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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 age (the Misty Creek Embayment of the Selwyn Basin) and Middle Paleozoic age (a post-Selwyn basin).

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, 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 west part is in the Gwichin settlement area and the east part is in the Sahtu settlement area. 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.

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

2009: Geological reconnaissance and follow-up of anomalous metals in stream silts. 

2011: Mapping by a single team for four weeks. Airborne geophysical survey.

2012: Mapping by two teams for seven weeks.

2013: Spot checks during one week.

2016: Compilation and final map (Fischer, 2016).

017: A report published on the Carlin-type gold potential of the area (Fischer, 2017). NTGS participated in a Geological Survey of Canada (GSC) mapping project covering the north part of NTS 106B.

Upcoming: The GIS data for the published map are being readied for publication, as is a report on the stratigraphy of the basinal units. A detrital zircon study of Proterozoic and Paleozoic strata (Turner) and carbon-isotope stratigraphy of the Lower Paleozoic basinal units (Turner) are ongoing. The results of the GSC’s 2017 mapping will include a bedrock map to be published by the GSC ,as well as a number of thematic studies to be published by various agencies, including NTGS.

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

Partners and Support

Dr. Elizabeth Turner, Laurentian University

Canadian Northern Economic Development Agency (SINED Program)
Polar Continental Shelf Project

Keywords

Mackenzie Mountains, bedrock, magnetic, radiometric, Road River, Duo Lake, Rabbitkettle, Hess, Marmot, Dudley, Porter Puddle, Mountain River, Arctic Red, Earn, Canol, Horn River, Imperial, Tsichu, geology, lithogeochemistry, Carlin-type, gold, zinc, lead, Au, Zn, Pb