Abstract:

Some important basic geological issues about Dabieshan and its adjacent regions have been expounded in detail in this paper, and further defined that (1) North Huaiyang region belongs to the northern margin of Yangtze Block, the boundary between it and the southern margin of the North China Landmass is the north of GushiFeizhong Fault Zone; that (2) Neoproterozoic lowgrade metamorphic rock series certainly existed in the ultrahigh pressure metamorphosed belt, it has undergone two phases of fold deformation with the eclogite and other ultrahigh pressure rocks, forming a deformed belt which was extensional detachment in the early stage, and contractive compression in the major stage, which are not the foreign tectonic remnants or tectonic accretionary wedge caused by the subduction process; that (3) the Blue Schist was formed during the extensional detachment, eclogites are pyrolite and magmatic origin, and other ultrahighpressure rocks and “coesite” could be formed by the joint action of the “Earths crust abnormal pressure ” and “high pressure autoclave”, in the extensional detachment environment within the entire shallow crust; that (4) widespread Neoproterozoic volcanic and intrusive rocks represent the intense tension cracking expansion event occurred during the Jinningian, but no ocean crust type basin formed; that 5. the characteristics and forming mechanism of the stretching and growth lineation in Dabieshan and its adjacent regions have been described in detail, and this paper suggests that it was formed in extensional detachmentslip shear process within the lithosphere and different layers of crust caused by “mantle differential circulation”. The Dabie Orogen Belt has undergone multistage tectonic movements, including cracking into a basin, extensional detachment, compressive squeezing and thermal uplift to form mountains, which was not formed by platecollision orogenesis.

Key words: tectonic subdivision of North Huaiyang region, low grade metamorphic rock series, genesis of eclogite, stretching and growth lineation, mantle differential circulation, nonplate collision orogenesis