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Seasonally-laminated diatom-rich sediments from Dumont d’Urville Trough, East Antarctic Margin: Late Holocene Neoglacial sea-ice conditions

Maddison, Eleanor J., Pike, Jennifer and Dunbar, Robert 2012. Seasonally-laminated diatom-rich sediments from Dumont d’Urville Trough, East Antarctic Margin: Late Holocene Neoglacial sea-ice conditions. The Holocene 22 (8) , pp. 857-875. 10.1177/0959683611434223

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Abstract

Laminated sediments are unique archives of palaeoenvironmental and palaeoceanographic conditions, recording changes on seasonal and interannual timescales. Diatom-rich laminated marine sediments are examined from Dumont d’Urville Trough, East Antarctic Margin, to determine changes in environmental conditions on the continental shelf from 1136 to 3122 cal. yr BP. Scanning electron microscope backscattered electron imagery (BSEI) and secondary electron imagery are used to analyse diatom assemblages from laminations and to determine interlamina relationships. Diatom observations are quantified with conventional assemblage counts. Laminae are primarily classified according to visually dominant species identified in BSEI and, secondarily, by terrigenous content. Nine lamina types are identified and are characterized by: Hyalochaete Chaetoceros spp. resting spores (CRS); CRS and Fragilariopsis spp.; Fragilariopsis spp.; Corethron pennatum and Rhizosolenia spp.; C. pennatum; Rhizosolenia spp.; mixed diatom assemblage; Stellarima microtrias resting spores (RS), Porosira glacialis RS and Coscinodiscus bouvet; and P. glacialis RS. Formation of each lamina type is controlled by seasonal changes in sea ice cover, nutrient levels and water column stability. Quantitative diatom assemblage analysis revealed that each lamina type is dominated by CRS and Fragilariopsis sea ice taxa, indicating that sea ice cover was extensive and persistent in the late Holocene. However the lamina types indicate that the sea ice regime was not consistent throughout this period, notably that a relatively warmer period, ~3100 to 2500 cal. yr BP, was followed by cooling which resulted in an increase in year round sea ice by ~1100 cal. yr BP.

Item Type: Article
Date Type: Publication
Status: Published
Schools: Earth and Ocean Sciences
Subjects: G Geography. Anthropology. Recreation > GC Oceanography
Q Science > QE Geology
Uncontrolled Keywords: diatoms; Dumont d’Urville Trough; East Antarctica; laminated sediments; late Holocene; sea ice
Publisher: SAGE Publications
ISSN: 0959-6836
Funders: NERC
Last Modified: 04 Jun 2017 04:07
URI: http://orca.cf.ac.uk/id/eprint/33135

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