A new division of late Cretaceous Erlian Basin tectonic units based on differential basement characteristics

The Erlian Basin, a significant continental sedimentary basin in northeastern China, is renowned for its abundant hydrocarbon resources. Extensive research has been conducted on its sedimentary sequences, hydrocarbon accumulation, and geodynamic background. However, previous tectonic units classifications of the Erlian Basin predominantly reflect its post-Cenozoic tectonic framework, neglecting the Early Cretaceous period. This oversight fails to explain recent petroleum discoveries in the Wulanhua area of the Ondor Sum Uplift. In this study, geological, well log, seismic, gravity, and magnetic data, along with large, deep fault distributions and the regional geology of the Erlian Basin, were utilized to analyze its basement characteristics and propose a new tectonic division. Our findings reveal that the Erlian Basin's basement exhibits composite characteristics, resulting in a north-south zonation of basin depressions. Consequently, the basin's tectonic units were divided into northern, central, and southern depressions, delineated by two major deep faults: Xilinhot and Chifeng–Kaiyuan. This revised tectonic division clarifies the Early Cretaceous tectonic framework, enhances the basin's hydrocarbon exploration potential, and will guide future exploration efforts. Our study identifies nine favorable sags within the Erlian Basin with significant hydrocarbon potential.