Abstract:

In this study, based on the analysis of seismic sections we identified three stage development of thrust and fold structures and built up the geometric models of the Yasongdi and adjacent belts in the Bachu Uplift, Tarim Basin. Firstly, the NWW trending Bashituo Fault was formed after the Permian but prior to the Paleogene, which slipped along the Middle Cambrian gypsum salt layer.Then, the Selibuya Fault with a NNW strike characterized by basement involved structures was formed in the Late Miocene. Finally, the Yasongdi Faults in the shallow and deep domains were developed during the Pleistocene to Holocene with the same NW trends, however, slipped along the Paleogene and Middle Cambrian gypsum salt layers, respectively. In map view, the development of the Yasongdi faults is restricted by the extent of the Paleogene salt. Influenced by the rejuvenated Bashituo and Selibuya faults, the Yasongdi fault belt can be divided into three segments: the eastern segment is featured by the upper fault propagation fold and lower detachment fold; the central segment is mainly composed of the upper fault propagation fold, middle detachment fold, and lower basement involved structure; and the western segment consists of the upper detachment fold and lower fault bend fold. All the geometries of superposed folds described above have been reproduced by our numerical analog modeling.

Key words: fault related fold, detachment structure, basement involved, Yasongdi Fault, Bachu Uplift