HR: 1340h
AN: PP33B-1284    [Abstracts]
TI: A Cosmogenic 10Be Chronology of the Last Deglaciation of Western Ireland, and Implications for Sensitivity of the Irish Ice Sheet to Climate Change
AU: * Clark, J
EM: jorieclark@hotmail.com
AF: Environmental Science, University of Ulster, Coleraine, BT52 1SA, United Kingdom
AU: McCabe, M
EM: m.mccabe@ulster.ac.uk
AF: Environmental Science, University of Ulster, Coleraine, BT52 1SA, United Kingdom
AU: Schnabel, C
EM: C.Schnabel@suerc.gla.ac.uk
AF: NERC Cosmogenic Isotope Analysis Facility, Scottish Enterprise Technology Park, East Kilbride, G75 0QF, United Kingdom
AU: Clark, P U
EM: clarkp@onid.orst.edu
AF: Geosciences, Oregon State Univ., Corvallis, 97331,
AU: McCarron, S
EM: stephen.mccarron@nuim.ie
AF: Geography, National University of Ireland, Maynooth, AT5 1SA, Ireland
AU: Freeman, S
EM: s.freeman@suerc.gla.ac.uk
AF: SUERC, Scottish Enterprise Technology Park, East Kilbride, G75 0QF, United Kingdom
AB: AMS 14C dates of fossiliferous marine mud identify two readvances of the Irish ice sheet from the north and central lowlands of Ireland into the northern Irish Sea Basin during the Killard Point Stadial at approximately 16.5 cal ka, with subsequent deglaciation occurring by ~15.0 – 15.5 cal ka. Killard Point Stadial moraines have been mapped elsewhere in Ireland, but have previously remained undated. Here we report sixteen 10Be surface exposure dates that constrain retreat of the Killard Point Stadial ice margin from western Ireland. Eight 10Be dates from the Ox Mountains (13.9 – 18.1 10Be ka) indicate that final deposition of the moraine occurred 15.6 + 0.5 10Be ka (mean age). Eight 10Be dates from Furnace Lough (14.1 – 17.3 10Be ka, mean age of 15.6 + 0.4 10Be ka) are statistically indistinguishable from the Ox Mountain samples, suggesting that the moraines were deposited during the same glacial event. Given the agreement between the two age groups, and their common association with a regionally significant moraine system, we combine them to derive a mean age of 15.6 + 0.3 10Be ka. This age is in excellent agreement with the timing of deglaciation from the Irish Sea Basin (~15.3 + 0.2 cal ka), and suggests the onset of near-contemporaneous retreat of the Irish Ice Sheet from its maximum Killard Point Stadial limit. A reconstruction of the ice surface indicates that the Irish Ice Sheet reached a maximum surface elevation of ~500 m over the central Irish Lowlands during the Killard Point Stadial, suggesting a high sensitivity of the ice sheet to small changes in climate.
DE: 0726 Ice sheets
DE: 1100 GEOCHRONOLOGY
DE: 1150 Cosmogenic-nuclide exposure dating (4918)
SC: Paleoceanography and Paleoclimatology [PP]
MN: 2007 Fall Meeting