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Signatures and significance of aeolian, fluvial, bacterial and diagenetic magnetic mineral fractions in Late Quaternary marine sediments off Gambia, NW Africa 5
Just, Janna; Dekkers, Mark J.; Von Dobeneck, Tilo; Van Hoesel, Annelies; Bickert, Torsten.
Two gravity cores retrieved off NW Africa at the border of arid and subtropical environments (GeoB 13602-1 and GeoB 13601-4) were analyzed to extract records of Late Quaternary climate change and sediment export. We apply end-member (EM) unmixing to 350 acquisition curves of isothermal remanent magnetization (IRM). Our approach enables to discriminate rock magnetic signatures of aeolian and fluvial material, to determine biomineralization and reductive diagenesis. Based on the occurrence of pedogenically formed magnetic minerals in the fluvial and aeolian EMs, we can infer that goethite formed in favor to hematite in more humid climate zones. The diagenetic EM dominates in the lower parts of the cores and within a thin near-surface layer probably...
Tipo: Text Palavras-chave: IRM end-member modeling; NW Africa; Environmental magnetism; Magnetotactic bacteria; Paleoclimate; Terrigenous input.
Ano: 2012 URL: https://archimer.ifremer.fr/doc/00265/37617/36987.pdf
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Variations of the ACC-CDW during MIS3 traced by magnetic grain deposition in midlatitude South Indian Ocean cores: Connections with the northern hemisphere and with central Antarctica 5
Mazaud, A.; Kissel, C.; Laj, C.; Sicre, M. A.; Michel, E.; Turon, J. L..
We examine the magnetic mineral deposition in three cores located at midlatitude sites in the South Indian Ocean, in an area where sediment eroded from the Kerguelen-Crozet plateau and transported by the marine currents, principally the Antarctic Circum Current, accumulates at a high sedimentation rate. We focus on Marine Isotopic Stage 3, characterized by large climatic fluctuations at northern latitudes, and compare the obtained records to the climatic records at Byrd ( Antarctica) and Summit (GISP2, Greenland) and to the North Atlantic Deep Water variations in the North Atlantic. Magnetic mineral deposition at the studied sites exhibits a profile with maxima at the time of Heinrich events H4 and H5, which suggests a strong Antarctic Circum Current when...
Tipo: Text Palavras-chave: Paleoceanography; South; Indian; Ocean; Paleoclimatology and paleoceanography; Environmental magnetism; Interhemispheric phasing.
Ano: 2007 URL: https://archimer.ifremer.fr/doc/00235/34612/32954.pdf
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