HOLOCENE
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Reconstructed sea spray and minerogenic data for a 12,000 year lake sediment record from Emerald Lake, Macquarie Island. Proxies are based on biological (diatoms) and geochemical (micro x-ray fluorescence and hyperspectral imaging) indicators. Data correspond to the figures in: Saunders et al. 2018 Holocene dynamics of the Southern Hemisphere westerly winds and possible links to CO2 outgassing. Nature Geoscience 11:650-655. doi.org/10.1038/s41561-018-0186-5. Detailed supplementary information: https://static-content.springer.com/esm/art%3A10.1038%2Fs41561-018-0186-5/MediaObjects/41561_2018_186_MOESM1_ESM.pdf Abstract: The Southern Hemisphere westerly winds (SHW) play an important role in regulating the capacity of the Southern Ocean carbon sink. They modulate upwelling of carbon-rich deep water and, with sea ice, determine the ocean surface area available for air–sea gas exchange. Some models indicate that the current strengthening and poleward shift of these winds will weaken the carbon sink. If correct, centennial- to millennial-scale reconstructions of the SHW intensity should be linked with past changes in atmospheric CO2, temperature and sea ice. Here we present a 12,300-year reconstruction of wind strength based on three independent proxies that track inputs of sea-salt aerosols and minerogenic particles accumulating in lake sediments on sub-Antarctic Macquarie Island. Between about 12.1 thousand years ago (ka) and 11.2 ka, and since about 7 ka, the wind intensities were above their long-term mean and corresponded with increasing atmospheric CO2. Conversely, from about 11.2 to 7.2 ka, the wind intensities were below their long-term mean and corresponded with decreasing atmospheric CO2. These observations are consistent with model inferences of enhanced SHW contributing to the long-term outgassing of CO2 from the Southern Ocean.
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Ellis Fjord is a small, fjord-like marine embayment in the vestfold Hills, eastern Antarctica. Modern sediment input is dominated by a biogenic diatom rain, although aeolian, fluvial, ice-rafted, slumped and tidal sediments also make a minor contribution. In areas where bioturbation is significant relict glaciogenic sediments are reworked into the fine-grained diatomaceous sediments to produce poorly sorted fine sands and silts. Where the bottom waters are anoxic, sediments remain unbioturbated and have a high biogenic silica component. Three depositional and non-depositional facies can be recognised in the fjord: an area of non-deposition around the shoreline; a relict morainal facies in areas of low sedimentation and high bioturbation; and a basinal facies in the deeper areas of the fjord.
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Cores from lakes and the shallow marine were taken for investigation of palaeoclimate through proxies such as grain size, TOC, C:N:S and diatoms. The cores have been 14-C dated with some sheel fragments having been analysed using Amino Acid geochronology. The full postglacial record, plus till and pre-glacial sediments, were recovered from two marine cores at 10.3 and 12 m depth in the sediment respectively. These cores are presently (2000) being analysed. Contact the Chief Investgator for queries about these samples or the project, ASAC1071 - 'Palaeoenvironments of the East Antarctic coast between 50E and 120E'. The fields in this dataset are: core number station-employ lake/marine basin latitude longitude water depth (m) date gear recovery (cm) liner (cm) potsdam storage