牯牛潭组与庙坡组的界线

<正> 牯牛潭组和庙坡组是张文堂(1962)命名建立的,标准剖面位于湖北宜昌分乡镇西侧的牯牛潭。牯牛潭组以灰岩与瘤状灰岩为主,厚约20m;庙坡组为页岩夹灰岩,厚约2m,页岩的出现为庙坡组的开始。长期以来这一观点被广大地质工作者所接受。70年代初南京地质古生物研究所西南队在湖北宜昌黄花场重测奥陶系剖面时,在牯牛潭组顶部约0.5m厚的地层中发现了三叶虫Birmanites hupeiensis Yi,Lonchodomas brevicis Lu,

The boundary between the Kuniutan and Miaopo Formations

The Ordovician Kuniutan and Miaopo Formations (Llanvirn-Lower Caradoc) are extensively distributed on the central Yangtze Platform. On the basis of the lithology and litho-facies of the top part of the Kuniutan Formation, it, about 30-50cm think, belongs to the Miaopo Formation at the type section located near Fengxiang, Yichang. The new boundary between the Kuniutan and Miaopo Formations corresponds to the base of the Eoplacognathus foliaceus conodont subzone in the eastern Yangtze Gorge area of the western part of Hubei Province, China.