| Titre | Microfossils suggest separate triggers for mass transport deposits in two lakes within the Western Quebec Seismic Zone, southwest Quebec, Canada |
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| Auteur | Alderson, A; Brooks, G R ; McCarthy, F M G; Boyce, J I; Hoggar, J; Esmaeilzadeh, A |
| Source | GSA 2020 Connects Online; Geological Society of America, Abstracts With Programs vol. 52, no. 6, 165-10, 2020 p. 1, https://doi.org/10.1130/abs/2020AM-354953 |
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| Année | 2020 |
| Séries alt. | Ressources naturelles Canada, Contribution externe 20210418 |
| Éditeur | Geological Society of America |
| Réunion | Geological Society of America Annual Meeting 2020; Octobre 25-28, 2020 |
| Document | publication en série |
| Lang. | anglais |
| DOI | https://doi.org/10.1130/abs/2020AM-354953 |
| Media | numérique; en ligne |
| Formats | html; pdf |
| Province | Québec |
| SNRC | 31 |
| Région | Lac de l'Argille; McArthur Lake |
| Lat/Long OENS | -80.0000 -73.0000 48.0000 44.0000 |
| Sujets | sediments lacustres; dépôts de glissement de terrain; micropaléontologie; microfossiles; palynologie; palynomorphes; pollen; glissements de terrain; mouvement de masse; sismicité; risque sismique;
secousses séismiques; risque de tremblement de terre; analyses stratigraphiques; levés géophysiques; levés acoustiques; carottes de sediments lacustres; méthodes de fluorescence aux rayons x; antecedents de sedimentation; Dépôts de Champlain Sea ;
Picée; géologie des dépôts meubles/géomorphologie; paléontologie; stratigraphie; géophysique; géochimie; Sciences et technologie; Nature et environnement; Phanérozoïque; Cénozoïque; Quaternaire |
| Programme | Géoscience pour la sécurité publique Société de gestion des déchets nucléaires |
| Diffusé | 2020 10 01 |
| Résumé | (disponible en anglais seulement)
Reconstructing regional earthquake history is important for assessing earthquake hazards, especially in intraplate regions with short historic records and
infrequent, but potentially high-magnitude earthquakes. A useful method of identifying paleoseismic events is through the identification of multiple mass transport deposits (MTDs) at a common stratigraphic level in a lake basin. Where such signatures
are present in separate lake basins, and it can be established that they are the same age, a paleoearthquake may be the best explanation for a coeval trigger. Sub-bottom acoustic profiling revealed multiple stratigraphic levels of MTDs within early
postglacial Champlain Sea deposits preserved within the basins of Lac de l'Argille and McArthur Lake, located about 25 km apart, in southwest Quebec. The sediment cores recovered at the sites overlying the two stratigraphically youngest MTDs in each
lake were CT scanned, underwent ITRAX XRF analysis, and subsampled for microfossils and pollen. Microfossils (palynomorphs and testate amoebae) from the MTDs show re-sedimentation of nearshore planktonic taxa and into the deep basins of both lakes,
and confirm the mass transport origin of the deposits. The pollen record leading into the MTD in McArthur Lake is rich in Picea and Pinus resinosa, indicating deposition between 11-13 ky BP, while the equivalent record overlying the Lac de l'Argille
MTD is rich in Pinus strobus pollen, placing deposition between 8-10 ky BP. These two mass transport events thus are of distinctly different ages and cannot be attributed to a coeval trigger. This study demonstrates the importance of dating MTDs from
relatively close lake basins, and not inferring a coeval trigger based on similar stratigraphic locations in sub-bottom profile records. |
| Sommaire | (Résumé en langage clair et simple, non publié)
Le résumé résume l'enquête sur deux lacs voisins pour voir si un ensemble d'anciens glissements de terrain sous-marins dans chaque lac a le même
âge. Il s'avère qu'ils ont des âges différents et ne sont donc pas la preuve d'un déclenchement commun comme un tremblement de terre important. |
| GEOSCAN ID | 329267 |
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