HR: 10:50h
AN: PP32A-03 INVITED    [Abstracts]
TI: Allerod Collapse of the Newfoundland Ice Cap, northwestern Atlantic Ocean
AU: * Gosse, J C
EM: john.gosse@dal.ca
AF: Dalhousie University, Earth Sciences 3006 LSC, Halifax, NS B3H4J1, Canada
AU: Bell, T
EM: tbell@mun.ca
AF: Memorial University of Newfoundland, Geography, St. John's, NL A1B3X9, Canada
AU: Yang, G
EM: gyang@dal.ca
AF: Dalhousie University, Earth Sciences 3006 LSC, Halifax, NS B3H4J1, Canada
AU: Fastook, J
EM: fastook@maine.edu
AF: University of Maine, Computer Sciences, Orono, ME 04469, United States
AB: Control on the timing of deglaciation of the island of Newfoundland was mostly restricted to offshore records although a few lakes have yielded latest Pleistocene paleovegetation proxies of paleoclimate. Twenty-three cosmogenic 10Be ages on boulders throughout Newfoundland have a range of 11.6 to 14.1 ka and mean of 13.1 +/- 0.1 ka (standard error). The samples indicate near-synchronous deglaciation (collapse) in all the regions sampled over a >100,000 km2 area: St. John's Highlands (on the Great Northern Peninsula once believed to be a nunatak); head of White Bay (northcentral NF); Gaff Topsails Region central NF; Anniopsquotch Mountains and Burgeo region (southwestern NF); Granite Lake (southcentral NF); head of Baie d'Espoir (southern NF); and northern Burin Peninsula (southeastern NF). The large (>2 m) boulders with flat horizontal surfaces are unlikely to have been influenced by snow cover, exhumation through till, boulder erosion, or inheritance. Lake bottom (most bulk sediment) conventional and AMS radiocarbon dates support this exposure chronology, and UMISM simulations of ice sheet decay (driven by a scaled GISP temperature record) is consistent with a rapid melting of the ice cap after retreating from (modern) continental shelf regions. Coincidence of the collapse of the Newfoundland Ice Sheet with the timing of Allerod warming provides an example of the sensitivity of large peripheral ice caps to rapid regional climate change.
DE: 0726 Ice sheets
DE: 1150 Cosmogenic-nuclide exposure dating (4918)
DE: 1605 Abrupt/rapid climate change (4901, 8408)
SC: Paleoceanography and Paleoclimatology [PP]
MN: 2007 Fall Meeting