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Late Oligocene XRF scanner data from IODP Site 318-U1356 Willkes Land Margin, Antarctica

Authors: Salabarnada, Ariadna; Escutia, Carlota; Röhl, Ursula; Nelson, C Hans; McKay, Robert M; Jiménez-Espejo, Francisco Jose; Bijl, Peter K; +9 Authors

Late Oligocene XRF scanner data from IODP Site 318-U1356 Willkes Land Margin, Antarctica

Abstract

Antarctic ice sheet and Southern Ocean paleoceanographic configurations during the late Oligocene are not well resolved. They are however important to understand the influence of high-latitude Southern Hemisphere feedbacks on global climate under CO2 scenarios (between 400 and 750 ppm) projected by the IPCC for this century, assuming unabated CO2 emissions. Sediments recovered by the Integrated Ocean Drilling Program (IODP) at Site U1356, offshore of the Wilkes Land margin in East Antarctica, provide an opportunity to study ice sheet and paleoceanographic configurations during the late Oligocene (26-25 Ma). Our study, based on a combination of sediment facies analysis, magnetic susceptibility, density, and X-Ray Fluorescence geochemical data, shows that glacial and interglacial sediments are continuously reworked by bottom-currents, with maximum velocities occurring during the interglacial periods. Glacial sediments record poorly ventilated, low-oxygenation bottom water conditions, interpreted to result from a northward shift of westerly winds and surface oceanic fronts. Interglacial sediments record more oxygenated and ventilated bottom water conditions and strong current velocities, which suggests enhanced mixing of the water masses as a result of a southward shift of the Polar Front. Intervals with preserved carbonated nannofossils within some of the interglacial facies are interpreted to form under warmer paleoclimatic conditions when less corrosive warmer northern component water (e.g. North Atlantic sourced deep water) had a greater influence on the Site. Spectral analysis on the late Oligocene sediment interval show that the glacial-interglacial cyclicity and related displacements of the Southern Ocean frontal systems between 26-25 Ma were forced mainly by obliquity. The paucity of iceberg rafted debris (IRD) throughout the studied interval contrasts with earlier Oligocene and post-Miocene Climate Optimum sections from Site U1356 and with late Oligocene strata from the Ross Sea, which contain IRD and evidence for coastal glaciers and sea ice. These observations, supported by elevated sea surface paleotemperatures, the absence of sea-ice, and reconstructions of fossil pollen between 26 and 25 Ma at Site U1356, suggest that open ocean water conditions prevailed. Combined, these evidences suggest that glaciers or ice caps likely occupied the topographic highs and lowlands of the now marine Wilkes Subglacial Basin (WSB). Unlike today, the continental shelf was not over-deepened and thus ice sheets in the WSB were likely land-based and marine-based ice sheet expansion was likely limited to coastal regions.

Supplement to: Salabarnada, Ariadna; Escutia, Carlota; Röhl, Ursula; Nelson, C Hans; McKay, Robert M; Jiménez-Espejo, Francisco Jose; Bijl, Peter K; Hartman, Julian D; Strother, Stephanie L; Salzmann, Ulrich; Evangelinos, Dimitris; López-Quirós, Adrián; Flores, José Abel; Sangiorgi, Francesca; Ikehara, Minoru; Brinkhuis, Henk (2018): Paleoceanography and ice sheet variability offshore Wilkes Land, Antarctica – Part 1: Insights from late Oligocene astronomically paced contourite sedimentation. Climate of the Past, 14(7), 991-1014

Keywords

Silicon (peak area), Integrated Ocean Drilling Program / International Ocean Discovery Program (IODP), Zirconium peak area, Strontium peak area, Estimated, DEPTH, sediment/rock, Zirconium (peak area), Aluminium (peak area), Zirconium/Titanium ratio, Zirconium/Barium ratio, Calcium peak area, Barium peak area, Silicon peak area, Barium Titanium ratio, X-ray fluorescence core scanner (XRF), Sample code/label, Aluminium peak area, Manganese (peak area), Exp318, Strontium (peak area), Zirconium Rubidium ratio, Joides Resolution, Sample code label, Drilling/drill rig, Bromine Titanium ratio, Drilling drill rig, Zirconium Titanium ratio, Barium (peak area), Zirconium Barium ratio, sediment rock, Bromine/Titanium ratio, Integrated Ocean Drilling Program International Ocean Discovery Program IODP, Manganese peak area, Barium/Titanium ratio, DEPTH, Earth System Research, Calcium (peak area), X ray fluorescence core scanner XRF, Calcium carbonate, Zirconium/Rubidium ratio

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    popularity
    This indicator reflects the "current" impact/attention (the "hype") of an article in the research community at large, based on the underlying citation network.
    Average
    influence
    This indicator reflects the overall/total impact of an article in the research community at large, based on the underlying citation network (diachronically).
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    This indicator reflects the initial momentum of an article directly after its publication, based on the underlying citation network.
    Average
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citations
This is an alternative to the "Influence" indicator, which also reflects the overall/total impact of an article in the research community at large, based on the underlying citation network (diachronically).
BIP!Citations provided by BIP!
popularity
This indicator reflects the "current" impact/attention (the "hype") of an article in the research community at large, based on the underlying citation network.
BIP!Popularity provided by BIP!
influence
This indicator reflects the overall/total impact of an article in the research community at large, based on the underlying citation network (diachronically).
BIP!Influence provided by BIP!
impulse
This indicator reflects the initial momentum of an article directly after its publication, based on the underlying citation network.
BIP!Impulse provided by BIP!
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