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 (G. muellerae, C. pelagicus pelagicus and E. huxleyi >4µm), F. profunda, U. sibogae and C. pelagicus azorinus trends suggest the occurrence of substantial changes in surface water dynamics. Paleoproductivity 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 sub-polar waters as indicated by the presence of the subarctic species C. pelagicus pelagicus and increased percentages of tetra unsaturated alkenones. Abrupt variability at core MD03-2699, during the last Glacial and the Holocene was observed in paleoproductivity and sea surface temperatures proxies. Increases of reworked species fluxes were observed during the Last Glacial Maximum (LGM) and during the transition to the Holocene,likely connected to turbidity currents and/or contourites formed by Mediterranean Outflow (MOW) intensification. In addition, C. pelagicus pelagicus presence, G. muellerae and tetra alkenones’ percentages reveal rapid coolings coeval with the Holocene Bond cycles and Rapid Climate Coolings (RCCs) recognised for the Northern Hemisphere (NH) between 11.02 and 1.7 ka and associated with sub-polar water arrival at the site.

Abrupt variability of the last 24ka BP recorded by coccolithophore assemblages off the iberian margin (CORE MD03-2699)

PERUGIA, Carmen;Amore F. O.
2013

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 (G. muellerae, C. pelagicus pelagicus and E. huxleyi >4µm), F. profunda, U. sibogae and C. pelagicus azorinus trends suggest the occurrence of substantial changes in surface water dynamics. Paleoproductivity 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 sub-polar waters as indicated by the presence of the subarctic species C. pelagicus pelagicus and increased percentages of tetra unsaturated alkenones. Abrupt variability at core MD03-2699, during the last Glacial and the Holocene was observed in paleoproductivity and sea surface temperatures proxies. Increases of reworked species fluxes were observed during the Last Glacial Maximum (LGM) and during the transition to the Holocene,likely connected to turbidity currents and/or contourites formed by Mediterranean Outflow (MOW) intensification. In addition, C. pelagicus pelagicus presence, G. muellerae and tetra alkenones’ percentages reveal rapid coolings coeval with the Holocene Bond cycles and Rapid Climate Coolings (RCCs) recognised for the Northern Hemisphere (NH) between 11.02 and 1.7 ka and associated with sub-polar water arrival at the site.
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Utilizza questo identificativo per citare o creare un link a questo documento: http://hdl.handle.net/20.500.12070/579
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