Multiple thrust detachments and their implications for hydrocarbon accumulation in the northeastern Sichuan Basin, southwestern China
Chuanxin Li, Dengfa He, Lu Guo, Kai Wen, Abijah Simon, Yanpeng Sun
Abstract
ABSTRACT 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.