The application of radiolaria to the late Quaternary palaeoceanography of the Scotia and Weddell Seas
The late Quaternary palaeoceanographic history of the South Atlantic sector of the Southern Ocean (Scotia Sea), has been investigated from a core transect of nine piston, kasten, and gravity cores and modern samples from five sediment traps between the northern Scotia Sea and the northern Weddell Se...
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| Format: | Doctoral or Postdoctoral Thesis |
| Language: | English |
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UCL (University College London)
2000
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| Online Access: | https://discovery.ucl.ac.uk/id/eprint/10104435/1/out.pdf https://discovery.ucl.ac.uk/id/eprint/10104435/ |
| Summary: | The late Quaternary palaeoceanographic history of the South Atlantic sector of the Southern Ocean (Scotia Sea), has been investigated from a core transect of nine piston, kasten, and gravity cores and modern samples from five sediment traps between the northern Scotia Sea and the northern Weddell Sea. Radiolarian distribution patterns have enabled the reconstruction of Last Glacial Maximum conditions, in conjunction with other microfossil groups (diatoms), sedimentological data (texture, composition, and magnetic susceptibility), geochemical data (Barium, Thorium). The sediments have been dated using Cycladophora davisiana stratigraphy of Hays (1965) and radiocarbon dates back to oxygen isotope stage 9. Four Holocene radiolarian associations have been identified from the Scotia and Weddell Seas, (Weddell Gyre, Weddell Sea, Southern Scotia Sea and Polar Front assemblages). The Weddell Gyre assemblage is poorly preserved, has low productivity and low diversity, the Weddell Sea assemblage is moderately preserved, and is dominated by cold water species. The southern Scotia Sea assemblage has the highest productivity, has good preservation and warmer water species present. The Polar Front assemblage contains the highest abundances of warmer water species and has good preservation. The maximum extent of sea ice at the Last Glacial Maximum can be reconstructed using the northward movement of the above assemblages. In the Polar Front assemblage grouping the species Cycladophora bicornis and Phorticium clevei record interglacial/glacial cycles. This study reports 180 species of radiolarians, and documents the first record of Antarctissa equiceps and Corythomelissa horrida in Quaternary sediments, Lorella tortuosa in Antarctic sediment trap material and confirms the presence of the species Cinclopyramis giganthea and Dumetum rectum in Antarctic sediments, which have previously only been recorded by Petrushevskaya (1967). |
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