A potential terrestrial Albian–Cenomanian boundary in the Yanji Basin, Northeast China

Abstract The terrestrial Albian–Cenomanian (A–C) transition was an important time interval for the co-evolution of animals and flowering plants, as well as for the diversification of dinosaurs and mammals on continents. Due to a worldwide lack of terrestrial sedimentation at that time, and the difficulty of direct correlation between marine and non-marine stratigraphy, only a few studies have discussed the terrestrial A–C boundary; therefore, it remains poorly understood compared with other stratigraphic boundaries. Northeast China is an ideal place to study the terrestrial A–C boundary because the area contains the most complete and continuous terrestrial Cretaceous succession in the world. Here, we report a SIMS U Pb zircon age of 105.14 ± 0.37 Ma for the uppermost part of the Dalazi Formation in the Yanji Basin. Additional ostracod-based biostratigraphic data indicate an Albian to Cenomanian age for the conformably overlying Longjing Formation. Alignment of the new comprehensive geochronological and biostratigraphic data with previously published chronological data suggests that a potential terrestrial A–C boundary occurs within the Longjing Formation of the Yanji Basin. This study provides an updated, precise chronostratigraphic framework for the evolution of the major terrestrial faunas and flora in the Yanji Basin, and represents a new contribution to the terrestrial Cretaceous timescale recorded in northeast China.