GEOSCAN, résultats de la recherche


TitreDetecting massive ice using ground-penetrating radar in the Northwest Territories
AuteurOdell, D E; Moorman, B J; Smith, I R
Source40th Annual Yellowknife Geoscience Forum, abstracts of talks and posters; par Watson, D M (éd.); Northwest Territories Geoscience Office, Yellowknife Geoscience Forum Abstracts Volume 2012, 2012 p. 64 (Accès ouvert)
LiensOnline - En Ligne
Séries alt.Secteur des sciences de la Terre, Contribution externe 20120290
Réunion40th annual Yellowknife Geoscience Forum; Yellowknife; CA; Novembre 13-15, 2012
Documentpublication en série
ProvinceTerritoires du Nord-Ouest
RégionLittle Chicago
Sujetsglace; glace massive; géoradar; pergélisol; glace fossile; géologie des dépôts meubles/géomorphologie; géophysique; Nature et environnement; Cénozoïque; Quaternaire
ProgrammeGéosciences de changements climatiques, Infrastructures terrestres
Résumé(disponible en anglais seulement)
Massive ice and related thaw subsidence present a significant challenge to the geotechnical engineering and design of infrastructure such as roads, pipelines and buildings in permafrost regions. Development in these areas requires an understanding of the distribution of massive ice and the establishment of effective methods for its quantification at a local scale. The research discussed here demonstrates the application of Ground-Penetrating Radar (GPR), seismic shothole drillers¿ lithostratigraphic logs, and other complimentary data in the identification of massive ice along recent seismic cutlines at Little Chicago and Lac des Bois, central Northwest Territories.
Three occurrences of massive ice along 58 km of ground traverses were identified using 100 MHz GPR data, velocity analysis, shothole drillers¿ logs and air photos. At Little Chicago (120 km north of Fort Good Hope), an ice body measuring 55 m in lateral extent and having a maximum thickness of 2.6 m was identified. Inverse modeling of the propagation velocity from a hyperbolic return below the ice yielded a calculated velocity of 0.16 m/ns, supporting the conclusion of massive ice. A second example of massive ice, measuring 90 m in lateral extent, was also identified at Little Chicago using data interpreted from 2008 drillers` logs in conjunction with GPR facies analysis. In the Lac des Bois, Colville Hills area, massive ice measuring 50 m horizontally and with a maximum thickness of 1.7 m was detected in an area of active thermokarst.
The successful identification of massive ice at three sites from two different field areas highlights the effectiveness of GPR in detecting and mapping such occurrences, while emphasizing the importance of complementary data in studies using GPR as a primary methodology.