陕西镇巴下寒武统筇竹寺阶小壳动物及有关问题的讨论

镇巴早寒武世筇竹寺期以富含Rhomhbocorniculum,Microcornus.Camhroclavus等小壳动物为特征,其产出层位与湖北房县灯影组西蒿段坪,陕西西乡灯影组“杨家沟段”大致相当。筇竹寺阶可建立两个小菱角刺顶峰带:即上部的Rhombocorniculumcancellatum带,下部R.nsolutum带,分别与Eorcdlichia带的中上部及下部相当。两个软舌螺组合带:上带Microcornus parvulus-Inflctithecazhenbaensis带,下带Sulcavitus-Linevitus带。

SMALL SHELLY FOSSILS IN QIONGZHUSI STAGE OF LOWER CAMBRIAN IN ZHENBA COUNTY SHAANXI PROVINCE

Basic characteristics of the small shelly fauna in the studied area are discussed. The stratigraphy i?correlated with relevant formations in Hubei, Shaanxi and Xinjiang. Two Rhombocorniculum acme zones and two Hyolithids assemblage zones are established for the Qiong-zhusi Stage in Zhenba, Shaanxi. The lower Rhombocorniculum insolutum zone and the upper R. cancellatumzone are respectively equivalent to the lower and mid-upper part of the Eoredlichia zone. Hyolithids can bedivided into the lower Sulcavitm-Linevitus zone and the upper, Microcornus parvull?s-Inflata?heca zhenbaensiszone, which approximately correspond to Parabadiella zone and Eoredlichia zone. After comparison ofRhombocorniculum in the studied area with that of other countries, it is confirmed that Fallotaspis is laterthan Parabadiella and is equivalent to Eoredlichia.