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The uranium-hosting Paleoproterozoic Amer Group, central Nunavut, comprises four dominantly sedimentary sequences (Ps1 through Ps4) deposited unconformably on Archean basement of the Rae sub-province. Ps1 is characterized by Ayagaq fm. quartzites formed in a stable cratonic and/or marine setting, with minor conglomerate and/or a distinctive schist at its base. PS2 is a sharply transgressive sequence of graphitic siltstone (Resort Lake fm.) shallowing up to dolostone (Aluminium River fm.) and intercalated to overlying porphyritic basalt (Five Mile Lake fm.). Ps3 comprises three units recording an overall coarsening- then shallowing-upward sequence involving siltstone to feldspathic arenite (Three Lakes, Oora Lake and Showing Lake formations). Ps3 is the primary host of U-mineralization in this region. Ps4 arkose (Itza Lake fm.) is preserved as isolated occurrences above a profound unconformity. The Amer Group is intensely deformed. D1 produced multiple transposition (three fold generations) and displacement along discrete detachments resulting in sub-horizontal axial surfaces and tectono-stratigraphy. D2 generated the regional, generally upright synclinoria, and is separated from D1 by the Ps3-Ps4 unconformity. Late D3 folds with sub-horizontal axial surfaces are rare. The region is transected by arrays of ENE- and NW- trending faults. Elucidation of the structure of Ps3 units is central to determining the distribution of U-mineralization in the Amer Group. The difficulties of dealing with a polydeformed terrane are exacerbated by the absence of exposure in critical areas. This problem has been overcome by integrating detailed outcrop examination with high-resolution aeromagnetic data, and legacy drill hole data. The analysis is dependent on the strong, but distinct magnetic responses of the euhedral disseminated magnetite-bearing fine siliciclastic Three Lakes and Showing Lakes formations that, in preserved stratigraphic sequences, are separated by the Oora Lake fm. The aforesaid approach has enabled identification of a consistent, yet distinctly different geometry for the Amer Group "basins". In contrast to the apparent straightforward structure of the regional D2 synclinoria, it is demonstrated that the D1 tectono-stratigraphy forms large, regional recumbent structures masked by the lack of outcrop, but for which evidence occurs at all scales and within separate data sets i.e. field, geophysics, drill hole. The occurrence in some areas of elongate "cigar-shaped" mineralized zones reflects U-concentration within D1 hinge zones coaxially overprinted by D2. The success of this study in integrating diverse data bases, especially high-resolution geophysics and detailed outcrop mapping, argues for the future extension of such approaches.

A quantitative pollen and spore zonation for the Neogene and Quaternary of Yukon, western Northwest Territories and central and northern Alaska has been assembled from seven sections and one borehole. The palynological spectra from 163 samples from these sections were grouped and averaged within the groups to produce twenty-one composite spectra that depict the long-term pattern of vegetation change. The oldest record included in the study is estimated to be within the late Early Miocene (ca. 18.3 Ma) and the record extends to the late Quaternary. Pollen and spores are grouped and summed by environmental tolerances and physiognomy of the modern families and genera of plants to which they are related. Using these groups, pollen and spore ratios are drawn to track environmental parameters - temperature, forest canopy cover, and paludification of the study sites. Biostratigraphic and paleoecological patterns are explained in terms of known changes in global climate and the climatic effects of regional tectonics. Six assemblage zones and five subzones are proposed to describe the palynological succession.