THE MESOZOIC STRATA AND THE JURASSIC-CRETACEOUS BOUNDARY IN THE DAXINGANLING REGION

The Jurassic-Cretaceous strata in Daxinganling region are studied regarding the lithostratigraphic units, contact relation, distribution, paleontology and isotopic chronology. The J-K boundary is discussed on the basis of such study. The U-Pb isotopic ages of zircon by SHRIMP are greater than 145 Ma. With the support of fossil assemblages of Peipiaosteus, Nestoria-Keratestheria and Ferganoconcha, the J-K boundary is set between Baiyingaolao formation and Meiletu and Yixian formations.