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| Titel |
Stratification of surface waters during the last glacial millennial climatic events: a key factor in subsurface and deep-water mass dynamics |
| VerfasserIn |
M. Wary, F. Eynaud, M. Sabine, S. Zaragosi, L. Rossignol, B. Malaizé, E. Palis, J. Zumaque, C. Caulle, A. Penaud, E. Michel, K. Charlier |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1814-9324
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| Digitales Dokument |
URL |
| Erschienen |
In: Climate of the Past ; 11, no. 11 ; Nr. 11, no. 11 (2015-11-12), S.1507-1525 |
| Datensatznummer |
250117457
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| Publikation (Nr.) |
 copernicus.org/cp-11-1507-2015.pdf |
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| Zusammenfassung |
| The last glacial period
was punctuated by abrupt climatic events with extrema known as Heinrich
and Dansgaard–Oeschger events. These millennial events have been the
subject of many paleoreconstructions and model experiments in the past
decades, but yet the hydrological processes involved remain elusive. In the
present work, high-resolution analyses were conducted on the 12–42 ka BP
section of core MD99-2281 retrieved southwest of the Faeroe Islands, and combined with
analyses conducted in two previous studies (Zumaque et al., 2012; Caulle et
al., 2013). Such a multiproxy approach, coupling micropaleontological,
geochemical and sedimentological analyses, allows us to track surface,
subsurface, and deep hydrological processes occurring during these rapid
climatic changes. Records indicate that the coldest episodes of the studied
period (Greenland stadials and Heinrich stadials) were characterized by a
strong stratification of surface waters. This surface stratification seems to
have played a key role in the dynamics of subsurface and deep-water masses.
Indeed, periods of high surface stratification are marked by a coupling of
subsurface and deep circulations which sharply weaken at the beginning of
stadials, while surface conditions progressively deteriorate throughout these
cold episodes; conversely, periods of decreasing surface stratification
(Greenland interstadials) are characterized by a coupling of surface and deep
hydrological processes, with progressively milder surface conditions and
gradual intensification of the deep circulation, while the vigor of the
subsurface northward Atlantic flow remains constantly high. Our results also
reveal different and atypical hydrological signatures during Heinrich
stadials (HSs): while HS1 and HS4 exhibit a "usual" scheme with reduced
overturning circulation, a relatively active North Atlantic circulation seems
to have prevailed during HS2, and HS3 seems to have experienced a
re-intensification of this circulation during the middle of the event. Our findings thus bring
valuable information to better understand hydrological processes occurring in
a key area during the abrupt climatic shifts of the last glacial period. |
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