Decoding the North Atlantic Ocean circulation breakthrough in the Aptian–Albian transition

Abstract. The Cretaceous experienced marked climatic variability driven by large igneous province volcanism, monsoonal dynamics and changes in ocean circulation, which strongly influenced the expression of oceanic anoxic events and Cretaceous Oceanic Red Beds (CORBs). Here we integrate cyclostratigraphic analysis of magnetic susceptibility records from Ocean Drilling Program Site 1049 (western North Atlantic) to evaluate the timing and synchronicity of CORB deposition between the Tethyan and North Atlantic realms. Our results show that long-lived Aptian CORBs coincided with global cooling and enhanced thermohaline circulation, whereas Albian CORBs were shorter lived and orbitally paced, reflecting greenhouse conditions dominated by circulation driven primarily by mesoscale eddies. Astrochronological tuning further constrains two short geomagnetic polarity reversals within the Cretaceous Normal Polarity Superchron, dating the M–2r reversal to 110.76 Ma (duration ∼ 150 kyr) and placing reversed-polarity subchron 3 between 111.45 and 111.53 Ma. These ages provide robust geochronological tie points for Aptian–Albian stratigraphic correlations.