Holocene environmental evolution of the SE Greenland Shelf North and South of the Denmark Strait: Irminger and East Greenland current interactions |
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| Authors: | A Jennings J Andrews L Wilson |
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| Institution: | 1. School of Earth and Environmental Sciences (SEES), Queens College, CUNY, 6530 Kissena Blvd, Flushing, NY 11367-1507, USA;2. Institute of Marine Sciences (IMS), University of California, Santa Cruz (UCSC), 1156 High Street, Santa Cruz, CA 95064, USA;3. Dipartimento di Scienze della Terra, Universita'' degli Studi di Firenze, Via G. La Pira 4, 50121 Firenze, Italy;4. CNR-Institute of Geosciences and Earth Resources (Section of Florence) Via G. La Pira 4, 50121 Florence, Italy;5. GEOTOP, Université du Québec à Montréal, CP 8888, Montréal, Québec H3C 3P8, Canada;1. Laboratoire Environnements et Paléoenvironnements Océaniques et Continentaux (EPOC) -UMR CNRS 5805, Université de Bordeaux, 33615 Pessac, France;2. GEOTOP, Université du Québec à Montréal, CP 8888, Montréal, Québec H3C 3P8, Canada;3. Laboratoire Géosciences, Université de Paris-Sud, 91405 Orsay Cedex, France |
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| Abstract: | Holocene climatic and paleoceanographic development of the SE Greenland Shelf is studied from cores MD99-2317 and MD99-2322, at sites north and south of the Denmark Strait, respectively. Lithofacies, IRD counts, calcium carbonate percentages, benthic and planktic foraminiferal assemblages and oxygen isotope analyses, and summer SSTs reveal significant climate variations in the Holocene driven by declining solar insolation and its interaction with waning continental ice sheets, and changing atmospheric pressure patterns. Large changes in the East Greenland and Irminger Currents and the Greenland Ice Sheet are manifested as a 4-part division of the Holocene. An early Holocene cold interval dominated by melting of the Greenland Ice Sheet and Polar Front retreat extends from 11.8 to 9.5 cal kyr BP. A cold interval from 9.5 to 8.1 cal kyr BP involved episodic cooling of the Irminger Current resulting from the last phases of Laurentide Ice Sheet deglaciation and delayed the Holocene optimum off East Greenland by 3 kyr relative to peak summer solar insolation, which likely helped to limit the early Holocene melting of the Greenland Ice Sheet. The period 8.1–3.5 cal kyr BP represents a climatic optimum interval of maximum Greenland Ice Sheet retreat and strong Irminger Current inflow to the Denmark Strait. Between 6.8 and 3.5 cal kyr BP, the Irminger Current penetrated further North into the Nordic Seas than has been observed in recent decades. This signal is consistent with diminished northerly winds, a weaker Greenland High and contracted subpolar gyre. By 5 cal kyr BP, periods of increased Polar Water and decreasing salinity in the Irminger Current suggest a transition toward expansion of the subpolar gyre and increased Polar Water in the EGC. The Neoglacial interval from 3.5 to 0.2 cal kyr BP was cold and variable with increased freshwater forcing from the Arctic Ocean, advance of the Greenland Ice Sheet and southward advance of the Polar Front. Enhanced northerly winds and a strengthened Greenland High are consistent with thicker and more extensive Polar Water and greatly diminished northward advection of Irminger Current in the Denmark Strait. |
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