Open File Report 1991-06

Open File Report 1991-06

OFR 1991-06

Geology and Metallic Mineral Potential of Northeastern Alberta

This report provides a general background for geologists unfamiliar with the region. It contains an extensive bibliography to the publications which supply our knowledge on Alberta's Shield including assessment reports.

The exposed Canadian Shield of northeastern Alberta consists of a north-trending belt of Archean granite gneisses intruded by Aphebian granitoids. South of Lake Athabasca an angular unconformity separates the Helikean Athabasca Group from the underlying Shield rocks. Basement rocks outcrop both north (exposed Shield) and south (Marguerite River area) of the basin structure (Athabasca basin) in which the Helikean rocks were deposited. Geophysical information for northeastern Alberta includes regional magnetic, gravity and gamma- ay data and local electromagnetic and radiometric data from prospecting.

During routine geological mapping in the region by the Alberta Research Council over 200 mineral showings were identified. No attempt was made to prospect favourable areas nor were areas investigated between traverses at the time. In some cases these showings were prospected later by exploration interests and assessment reports filed. In thirty four cases these prospects were seen as anomalous and further work conducted. None of these has been taken to a prospect stage.

The greatest potential for metallic minerals lies within the low grade and high grade metasedimentary rocks. The majority of high grade metasediments have not been explored. If the mafic mylonites south of Lake Athabasca are derived from metasediments or metavolcanics and are associated with faults they are also excellent exploration targets.

Zones of radioactivity are associated with massive biotite granites and faults and eight of the anomaly records appear to be associated with faults, shear zones or mylonites. Faults and shear zones are favourable targets and merit close examination.

There is a strong foundation of fundamental geological information on the exposed and shallow Shield of northeastern Alberta. Although the purpose of the original mapping in the area was research and not exploration, hundreds of mineral showings were identified. This appears to have aided or initiated mineral exploration by industry. More focused investigation on the areas or formations with probable mineral potential should be sponsored and undertaken by the Provincial or Federal governments as the next step in attracting further industrial interest.

Edwards, W.A.D., Richardson, R.J.H. and Fildes, B.J. (1991): Geology and metallic mineral potential of northeastern Alberta; Alberta Research Council, ARC/AGS Open File Report 1991-06, 81 p.