Control-basin structure around the Taiyuan Basin

ObjectiveTo determine the basin control structure of the Taiyuan Basin and its surrounding areas using geomechanical methods, and to characterize the structural properties of the Taiyuan Basin. MethodA conjectural tectonic line analysis was applied to integrate the fault system with the distribution of Quaternary sedimentary bands, linear geomorphology, basin boundary geomorphology, and the systematic extension of identified faults. ResultsThe study identifies meridional, latitudinal, Cathaysian, and NW tectonic systems in the region. Based on local-structure analysis, four local torsion structural systems are identified in the northern part of Taiyueshan: ξ-shaped, North-South brush-shaped, NW oblique torsion, and SN "λ"-shaped torsion structural system. Two global torsional systems are also recognized: NW vertical torsion and EW vertical torsion. By dividing the study area's enclosed geomorphic elevation into regions and applying modern geomorphic step analysis, the results indicate that basin formation and the development of enclosed mountain geomorphology share a coupled movement and a unified mechanism. ConclusionThe extension of Shanxi graben system represents a phased, comprehensive extension and collapse of the enclosed orogenic belt. Six regional activity patterns were inferred to contribute to basin formation. Regarding extensional behavior, there were Neogene extensional collapse events with a NNW-SSE orientation in Xizhoushan, Taiyueshan, and Yunzhongshan within and around the Taiyuan Basin. The Taiyuan Basin is a complex fault-block-controlled basin in which multiple local and global movement modes interact to shape basin morphology and the distribution of secondary tectonic units; however, the controlling factors of basin formation vary across sub-regions. This yields a complex, multi-factorial basin-formation model involving multiple tectonic systems and formation mechanisms.