| Abstract:The Caledonian subduction-accretionary complex/volcanic zone,which located in the middie sec-tor of North Qilian Mountains,can be falled into Tuolaishan subduction complex zone and Zhoulang-nanshan accretionary complex/volcanic zone. The former consists of ophiolites,ophioIite melangesand abyssal flysches,which are preducts of offscraping during late peried of sueduction of ancient Qil-ian Ocean.The later,including residual ophiolite lens,high-pressure metamorphic rocks,arc volcanic rocks and metamorphic clastic rocks,displays the complicated evolution hist0ry which ancient Qilian Ocean subducted to the north,the frontier of volcanic arc moved to the south,the accretionary com-plex thickened and underplated successively and ancient ocean trench retreated to the south. Subeuc-tion-accretionary complexes experienced three stage deformations(D_1,D_2, D_3)during caledonian pori-od. D_1 and D_2,deformation mechanisms of simple shcar, indicate thrusting from N(NE)to S (SW),D_3,a deformation mechanism of flattening,shows compressive deformation of collision of Zhoulang-nanshan ancient island arc with Qilian block. |
