Characteristics and genetic mechanism of the Mesoproterozoic rift system, Ordos Basin, China

Abstract

The Mesoproterozoic rifts are developed in the Ordos Basin located in the western margin of the North China Plate. Based on the latest 3D seismic data and previous research results, this study intends to discuss the zonal differential deformation characteristics and genetic mechanism of the Mesoproterozoic rifts in the Ordos Basin. NE-trending rifts are developed in the Mesoproterozoic in the south-central Ordos Basin, the main part of which are located near the western margin of the North China Plate. NNW-trending rifts are developed in the north of the basin, while NW-NNW rifts in the Mesoproterozoic in Hangjinqi area. The genetic mechanism of the Mesoproterozoic rifts is related to regional extensional stress field, plate boundary conditions and internal preexisting structures. The main extensional stress direction strikes NWW-SSE (120°) in the western margin of the North China Plate, based on the forward rift trend of the northern Mesoproterozoic. In Hangjinqi area, the reactivation of the existing NW-trending Wulansu fault and NW-NW-trending Daolao fault, results in dextral shear stress field. The boundary between the western margin of the North China Plate and its adjacent plates forms a nearly NS-trending preexisting basement tectonic belt, which intersects with the NWW-SSE (120°) extensional stress at an acute angle of 60°. Therefore, the western margin of the North China Plate is formed by oblique normal faults under oblique extension. Due to the long time span of Columbia Supercontinent breakup (1.8–1.6 Ga), the oblique rift in the south-central Ordos Basin is formed under the continuous oblique extension at the western margin of the North China Plate.

Keywords

• Columbia Supercontinent
• Ordos Basin
• Rift system
• Mesoproterozoic
• Genetic mechanism