Abstract:
The eastern sector of the Dabieshan collision orogen may be divided into three tectonic units:the North Huaiyang block, Yuexi block and Siwang block.The Precambrian geologic bodies in the Yuexi block,which generally underwent high-pressure metamorphism,form the“core"of a high-pressure(HP)-ultra-high-pressure(UHP)metamorphic block,and its hanging wall and foot-wall are low-pressure metamorphic or unmetamorphosed layers, displaying a “sandwich"-style tectonic framework in space.The normal fault at the upper boundary and the reversed fault at the lower boundary of the HP metamorphic block are the direct indications of its “extrusion" and uplifting mechanism.The formation of the “sandwich"-style tectonic model of the Dabieshan orogen was closely related to Paleozoic subduction of the Yangtze plate towards the Sino-Korean plate and Mesozoic collision and subsequent rapid uplifting of the two plates.