浙西及邻区下奥陶统牙形刺序列及不同相区的对比

Lower Ordovician conodont sequences in western Zhejiang and the adjacent areas and their correlation with those in different facies realms

浙江省常山县黄泥塘,江山市拳头棚及江西省玉山县山头底等地(图1)下奥陶统宁国组主要为笔石相,偶夹石灰岩透镜体,化石丰富,化石带齐全。少量的牙形刺可直接采自页岩层面,大部份从灰岩中酸解出。由于页岩中含笔石,灰岩透镜体中产牙形刺,使笔石带和牙形刺带得以相互引证,进而为笔石相和壳相地层的对比提供直接证据。

The Lower Ordovician Ningguo Formation in western Zhejiang and the adjacent.areas is made up of mainly the graptolitic shale facies, which contains occasionally limestone lenses and, with very abundant graptolites, perfect fossil zones.It is one of the typical sections in the Jiangnan Region.The conodonts reported in this paper were collected partially from layers of shales, and mostly from limestone lenses.In this case, it is very convenient for us to correlate directly the graptolite zones with the condont zones.Further, the reliable evidences will be provided for correlating the graptolitic facies witli shell facies.In this region, the Ningguo Formation contains ascendingly the following six conoddnt zones: Prioniodus elegans Zone, Oepikodus evae Zone, Baltoniodus triangularis Zone, Paroistodus ortginalis Zone, Amorphognathus variabilis Zone and Pygodus serrus Zone.