Abstract Ice streams are sites of ice-sheet drainage and together with other processes, such as calving, have an impact on deglaciation rates and ice-sheet mass balance. Proglacial lake deposits provide records of ice-sheet deglaciation and have the potential to supplement other paleoclimate records. Oneida Lake, northeastern USA, contains a thick proglacial lake sequence that buries evidence of ice streaming and a paleo-calving margin that developed during retreat of the Laurentide Ice Sheet. Previous high-resolution digital elevation models identified the Oneida Ice Stream from glacial landforms northwest of the lake. In this study, we utilize seismic refractions from a multichannel seismic (MCS) reflection dataset to estimate the thickness of glacial deposits using seismic tomography. With this method we constrain the depth to top of Paleozoic strata, especially in areas where the reflection data yielded poor outcomes and validate our reflection data in regions of good coverage. We demonstrate that where long offset seismic data are available, the first-arrival tomography method is useful in studies of formerly glaciated basins. Our study identifies a ~108 m thick sedimentary section and potentially long paleoclimate record in Oneida Lake, and identifies a paleotopographic low that likely encouraged formation of the Oneida Ice Stream.
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Evidence for ice-calving at the terminus of a Laurentide ice stream from multichannel seismic reflection data, Oneida Lake, NY
The deglaciation record of the Ontario Lowland and Mohawk Valley of North America is important for constraining the retreat history of the Laurentide Ice Sheet, end-Pleistocene paleoclimate, and ice-sheet processes. The Mohawk Valley was an important meltwater drainage route during the last deglaciation, with the area around modern Oneida Lake acting as a valve for meltwater discharge into the North Atlantic Ocean. The Mohawk Valley was occupied by the Oneida Lobe and Oneida Ice Stream during the last deglacial period. Multichannel seismic reflection data can be used to generate images of preglacial surfaces and internal structures of glacial bedforms and proglacial lake deposits, thus contributing to studies of deglaciation. This paper uses 217 km of offshore multichannel seismic reflection
data to image the entire Quaternary section of the Oneida basin. A proglacial lake and paleo-calving margin is interpreted, which likely accelerated the Oneida Ice Stream, resulting in elongated bedforms observed west of the lake. The glacial bedforms identified in this study are buried by proglacial lake deposits, indicating the Oneida basin contains a record of glacial meltwater processes, including a
60-m-thick proglacial interval in eastern Oneida Lake.
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- Award ID(s):
- 1804460
- NSF-PAR ID:
- 10336283
- Date Published:
- Journal Name:
- Quaternary research
- ISSN:
- 1096-0287
- Page Range / eLocation ID:
- 1-18
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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Oneida Lake, New York, is the remnant of Glacial Lake Iroquois, a large proglacial lake that delivered fresh water to the Atlantic Ocean during the last deglaciation. The formation of Glacial Lake Iroquois and its subsequent drainage into the Atlantic Ocean via the Mohawk Valley was a significant shift in the routing of Laurentide Ice Sheet meltwater to the east instead of south via the Allegheny or Susquehanna Rivers. Catastrophic drainage of Glacial Lake Iroquois into the Atlantic Ocean via the Champlain Valley is interpreted as the meltwater pulse responsible for the Intra-Allerod cold stadial. Therefore, understanding the evolution of Glacial Lake Iroquois has significant implications for understanding late Pleistocene paleoclimate. High-resolution CHIRP seismic reflection data provides insight into the evolution of Glacial Lake Iroquois and Oneida Lake. Three seismic units image distinct stages of the Oneida Basin. Unit 1 is interpreted as proglacial lake deposits that overlie glacial till. Unit 2 is interpreted as sediments deposited when the Oneida Basin became isolated from Glacial Lake Iroquois and Unit 3 is interpreted as lacustrine sediments of the modern lake. Distally sourced turbidites possibly triggered by seismic activity or ice sheet meltwater pulses are represented as reflection- free acoustic facies that infill topographic lows and range in thickness from ~1–5m within otherwise conformable proglacial lake deposits. Local slump deposits imaged at the boundary between Unit 1 and 2 were likely triggered by the drainage of Glacial Lake Iroquois. Wave cut terraces indicative of a low stand on the upper bounding surface of Unit 2 are likely the result of drier conditions during the Holocene Hypsithermal. Furthermore, preservation of this low stand suggests a rapid rise in lake level, possibly the result of the same transition to a wetter climate responsible for the Nipissing transgression observed in the Laurentian Great lakes.more » « less
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Abstract. The timing of the Laurentide Ice Sheet's final retreat from North America's Laurentian Great Lakes is relevant to understanding regional meltwater routing, changing proglacial lake levels, and lake-bottom stratigraphy following the Last Glacial Maximum. Recessional moraines on Isle Royale, the largest island in Lake Superior, have been mapped but not directly dated. Here, we use the mean of 10 new 10Be exposure ages of glacial erratics from two recessional moraines (10.1 ± 1.1 ka, one standard deviation; excluding one anomalously young sample) to constrain the timing of Isle Royale's final deglaciation. This 10Be age is consistent with existing minimum-limiting 14C ages of basal organic sediment from two inland lakes on Isle Royale, a sediment core in Lake Superior southwest of the island, and an estimated deglaciation age of the younger of two subaqueous moraines between Isle Royale and Michigan's Keweenaw Peninsula. Relationships between Isle Royale's landform ages and Lake Superior bottom stratigraphy allow us to delineate the retreat of the Laurentide ice margin across and through Lake Superior in the early Holocene. We suggest that Laurentide ice was in contact with the southern shorelines of Lake Superior later than previously thought.
- Free Publicly Accessible Full Text
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Accepted Manuscript1.0
- Journal Article:
- https://doi.org/doi:10.1017/qua.2021.53
