Segmentation of the Longmen Mountains thrust belt, Western Sichuan Foreland Basin, SW China

Many complex structures have developed in the Longmen Mountains thrust belt, SW China, over the course of polyphase tectonic movements in the region. Based on field investigations and interpretations of seismic sections, we divided the belt into the following three segments and two transfer zones (from northeast to southwest): the northern segment, Anxian transfer zone (Ta), central segment, Guanxian transfer zone (Tg), and southern segment. The northern segment, located north of Anxian County, consists of the Jiaoziding nappe, comprising a Triassic–Jurassic fold belt and a plastically deformed Silurian belt. The northern segment can be further divided into four sub-segments: the Guangyuan–Chaotianyi sub-segment (N1), Baitianba–Guangyuan sub-segment (N2), Wenxingchang–Baitianba sub-segment (N3), and Wuzhong Mountain–Tangwangzhai nappe sub-segment (N4). The Anxian transfer zone (Ta), located between Yuanmenba Town and Hanwangchang Town, consists of numerous thrust faults and strike-slip faults at shallow levels, with duplexes and detachment structures at deeper levels. The central segment, which consists of the Jiudingshan nappe and numerous klippes and thrust faults, is located between Hanwangchang Town and Guanxian County. This segment can be divided into two sub-segments: the Mianzhu–Mianyang sub-segment (C1) and the Dayuanbao sub-segment (C2). The Guanxian transfer zone, which is characterized by numerous thrust faults, strike-slip faults, and duplexes, is located between Guanxian County and Huaiyuan County. The southern segment, which consists of the Baoxing nappe and contains arcuate thrust faults, is located south of Huaiyuan County. The southern segment is divided into three sub-segments: the Huaiyuan–Xinchang sub-segment (S1), Xinchang–Lushan sub-segment (S2), and southern arcuate sub-segment (S3).