Abstract:

The Shiwu Formation in Shiwu half-graben developed well and widely spread. In well-SN 10 near Shiwu township in Gongzhuling City, its sequence is complete and the boundaries of top and bottom are clear, and its lithological character, sporopollen assemblage and thickness are distinct, thus the stratum is named Shiwu Formation. The sporopollen assemblage of the formation is characterized by abundant Classopollis, Cyathidites and a few Tricolpopollenites, Clavatipollenites etc. Therefore, it is called as Classopollis-Cyathidites- Thicolpopollenites assemblage, which could compare with that of the Guantao and Gecun Formations in South China. Its age should belong to Aptian of Early Cretaceous.