CGRG Bibliography of Canadian Geomorphology
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Author : Doupe, J.; England, J.; Doornbos, C.; Heaman, L.; Furze, M.; and Lajeunesse, P.
Date : 2005.
Title : Erratic Rocks, Erratic Bears: Determining the provenance of glacial erratics and a grizzly bear on Melville Island, N.W.T. and Nunavut, Canada
Publication : 35th Annual International Arctic Workshop. March 9-12, 2005. Timms Centre for the Arts, University of Alberta, Edmonton, Alberta, Canada.
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Abstract
Part I: Erratic Rocks - As an extension of the Doornbos et al. provenance study on glacial erratics (this conference), 18 glacial erratic samples collected on Melville Island over three field seasons (2002-2004) were submitted for petrographic, geochemical, and geochronological analyses. Most of these samples are various types of gneiss (12), along with quartzites (4), granite and diabase (1 each). The radiometric age of suitable samples was determined by Laser Ablation–Multicollector–ICP-MS in situ U-Pb dating of zircon grains in thin section. Initial results on a gneiss sample from the Sabine Peninsula, Northeastern Melville Island, Nunavut have demonstrated that the technique is highly precise and reproducible. Five analyses on four zircon grains in this sample yielded an age of 2474.9 ± 9.4 Ma. Erratic ages in the eastern part of Melville Island tend to be older than those in the west, perhaps corresponding to different source provinces in the Canadian Shield. Part II: Erratic Bears - For the past two field seasons (2003 and 2004), expeditions to Melville Island led by Dr. John England have encountered evidence of grizzly bears (Ursus arctos). These observations represent the most northerly observations of grizzly bears ever recorded, and add to several sightings reported over the past decade to the south of Melville Island. In the 2003 field expedition, a grizzly bear was observed from a helicopter over Cape Clarendon, whereas in 2004, photographs of tracks and a hair sample were obtained from a ‘polar bear cabin’ at Cape Providence. This sample provided enough DNA for microsatellite analysis, generating a 15 marker microsatellite genotype. This analysis indicated that the hair sample genotype strongly clustered with those of Barren Ground Grizzly Bears, and not with those of Viscount Melville Polar Bears. Additional analyses determined that this individual was male. More research will be required to determine long-term population trends in this region, as well as possible consequences for the long-established polar bear population.
Bibliography of Canadian Geomorphology