Age of the Barremian–Aptian boundary and onset of the Cretaceous Normal Superchron

摘要: Abstract The age assigned to the boundary of Barremian and Aptian stages remains one most poorly constrained post-Pangean stratigraphic boundaries. lack a Global Boundary Stratotype Section Point (GSSP) for stage has hampered efforts calibrate absolute Cretaceous period in geological time scale. current definition Barremian–Aptian also approximates onset magnetic polarity chron M0r; end this denotes start Normal Superchron that is fundamental importance plate reconstructions. Currently, there up 5% discrepancy estimates (ca. 126–121 Ma) Superchron. Here, we review available geochronological information from late early collected Pacific Ocean, China, California, Ontong Java Nui large igneous province High Arctic province. By utilizing only robust data including U-Pb recalibrated 40Ar/39Ar ages sites with and/or paleontological constraints, calculate best estimate between 123.8 121.8 Ma M0r at 2σ confidence. Using duration (0.49 ± 0.10 Myr, 2σ), conservatively compute 123.4 121.2 Ma (2σ). an 83.07 ± 0.15 Ma (2σ) Superchron, superchron 38.0 40.5 Myr These ranges boundary, currently provide until GSSP formally ratified.