Magnetostratigraphy of the Upper Cretaceous and Lower Paleocene terrestrial sequence, Jiaolai Basin, eastern China

The Cretaceous is a crucial period in the Earth's evolutionary history. However, the lack of a consolidated chronology for continental strata has precluded a better understanding of terrestrial processes and the integration of marine and terrestrial records. Here, we present an integrated chronology for the Upper Cretaceous to Paleocene terrestrial strata in the Jiaolai Basin, eastern China, based on new magnetostratigraphic results and 40Ar/39Ar analyses of the Cretaceous Continental Scientific Drilling borehole (CCSD-LK-I). Our geochronologic results suggest that, in the Jiaolai Basin, the Cretaceous-Paleogene (K/Pg) boundary is within the magnetozone R6 (560.62-570.13 m) and that the age of the Hongtuya Formation (containing late Cretaceous dinosaur bone and egg fossils) ranges from 84 Ma to 73.5 Ma, thus corresponding mainly to the Campanian. The comprehensive geochronologic framework allows the accurate correlation of the terrestrial Upper Cretaceous strata in the Jiaolai Basin to marine strata and other continental sequences, and also lays the foundation for the study of the structural evolution of eastern China.