The characteristics and sedimentary model of Storm deposits in the Lower Devonian strata of Beichuan

Based on the actual measurement data of the storm depositional sections in the Lower Devonian strata of Beichuan and the study of section structures and sedimentary evolution of Ganxi Formation and Xiejiawan Formation, the authors established storm depositional sequences and depositional models of the study area. Storm deposits are widely developed in the Lower Devonian strata of Beichuan, and such geological phenomena as the erosion surface, gutter casts, shell lag deposits, parallel bedding, hummocky cross-stratification, biological genesis structures and other storm sedimentary structures are well developed. In the study area, 3 types of storm deposits and 7 types of storm depositional sequences are developed. The storm deposits in the Lower Devonian strata of Beichuan have good significance for the study of palaeolatitude, palaeoclimate and palaeogeography, because they provide proper evidence for the northward movement of Yangtze plate and tropical or subtropical climate environment of Beichuan area in the Early Devonian period.