Open File Report 1994-08

Open File Report 1994-08

OFR 1994-08

Regional Metallogenic Evaluation of Alberta

Alberta's geology is both complex and diverse. Proterozoic to Tertiary sedimentary and, locally, volcanic rocks overlie Proterozoic and Archean metamorphic and granitoid rocks. In general, the province can be broadly divided into (a) the northeastern Precambrian Canadian Shield, (b) the Plains Region, and the Rocky Mountains and Foothills. To the west in the Cordillera, fault and fold structures are common, Although most of this faulting is related to Laramide Orogeny which produced the Rocky Mountains and Foothills, there are also several other faults and fault zones that are related to older tectonic events. To the east, in the Plains region, faults are uncommon but they do exist in a few places. As well, there are a number of other anomalous structural features, such as the Steen River Anomaly, the Eagle Butte Anomaly, and numerous collapse structures related to dissolution of the Phanerozoic evaporites in the Plains Region. Igneous rocks are uncommon in Alberta, but do occur locally in at least Proterozoic, Devonian, Cretaceous and Tertiary strata.

The reconnaissance metallogenic study has identified in excess of 630 mineral occurrences, or geological, geochemical or geophysical anomalies in Alberta. These occurrences comprise a diverse suite of metals and minerals including precious metals, base metals, uranium, iron and even diamond occurrences in surficial sediments or, possibly, bedrock. Although there are more known mineral occurrences in the Precambrian rocks of northeastern Alberta and in the Proterozoic to Tertiary rocks of southwest Alberta than in the Plains Region or in the central to northern Mountains and Foothills Region, this may be a reflection of a greater intensity of past exploration rather than the Plains Region or the northwestern part of the Alberta Cordillera being geologically less favourable.

Potential exists in Alberta for the discovery of a large number of diverse metallic and precious mineral deposits. These include both syngenetic and epigenetic precious metal deposits, base metal deposits, uranium deposits, and bedrock and alluvial diamond deposits. Some of the potential deposit types that may be present in Alberta include: (a) both bonanza lode and disseminated epithermal gold deposits; (b) Mississippi Valley type lead-zinc deposits; and sediment hosted base metal deposits comprised of one or more of zinc, lead, copper and nickel with, possibly, associated precious; (d) volcanogenic massive sulphide base metal deposits; (e) granitoid-related precious metal and base metal deposits; (f) Olympic Dam type copper-uranium-gold-silver deposits; (g) magmatic-related nickel-copper deposits; (h) sediment hosted oolitic iron deposits; (I) unconformity-related, sandstone hosted or vein type uranium deposits, or uraniferous coals or conglomerates; (j) diamondiferous diatremes; and (k) various types of placer or paleoplacer deposits with the important placer metals/minerals being gold, magnetite, diamonds or other 'heavy minerals' of economic interest.

Olson, R.A., Dufresne, M.B., Freeman, M.E., Richardson, R.J.H. and Eccles, D.R. (1994): Regional metallogenic evaluation of Alberta; Alberta Research Council, ARC/AGS Open File Report 1994-08, 227 p.