北川甘溪下泥盆统风暴岩沉积特征及其沉积模式

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

依据风暴沉积野外剖面实测资料,通过对北川下泥盆统甘溪组和谢家湾组风暴沉积野外剖面结构和沉积演化等的研究,建立了该区风暴沉积序列模式及分布模式。北川甘溪下泥盆统广泛发育侵蚀冲刷面、渠模构造、生物介壳滞留沉积、丘状交错层理和生物成因构造等风暴沉积构造,其中发育3类风暴沉积与7类风暴沉积序列。研究区广泛发育的风暴沉积具有良好的古气候和古地理意义,亦为前人提出的扬子板块北移和北川早泥盆世所处的温暖热带—亚热带气候环境提供了一定证据。

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.