Structural style differences under the control of multiple detachment layers and their implications for the Carboniferous hydrocarbon exploration in the eastern Sichuan Basin

The Carboniferous reservoirs in the eastern Sichuan Basin are generally thin， rendering the exploration of stratigraphic-lithologic hydrocarbon accumulations therein more challenging. Therefore， there is an urgent need to determine the coupling relationship between the distribution of detachment layers and regional structural styles， aiming to provide a novel philosophy for the structural trap exploration. Using seismic reflection data， drilling and log data， and the research results of regional geology， we analyze the controlling effects of detachment layers on structural styles in the eastern Sichuan Basin from the perspective of structural geometry. Furthermore， the formation process of the Carboniferous traps under the layered structural deformation pattern is investigated in depth. The research results reveal that the Dachigan-Datianchi area in the eastern Sichuan Basin exhibits thin Triassic but thick Silurian and Cambrian detachment layers. The deformation exhibits distinct stratification bounded by the Silurian： below it， east-dipping reverse faults and folds occur， while fault-propagation folds dominate above. Under this layered deformation system， fault-propagation folds overlying the Silurian strata exhibit steeply dipping faults at the base of their forelimbs， while their gently dipping faults extend forward along detachment layers. These faults jointly control the formation of the Carboniferous faulted anticline traps. Across the eastern Sichuan Basin， the differential distribution of detachment layers is coupled with structural styles. Notably， the Carboniferous traps associated with fault-propagation folds within the layered deformation system of the Dachigan-Datianchi tectonic zone serve as key potential targets for hydrocarbon exploration in the region.