Menu Search

Selwyn-Mackenzie Shale Basins

Selwyn-Mackenzie Shale Basins

Sharp mountains partly covered by snow, cloudy stormy grey sky

Description

A previously poorly understood area of the northern Mackenzie Mountains was mapped to improve understanding of its geological history and potential to host economic deposits of metals. Mapping focussed on shale-dominated strata deposited in paleo-basins of Lower Paleozoic and Middle Paleozoic age (roughly 540 to 350 million years old).

A colored bedrock geology map, showing the geographic extent of each rock unit in a different colour.

Location

Mapping took place in the Backbone Ranges, which are in the heart of the Mackenzie Mountains (National Topographic System mapsheet 106B, Bonnet Plume sheet). Rugged mountains, including the Source Peaks at Four-Way Pass, are glaciated throughout the summer and feed the watersheds of the Mountain and Arctic Red rivers, which drain north and east into the Mackenzie River. The project area lies about midway between Norman Wells, NWT and Mayo, YT, and covers 7300 km2. The western part is in the Gwichin settlement area and the eastern part is in the Sahtu settlement area.

Mountain peaks from helicopter. Mountains are made of layered dark to pale grey rocks. Dark scree slopes are shale, pale bands are resistant carbonate. Sky intense blue.

Justification

The area is prospective for zinc-lead deposits of the same type as the world-class Howard’s Pass deposit to the south.  It is also prospective for Carlin-type gold, a class of deposit discovered for the first time in Canada 60 km southwest of the project area (Rackla trend).  Moreeover, the geological history of the area is relevant to understanding the tectonic development of the northern Canadian Cordillera. Despite the economic potential of the area and because of its remoteness, previously published bedrock-geology maps are preliminary and lack detail. Improving the map database enables exploration efforts to be better focussed, lessening the risk inherent in exploration activity.

In foreground is male geologist walking toward us with head down, hat on, hammer dangling from hand, pack on back, "surveyor's" vest. Ground drops away behind him to braided river far below, dark mountains of subvertical strata beyond river.

Approach

Mapping at a range of scales in selected areas was supplemented by petrographic studies, geochemistry, biostratigraphy, and an airborne magnetic and radiometric survey. New mapping was combined with pre-existing data from federal government studies and industry exploration activities to generate the new bedrock geology map.

From helicopter looking down & across. Eroded mountains with smooth tops, gullies; silvery grey on upper slopes, yellow-green with vegetation on lower slopes, intermittent resistant bands describe open folds. Sliver of sky is darkly cloudy.

Schedule

Geological reconnaissance and follow-up of anomalous metals in stream silts led to discovery of the Dap carbonate-hosted Pb-Zn-Cu showing in 2009. An airborne geophysical survey was undertaken in the fall of 2011. Mapping was carried out by a single team based in fly camps for four weeks in 2011, and by two teams based in a helicopter-supported camp for 7 weeks in 2012 (Fischer, 2014). A final week of spot checks in 2013 completed the field portion of the project. The new bedrock geology map has been reviewed and the final edits are being finished (Fischer). A petrographic and geochemical study of the Dudley Lake mafic-volcanic complex (Gochnauer) and a detrital zircon study of Proterozoic and Paleozoic strata (Turner) are ongoing.

A map in shades of red, cyan, and green, centered on 64.5 degrees N and 130.7 W.

Partners and Support

NTGS Participation: Beth Fischer, Karen Gochnauer
Partners:
Dr. Sandy MacCracken and Dr. Brian Norford,Geological Survey of Canada
Dr. Elizabeth Turner, Laurentian University
Dr. Victor Owen  and Dr. Jarda Dostal, St. Mary’s University
Scavo Resources
Canadian Northern Economic Development Agency
Polar Continental Shelf Project