STRUCTURAL STYLE IN A TENSION-SHEAR FAULT BASIN AND ITS BEARING ON HYDROCARBON ACCUMULATION: A CENOZOIC EXAMPLE IN ENPING SAG, PEARL RIVER MOUTH BASIN

Taking the Enping Sag as an example, we studied the structural characteristics of a tension-shear fault basin in this paper. Discussed are the influence of structural figuration and structural dynamics on the formation of hydrocarbon source rocks and hydrocarbon enrichment zone and the types of traps. The results show that there are 4 kinds of extensional structural styles in the Cenozoic of the Enping Sag, which are constrained by a NE-EW extensional tectonic system in the lower tectonic layer and a NW-NWW tension-shear tectonic system in the upper layer, showing a combined structure of tectonic two-way stretch in general. The evolution of structural style constraints the development of the half graben and the formation and distribution of hydrocarbon source rocks as well as the formation of trap types and structural zones. It also determines the initial migration direction of hydrocarbon when it reaches the threshold of hydrocarbon generation. Therefore, the structural style has provided favorable conditions for the formation of Cenozoic oil and gas reservoirs in the study area.