Multiple thrust detachments and their implications for hydrocarbon accumulation in the northeastern Sichuan Basin, southwestern China

The northeastern Sichuan Basin thrust belt located in southwestern China, is a large-scale intracontinental thrust system with multiple detachments represented by a series of subparallel chevron anticlines. We conduct a comprehensive study of the geometry and kinematics of the thrust belt and its implications for the petroleum system based on seismic-reflection profile interpretation, field investigation, analysis of wells, and geochronology. Two major detachments occur within the allochthonous succession: the (1) gypsum-bearing lower to middle Cambrian Longwangmiao and Gaotai Formations and (2) Lower Triassic Jialingjiang Formation. The dark gray shales in the lower Silurian Longmaxi Formation are a favorable source rock that may also act as a third detachment in this study area. The stratigraphic succession is divided by three detachments into three structural intervals: (1) lower Cambrian–Silurian structural interval, (2) middle Silurian–Triassic structural interval, and (3) upper Triassic–Jurassic structural interval. The lower structural interval may be a good candidate for hydrocarbon exploration because of the occurrence of high-quality source rock and its reservoir-trapping evolutionary history.