东濮凹陷沙三段正常三角洲沉积中遗迹化石及意义

Trace fossils from the normal delta deposits in the third member of the Shahejie Formation in the Dongpu depression and their significance

通过对钻井岩心的观察和遗迹化石的鉴定,在东濮凹陷古近纪沙河街组沙三段发现遗迹化石10属15种,包括:Skolithos vertivalis,Skolithos linearis,Skolithos isp.,Palaeophycus tubularis,Palaeophycus isp.,Planolites montanus,Planolites beverlegensis,Planolites isp.,Mermoides isp.,Taenidium isp.,Teichichnus isp.,Helminthoidichnites tenuis,Helminthopsis isp.,Beaconites isp.和Thalassinoides isp.。根据岩性特征、沉积构造和遗迹化石的组成、分布特征,研究区沙三段主要发育正常三角洲前缘亚相、前三角洲亚相,并划分了反映不同沉积环境和水体深度的2种遗迹组合,分别为Palaeophycus-Planolites遗迹组合和Planolites-Helminthoidichnites遗迹组合。

The trace fossils from the third member of the Palaeogene Shahejie Formation in the Dongpu depression are divided,on the basis of core observation and trace fossil identification,into 10 genera and 15 species,including Skolithos vertivalis,Skolithos linearis,Skolithos isp. and Palaeophycus tubularis,Palaeophycus isp.,Planolites montanus,Planolites beverlegensis,Planolites isp.,Mermoides isp.,Taenidium isp.,Teichichnus isp.,Helminthoidichnites tenuis,Helminthopsis isp.,Beaconites isp.,and Thalassinoides isp. According to lithology,sedimentary structures,and the types and distribution of the trace fossils,the normal delta front subfacies and prodelta subfacies are separated in the third member of the Palaeogene Shahejie Formation. Two trace fossil assemblages are also recognized,including the Palaeophycus-Planolites and Planolites-Helminthoidichnites trace fossil assemblages which have reflected different sedimentary environments and water depths in the study area.