Abrupt variability of the last 24 ka BP recorded by coccolithophore assemblages off the Iberian Margin (core MD03-2699)

Authors


Correspondence: E. Palumbo, as above. Email: epalumbo@unisannio.it

ABSTRACT

A high-resolution coccolithophore study allowed reconstructing sea surface conditions during the last 24 ka BP off the Iberian Margin. Variations in nannoplankton accumulation rate, cold-water species, Florisphaera profunda, Umbilicosphaera sibogae and Coccolithus pelagicus ssp. azorinus trends suggest the occurrence of substantial changes in surface water dynamics. Palaeoproductivity shows changes during the glacial and the interglacial transition from intense glacial upwelling to persistent interglacial stratification. A drastic productivity decline occurred between ∼18 and 13 ka BP related to the arrival of subpolar waters indicated by the presence of the subarctic subspecies C. pelagicus pelagicus and increased percentages of tetra-unsaturated alkenones. Abrupt variability at core MD03-2699 during the last 24 ka BP was observed in palaeoproductivity and sea surface temperatures proxies. Increases of reworked species fluxes were observed during the Last Glacial Maximum and during the transition to the Holocene, likely connected to turbidity currents and/or contourites formed by Mediterranean outflow intensification. In addition, C. pelagicus ssp. pelagicus presence, Gephyrocapsa muellerae and tetra-alkenone percentages reveal rapid coolings coeval with the Holocene Bond cycles and rapid climate coolings recognized for the Northern Hemisphere between 11.02 and 1.7 ka BP and associated with subpolar water arrival at the site. Copyright © 2013 John Wiley & Sons, Ltd.

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