Multiphase deformation and its impacts on hydrocarbon distribution in the Hetianhe–Madong region, southwestern Tarim Basin

Abstract

The Hetianhe–Madong region of the southwestern Tarim Basin contains two thrust systems: the Cenozoic Mazhatage thrust belt in the northwest and the Paleozoic Madong fold-thrust belt in the southeast. The two structural belts have almost vertical propagation directions of deformation and abut in a narrow interaction zone between them. Proven hydrocarbons are closely related to the structural deformation experienced in this region and restricted along the fault system of the Mazhatage structure and the narrow interaction zone. Based on seismic interpretations and analogue modeling, structural models were constructed in this study for the two thrust systems and the interaction zone. Then, the controlling factors of the restricted distribution of hydrocarbon plays are discussed. The results suggest that the Mazhatage structure is a basement-controlled structure, whereas the Madong fold-thrust belt reflects a thin-skinned structural style with a middle Cambrian salt as the detachment layer. The interaction zone is controlled by a strike-slip fault, and the preexisting structures and the salt layer affect its structural geometry. The basement-continued thrust fault and the strike-slip fault of the interaction zone cut through the salt layer, providing conduits for hydrocarbons from subsalt source rocks to suprasalt traps, explaining the restricted hydrocarbon distribution in the Hetianhe–Madong region. This study provides insight into regions undergoing multiphase deformation and its control on hydrocarbon distribution. The results may be helpful for understanding such structures.