Transform strike-slip structures in extensional basins and their hydrocarbon significance

Transform structures are commonly developed in extensional basins. The transform strike-slip structures are passive strike-slip structures with significant horizontal displacement between different extensional fault domains to maintain regional or local strain conservation and transfer displacement between extensional faults, forming under non-strike-slip stress regimes. The transform strike-slip structures are commonly developed in the extensional basins in East China, and could be divided into two major types: transform strike-slip faults and transform strike-slip zones according to whether obvious strike-slip faults formed or not, and their structural styles are related to the difference in extension of faults on both sides. Furthermore, based on the tendency of the extensional faults on both sides, each type could be divided into three subtypes: i.e., opposite tendency, same tendency, and complex tendency. The transform strike-slip structures play an important role in controlling the hydrocarbon accumulation, and provide the base for the explanation and identification of structural traps in the extensional basin. The transform strike-slip structure causes the bending and deformation of local strata and controls the distribution of paleotopography or micro-paleotopography, and controls the development of sedimentary reservoirs. In addition, transformation strike-slip structures can act as favorable zones for oil and gas accumulation, as well as separators for oil and gas distribution.