Orbitally paced global oceanic deoxygenation decoupled from volcanic CO2 emission during the middle Cretaceous Oceanic Anoxic Event 1b (Aptian-Albian transition)

Abstract The ongoing oceanic oxygen loss will have a profound impact on the distribution and density of life Earth. However, drivers initiation termination global deoxygenation are poorly understood. Here we present thallium isotope record that reveals three rapid (50 k.y.) intervals during mid-Cretaceous postdate massive volcanism by at least 1 m.y. New strontium data reveal gradually enhanced continental weathering under warmer climate following volcanism. occurred only combined influences long-term increase in rates short-term orbital modulation led to atmospheric-circulation reorganization. Interactions multiple consistent with abrupt each interval. Dynamic oxygenation responses highlight role these processes for understanding consequences potential current deoxygenation.