四川龙门山中段早埃姆斯期生态地层及古环境新认识

本文讨论了龙门山中段白石 苟家大型飞来峰内早埃姆斯期的甘溪组分布及岩性特征。首次将甘溪组划分为两个生态地层单元 ,即Anetoceras Plectodonta群落及Dicoelostrophia Eosophragmophora群落 ;指定了群落的层型剖面 ,分析了各群落的生物组成、丰富度、生态特征及生态环境。认为区内早埃姆斯期属深水陆棚至深水盆地沉积环境 ,为龙门山区泥盆纪沉积盆地的性质和演化提供了新资料。

Ecostratigraphy and palaeoenvironments in central Longmen Mountains, Sichuan during the early Emsian

The stratigraphy and lithology are discussed for the early Emsian Ganxi Formation within the Baishi Goujia klippe in central Longmen Mountains, Sichuan. Two ecostratigraphic units including the Anetoceras Plectodonta community and Dicoelostrophia Eosophragmophora community have been identified for the Ganxi Formation for the first time. The emphasis is placed on stratotype section, biology, abundance, ecology, living styles and habits of individual communities. The results of research show that the study area may be assigned to deep water shelf to deep water basin environments during the early Emsian. This new explanation has provided new evidences for the interpretation of the nature and evolution of the Devonian sedimentary basins in the Longmen Mountain area.