Collaborative Research: P2C2: A High Resolution Paleoclimate Archive of Termination I in Oneida Lake and Glacial Lake Iroquois Sediments

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At the end of the last ice age, the vast ice sheet still covering much of northeastern North America served as a dam for ponded meltwaters along its southern edge. When the ice sheet collapsed, those fresh lake waters were released to the Atlantic Ocean, and are thought to have disrupted ocean circulation, causing abrupt cold spells in the northern hemisphere, and perhaps globally. Near southern Ontario and northern New York State, enormous Glacial Lake Iroquois contained massive amounts of cold fresh water, and modern remnants of that lake include Lake Ontario and Oneida Lake. Oneida Lake is located near the easternmost part of ancient Glacial Lake Iroquois, and this area and the Mohawk Valley were a key valve for the release of meltwaters to the Hudson River and to the Atlantic. The Oneida Lake project will study the ancient sediments laid down during these meltwater releases, to determine their precise timing, and will then compare those timings to past climate records derived from Greenland ice cores and from sediments from the Southern and the Atlantic Oceans. The researchers will use geophysical (sonar) methods to image the sediments below the bottom of Oneida Lake, and then collect sediment cores for detailed analyses. Special Carbon-14 dating techniques will be used to date sediments in the cores and to correlate the layered sediments to similar records previously collected in New England. Project outreach efforts include a public lecture series for lake-side communities, engagements with Oneida Nation high school science classes, and the installation of science information kiosks at a State Park on the lake?s eastern edge.This project is examining the Late Quaternary sediment record from the Oneida Basin in Upstate New York, through analyses of new geophysical data and new sediment cores. The unusually rich stratigraphic archive will constrain the paleoclimate evolution along the SE margin of the Laurentide Ice Sheet in the terminal Pleistocene. The researchers will also develop an energy balance hydrologic model of ancient Glacial Lake Iroquois to better constrain fill and discharge events from this basin. Non-linear episodes that perturb the global climate system (e.g., the Younger Dryas cooling) include major meltwater pulses and drainage pathway switches associated with Glacial Lake Iroquois and its precursors. The researchers will evaluate Termination I (the end of the last glaciation, ~20,000 years ago) at seasonal resolution over several millennia, using the rich varved sediment record in Oneida Lake and surrounding outcrops. Outcrop observations of newly discovered lake sediment exposures (varves) in the basin will be integrated with correlative sedimentary sequences recovered by cores from Oneida Lake. The glacial varve record will be chronologically constrained via paleomagnetic methods (cross-dating) with the North American Varve Chronology and further fixed by selective use of Ramped PyrOx radiocarbon dating of organic matter and separately of pollen 14C dating. Preliminary high-resolution seismic data reveal a remarkable, high-fidelity stratigraphy with evidence for outburst flood events, ice sheet instabilities, and a continuous time series from deglaciation through the Holocene. The full lake will be surveyed at high spatial resolution using CHIRP (sweep signal seismic) and multichannel seismic reflection methods. The calibrated time series of events will be compared to three well-established global archives: the Greenland ice core record, the Antarctic Peninsula Palmer Deep and Cariaco Basin marine sections. Beyond the direct scientific outcomes and graduate student training, the researchers will mount an outreach effort including: 1) a riparian community lecture series; 2) construction of two information kiosks describing the geologic evolution of Glacial Lake Iroquois and subsequent evolution of Oneida Lake at two lakeside parks; and 3) engage under-represented groups including secondary school students from the Oneida Nation during both field and laboratory activities.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.