HR: 1340h
AN: PP13B-1269    [Abstracts]
TI: A multi-phased ~17-15.5 ka BP (~H1 age) advance of the last British Ice Sheet into the North Sea – linking paleoceanographic and continental records
AU: * Nygard, A
EM: Atle.Nygard@geo.uib.no
AF: Dept. of Earth Science, Univ. of Bergen, Allegaten 41, Bergen, 5007, Norway
AU: Sejrup, H
EM: Sejrup@geo.uib.no
AF: Dept. of Earth Science, Univ. of Bergen, Allegaten 41, Bergen, 5007, Norway
AU: Haflidason, H
EM: Haflidi.Haflidason@geo.uib.no
AF: Dept. of Earth Science, Univ. of Bergen, Allegaten 41, Bergen, 5007, Norway
AU: Mardal, I
EM: Ivar.Mardal@gmail.com
AF: Dept. of Earth Science, Univ. of Bergen, Allegaten 41, Bergen, 5007, Norway
AB: The last British Ice Sheet's (BIS) relatively small size and maritime setting suggests it was strongly susceptible to changes in the North Atlantic oceanic circulation, through associated fluctuations in precipitation and temperature. Marine records have shown clear evidence of recurrent BIS instabilities, however firm data on ice sheet extent for the period are sparse. We present seismostratigraphical and chronological data from the central/northern North Sea showing that after disconnecting from the Fennoscandian Ice Sheet around ~24 ka BP (cal. yrs) the BIS reached the central/northern North Sea again only between ~17-15.5 ka BP (cal. yrs). This is based on the identification and radiocarbon dating of ice-marginal grounding-line wedges interstratified with marine sediments spanning the last 24 ka. The grounding-line wedges indicate at least two major oscillations of the ice front between ~17-15.5 ka BP, implying that the British Ice Sheet was significantly larger at a much later stage than previously thought. Recent work published on North Atlantic marine cores from positions near the western margin of the BIS suggest a strongly falling trend in sea surface temperatures after 18 ka BP, accompanied by an increased IRD flux, lasting until the abrupt warming after H1 at around 15 ka BP. Based on the radiocarbon chronology we explore the possibilities that our ice marginal positions are correlative to the IRD depositional events, and that the IRD signal reflects oscillations of an active ice sheet culminating at ~17-15.5, rather than ice sheet disintegration, as has previously been suggested.
DE: 0726 Ice sheets
DE: 4901 Abrupt/rapid climate change (1605)
SC: Paleoceanography and Paleoclimatology [PP]
MN: 2007 Fall Meeting