Structural characteristics of the northern Longmenshan fold-thrust belt and the favorable exploration areas, Sichuan Basin, Southwest China

Abstract

Based on the latest data from oil and gas exploration, the structural geometry features of the northern Longmenshan fold-thrust belt and its forming process were examined, and then favorable hydrocarbon prospecting areas were predicted. Two major orogenic events occurred in the Longmenshan belt since the Mesozoic: thrusts and folds were formed by a late Triassic compressional event, and later transformed by the late Cenozoic deformation featuring base-involved large folds. Due to the influence of the two events, thrust nappes, autochthonous thrusts and in-situ blind thrusts developed from the orogen to the foreland basin sequentially, and these structural units show different profile combination from the north to south. Among these structural units, the autochthonous thrusts and folds under lower allochthonous nappes have high potential for oil and gas exploration. Key words: Longmenshan, fold-thrust belt, structural analysis, favorable target