滇西北衙地区中三叠统北衙组风暴沉积特征及其古地理意义

在滇西北衙地区中三叠统北衙组中首次发现风暴沉积,其表现为砾屑灰岩、网纹状灰岩的频繁互层,见丰富的风暴沉积构造。通过对笔架山及倒流箐剖面详细的野外观察及室内分析,识别出4种类型的风暴沉积序列。研究区风暴沉积的背景沉积为薄层网纹状灰岩,发育波状层理、鸟眼等构造,指示潮坪环境。潮坪风暴沉积在研究区的首次发现,对区内中三叠世古地理、古气候的研究具有重要的意义。

The storm deposits from the Middle Triassic Beiya Formation in the Beiya region, western Yunnan and their palaeogeographic implications

The storm deposits are recognized for the first time from the Middle Triassic Beiya Formation in the Beiya region,western Yunnan,and consist of alternating gravelly limestones and reticulated limestones with abundant sedimentary structures of storm deposits such as erosional soles,lag deposits,graded beddings and hummocky cross-beddings. The background deposits of the storm deposits are dominated by thin-bedded reticulated limestones with wavy beddings and bird’s-eye structures,suggesting a tidal-flat environment in the study area. The discovery of the tidal-flat storm deposits may be important to the research of the palaeogeography and palaeoclimatology in the study area during the Middle Triassic.