Chronology of the terrestrial Upper Cretaceous in the Songliao Basin, northeast Asia

The Cretaceous was a period of great environmental, biological and geodynamical change, but a paucity of an accurate time frame for continental strata has prevented our understanding of the terrestrial processes and the integration of marine and terrestrial records. Here we present an integrated chronology for the terrestrial Upper Cretaceous in East Asia based on new high-resolution magnetostratigraphic results and previously published SIMS U–Pb zircon analyses of the Cretaceous Continental Scientific Drilling borehole sequence from the Songliao Basin in northeast China (hereafter termed CCSD-SK-I), which consists of a sedimentary sequence from the upper Quantou Formation (K2q) to the Mingshui Formation (K2m). Correlation to the geomagnetic polarity timescale was achieved by combining magnetostratigraphic and SIMS U–Pb zircon geochronologic data, and lithostratigraphy. Our correlation suggests that the CCSD-SK-I sedimentary sequence spans from the upper chron C34n to chron C29r. The age of the sedimentary sequence from the upper Quantou Formation (K2q) to the Mingshui Formation (K2m) in the Songliao Basin can thus be constrained to an interval from the Turonian to the Maastrichtian ages. In addition, our correlation puts the Cretaceous–Paleogene boundary in the upper part of Member 2 of the Mingshui Formation (K2m2). The constructed comprehensive chronology allows the precise correlation of the terrestrial Upper Cretaceous of the Songliao Basin to marine strata as well as other continental sequences.