Lithostratigraphy and structure of the eastern Amer group, Nu, using combined surface mapping and enhanced sub-surface geophysical data

Abstract

The uranium-hosting, Paleoproterozoic Amer Group comprises four lithological sequences (Ps1 through Ps4) unconformably overlying Archean basement of the Rae sub-province. The deformational geometry and history of the Amer Belt was re-evaluated by integrating field mapping data with legacy data from previous works. Deformation of the Amer Belt details the aggregation of the supercontinent Nuna during the Trans-Hudson orogen. Four deformation events are identified: D1 produced multiple transposition and displacement along discrete, sub-horizontal detachments resulting in tectono-stratigraphy, D2 generated upright synclinoria and thrusts, D3 open folds are rare, and D4 transtensional faults. Distribution of uranium occurrences is concentrated in the area of the Amer Belt that accommodated the greatest amount of transpression and faulting during D4. Geological observations were correlated with patterns in high resolution aeromagnetic maps and in subsurface models for magnetic susceptibility to develop a framework for extending mapping into regions of the Amer Belt with limited outcrop. A 1:50 000 scale GIS-based map of the eastern Amer Belt was produced.