CRETACEOUS OCEAN RED BEDS (CORBe) AND OXYGENATION: UNVEILING THE UPPER APTIAN AND UPPER ALBIAN PALEOCLIMATE AND PALEOCEANOGRAPHY

Cretaceous Oceanic Red Beds (CORBs) represent important archives of paleoceanographic and paleoclimatic conditions during Earth’s greenhouse intervals. In this study, we focus on Upper Aptian and Upper Albian CORBs from the Trento Plateau (Southern Alps, NE Italy), integrating geochemical (ICP-OES, ICP-MS), rare earth element (REE), and thermomagnetic analyses to elucidate local and global factors controlling their deposition. Aptian CORBs exhibit higher and more variable oxygenation, favoring hematite formation and enrichment in light rare earth elements (LREEs), whereas Albian CORBs reflect slightly lower O₂ levels and greater climatic stability. The absence of redox-sensitive elements such as Mo and Cr confirms that anoxia was not a limiting factor in either interval. Thermomagnetic data reveal incomplete magnetite oxidation in both Aptian and Albian samples, indicative of reduced oxygen availability during deposition. These depositional differences are linked to local tectonic subsidence of the Trento Plateau, which influenced sedimentation rates, as well as global climatic shifts following major Oceanic Anoxic Events (OAEs). Our multi-proxy approach highlights that, despite contrasting oxygenation histories, both intervals maintained sufficiently oxic bottom waters—whether through higher dissolved O₂ or lower sedimentation rates—to enable the formation of CORBs. Our findings advance the understanding of mid-Cretaceous paleoceanography, demonstrating that CORBs can form under varying yet consistently oxic conditions, shaped by the interplay of tectonics, sediment supply, and climate feedbacks.