General Information
Capsule
The Einarson district is underlain by sedimentary rocks of the Selwyn Basin deposited in a marine environment along the margin of ancestral North America from Late Proterozoic into Paleozoic times, following the breakup of the Rodinia supercontinent. These rocks comprise siliciclastic units like argillites, shales, sandstones grading to quartz pebble conglomerates with varying degrees of carbonate content, interlayered with carbonate units like limestones and dolomites, with minor turbidite and debris flow units.
The oldest units in the area are the Yusezyu and Algae Lake formations, comprising mainly arenites and carbonates respectively. These are overlain by the Narchilla formation, which has its basal Senoah member, which are overlain by the distinctive maroon and green argillites and shales of the Arrowhead Lake member, and the clastic Gull Lake formation, which includes minor volcanic units. Instances of the overlying Old Cabin volcanic formation are also present in the project area.
Structurally, the Einarson district sits in a broad zone of tectonic flexure, wherein major east-west trending features like the Dawson thrust and the Kathleen Lakes fault west of the district give way to a network of northwest-southeast and north-south trending deep-seated faults at Einarson (Moynihan, 2014). South of Einarson, this tectonostratigraphic package wraps around further in a 10’s-of-km wide synclinal feature attributed to motion along the Hess-Macmillan Fault system, the nose of which is intruded by members of the Cretaceous Emerald Lake plutonic suite south of Einarson. This deformation has resulted in a high degree of shortening, particularly in the upper Narchilla formation and above.
Steeply dipping faults cut stratigraphy that is relatively flat lying on a regional scale, but variably folded at smaller scales depending on formation. The Yusezyu and Algae Lake formations and the Senoah member of the Narchilla formation form broad anti- and synclinal features across the district, with large (multiple km-scale) faulted anticlines corresponding to three domal structural features that expose both Yuzesyu and Algae Lake formations. Within the Narchilla formation, between the Senoa and Arrowhead Lake members, is a detachment surface that sees heavy isoclinal folding and shortening of up to 80% in overlying units, including the Gull Lake and Old Cabin formations.
Grid soil sampling across the Waldo and Emerson claim blocks revealed an open, 500 m by 400 m gold in soil anomaly on the Emerson block, accompanied by elevated to anomalous arsenic and antimony. A float grab sample of limestone below this anomaly returned 0.508 g/t Au, while an outcrop grab sample of limestone roughly 1 km to the north returned 0.542 g/t Au.
Work History
Date | Work Type | Comment |
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4/1/2013 | Geochemistry | |
4/1/2013 | Geology | |
4/1/2013 | Geochemistry | |
4/1/2013 | Geochemistry | |
4/1/2012 | Geochemistry | |
4/1/2012 | Geochemistry | |
4/1/2012 | Geology |
Related References
Number | Title | Page(s) | Reference Type | Document Type |
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2014-1 | Geological map of NTS 106B/04, east-central Yukon | Yukon Geological Survey | Open File (Geological - Bedrock) |