Dazhang Fm

The naming section is located at Xiliang and Wangping Village, Dazhang, ~7 km northeast of Songxian County, Henan, and the reference section is located at Zhutoupo and Yaoshan ~3 km east of Tantou Township, Luanchuan County. Named by Tong Yongsheng and Wang Jingwen in 1980.

Lower part is grayish brown conglomerate with brownish red sandstone. Middle part is brownish red mudstone with sandstone and grayish black and yellowish green sandy mudstone. Upper part is yellowish green and dark brown sandstone and grayish green mudstone with cream-colored marlstone and oil shale. The lithology changes greatly laterally: the lithology becomes coarse east of the old seat of Songxian County and limestone increases at Tantou and Dazhang. The thickness is ~100–475 m.

Up to now bivalves, gastropods, ostracods, mammals and sporopollen have been found in this horizon. The mammals are mainly the families Pastoralodontidae and Pseudictopidae that were common in the late Paleocene in Asia; the ostracods include such genera and species as Cypris heamensis (=C. decaryi), Cyprideis, Metacypris and Cyprinotus; mollusks have 8 genera and 12 species such as Parhydrobia, Aplexa, Physa and Eupera. Sporopollen is dominated by angiosperms and the pollen that is better preserved is the pollen type of old angiosperms such as Aquilapollenites; gymnosperms include Monocolpopollenites similar to Bennettitales, primitive conifers with a large form and Ephedra and Ginkgo.

It is interpreted to lacustrine or lacustrine-swampy deposits.