| Titre | Plio-Pleistocene glacial geology of the Smoking Hills, northwestern Arctic Canada |
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| Auteur | Smith, I R ;
Evans, D J A; Gosse, J C |
| Source | GSA 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 |
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| Année | 2019 |
| Séries alt. | Ressources naturelles Canada, Contribution externe 20190262 |
| Éditeur | Geological Society of America |
| Réunion | GSA 2019 - Geological Society of America, Annual Meeting; Phoenix, AZ; US; Septembre 22-25, 2019 |
| Document | site Web |
| Lang. | anglais |
| DOI | https://doi.org/10.1130/abs/2019AM-339168 |
| Media | en ligne; numérique |
| Formats | html; pdf (Adobe® Reader®) |
| Province | Territoires du Nord-Ouest |
| SNRC | 97C/04 |
| Région | Smoking Hills |
| Lat/Long OENS | -127.5000 -127.0000 69.2500 69.0000 |
| Sujets | antecedents glaciaires; dépôts postglaciaires; dépôts glaciaires; tills; épandage fluvio glaciaire; tectonique glaciaire; dépôts interglaciaires; levés géophysiques; levés magnétiques; corrélations
stratigraphiques; historique de l'enfouissement; etudes isotopiques; beryllium; aluminium; Pléistocène; Pliocène; sédiments alluviaux; sédiments fluvioglaciaires; sédiments de terrasses de kames; géologie des dépôts meubles/géomorphologie;
stratigraphie; géophysique; Nature et environnement; Sciences et technologie; Phanérozoïque; Cénozoïque; Quaternaire; Tertiaire |
| Programme | GEM2 : La géocartographie de l'énergie et des minéraux Gestion de programme de l'ouest de l'Arctique |
| Diffusé | 2019 09 01 |
| Résumé | (disponible en anglais seulement)
The 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. |
| Sommaire | (Résumé en langage clair et simple, non publié)
Présente des observations de terrain et des résultats analytiques qui soutiennent une réinterprétation fondamentale de la stratigraphie et de
l'histoire glaciaires régionales. Ce travail documente l'existence d'une vaste et ancienne glaciation (> 2,5 Ma) et de l'absence de dépôts fluviaux régionaux précédemment identifiés dans le Tertiaire. Les résultats ont des implications importantes
pour les études régionales sur les minéraux indicateurs de kimberlite (diamant), ce qui suggère que les minéraux indicateurs trouvés sur les îles Banks et Victoria n'ont pas été dérivés des kimberlites des régions continentales entourant les collines
Smoking. |
| GEOSCAN ID | 314890 |
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