Distribution, evolution and structural properties of Wushenqi paleo-uplift in Ordos Basin

This paper depicts the distribution of the Wushenqi palaeo-uplift in the Ordos Basin by using the latest drilling and seismic data, and analyzes the tectonic evolution of the paleo-uplift with the support of Bischke curve and balanced section. The compressional Wushenqi palaeo-uplift which developed in the Early Caledonian orogeny (Huaiyuan orogeny) is approximately a flat ellipse extending in S-N direction. Its long axis is about 194 km and short axis is about 55–94 km in nearly W-E direction. The denudation thickness and area of the Cambrian in the core are 170–196 m and 11 298 km2, respectively. It was mainly formed during the Huaiyuan orogeny according to the chronostratigraphic framework. It was in the embryonic stage in the Middle–Late Cambrian, denuded after developed obviously at the end of Late Cambrian. The paleo-uplift of the 3rd member of the Ordovician Majiagou Formation was reactivated and reduced in area. In the sedimentary period of the Ma4 Member–pre-Carboniferous, the paleo-uplift experienced non-uniform uplift and denudation. It entered the stable period of burial and preservation in the Carboniferous and later period. The Wushenqi paleouplift was formed on the weak area of the basement and tectonic belts, into an compressional structure with irregular morphology, under the control of the non-axial compression in the south and north and the stress transmitted by the uplift in the basin. The Wushenqi paleo-uplift has a controlling effect on the sedimentary reservoirs and hydrocarbon accumulation. © 2023 Science Press. All rights reserved.