Late Pleistocene-Holocene coccolithophore variations in the Subantarctic South Pacific

Abstract

International Ocean Discovery program (IODP) Expedition 383 Dynamics of the Pacific Antarctic Circumpolar Current (DYNAPACC) (Lamy et al., 2019; 2021) drilled a series of cores from the Pacific sector of the Southern Ocean in order to explore atmosphere-ocean-cryosphere glacial-interglacial dynamics their implications for regional and global climate changes. IODP Expedition 383 sites constitute the first continuous drill cores at key locations of the Subantarctic Pacific Southern Ocean extending through the Pleistocene and back into the Pliocene.Here we focus on coccolith relative and absolute abundance as well as productivity variations for the last 0.5 Million year, in order to understand the nannofloral response to glacial-interglacial cycles and related changes in carbonate production and export. Our data has been generated at IODP Sites U1539 (56°09.0655′S, 115°08.038′W, ~1600 nmi west of the Strait of Magellan at 4070 m water depth) and U1540 (55°08.467′S, 114°50.515′W, ~1600 nmi west of the Strait of Magellan at 3580 m water depth), drilled at a southern and northern location in the central Pacific within the ACC, respectively. Coccolithophore diversity and coccolith numbers change dramatically in the studied cores, ranging from high values during interglacials (up to ca. 1011 coccoliths per gram of sediment, as in MIS11, Saavedra-Pellitero et al., 2017) to low values during the glacials, where they are outcompeted by siliceous microfossils, mostly diatoms.ReferencesLamy, F., Winckler, G., Alvarez Zarikian, C.A., and the Expedition 383 Scientists, 2019. Expedition 383 Preliminary Report: Dynamics of the Pacific Antarctic Circumpolar Current. International Ocean Discovery Program. https://doi.org/10.14379/iodp.pr.383.2019Lamy, F., Winckler, G., Alvarez Zarikian, C.A., and the Expedition 383 Scientists, 2021. Dynamics of the Pacific Antarctic Circumpolar Current. Proceedings of the International Ocean Discovery Program, 383: College Station, TX (International Ocean Discovery Program). https://doi.org/10.14379/iodp.proc.383.2021Saavedra-Pellitero M., Baumann K.-H., Lamy F., and Köhler P., 2017. Coccolithophore variability across Marine Isotope Stage 11 in the Pacific sector of the Southern Ocean and its potential impact on the carbon cycle. Paleoceanography, 32, 864–880, doi:10.1002/2017PA003156.