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TitleEffects of marine inundation on till composition in permafrost terrain south of Wager Bay, central mainland Nunavut
AuthorRandour, I; McMartin, IORCID logo; Roy, M
SourceGAC-MAC 2017; Geological Association of Canada-Mineralogical Association of Canada, Joint Annual Meeting, Programs with Abstracts vol. 40, 2017 p. 323 Open Access logo Open Access
LinksOnline - En ligne
Alt SeriesEarth Sciences Sector, Contribution Series 20160448
PublisherGeological Association of Canada
MeetingGeological Association of Canada-Mineralogical Association of Canada Joint Annual Meeting 2017; Kingston, ON; CA; May 14-18, 2017
Mediapaper; on-line; digital
File formatpdf
NTS56B; 56C
Subjectstill samples; mineral exploration; drift prospecting; drift deposits; drift geochemistry; permafrost
ProgramGEM2: Geo-mapping for Energy and Minerals Rae Province, Tehery-Wager Bay
AbstractIn northern Canada, systematic till sampling in frost boils is an exploration technique commonly used to find commodities of economic value. Post-depositional alteration can modify the so-called first order sediment, leaving a less suitable sediment for drift prospecting. Below the post-glacial limit of marine invasion, reworking and winnowing processes by waves and currents may remove the fine fraction of till, whereas the incorporation of fine-grained marine sediments may dilute the signature from local bedrock, leaving a completely different material from till collected above the marine limit. A detailed study to evaluate the effects of the post-glacial marine processes on till texture and geochemical composition was initiated in the summer of 2016 at two separate sites in central mainland Nunavut (NTS 56B and NTS 56C) in paired frost boils located on either sides of the well-defined local marine limit. The sampling sites were carefully chosen using airphoto interpretation and ground truthing observations, concentrating on the presence of thick till above and below the marine trimline, and continuous bedrock units along the trimline. The first site is characterized by intensely wave-washed surfaces surrounded by bouldery beaches forming a distinct trimline with unmodified till-covered surfaces above; the second site forms a clear trimline around a small topographic high forming wave-cut notches between intact till above and reworked till below the marine limit. For each site, two frost boils were sampled; one was located immediately below the marine limit and the other directly above. Several samples were collected from each frost boil along a vertical profile at 10-15 cm intervals, down to 95 cm maximum depth. Five small field duplicate samples were also collected near each frost boil at approximately 40 cm depth to measure the local variability. A total of 54 small (~3 kg) samples were collected for this study. Geochemical and textural analyses were performed on the samples to evaluate variations with depth and between sites. The results presented here in detailed profiles from frost boils above and below the marine limit will help assess the impact of marine invasion on till composition in soils affected by cryoturbation.
Summary(Plain Language Summary, not published)
The post-glacial sea invaded the coastal lowlands along the northwestern part of Hudson Bay following deglaciation. This poster will present the results of a detailed study on till composition of surface sediments collected above and below the marine limit in frost boils. The findings will help characterize the nature of surface sediments potentially affected by marine processes and will help assess the impact of marine inundation on till composition in soils affected by cryoturbation, commonly collected for mineral exploration to find commodities of economic value. This work forms part of a MSc thesis undertaken as part of the surficial geology component of the GEM 2 Tehery-Wager Activity within the Rae Project area.

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