Middle Wisconsinan marine shells near Repulse Bay, Nunavut, Canada: implications for Marine Isotope Stage 3 ice‐free conditions and Laurentide Ice Sheet dynamics in north‐west Hudson Bay

ABSTRACT Evidence suggesting a reduction of the Laurentide Ice Sheet (LIS) during Marine Isotope Stage 3 (MIS 3) is widespread but the boundaries of the ice sheet and the timing of minimum ice extent are still poorly constrained. Radiocarbon dating of glacially transported marine mollusks in Rae Ist...

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Bibliographic Details
Published in:Journal of Quaternary Science
Main Authors: McMartin, Isabelle, Campbell, Janet E., Dredge, Lynda A.
Format: Article in Journal/Newspaper
Language:English
Published: Wiley 2019
Subjects:
Paleontology
Earth and Planetary Sciences (miscellaneous)
Arts and Humanities (miscellaneous)
Nunavut
Hudson Bay
Canada
Hudson
Repulse Bay
Gulf of Boothia
Roes Welcome Sound
Rae Isthmus
Rae
Committee Bay
Ice Sheet
Keewatin
Online Access:http://dx.doi.org/10.1002/jqs.3081
https://api.wiley.com/onlinelibrary/tdm/v1/articles/10.1002%2Fjqs.3081
https://onlinelibrary.wiley.com/doi/pdf/10.1002/jqs.3081
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Summary:ABSTRACT Evidence suggesting a reduction of the Laurentide Ice Sheet (LIS) during Marine Isotope Stage 3 (MIS 3) is widespread but the boundaries of the ice sheet and the timing of minimum ice extent are still poorly constrained. Radiocarbon dating of glacially transported marine mollusks in Rae Isthmus ice stream till south of Repulse Bay, Nunavut, Canada, provides new evidence for MIS 3 deglaciation in the north‐west part of Hudson Bay. Middle Wisconsinan finite 14 C ages varying between 31.7 and 39.2k 14 C a BP (∼35.0 and 43.7k cal a) indicate a marine event(s) for a minimum of ∼8.7k cal years. Our findings suggest ice‐free conditions in the ice stream source area in proto‐Roes Welcome Sound, and therefore significant glacial recession of the LIS margin during the Middle Wisconsinan, much farther in the interior of the ice sheet than previously known. The marine incursion possibly occurred because of a calving bay developed from the north in the Gulf of Boothia − Committee Bay area following the recession and collapse of the ice stream. After the MIS 3 marine episode(s), the topographically controlled ice stream stemming from the eastern end of the Keewatin Ice Divide was re‐activated, and maintained until deglaciation.

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