A bio- and carbon isotope stratigraphy for dating late Cretaceous paleoceanographic changes of southern high latitudinal sedimentary successions (Expedition 392 Agulhas Plateau)

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The nearly complete sedimentary records obtained from the southern high-latitudes during Expedition 392 (early 2022) offer a unique opportunity to explore the evolution of Earth's climate during the Late Cretaceous period at timescales from millennial to millions of years. The period is well known for a marked transition from peak hothouse climate in the mid Cretaceous to late Cretaceous-early Paleogene cooling. This global climate transition holds great potential for enhancing our understanding of the interplay between climatic change and carbon sequestration processes on short to long times scales. A fundamental requirement to successfully address these overarching climate-carbon trends is the development of a robust stratigraphic framework. This project will take this task by combining existing shipboard biostratigraphy and magnetostratigraphy with new high resolution chemostratigraphic data from bulk carbon for three sites from Expedition 392 including Site U1579 (Central Agulhas Plateau), Site U1580 (Southern Central Agulhas Plateau), and Site U1581 (deep flat part of the Transkei Basin). These sites cover a nearly complete early Cenomanian to Maastrichtian sedimentary record from initial sedimentation to open and deep marine settings for the Central and Southern Central Agulhas Plateau and the permanently deep basin setting of the Transkei Basin. This approach will provide insights into how sedimentation on the Agulhas Plateau started immediately after crustal emplacement at ~100 Ma and how the evolving gateways between the South Atlantic, Southern Ocean, and southern Indian Ocean basins impacted on sedimentation and climate variables at different timescales. Complementary D13C (offset between d13Ccarb. and d13Corg.), organic (TOC) and inorganic (CaCO3) carbon, nitrogen, and sulfur records will be generated which provide a critical context to discuss the history of pCO2, carbon richness and bottom water redox as evidence of environmental change. The proposed project is low risk and low cost but likely to deliver a critical foundation to further excel the IODP 392 post-cruise research.