U-Pb zircon geochronology of the Aptian/Albian boundary implies that the GL-O international glauconite standard is anomalously young

A new U-Pb zircon age for the Aptian/Albian boundary (113.1 ± 0.3 Ma) indicates that an alternate Early Cretaceous timescale that is largely devised using the K-Ar date for GL-O glauconite international standard and other K-Ar glauconite geochronology, is inaccurate. Both 40Ar/39Ar sandine and U-Pb zircon ages indicate that the K-Ar date for the GL-O international standard does not record the timing of sediment deposition and thus should not be used for timescale calibration. This issue is not solely constrained to the Early Cretaceous, because other geological time intervals also reveal younger K-Ar glauconite ages in comparison to other radioisotopic dating techniques (e.g., U-Pb, Ar-Ar, Re-Os).