滇西南二叠纪放射虫化石

PERMIAN RADIOLARIAS ON SOUTHWEST YUNNAN

系统地描述了采自滇西南二叠纪拉巴群上部、老厂组、澜沧江带火山岩的放射虫化石,共计17属32种。该动物群可划分为3个组合带:Follicucullus组合、Neoalbaillella optima组合和Neoalbaillella ornithoformis组合,据这些放射虫组合讨论了相应地层单元的时代归属。

A radiolarian fauna,consisting of 32 species belonging to 1 7 genera,found in Laochang and Nanpan of Lancang County and Bangsha of Jinghong County,is described in this paper. The fauna can be divided into 3 assemblage zones. The sequence of these zones is listed ascendingly as follows : (1 )F ollicucullus assemblage zone,collected from the upper part of Laba Group in Nanpan, Late Maokou-Early Longtan. (2) Neoalbaillella optima assemblage zone ,occurring in the upper part of Laba Group in Nanpan and the middle part of Laochang Formation in Laochang, Late Longtan. (3) Neoalbaillella ornithoformis assemblage zone preserved in the upper part of Laba Group in Nanpan and the chert interbed of volcanic rocks in Bangsha,Early Changxing. The geological times of the litho-stratigraphic units are discussed based on the three assemblage zones.