Decoding the North Atlantic Ocean Circulation Breakthrough in the Aptian–Albian Transition

Abstract. The Aptian–Albian interval was marked by significant climatic changes driven by intense volcanism, monsoonal activity, and shifts in ocean circulation, which influenced sedimentary expression of oceanic anoxic events (OAEs) and Cretaceous oceanic red beds (CORBs). The formation of CORBs was primarily influenced by oxygen flux, sea-level changes, and atmospheric dust, with thermohaline circulation playing a key role in deep-water oxygenation. This study combines magneto-cyclostratigraphic analyses from Ocean Drilling Program (ODP) Site 1049 to assess the temporal synchrony of CORB-related events between the Tethys and North Atlantic. The results provide new insights into CORB formation and paleoclimatic conditions during the Aptian–Albian interval. The onset of long-term Aptian CORBs is linked to global cooling and intensified thermohaline circulation, while Albian CORBs exhibit shorter, cyclic deposition influenced by orbital forcing. Orbital tuning of short geomagnetic reversals at ODP Site 1049 reveals that the M-2r reversal occurred at 110.76 Ma with a timespan of 150 kyr, and the reversed-polarity subchron "3" was between 111.45 and 111.53 Ma, which represent important tie points for geochronological models of Aptian–Albian interval.