d163db90-7a7e-4a58-92b4-1c8c0432274b urn:uuid Antarctica New Zealand adminteam@antarcticanz.govt.nz 2025-09-04T02:25:36.543Z 2025-09-04T03:04:47.792Z 2023-08-13T22:52:18 ISO 19115-1 2018 https://doi.org/10.1594/PANGAEA.945936 Radiolarian Based Subsurface Temperatures in Sediment Core MD11-3353 (360kyrs Record) 2022-07-05 2022-07-05 https://doi.org/10.1594/PANGAEA.945936 In the Southern Ocean (SO), climate-driven latitudinal migrations of the Antarctic Circumpolar Current (ACC) frontal system impact large-scale ocean circulation and primary productivity. Latitudinal migrations may not have been identical in all SO basins due to the presence or absence of regional bathymetric obstacles. The Antarctic Polar Front (APF), defined by the 3–5 ◦C surface temperature range and the 2 ◦C subsurface temperature minimum at 200 m, is particularly important for nutrient redistribution and biodiversity, influencing the soft tissue carbon pump in the modern SO. However, previous assessments of its migrations in the past, mostly based on a single metric or indirect observations, were not always robust. Here, we combine a new proxy for subsurface temperature (sub-ST) reconstructions based on radiolarian assemblages (sub-STrad), with relative abundance variations of key radiolarian species, and sea-surface temperatures (SST) reconstructions, based on diatom assemblages (SSTdiat), to refine estimations of the past mean APF locations in the Kerguelen Plateau (KP) region. Data from three sediment cores on a south (55◦S) to north (47◦S) transect are used to trace the mean APF locations for three climate states, glacials, peak-interglacials and mild-interglacials. Our results suggest that the APF, presently located south of Kerguelen Islands, shifted by 6–7 degrees of latitude and was located north of the KP during all glacial periods of the last 360 kyrs. This suggests that the ACC major flow interacted less with the bottom topography relative to its modern counterpart, probably resulting in less mixing of the water column over and in the lee of the KP. We propose that this process participated in the isolation of Antarctic surface waters (AASW) and in the reduction of macro-nutrient supply, thus resulting in lower regional productivity. During the warmer-than-present early interglacial periods, the APF probably migrated south by ~5 degrees of latitude relative to its modern position, to pass through the Fawn Trough. Contrary to glacial periods, the APF was forced in an “S” shape while the ACC main flow was constrained against the northern tip of the KP. In this configuration, a stronger interaction between the ACC, its associated fronts, and topography is expected, resulting in more mixing of the water column over and east of the KP. Congruently, siliceous productivity was probably restrained to latitudes south of the Fawn Trough. Civel-Mazens, Matthieu. ORCid Crosta, Xavier; Cortese. ORCid Cortese, Giuseppe. ORCid Michel, Elisabeth. ORCid Mazaud, Alain. ORCid Ther, Olivier. ORCid Ikehara, Minoru. ORCid Itaki, Takuya. ORCid PANGAEA info@pangaea.de geoscientificInformation oceans 68.349 68.42 -50.589 -50.544 2011-01-30 2011-01-30 First commit https://antcat.antarcticanz.govt.nz/geonetwork/cat/api/records/d163db90-7a7e-4a58-92b4-1c8c0432274b/attachments/d163db90-7a7e-4a58-92b4-1c8c0432274b.png PALEOCLIMATE RECONSTRUCTIONS RADIOLARIANS GCMD Earth Science and Earth Science Services Keywords 2025-07-10 2025-07-10 geonetwork.thesaurus.external.theme.ardc-curated_gcmd-sciencekeywords_20-2-2024-12-17 GCMD Earth Science and Earth Science Services Keywords https://gcmd.earthdata.nasa.gov/kms/concepts/concept_scheme/sciencekeywords sciencekeywords https://gcmd.earthdata.nasa.gov/kms/concepts/concept_scheme/sciencekeywords Ships GCMD Platform/Sources Keywords 2025-07-10 2025-07-10 geonetwork.thesaurus.external.platform.ardc-curated_gcmd-platforms_20-2-2024-12-17 GCMD Platform/Sources Keywords https://gcmd.earthdata.nasa.gov/kms/concepts/concept_scheme/platforms platforms https://gcmd.earthdata.nasa.gov/kms/concepts/concept_scheme/platforms Corers GCMD Instrument/Sensors Keywords 2025-07-10 2025-07-10 geonetwork.thesaurus.external.instrument.ardc-curated_gcmd-instruments_20-2-2024-12-19 GCMD Instrument/Sensors Keywords https://gcmd.earthdata.nasa.gov/kms/concepts/concept_scheme/instruments instruments https://gcmd.earthdata.nasa.gov/kms/concepts/concept_scheme/instruments SOUTHERN OCEAN GCMD Locations Keywords 2025-07-10 2025-07-10 geonetwork.thesaurus.external.place.ardc-curated_gcmd-locations_20-2-2024-12-13(1) GCMD Locations Keywords https://gcmd.earthdata.nasa.gov/kms/concepts/concept_scheme/locations locations https://gcmd.earthdata.nasa.gov/kms/concepts/concept_scheme/locations This data set conforms to the CC BY Attribution License (https://creativecommons.org/licenses/by/4.0/) Attribution 4.0 International (CC BY 4.0) https://creativecommons.org/licenses/by/4.0/ https Attribution 4.0 International (CC BY 4.0) Human Readable summary of the CC BY copyright license. 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