Formation and Structural Evolution of the Daba Shan Fold-Thrust Belt, Qinling Orogen, China

Xiaoyu Guo
Department of Earth and Atmospheric Sciences, Saint Louis University Saint Louis, MO
[email protected]

The Daba Shan is a fold-thrust belt located along the northeastern Sichuan Basin. It has a large SSW-convex asymmetric arc-shape in plane view. Daba Shan can be divided into two belts which are separated by the Mianlue suture zone. This zone is exposed in the Daba Shan area as the large Chengkou fault zone. We accomplished both surface and subsurface structural analysis to elucidate the structural history of the region. . Previous geochronologic work showed that the amalgamation between the North China block and South China block was diachronous and heterogeneous. Therefore, we propose that the collision between east Qinling and Sichuan Basin started at the point between the Huangling Dome and Wudang Dome in the southeast of Daba Shan during late Mid-Triassic to the early Late-Triassic. Because of the buoyancy of the Huangling Dome and the Wudang Dome, subduction resistance in the east caused clockwise rotation of the Yangtze Block. With this rotation and penetration of the Yangtze block in the west, the indentation of Hannan Dome occurred later in early to middle Late Triassic time accompanied by the closure of the Mianlue Ocean and curvature of the major Chengkou Fault zone, as well as the arc-shape of Daba Shan fold-thrust belt. Understanding the evolution of Daba Shan Fold-Thrust belt is important in that it may contribute to the understanding of the exhumation of deep subducted continental crust and the world’s largest ultrahigh-pressure metamorphic belt (the Dabie Shan).

AAPG Search and Discovery Article #90094 © 2009 AAPG Foundation Grants in Aid