NEW ADVANCE IN THE STUDY OF THE CRETACEOUS AND PALEOGENE STRATA OF THE NANXIONG BASIN

Oviraptorid dinosaur fossils were found in the Zhengshui Formation of the Luyuan area, Shixing and the Pingling Member of the Shanghu Formation of Nanxiong, and hadrosaurids were also found in the latter formation. The Dafeng Formation at Jiezhi, Shuikou, Xiaping, Xietan of Shixing and other sites yields a great number of Spheroolithus-type egg-dominated fossil eggs. Conchostracans, insects, Priops, and foraminiferans were found in the Nanxiong Group of the west of the Nanxiong Basin. Bemalambda made its first appearance in the Datang section, about 60m above the basal boundary of the Shanghu Formation, its highest occurrence being in the Longshan Formation. The dating of the stable isotope of the egg shell and the enrichment anomaly of Iridium is used to inquire into the extinction of the dinosaurs. There are 4 views in the placement of the Cretaceous-Paleogene boundary: 1) near the basal part of the Shanghu Formation ( based on the extinction of dinosaurs ), 2) between the Pingling and Xiahui Members ( based on ostracodes ), 3) in the upper part of the Pingling Member ( based on bemalambdids and gastropods ), and 4) in the middle and upper parts of the Zhengshui Formation ( based on sporo-pollen ).