峡东地区灯影组顶部,即天柱山(或黄鳝洞)段的小壳化石通过近年来的多次研究证实它们属于下寒武统,并可与国内外相对比。其中天柱山和松林坡剖面被确定为国际寒武系—前寒武系界限层型的参考剖面。但是以往的研究工作侧重于黄陵背斜东翼,对于背斜南翼的同期地层,由于岩性和岩相不同,迄今未见有关小壳化石的正式报导。自1980 The small shell fossils at the top of the Dengshui Formation in the Gap East region, ie, the Tianzhu Mountain (or the Huanglv Cave), have been confirmed by many studies in recent years as belonging to the Lower Cambrian and can be compared with those at home and abroad. The sections of Tianzhushan and Songlinpo are identified as reference sections of the International Cambrian-Precambrian Boundary Layer. However, previous studies focused on the eastern wing of the Huangling anticline. For the same period of the southern wing of the anticline, no official reports on small-shell fossils have been reported so far because of lithology and lithofacies. Since 1980