【摘要】 根据最近在陕西紫阳地区芭蕉口仙中沟口剖面文洛克统底界附近采到的弓笔石之层位分布,划分出5个连续的弓笔石带C.lapworthi带—C.sakmaricus带—C.insectus带—C.centrifugus带—C.murchisoni带。这是目前世界上最完整的文洛克统底界附近弓笔石带序列之一,为文洛克统底界的确定提供了一个重要地点。更多还原

【Abstract】 According to the characteristics and horizons of 6species of Cyrtograptus collected recently near the lower boundary of the Wenlock at the Xianzhonggoukou section,Bajiaokou,Ziyang,Shaanxi ,five continuous cyrtograptid zones are recognized;they are the Cyrtograptus murchisoni zone,C.centrifugus zone,C.insectus zone,C.sakmaricus zone and C.lapworthi zone.This is one of the most complete cyrtograptid zone sequence near the lower boundary of the Wenlock in the world and provides an impor-tant locality for the determination of the lower boundary of the Wenlock Series.更多还原