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TitlePlio-Pleistocene glacial geology of the Smoking Hills, northwestern Arctic Canada
 
AuthorSmith, I RORCID logo; Evans, D J A; Gosse, J C
SourceGSA 2019 - Geological Society of America, Annual Meeting 2019, technical programs ; Geological Society of America, Abstracts With Programs vol. 51, no. 5, 3-11, 2019 p. 1, https://doi.org/10.1130/abs/2019AM-339168
Image
Year2019
Alt SeriesNatural Resources Canada, Contribution Series 20190262
PublisherGeological Society of America
MeetingGSA 2019 - Geological Society of America, Annual Meeting; Phoenix, AZ; US; September 22-25, 2019
DocumentWeb site
Lang.English
Mediaon-line; digital
File formathtml; pdf (Adobe® Reader®)
ProvinceNorthwest Territories
NTS97C/04
AreaSmoking Hills
Lat/Long WENS-127.5000 -127.0000 69.2500 69.0000
Subjectssurficial geology/geomorphology; stratigraphy; geophysics; Nature and Environment; Science and Technology; glacial history; postglacial deposits; glacial deposits; tills; outwash; glacial tectonics; interglacial deposits; geophysical surveys; magnetic surveys; stratigraphic correlations; burial history; isotopic studies; beryllium; aluminum; Pleistocene; Pliocene; alluvial sediments; glaciofluvial sediments; glaciofluvial kame terrace sediments; Phanerozoic; Cenozoic; Quaternary; Tertiary
ProgramGEM2: Geo-mapping for Energy and Minerals Western Arctic Project Management
Released2019 09 01
AbstractThe glacial geological record of Smoking Hills, situated along the northwest coastal mainland of arctic Canada (69°13'N; 127°03'W) was first described in the late 1960s when a single 32 m high stratigraphic section was reported to contain 3-5 glacials and associated inter-glacial deposits. Subsequent magnetostratigraphic investigations indicated that a fluvial gravel unit underlying this section was reversed, as were 3 overlying tills, and that the section was capped by two magnetically normal tills. Correlations were then made with complex Quaternary glacial histories on Banks Island and elsewhere, and with Neogene fluvial Beaufort Fm deposits along the western Canadian Arctic Archipelago.
Recent field investigations conducted in 2018 have fundamentally revised the interpretation of this site, and with it, understanding of the regional Plio-Pleistocence glacial history. Preliminary cosmogenic 10Be-26Al burial age dating of the basal (?glaciofluvial) gravel and the immediately overlying till suggest a pre-Pleistocene age. The former complex glacial and inter-glacial stratigraphy is rejected, owing in large measure to the previous lack of recognition and misidentification of extensive rafts of local poorly- to un-lithified Cretaceous bedrock, in some cases upwards of 6 m thick. The composite 52 m high section displays interlayered glaciotectonized till, diamict and bedrock deposits with eastward clast azimuths, save one with a westward azimuth. It is possible that rather than separate glacials, much of the lower 34 m of the section records a glaciotectonized accretion of diamicts and bedrock through a single, pre-Pleistocene glaciation. Whether a large (6+ m thick) bedrock raft at the 10-16 m depth marks the end of the previous glacial or the truncation of underlying stratigraphy consequent with the advance of a subsequent glaciation is uncertain. However, overlying this prominent upper bedrock raft is an 8 m thick massive to laminated diamict interpreted to be a Late Wisconsinan Laurentide till. No convincing evidence of fluvial Beaufort Fm deposits are found within the area, and those deposits previously identified as such are rejected instead as local fluvial and Late Wisconsinan glaciofluvial outwash and kame terraces.
Summary(Plain Language Summary, not published)
Presents field observations and analytical results that support a fundamental reinterpretation of regional glacial stratigraphy and history. This research documents the existence of an extensive old (>2.5 Ma) glaciation, and the absence of formerly identified regional Tertiary fluvial deposits. Findings have important implications for regional kimberlite (diamond) indicator mineral studies, suggesting that indicator minerals found on Banks and Victoria islands have not been derived from kimberlites on mainland regions around the Smoking Hills.
GEOSCAN ID314890

 
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