Climatic and biotic impact of the Middle Cenomanian Event: A cryptic Oceanic Anoxic Event?

• Applicant: Dr. Sebastian Beil
• Subject Area: Geology ; Mineralogy, Petrology and Geochemistry
• Term: from 2021 to 2024
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 458854663

The Cretaceous Greenhouse Period was punctuated by Oceanic Anoxic Events (OAEs), episodes of widespread burial of organic matter exhibiting prominent carbon isotope excursions (CIEs). However, the causes and consequences of these global climate carbon cycle perturbations, especially the role of volcanic CO2 release and of radiative forcing by the Earth’s 405 kyr and 2.4 Myr eccentricity cycles, remain highly controversial. Unraveling the timing, climatic response and environmental impact of lower amplitude Cretaceous CIEs, such as the Middle Cenomanian Event (MCE), is crucial for understanding the dynamic response of the global ocean-atmosphere system during periods of global warming and increasing ocean acidification. The continuous, extended sedimentary archive recovered in Core SN°4 from the center of the Tarfaya Basin (SW Morocco) offers a unique opportunity to reconstruct in unprecedented resolution the evolution of the global carbon cycle across the MCE. I propose to analyze this well-preserved succession of carbonate and organic carbon rich sediments using high-resolution organic carbon and carbonate stable isotopes, foraminiferal assemblage counts, XRF-scanner elemental measurements and phosphorus speciation analyses. I will focus my analysis on the onset and development of the MCE including the Primus Cold Event, a globally recognized episode of reduced sea surface temperatures, comparable to the Plenus Cold Event during OAE2. Both cold events were associated with re-oxygenation events at the seafloor indicated by increased abundance and diversity of benthic foraminifera and important changes in the evolution of planktic foraminifera. The rich foraminiferal assemblages in Core SN°4 will allow anchoring of the oxygenation and extinction/speciation events within a high-resolution chemostratigraphic framework and exploration of causal relationships. This project will advance our understanding of the dynamic feedback processes driving global carbon cycle perturbations and their impact on climate and marine plankton evolution during periods of global warmth. This study will also contribute to resolve the question whether Cretaceous OAEs were stochastic events or were modulated by external radiative forcing in a Greenhouse climate.

• DFG Programme: Research Grants