Variations in export production, lithogenic sediment transport and iron fertilization in the Pacific sector of the Drake Passage over the past 400 kyr

Abstract. Changes in Southern Ocean export production have broad biogeochemical and climatic implications. Specifically, iron fertilization likely increased subantarctic nutrient utilization enhanced the efficiency of biological pump during glacials. However, past southeastern Pacific is poorly documented, its connection to Fe fertilization, potentially related Patagonian Ice Sheet dynamics, unknown. We report productivity changes over 400 kyr, based on a combination 230Thxs-normalized stratigraphy-based mass accumulation rates biogenic barium, organic carbon, opal calcium carbonate as indicators paleo-export sediment core upstream Drake Passage (57.5? S, 70.3? W). In addition, we use fluxes lithogenic material proxies for terrigenous input, thus potential micronutrient supply. Stratigraphy-based are strongly influenced by bottom-current which result variable focussing or winnowing at our site. Carbonate virtually absent core, except peak interglacial intervals Holocene, Marine Isotope Stages (MIS) 5 11, caused transient decreases dissolution. All other suggest that most glacial periods, coinciding with high fluxes. Such augmented site were derived from glaciogenic input promoting growth phytoplankton. Additionally, peaks also consistent northward shifts Subantarctic Polar Fronts, positioned south Front closer silicic acid-rich waters Frontal Zone. near was lower than Atlantic Indian sectors Ocean, may relate complete consumption acid study area. Our results underline importance micro-nutrient through lateral South America rather eolian transport exemplify role frontal limitation entrance Passage.