11:30 AM - 11:45 AM
[SGL37-10] Refining the Geomagnetic Polarity Timescale: High-precision U-Pb geochronology from Late Cretaceous of US Western Interior and NE China
Keywords:U-Pb geochronology, Geomagnetic Polarity Timescale, Cretaceous, Western Interior Basin, Songliao Basin
The Late Cretaceous to Paleocene segment of the GPTS is of particular interest as it encompasses a critical period of Earth history marked by the Cretaceous greenhouse climate, the peak of dinosaur diversity, the end-Cretaceous mass extinction and its paleoecological aftermaths. Here we present a refined calibration of the GPTS based on high-precision U-Pb geochronology of ash beds within predominantly continental strata of the Western Interior Basin of North America and the Songliao Basin of Northeast China. Results from the Songliao Basin (end-C34), Bighorn Basin of Wyoming (end-C32) and Denver Basin of Colorado (C29 to C28) place tight constraints on the Late Cretaceous – Paleocene GPTS, by either directly constraining the chron boundaries and/or by testing their underpinning astrochronological age models. Our new GPTS calibration displays good consistency with those from the most recent astrochronology- and radioisotope-based studies of other coeval continental and marine records. Together, they demonstrate the power of a multi-chronometer approach to the calibration of the Earth history.