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| Titel |
Contrasted ocean conditions in the northwest North Atlantic during marine isotope stages (MIS) 11, 5e and 1 |
| VerfasserIn |
Anne de Vernal, Bianca Fréchette, Claude Hillaire-Marcel |
| Konferenz |
EGU General Assembly 2014
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 16 (2014) |
| Datensatznummer |
250093774
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| Publikation (Nr.) |
 EGU/EGU2014-8835.pdf |
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| Zusammenfassung |
| Cores raised during the IODP Expedition 303 in the north Atlantic were analysed to
document paleoceanographical conditions during recent interglacials (cf. Hillaire-Marcel et
al., Marine Geol. 2011). Two key sites illustrate conditions in the inner vs outer Labrador Sea,
respectively at the southwest Greenland margin (Eirik Ridge Site 1305; 57°N-48°W) and
the southern Labrador rise (Orphan Knoll Site 1302/1303; 50°N-45°W). Special attention
was paid to marine isotope stages (MIS) 11 (ca. 424-324 ka), 5e (ca. 128-117 ka) and the
Holocene (last 11,000 years). The microfossil content of sediments (dinocyst notably) and the
isotopic composition of foraminifers indicate significant differences in the conditions that
prevailed during these 3 interglacial stages. Optimal conditions with regard to sea-surface
temperatures (SSTs) prevailed during MIS 5e (anomalies of about + 5°C) at both sites.
However, occurrence of ice rafted debris (IRD) and variations in salinity suggest meltwater
discharge along the Greenland and Labrador margins during the last interglacial.
On the contrary, during MIS 11, SSTs were similar to modern off Greenland or
slightly lower at Orphan Knoll, but salinity was higher at both sites and IRD close to
nil, whereas both sites are presently under iceberg routes. Stable oxygen isotope
values in the mesopelagic Neogloboquadrina pachyderma left coiled (Npl), are
generally not unlike values observed during MIS 9 or 7, i.e., slightly higher than those
which characterized MIS 5e and the present interglacial, particularly in the outer
Labrador Sea. This points to either a higher salinity and or a lower temperature in
the subsurface water layer occupied by Npl. Low IRD, high salinity together with
relatively high 18O values in foraminifers suggest limited influence of meltwater
from ice cap and sea ice during MIS 11, especially the first part of the interglacial. |
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