Iceberg Alley and South Falkland Slope Ice and Ocean Dynamics1
Published May 2018
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International Ocean Discovery Program Expedition 382, Iceberg Alley and South Falkland Slope Ice and Ocean Dynamics, will investigate the long-term climate history of Antarctica, seeking to understand how polar ice sheets responded to changes in atmospheric CO2 in the past and how ice sheet evolution influenced global sea level. We will drill six sites in the Scotia Sea, east of the Antarctic Peninsula, providing the first deep drilling in this region of the Southern Ocean. We expect to recover >600 m of late Neogene sediment that will be used to reconstruct the past history and variability in Antarctic Ice Sheet (AIS) mass loss and associated changes in oceanic and atmospheric circulation.
Expedition 382 expects to deliver the first spatially and temporally integrated record of iceberg flux from “Iceberg Alley,” the main pathway by which icebergs are calved from the margin of the AIS and travel equatorward into warmer waters of the Antarctic Circumpolar Current (ACC). In particular, we will characterize the magnitude of iceberg flux during key times of AIS evolution:
- The middle Miocene glacial intensification of the East Antarctic Ice Sheet,
- The mid-Pliocene warm interval,
- The late Pliocene glacial expansion of the West Antarctic Ice Sheet,
- The mid-Pleistocene transition, and
- The “warm interglacials” and glacial terminations of the last 800 ky.
We will use the geochemical provenance of iceberg-rafted detritus and other glacially eroded material to determine regional sources of AIS mass loss in this region, address interhemispheric phasing of ice sheet growth and decay, study the distribution and history of land-based versus marine-based ice sheets around the continent over time, and explore the links between AIS variability and global sea level.
By comparing north–south variations across the Scotia Sea, Expedition 382 will also deliver critical information on how climate changes in the Southern Ocean affect ocean circulation through the Drake Passage, meridional overturning in the region, water-mass production, 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.
Comparing changes in dust proxy records between the Scotia Sea and Antarctic ice cores will also provide a detailed reconstruction of changes in the Southern Hemisphere westerlies on millennial and orbital timescales for the last 800 ky. Extending the ocean dust record beyond the last 800 ky 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.
The principal scientific objective of the South Falkland Slope sites to the north is to reconstruct and understand how ocean circulation and intermediate water formation responds to changes in climate with a special focus on the connectivity between the Atlantic and Pacific basins. The South Falkland Slope Drift, a contourite drift on the Falkland margin deposited between 400 and 2000 m water depth, is ideally situated to monitor millennial- to orbital-scale variability in the export of Antarctic Intermediate Water beneath the Subantarctic Front over at least the last 2 My. We anticipate that these sites will yield a wide array of paleoceanographic records that can be used to interpret past changes in the density structure of the Atlantic sector of the Southern Ocean and track the migration of the Subantarctic Front. We expect the cored sediments to capture the following significant climate episodes:
- The most recent warm interglacials of the late Pleistocene;
- The mid-Pleistocene transition, when δ18O records shifted from dominantly 41 to 100 ky periodicity; and possibly
- Mid-Pliocene warm intervals, often invoked as the best analog for possible future climate change.
1Weber, M.E., Raymo, M.E., Peck, V.L., and Williams, T., 2018. Expedition 382 Scientific Prospectus: Iceberg Alley and South Falkland Slope Ice and Ocean Dynamics. International Ocean Discovery Program. https://doi.org/10.14379/iodp.sp.382.2018
This work is distributed under the Creative Commons Attribution 4.0 International (CC BY 4.0) license.