关键词: 龙门山前锋带, 晚三叠世, 新生代, 冲断构造, 断层相关褶皱, 背斜构造, 油气勘探

Abstract: The northern Longmenshan front belt extends along Guangyuan to Anxian and includes the typical anticlines such as Kuangshanliang,Tianjingshan,Qinglinkou and Zhongba.Field investigations and seismic interpretation ascertained two episode tectonic deformations in the Late Triassic and the Cenozoic periods in this front belt.The Kuangshanliang and Tianjingshan structures show a duplex comprising of a shallow fault-bend fold in the Late Triassic period and a deep buried stacking anticline imbricated by several thrust sheets in the Cenozoic period.The Qinglinkou and Zhongba structures show a imbricate structure in the Late Triassic and a buried fault-bend fold and fault-propagation fold,which may be created or altered in the Cenozoic period.The front belt of the northern Longmenshan exhibits a double-layer structural style characterized by shallow thrust structures and deep buried ones.The buried thrust structures are the frontier fields for hydrocarbon exploration in the northern Longmenshan area.

Key words: Longmenshan front belt, Late Triassic, Cenozoic, thrust structures, fault-related fold, anticline, hydrocarbon exploration