华南过渡区凯里组及同期地层的初步研究

A preliminary study of the Kaili Formation in the transitional area in South China and its synchronous strata

凯里组为卢衍豪教授1963年所建,周志毅等(1980)详细工作后,面貌比较清楚。它是分布于贵州东部丹寨、台江、玉屏一带的以泥、页岩为主厚约300m的一套地层,属过渡区。化石丰富,以三叶虫Pagetia,Oryctocephalids,Ptychopariids最为发育,由下而上建立了4个三叶虫带。与滇东陡坡寺组对比,顶、底界线一致;与黔北扩大的高台组(周志毅等1980,278页)对比,顶界略高于高台组。时代暂定为中寒武世(周志毅等1979,

The Kaili Formation (Lower-Middle Cambrian) and its synchronous strata are widely distributed in the transitional belt between the Yangtze platform and the Southeast China geosyncline. This formation is characterized by well-developed shale, mudstone containing abundant trilobites and other organisms, such as echinoderms, medusae, hyolithes, sponges, brachiopods, vermes, gastropods and algae, which are named the Kaili Fauna by the authors. The synchronous strata of the Kaili Formation from northern Hunan, Jiangxi, southern Anhui are characterized by the developed shale, mudstone, limestone, dolomite yielding trilobites. The four trilobite zones of Kaili Formation are erected by Zhou Zhi-yi and others in ascending order, namely, 1. Nangaops-Kunmingaspis Zone, 2. Wuxunaspis Zone, 3. Oryctocephalus-Xingrenaspis Zone, and 4. Kootenia jialaoensis Zone. In the present paper we propose Bathynotus-Nangaops Zone instead of Nangaops-Kunmingaspis Zone, because this zone is restricted to the lowest part of the Kaili Formation and widely distributed in the transitional belt. By studying the Kaili Formation and its synchronous strata we suggest that the extinction of trilobite genera Bathynotus and Redlichia should be regarded as the end of the Lower Cambrian and the beginning of the Middle Cambrian, so that the Lower-Middle Cambrian boundary should be drawn between the Bathynotus-Nangaops Zone and the Wuxunaspis Zone.