大巴山西段寒武纪的三叶虫分带

<正> 本文的大巴山西段,包括宁强、勉县、南郑、城固及西乡等地区,寒武纪地层发育良好,从上到下包括中寒武统陡坡寺组(小关子组),下寒武统孔明洞组、阎王碥组、仙女洞组、郭家坝组及相当于梅树村阶的地层。化石非常丰富,包括三叶虫、腕足类、古杯、高肌虫,海绵及小亮化石等,其中以三叶虫属种和数量最多,除相当梅树村阶的地层和筇竹寺组下部

Zoning of the Cambrian trllobites from the western Daba Mountain

The present paper deals with the zoning of the Cambrian trilobites from the western Daba Mountain. The Cambrian System here is divided into the Middle Cambrian and Lower Cambrian Series and includes five formations: the Douposi, Kongmingdon, Yanwangbian, Xiantidong and Guojiaba Formations, The trilobites contained in these formations are grouped into seven zones in descending order: (7) the Chittidiella-Kunmingaspis Zone, (6) the Hoffetella-Pterore-dlichia Zone, (5) the Pscudichangia damiaoensis-Paokannia Zone, (4) the Drepanuroides-Mayi-ello Zone, (3) the Yunnanocephalus-Kuanyangia Zone,(2) the Pachyredlichia-Mianxiandiscus (Mianxiandiscus) Zone and (1) the Parabadiella-Mianxiadiscus (Liangshandiscus) Zone. Of these, the Chittidiella-kunmingaspis Zone belongs to the Middle Cambrian Douposi Formation, the Hoffetella-Pteroredlichia Zone to the Lower Cambrian Kongmindong Formation, the Pseudich-angia damiaoensis-Paokannia Zone and the Dreponuroides-Mayiella Zone to the upper and lower Yanwangbian Formation, the Yunnanocephalus-Kuanyongia Zone, Pachyredlichia-Mianxiand-iscus (Mianxiandiscus) Zone and Parabadiella-Mianxiandiscus (Liangshandiscus) Zone respectively to the upper, middle and lower parts of the Guojiaba Formation.