HR: 1340h
AN: PP13A-1477    [Abstracts]
TI: Evidence For A Series Of Large Freshwater Discharge Events To The North Atlantic Immediately Preceding The Younger Dryas
AU: * Rayburn, J A
EM: rayburja@plattsburgh.edu
AF: Center for Earth and Environmental Science, Plattsburgh State University 101 Broad St., Plattsburgh, NY 12901 United States
AU: Franzi, D A
EM: david.franzi@plattsburgh.edu
AF: Center for Earth and Environmental Science, Plattsburgh State University 101 Broad St., Plattsburgh, NY 12901 United States
AU: Knuepfer, P L
EM: knuepfr@binghamton.edu
AF: Department of Geological Sciences and Environmental Studies, Binghamton University, Binghamton, NY 13902 United States
AU: Cronin, T M
EM: tcronin@usgs.gov
AF: USGS National Center, 12201 Sunrise Valley Drive, Reston, VA 20192 United States
AU: Berke, M A
EM: mberke@usgs.gov
AF: USGS National Center, 12201 Sunrise Valley Drive, Reston, VA 20192 United States
AB: Sedimentary evidence including a thick sand unit between two rhythmically laminated glacial lacustrine clay units in the northern Champlain Valley of New York State indicates that a flood was directed through the valley during the last deglaciation. This flood occurred when ice-marginal retreat north of the Adirondack Uplands allowed the confluence of Glacial Lakes Iroquois (Ontario Basin) and Vermont (Champlain Valley). A rough discharge estimate of 0.16 Sv has been calculated for the flood. There is also evidence that this event was preceded by a smaller flood with an estimated discharge of 0.11 Sv. Both floods would have been directed southward to the North Atlantic through the Hudson Valley. Varve counts from the northern Champlain basin indicate that these floods occurred 150 - 300 years before the Champlain Sea marine incursion. Radiocarbon ages from terrestrial macrofossils date these floods to about 13,000 calibrated years B.P. A third flood event (estimated at about 0.10 Sv) was caused by ice retreat north of the St. Lawrence Lowland, and was immediately followed by the incursion of the Champlain Sea. This flood would have been directed through the Gulf of St. Lawrence sometime between 12,850 - 12,700 calibrated years B.P., about the time of initiation of the Younger Dryas. This was also the beginning of the re-routing of all Great Lakes discharge (estimated at around 0.05 Sv) from the Hudson Valley to the Gulf of St. Lawrence. A brief re-occurrence of freshwater ostrocodes in early Champlain Sea sediments may indicate that another freshwater flood, perhaps originating from the Great Lakes, discharged into the North Atlantic through the Gulf of St. Lawrence.
DE: 1605 Abrupt/rapid climate change (4901, 8408)
DE: 4926 Glacial
SC: Paleoceanography and Paleoclimatology [PP]
MN: Fall Meeting 2005