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TitleUpdating the limits of the postglacial marine transgression along western Hudson Bay in Nunavut and Manitoba, Canada
AuthorMcMartin, IORCID logo; Gauthier, M S; Page, A V
SourceINQUA Congress 2023, abstracts; 2023 p. 1
LinksOnline - En ligne
Alt SeriesNatural Resources Canada, Contribution Series 20220374
PublisherInternational Union for Quaternary Research
MeetingXXI INQUA Congress 2023; Rome; IT; July 14-20, 2023
Mediapaper; digital; on-line
File formatpdf
ProvinceManitoba; Nunavut
NTS54; 55
Lat/Long WENS -96.0000 -88.0000 64.0000 56.0000
Subjectsstratigraphy; surficial geology/geomorphology; landform classification; landforms; glacial landforms; ice sheets
Released2023 07 14
AbstractThe revised maximum limit (ML) of the Tyrrell Sea on the western side of Hudson Bay in mainland Nunavut and northern Manitoba provides robust constraints for glacio-isostatic adjustment models and the deglacial history of the region. The new compilation updates previous mapping of ML features, making use of high-resolution digital elevation models (DEM), new field-based observations and digital compilations of supporting datasets (marine deltas and sediments). DEM-extracted median elevations on 1595 features vary from 83 to 242 m asl (±1 m in Nunavut; ±1-15 m in Manitoba) between Churchill, Manitoba, and areas within the Arctic Ocean drainage basin in Nunavut. Regionally, the high values above the median of ~140 m reflect the proximity to a former ice-load centre of the Laurentide Ice Sheet (i.e. Keewatin Dome). However, the high elevations >200 m on the west side of Committee Bay are interpreted to result from incursion of the sea into depressed areas during the early phases of deglaciation. In contrast, the particularly low elevations at 82-110 m in inner Wager Bay suggest that remnant ice masses under the Keewatin Ice Divide (KID) prevented incursion of the sea late during deglaciation. Similarly, low elevations at ~100 m near Baker Lake indicate that ice remnants blocked invasion of the sea over the last position of the KID, as supported by relatively young ages on marine shells in this area. From Baker Lake, the ML increases westward to 150 m, and southward from 125 m, to 161 m at the Nunavut border and 165-175 m at Seal River, and then decreases to 145 m at Churchill River. These changes are related to contrasting ice loads associated with migration of the KID and/or different configurations and ages of the retreating ice margins. During deglaciation, proglacial lakes were also in contact with the ice margin, namely in the Thelon River basin and in northern Manitoba, complicating the delineation of accurate marine limits. More detailed mapping and additional ages are needed to decipher the location of, and drivers for, the changing marine limits in these areas and relationship with the history of the proglacial lakes.
Summary(Plain Language Summary, not published)
This poster will present the highlights from a compilation of the postglacial limit of marine transgression along the coastal regions of northern Manitoba and central mainland Nunavut. The compilation is based on field observations and measurements, computer-based mapping using high-resolution digital elevation models and integration with previous mapping of marine features. The work was completed as part of Natural Resources Canada's GEM-GeoNorth Program in collaboration with the Manitoba Geological Survey. The results can inform land-use planning and coastal evolution research for terrestrial and sea-transport infrastructures, and help in understanding the marine action on the composition of surficial sediments, contributing to efficiency in glacial drift exploration methods.

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