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  • Online-Ressource  (2)
  • SAGE Publications  (2)
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  • Online-Ressource  (2)
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  • SAGE Publications  (2)
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  • 1
    In: The Holocene, SAGE Publications, Vol. 29, No. 3 ( 2019-03), p. 467-480
    Kurzfassung: A mid- to late-Holocene paleohydrological reconstruction from the northeast Atlantic is proposed through the study of a high-resolution sedimentary record from the northern continental shelf of the Bay of Biscay (BoB). Three foraminiferal species dominate the assemblages with Rosalina globularis showing an overall decrease in absolute and relative abundances from ~7 to 0.4 cal. ka BP, whereas the opposite trend is observed for Cibicides refulgens and Lobatula. These long-term patterns are interpreted as a response to the overall cooling trend and/or the progressive deepening of the water column because of the relative sea-level (RSL) rise. Foraminiferal δ 18 O and grain-size analyses show a significant shift around 3.5–2.5 cal. ka BP toward a heavier isotopic signature and finer sediments. We mainly link this change to enhanced contribution of continental freshwaters and fine sediments after the near-stabilization of the RSL rise. By reducing coastal accommodation spaces, this led to a better channelization of river outflows and probably to the formation of the modern winter thermohaline front. Superimposed on these long-term patterns, our data highlight strong millennial-scale variability (1250-year peak). Such cyclicity is consistent with several records tracing changes in rainfall and storminess regimes in northern Europe, and the dynamics of the subpolar gyre (SPG). We suggest a millennial time-scale control of a NAO-like (North Atlantic Oscillation) climatic process modulating continental humidity (and the associated river discharges) and SPG dynamics through wind stress. Spectral analyses reveal an additional 500-year frequency peak implying a possible solar forcing.
    Materialart: Online-Ressource
    ISSN: 0959-6836 , 1477-0911
    RVK:
    Sprache: Englisch
    Verlag: SAGE Publications
    Publikationsdatum: 2019
    ZDB Id: 2027956-5
    SSG: 14
    SSG: 3,4
    Standort Signatur Einschränkungen Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 2
    In: The Holocene, SAGE Publications, Vol. 25, No. 2 ( 2015-02), p. 348-365
    Kurzfassung: The core MD03-2693 (43°39.258′N; 01°39.805′W; 431 m water depth) was collected on an abandoned meander of the Capbreton Canyon (SE Bay of Biscay), filled over the last millennia by very high sedimentation rates (mean sedimentation rate of 1.2 cm/yr) linked to its specific environmental location and fine-grained clayed sediment decantation from the proximal canyon axis. This archive thus permits to undertake the study of late Holocene regional climatic patterns at a decadal temporal resolution. In the present work, we use data derived from planktonic foraminifera assemblages coupled to a multiproxy approach that associates grain-size measurements, x-ray fluorescence (XRF) elemental analysis and stable oxygen isotope on Globigerina bulloides shells to infer Sea Surface Temperature (SST) and Sea Surface Salinity (SSS) changes over the last two millennia. Signals reconstructed in the Bay of Biscay show significant oscillations that are consistent with well-known temperature anomalies such as the ‘Little Ice Age’ (LIA) and the ‘Medieval Warm Period’ (MWP). It additionally displays strong similarities with other areas in the western temperate and northern North Atlantic Ocean, suggesting a narrow coupling between its main gyre surface systems. Abrupt decrease of SSS together with significant change in terrigenous inputs suggests a change in precipitation regime at the onset of the LIA (around ad 1400). Moreover, superimposed to the relative long-term change in environmental parameter, the core MD03-2693 records rapid and discrete pulses of sand grain–sized material that are correlated with the local history of migration of the mouth of the Adour River.
    Materialart: Online-Ressource
    ISSN: 0959-6836 , 1477-0911
    RVK:
    Sprache: Englisch
    Verlag: SAGE Publications
    Publikationsdatum: 2015
    ZDB Id: 2027956-5
    SSG: 14
    SSG: 3,4
    Standort Signatur Einschränkungen Verfügbarkeit
    BibTip Andere fanden auch interessant ...
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