lower crust.(3)Since 23 Ma,the eastern segment of the block has been mainly controlled by the strike-slip fault and inhomogeneously extruded eastward-southeastward.By～10 Ma,this inhomogeneous extrusion gradually extended to the entire eastern block.Therefore,compared with southern Tibet,the eastward migration across central Tibet is developed in an inhomogeneous mode.The tectonic evolution of the inhomogeneous crustal deformation and the controlling effect of the large-scale fault belt along central Tibet is of great significance to understanding the stress propagation and formation processes of the Tibetan Plateau.