IODP Expedition 382 (Iceberg Alley) - goals and first results
Abstract
Expedition 382 aims to investigate the dynamics of the Antarctic Ice Sheet (AIS) during the Plio-Pleistocene to understand the variability in AIS mass loss, associated changes in oceanic and atmospheric circulation, and global sea level. Three sites (U1536 to 1538) recovered continuously deposited sediment from the center of Iceberg Alley, the main exit route for Antarctic icebergs to the north, after calving from the margin of the AIS. Eventually, icebergs melt down when approaching the warmer waters of the Antarctic Circumpolar Current (ACC) in the general area of our core sites. Our sediment record will therefore allow us to assess the magnitude of iceberg flux during key times of AIS evolution, including the mid Piacenzian warm period, the late Pliocene glacial expansion of the West AIS, the mid-Pleistocene transition, and the glacial terminations of the last 800 ka.
Using the geochemical provenance of iceberg-rafted detritus and other glacially-eroded material we will determine regional sources of AIS mass loss. By comparing north-south variations across the Scotia Sea between the Pirie Basin (Site U1538) and the Dove Basin (Sites U1536 and 1537), we will also deliver critical information on how climate change in the Southern Ocean affects ocean circulation through the Drake Passage, meridional overturning in the region, water-mass production, ocean-atmosphere CO2 transfer by wind-induced upwelling, sea ice variability, bottom water outflow from the Weddell Sea, Antarctic weathering inputs, and changes in oceanic and atmospheric fronts in the vicinity of the ACC. First results indicate that changes in dust proxy records between the Scotia Sea and Antarctic ice cores are closely tied and therefore that Exp. 382 records have the potential to provide a detailed reconstruction of changes in the Southern Hemisphere westerlies on millennial and orbital timescales for the last 800 ka. Extending the ocean dust record beyond that time will help to evaluate climate-dust couplings since the Pliocene, the potential role of dust in iron fertilization and atmospheric CO2 drawdown during glacials, and whether dust input to Antarctica played a role in the mid-Pleistocene transition.- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2019
- Bibcode:
- 2019AGUFMPP53C1449W
- Keywords:
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- 0726 Ice sheets;
- CRYOSPHERE;
- 0732 Icebergs;
- CRYOSPHERE;
- 4901 Abrupt/rapid climate change;
- PALEOCEANOGRAPHY;
- 4910 Astronomical forcing;
- PALEOCEANOGRAPHY