Global reconstruction of ocean export productivity from the late Eocene to the early Oligocene

The Earth's climate shifted swiftly from a "greenhouse" state to an "icehouse" state ~34 million years ago (Ma). This climatic transition is characterized by abrupt atmospheric pCO₂ drawdown, the initiation of Antarctic glaciation, and perturbations of marine carbon cycling. While previous studies have suggested heterogeneous changes across ocean basins in primary productivity, but a global unchanged state of fish production. The net effect of the marine biological pump on sequestrating atmospheric pCO₂ is still an enigma. Marine barite (BaSO₄) is a reliable proxy of export productivity owing to its biologically induced formation and refractory nature. Here, we present global records of marine barite accumulation rates from multiple sediment cores representing different oceanographic regions from the late Eocene to the early Oligocene. We reconstruct the temporal and spatial evolution of export productivity between 41 and 28 Ma, and investigate its contribution to the global carbon budget before and after the Eocene–Oligocene Transition. Additionally, we use the Earth System Model IPSL-CM5A2 and biogeochemical model PISCESv2, and compare proxy data with model results of the 40 Ma and 30 Ma simulations. Together, they can help to explore the role of tectonic-driven reorganization of ocean circulation in export productivity. These findings offer implications for understanding feedbacks between tectonic, climate, and carbon cycling at the onset of the early Cenozoic icehouse world.