The co-operative Western Superior project produced a predictive model for high and low mineral potential assemblages and terranes, actively promoting and assisting mineral exploration. For example, the project demonstrated that gold deposits of the Red Lake mining camp, previously considered to be shear-zone hosted, have predictable stratigraphic settings related to belt-scale unconformities.

Western Superior NATMAP and Lithoprobe projects

Synopsis

These coordinated projects brought the expertise of government and university workers to bear on processes of crustal development in a mineral-rich part of the Canadian Shield and their relationship to gold, base metal and diamond deposits.

Rationale

The Western Superior Province hosts several world-class gold and base metal deposits and continues to attract significant exploration investment. To provide a first-order exploration guide, the projects revised the tectonic framework by determining the distribution of and contact relationships between older continental terranes and younger oceanic/arc crustal fragments.

Approach

Coordination effort by Geological Survey of Canada, Ontario Geological Survey, Manitoba Geological Survey and the Western Superior Lithoprobe project targeted two corridors in the developed southern part of the region, and in a frontier northern transect. Work within these areas involved integration of new and compiled information to produce belt-scale and regional maps. The Lithoprobe transect tested tectonic models of the western Superior Province through lithospheric imaging and associated surface studies.

Geology

Fragments of continental and oceanic crust were tectonically accreted between 2715 and 2680 million years ago to form the Superior Province. Rocks as old as 3600 Ma make up part of the northern Superior superterrane, one of several continental fragments separated by younger greenstone belts. Both gold and volcanogenic massive sulphide deposits are hosted by volcano-sedimentary arc sequences built on continental margin crust between 2990 and 2700 Ma. Seismic data provide support for the operation of subduction and accretion processes during tectonism in the form of mantle reflectors and high-velocity material interpreted as underthrust oceanic crust.

Outcomes

Results of the project serve as basis for land-use decisions, and as a guide future northern exploration and development initiatives. Discovery of Northern Superior ancient crust has provided new diamond exploration targets in northern frontier regions. Discovery of regional unconformities in the Red Lake gold mining camp overturned the shear zone model of gold mineralization, resulting in a new generation of exploration programs.

Participants

Geological Survey of Canada, Ontario Geological Survey, Manitoba Geological Survey, Royal Ontario Museum, Dalhousie University, McGill University, Queen's University, University of Alberta, University of Manitoba, University of Ottawa, Université du Québec à Montréal, University of Saskatchewan, University of Toronto, University of Waterloo.

More Information

For more information about this project, contact Dr. John Percival