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Titel |
Variability in intermediate water circulation of the western Tyrrhenian margin (NE Corsica) over the past 56 kyr |
VerfasserIn |
Maria Angela Bassetti, Angue Minto’o Charlie Morelle, Emmanuelle Ducassou, Toucanne Samuel, Caterina Morigi, Gwenael Jouet, Mulder Thierry |
Konferenz |
EGU General Assembly 2015
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Medientyp |
Artikel
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Sprache |
Englisch
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Digitales Dokument |
PDF |
Erschienen |
In: GRA - Volume 17 (2015) |
Datensatznummer |
250105655
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Publikation (Nr.) |
EGU/EGU2015-5189.pdf |
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Zusammenfassung |
The Marion Dufrene core MD01-2472 made of hemipelagic fine-grained sediments (silt and
clays) was collected at 501 m depth on the East Corsica continental slope in 2001 and studied
in detail in its 12 uppermost meters.
The correlation between sedimentological parameters (Sortable Silt), isotopic data and 14C
dating allowed to establish the chronology of main climate events (Younger Dryas/YD,
Bölling-Alleröd/B-A, Heinrich events/HS) on this record and to evaluate the impact of major
climate oscillations on bottom water condition variability.
The sea temperature changes are identified thanks to the planktonic foraminifera
assemblages. HS are marked by planktonic foraminifers with peaks of the polar species N.
pachyderma (left-coiling), whilst interstadials are marked by warm planktonics that become
very abundant during the B-A and Holocene.
The occurrence of reworked ostracod species (originating from the continental shelf) and the
presence of shallow water Elphidium/Ammonia benthic foraminifera are used to estimate the
degree of along-slope transport at the core site. This has revealed two intervals of along-slope
transport also associated with coarse-grained contourites, deposited during the YD and HS2
episodes.
Intervals with Krithe spp. (ostracod), C. wuellerstorfi (benthic foraminifera) indicate bottom
water oxygenation during stadials, whereas interstadials are typified by A. acuminata and
Paracypris sp (ostracods) indicating low oxygenated environments. The Last Glacial
Maximum is dominated by the planktonic foraminifer T. quinqueloba suggesting high surface
primary productivity associated with the establishment of mestrophic bottom conditions.
During the Holocene, benthic assemblages indicate oligo-mesotrophic conditions and weak
hydrodynamic bottom regime.
We hypothesize that there is relationship between the Levantine Intermediate Water (LIW)
intensification during cold rapid climate events and benthic fauna assemblages due to changes
in: 1) bottom water ventilation, corresponding to a significant reinforcement of
the LIW velocity, and 2) the export of nutrients (generating changes in trophic
conditions) and/or sediment particles by bottom currents (contributing to the formation of
contourites). |
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