Tectonic evolution of Xiannüshan fault and its influence on hydrocarbon traps in Changyang anticline, Western Hubei fold belt

The Western Hubei fold belt is an important oil and gas exploration area in South China. Located in the northeast of the fold belt, the Xiannüshan fault intersects the Changyang anticline, and has an important influence on the hydrocarbon traps in the Changyang anticline. However, the geometrical morphology and evolution history of the Xiannüshan fault has not been well studied due to the lack of accurate depth information, and the influence on hydrocarbon trap evolution was still unclear. Based on the interpretation of the latest seismic section in the central part of the fault, the quasi-three-dimensional shape and the formation process of the Xiannüshan fault were analyzed. Combined with the regional geological evolution and hydrocarbon accumulation process, the influence of the formation and evolution of faults on the preservation units in the Changyang anticline was analyzed. (1)The Xiannüshan fault belt can be divided into three parts. The northern part is dipping westwards, while the middle and southern parts are dipping eastwards. (2)The Xiannüshan fault was first formed during the Late Jurassic as a strike slip fault, pulling apart during the Late Cretaceous, and thrusted during the Middle and Late Paleogene. (3)The strike slip of the Xiannüshan fault in the Late Jurassic was favorable for hydrocarbon migration in the Changyang anticline. However, the stretching of the Xiannüshan fault in the Late Cretaceous destroyed tectonic traps in the Changyang anticline, leading to hydrocarbon loss. In areas where similar faults have occurred in the western Hubei, the potential for oil and gas exploration may have been adversely affected.