HR: 1340h
AN: PP13A-1475    [Abstracts]
TI: Micropaleontological Record of Post-glacial History in Lake Champlain and Adjacent Regions: Implications for Glacial Lake Drainage and Abrupt Climate Events
AU: * Cronin, T M
EM: tcronin@usgs.gov
AF: US Geological Survey, 926A National Center USGS, Reston, Va 20192 United States
AU: Manley, P L
EM: patmanley@middlebury.edu
AF: Middlebury College, Department of Geology, Middlebury, VT 05753 United States
AU: Guilbault, J
EM: jean-pierreguilbault@sympatico.ca
AF: BRAQ-Stratigraphie, 37 Chemin Cochrane, Compton, Que J0B 1L0 Canada
AU: Berke, M
EM: mberke@usgs.gov
AF: US Geological Survey, 926A National Center USGS, Reston, Va 20192 United States
AU: Rayburn, J A
EM: raybuja@plattsburgh.edu
AF: Center for Earth and Environmental Science, Plattsburgh State University, Plattsburg, NY 12901 United States
AU: Franzi, D A
EM: david.franzi@plattsuburgh.edu
AF: Center for Earth and Environmental Science, Plattsburgh State University, Plattsburg, NY 12901 United States
AU: Knuepfer, P L
EM: knuepf@binghampton.edu
AF: Department of Geological Sciences, Binghampton University, Binghampton, NY 13902 United States
AB: Post-glacial lacustrine and marine sediments of the Lake Champlain region range from 20 to >50 meters in thickness presenting an opportunity to assess the timing of North American glacial lake drainage at multidecadal timescales and evaluate its effect on North Atlantic salinity and abrupt climate events 13.5 to 10 kyr B.P. High-resolution analysis of foraminifera and ostracodes from cores taken onshore in the Plattsburgh, N.Y. vicinity and southern Quebec and offshore in southern Lake Champlain reveal complex changes in salinity during and after the transition from pro-glacial Lake Vermont (Lake Candona in Canada) to marine sedimentation in the Champlain Sea. The microfaunal sequence (bottom to top) includes: non-marine ostracodes ( Candona) in lacustrine varves, foraminiferal assemblages (common Cassidulina reniforme), another interval of Candona-bearing sediments (sometimes containing foraminifera), and, finally, sediments from the main phase of the Champlain sea episode containing diverse foraminiferal and marine ostracode assemblages. A decrease in salinity during the Champlain Sea is also in evidence from the shift in dominance of distinct variants of Elphidium in the deep basin. The marine episode ended with a progressive salinity decrease and the formation of Lake Champlain about 10 kyr B.P. Observed salinity changes could be caused by catastrophic fresh-water influx from large glacial lakes west of the Lake Champlain region, meltwater from the retreating Laurentide Ice Sheet margin, diminished influx of marine water from the St. Lawrence due to changes in the position of the ice sheet margin and isostatic adjustment, or a combination of factors. The ages of these events were determined by estimating the reservoir effect on radiocarbon dates on marine shells through comparison with AMS dates on plant material and palynology, and shed light on the hypothesis that glacial lake discharges catalyzed abrupt climate events.
DE: 1605 Abrupt/rapid climate change (4901, 8408)
DE: 1616 Climate variability (1635, 3305, 3309, 4215, 4513)
DE: 3344 Paleoclimatology (0473, 4900)
DE: 4914 Continental climate records
DE: 4926 Glacial
SC: Paleoceanography and Paleoclimatology [PP]
MN: Fall Meeting 2005