T231 On the Edge—New Insights into Ice-Marginal Conditions I

Thursday, 29 October 2020
5:30 PM - 8:00 PM
Meeting Rooms

TILL ARCHITECTURE AND PROGLACIAL LAKE STRATIGRAPHY DEPOSITED DURING THE RETREAT OF THE LAURENTIDE ICE SHEET, ONEIDA LAKE, NY FROM MULTICHANNEL SEISMIC REFLECTION DATA

Paper number: T231-3
Program: Technical Sessions
Time: 5:45 PM – 5:55 PM

Authors

Abstract

The Oneida Basin, located in Central New York State is a paleo-valley incised into Paleozoic strata and has been identified by previous studies as the likely site of the Oneida Stream, a paleo-ice stream active during the retreat of the Laurentide Ice Sheet (LIS). Modern day Oneida Lake occupies much of the Oneida Basin and provides a unique opportunity to collect high-fidelity marine-type reflection seismic data and image Glacial Lake Iroquois deposits as well as subglacial bedforms/till architecture related to the retreat of the LIS during the last deglaciation. Approximately 217 km of 30-fold multichannel seismic (MCS) reflection data were collected using a 120 channel streamer, and 40 cubic inch (655 cm3) airgun cluster. The data images the entire Quaternary section within Oneida Lake and reveals two northwest to southeast trending lows incised into the Paleozoic strata. These lows are aligned in the same direction as the adjacent megascale glacial lineations (MSGLs) associated with the Oneida Stream identified using LiDAR in previous studies. These lows contain up to ~70 meters of proglacial lake deposits overlying subglacial bedforms/ till unit formed during the last deglaciation. This dataset along with high-resolution single channel CHIRP seismic reflection data and sediment cores offer new insights into the evolution of Glacial Lake Iroquois. The underlying subglacial bedforms/till are highly variable in thickness, ranging from <1 m to more than 30 m. The till unit’s internal stratigraphy is commonly transparent, however in some localities internal reflections suggest multiple ice flow phases recorded in the till architecture. Glacial geomorphic features interpreted within the dataset include hummocky topography and drumlins. The MCS data provides valuable information on the bedrock topography and subglacial bedforms associated with the Oneida Stream within the Oneida Basin which, until now has never been imaged.

Geological Society of America Abstracts with Programs. Vol. 52, No. 6

doi: 10.1130/abs/2020AM-358482

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