Cosmogenic 10Be chronology of the last deglaciation of western Ireland and implications for sensitivity of the Irish Ice Sheet to climate change
Jorie Clark et al., School of Environmental Science, University of Ulster, Coleraine, County Londonderry BT52 1SA, UK. Pages 3-16.
Accelerator mass spectrometry carbon-14 dates of fossiliferous marine mud identify two re-advances 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 around 16.5 thousand years before present (B.P.), with subsequent deglaciation occurring by around 15.0-15.5 thousand years B.P. Killard Point stadial moraines have been mapped elsewhere in Ireland but have previously remained undated. Clark et al. report sixteen 10-beryllium (Be) surface exposure dates that constrain the age of retreat of the Killard Point stadial ice margin from western Ireland. Eight 10Be dates from the Ox Mountains (13.9-18.1 thousand years ago) indicate that final deposition of the moraine occurred at 15.6 plus or minus 0.5 thousand years ago. Eight 10Be dates from Furnace Lough (14.1-17.3 thousand years ago, mean age of 15.6 plus or minus 0.4 thousand years ago) 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 plus or minus 0.3 thousand years ago. This age is in excellent agreement with the timing of deglaciation from the Irish Sea Basin (at or older than 15.3 plus or minus 0.2 thousand years B.P.) and suggests the onset of near-contemporaneous retreat of the Irish Ice Sheet from its maximum Killard Point st
|Contact: Christa Stratton|
Geological Society of America