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Asian monsoon modulation of nonsteady state diagenesis in hemipelagic marine sediments offshore of Japan ArchiMer
Chang, Liao; Bolton, Clara T.; Dekkers, Mark J.; Hayashida, Akira; Heslop, David; Krijgsman, Wout; Kodama, Kazuto; Paterson, Greig A.; Roberts, Andrew P.; Rohling, Eelco J.; Yamamoto, Yuhji; Zhao, Xiang.
We have identified millennial-scale variations in magnetic mineral diagenesis from Pacific Ocean sediments offshore of Japan that we correlate with changes in organic carbon burial that were likely driven by Asian monsoon fluctuations. The correlation was determined by identifying offsets between the positions of fossil diagenetic fronts and climatically induced variations in organic carbon burial inferred from magnetic and geochemical analyses. Episodes of intense monsoon activity and attendant sediment magnetic mineral diagenesis also appear to correlate with Heinrich events, which supports the existence of climatic telecommunications between Asia and the North Atlantic region. Several lines of evidence support our conclusions: (1) fluctuations in...
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Ano: 2016 URL: https://archimer.ifremer.fr/doc/00356/46703/47266.pdf
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Direct terrestrial-marine correlation demonstrates surprisingly late onset of the last interglacial in central Europe ArchiMer
Sier, Mark J.; Roebroeks, Wil; Bakels, Corrie C.; Dekkers, Mark J.; Bruehl, Enrico; De Loecker, Dimitri; Gaudzinski-windheuser, Sabine; Hesse, Norbert; Jagich, Adam; Kindler, Lutz; Kuijper, Wim J.; Laurat, Thomas; Muecher, Herman J.; Penkman, Kirsty E. H.; Richter, Daniel; Van Hinsbergen, Douwe J. J..
An interdisciplinary study of a small sedimentary basin at Neumark Nord 2 (NN2), Germany, has yielded a high-resolution record of the palaeomagnetic Blake Event, which we are able to place at the early part of the last interglacial pollen sequence documented from the same section. We use this data to calculate the duration of this stratigraphically important event at 3400 +/- 350 yr. More importantly, the Neumark Nord 2 data enables precise terrestrial marine correlation for the Eemian stage in central Europe. This shows a remarkably large time lag of ca. 5000 yr between the MIS 5e 'peak' in the marine record and the start of the last interglacial in this region.
Tipo: Text Palavras-chave: Blake Event; Eemian; Last interglacial; MIS 5e; Palaeomagnetism.
Ano: 2011 URL: https://archimer.ifremer.fr/doc/00228/33891/32225.pdf
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Magnetic detection and characterization of biogenic magnetic minerals: A comparison of ferromagnetic resonance and first-order reversal curve diagrams ArchiMer
Chang, Liao; Roberts, Andrew P.; Winklhofer, Michael; Heslop, David; Dekkers, Mark J.; Krijgsman, Wout; Gerald, John D. Fitz; Smith, Paul.
Biogenic magnetic minerals produced by magnetotactic bacteria occur ubiquitously in natural aquatic environments. Their identification and characterization are important for interpretation of paleomagnetic and environmental magnetic records. We compare two magnetic methods for their identification and characterization in a diverse set of sedimentary environments: ferromagnetic resonance (FMR) spectroscopy and first-order reversal curve (FORC) diagrams, constrained by transmission electron microscope observations. The advantages and limitations of each method are evaluated. FMR analysis provides a strong diagnostic indicator because of its ability to detect the strong shape anisotropy that arises from the biogenic chain architecture, but it can be obscured...
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Ano: 2014 URL: https://archimer.ifremer.fr/doc/00290/40109/39375.pdf
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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 ArchiMer
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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