Geology of Uranium and Other Mineral Occurrences in the Andrew Lake Area, Canadian Shield, Northeastern Alberta (NTS 74M/16)

Alberta Geological Survey recently completed field and analytical work in the northeastern corner of the Alberta shield, which confirmed elevated radioactivity values at several locations south of Andrew Lake. Since the 1950s, the Andrew Lake-Waugh Lake area of the Alberta shield has been identified as an area of mineral exploration interest, particularly for uranium. Companies actively explored it in the 1960s and again in recent years. In the summer of 2006, Alberta Geological Survey mapped and sampled near Andrew and Waugh lakes to better understand the geological context, with direct metallogenic implications for the Alberta portion of the Canadian Shield.

We re-examined and sampled previously identified mineral occurrences on the west side of Pythagoras and Lindgren lakes, as well as several clusters of radioactive sites south of Andrew Lake. We confirmed elevated radioactivity values south of the elbow of the west arm of Andrew Lake, on the prominent peninsula at the north end of Spider Lake and at a few sites north of Cherry Lake.

Observations suggest that uranium enrichment was related to pegmatite veining during ductile deformation within the migmatitic Rutledge River Complex, and to minor shear zones and brittle faults. Granitoid bodies show only slightly elevated radioactivity at apparently randomly distributed spots, and mylonitic gneiss within the Taltson basement complex appears essentially barren of anomalous radioactivity. However, the extent of individual sites is limited. Furthermore, the authors did not observe in the Andrew Lake area the intense carbonate metasomatism that typically affects basement rocks in the Beaverlodge vein-type and Athabasca unconformity-type uraniferous zones.