CGRG Bibliography of Canadian Geomorphology
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Author : Campbell, J.E.; Shives, R.B.K.; and Klassen, R.A.
Date : 2003.
Title : Field investigations of airborne gamma ray spectral domain D, NEA-IAEA Test Area, eastern Athabasca Basin.
Publication : Summary of Investigations 2003 Volume 2, Saskatchewan Geological Survey, Saskatchewan Industry and Resources, Miscellaneous Report
Issue : Rep. 2003- 4.2.
Page(s) : Paper D-2, 14 p.
Abstract
Previous work in the NEA-IAEA test area, eastern Athabasca Basin, defined spectral domains based on prominent K-eU-eTh spectral patterns in airborne gamma ray survey data. Within the Basin, these domains reflect variation in sandstone lithology, bedrock structures and proportions of intra-(sandstone) and extra-(crystalline) basinal glacial detritus. A narrow, southwest-trending curvilinear K- and eU-rich trend referred to as the D domain, or "ribbon", is enigmatic. The "ribbon" has previously been modeled as a dispersal train of granitic boulders related to an older ice flow direction, and as the surface expression of local bedrock alteration. Preliminary work suggested that the "ribbon" domain spectral patterns may reflect a poly-genetic Quaternary feature. Field investigations in 2003 focused on determining the source(s) of the spectral signatures of the D Domain. Three additional sampling transects across the "ribbon" were completed up-ice of the previous Black Lake Road transect. The D domain does not appear to have any geomorphic association, as it crosses a variety of surficial deposits, including veneer (< 2m thick) and blanket (>2 m thick) ground moraine, streamlined moraine and stagnant ice hummocky moraine. The contact between domain D and the eTh-rich A domains is marked by a sharp compositional change in the till. Although compositionally variable, the surface material in D domain is predominantly crystalline-rich till. The greatest variability in sandstone versus crystalline composition is associated with the hummocky moraine. The highest proportion of crystalline detritus is found in the ground moraine. At several sites within the D domain a veneer of crystalline rich till overlies a more sandstone- rich till. This is opposite to the regional occurrence of sandstone -rich till capping crystalline-rich till. Preliminary field observations indicate the source of the "ribbon"'s radioactive element signature is K - U-(and Th)-bearing megacrystic calc-alkaline boulders which are more abundant in domain D relative to other spectral domains, including the moderately K and eU-rich B domain. These boulders are probably derived from the Late Hudsonian porphyritic calc alkaline granites and related granitoids in the western Wollaston Domain. No field evidence of a sandstone-derived source for the radioactive element signature of the "ribbon" was found. The D domain is a Quaternary feature composed predominantly of crystalline detritus derived from outside the Basin. Physical and compositional characteristics of the "ribbon" feature cannot be explained by simple down-ice glacial dispersal mechanisms. The genesis of this Quaternary feature is unresolved but appears to be at least in part related to the late southerly ice flow.
Bibliography of Canadian Geomorphology