Abstract:

Owing to the continent-continent collision between North China and Yangtze continental blocks during the late Indosinian period to early Yanshanian period, Jianghan plain is at the regional compress geodynamic field. Its boundary is east Qingfeng-Xiangfan-Guangji faulted zone and Jiangnan thrusted nappe structure belt and Huangling uplift. Dahongshan arc structure which cusp points to southwest is formed under the condition of the regional geodynamic field and the boundary environments. The formation and evolution of the arc structure are mostly controlled by major orogenic processes in the east Qinling-Dabie orogenic belt. Arc structure is a complex thrusted nappe system with multiple superimposed structures. Generally, the nappe structure moved from the northeast to the southwest. The structural deformation trend of the arc structure changes from strong to weak and deep to shallow from the northeast to the southwest.With the formation of longitudinal shear fracture belts Dahongshan arc structure is divided into three tectonic units, which are Dangyang-Jingshan structural area and Jingzhou-Xiantao structural area and Echeng-Daye structural area. Jianghan plain looks like structural framework with blocks in north-south direction and belts in west-east direction. The top of the arc structure is buried under Cretaceous-Paleogene stratum of Jianghan basin during the late Yanshanian period to the Himalayan period for the reason of tectonic inversion and rift faulting of the longitudinal shear fracture.

Key words: Dahongshan, arc structure, shear fracture, thrusted nappe structure, tectonic framework, geodynamic mechanism