A 1.4 Myr record of export production at the Pacific entrance of the Drake Passage considering syndepositional redistribution of sediments

Increased export production in the Subantarctic Zone of the Southern Ocean has been proposed as a key mechanism for explaining carbon drawdown during glacial times. Therefore, reconstructions of oceanic particle fluxes from the sedimentary record in this sector are vital. Traditionally, fluxes of various materials to the seafloor have been estimated from stratigraphy-based mass accumulation rates (MARs), which are calculated using a combination of sediment dry bulk density and linear sedimentation rates between dated sediment horizons. We refer to these MARs here as age model-derived bulk MAR (BMARs). However, BMARs and any resulting paleoceanographic interpretations may suffer from substantial errors if lateral redistribution of sediments is not considered. In fact, this is expected to be a common phenomenon in the Southern Ocean due to the strong bottom water circulation of the Antarctic Circumpolar Current. Here, using material from a marine sediment core recovered at the Pacific entrance of the Drake Passage, we evaluate export production and its drivers over the past 1.4 million years by applying several paleoproductivity indicators (biogenic barium, organic carbon, biogenic opal, calcium carbonate, and iron). Crucially, we determine MARs of these various sediment components that are corrected for the lateral movement of sediments that occurred simultaneously to or soon after initial deposition. The results show that the export production indicators varied according to some of the characteristic features of the main climatic events of Earth over the past 1.4 Ma. (The Mid-Pleistocene Transition and Mid-Brunhes Event). Additionally, the productivity response in the area was enhanced (weakened) during globally strong (faint) glacials or interglacials (e.g., MIS 16, MIS 11, MIS 5, and the Holocene for strong and MIS 15-12 for weak responses, respectively).