Between the Cretaceous granitic rocks (Hake Batholith on the west; Cassiar Batholith to the east) are three belts of metamorphic rocks, collectively part of Yukon-Tanana terrane. These are remnants of oceanic and continental volcanic arcs, and marginal basin sediments of Early to mid-Paleozoic age. At the head of Borden Creek are thick carbonate and andesitic volcanic rocks correlated with Klinkit Group. The Ram Creek fault and Hidden Lake fault are not exposed but deduced to be steeply dipping brittle structures with northeastward thrust or transpressional offset, based upon more complete exposure to the southeast in 105B/3 map area. The former is likely of Cretaceous age; the latter was active between mid-Permian and Early Jurassic time.

Recent mapping in the ‘Windy McKinley’ terrane of Stevenson Ridge area of western Yukon defined two subdivisions of the terrane, an imbricated ophiolite and a succession of predominantly fine-grained, variably carbonaceous and calcareous clastic rocks extensively intruded by Middle Triassic gabbro. Further work in 2007 has revealed a third subdivision of felsic metavolcanic and carbonaceous clastic rocks, also spatially associated with voluminous gabbro. The two subdivisions of the terrane containing gabbro are reminiscent of the two subdivisions of the Delta district of Alaska, and gabbroic rocks from the two areas are coeval and geochemically similar. If the Stevenson Ridge successions correlate with those of the Alaska Range, the mineral potential of the Stevenson Ridge area would be appropriately increased.

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The study area provides a clear record of the Proterozoic geological evolution of northern and central Yukon Territory. The area lies in the Wernecke Mountains of east-central Yukon, approximately 150 km north-northeast of the town of Mayo, and 20 km west of the Yukon-Northwest Territories border. The rocks record events of sedimentation, magmatism and deformation ranging in age from Early Proterozoic to Tertiary. Rocks of Early Proterozoic age predominate, but strata of Middle Proterozoic, Late Proterozoic, and Early Paleozoic ages are also abundant.

Reprocessing of magnetic data for Yukon was performed between November 2016 and March 2017. Aeromagnetic data were compiled, data of different resolutions were merged, and a series of images individually levelled for each map sheet were produced. For each 250k-scale map, the following magnetic derivative maps were produced: 1. Residual Total Magnetic Field; 2. Reduced-to-Pole Magnetic Field (RTP); 3. First Vertical Derivative of the Reduced-to-Pole Magnetic Field (RTP_VD); and 4. Tilt Derivative of the Reduced-to-Pole Magnetic Field (RTP_TDR). These maps are provided as pdfs, geotiffs and Geosoft grid files. Colour ramps/legends are provided for each map.

Reprocessing of magnetic data for Yukon was performed between November 2016 and March 2017. Aeromagnetic data were compiled, data of different resolutions were merged, and a series of images individually levelled for each map sheet were produced. For each 250k-scale map, the following magnetic derivative maps were produced: 1. Residual Total Magnetic Field; 2. Reduced-to-Pole Magnetic Field (RTP); 3. First Vertical Derivative of the Reduced-to-Pole Magnetic Field (RTP_VD); and 4. Tilt Derivative of the Reduced-to-Pole Magnetic Field (RTP_TDR). These maps are provided as pdfs, geotiffs and Geosoft grid files. Colour ramps/legends are provided for each map.

Reprocessing of magnetic data for Yukon was performed between November 2016 and March 2017. Aeromagnetic data were compiled, data of different resolutions were merged, and a series of images individually levelled for each map sheet were produced. For each 250k-scale map, the following magnetic derivative maps were produced: 1. Residual Total Magnetic Field; 2. Reduced-to-Pole Magnetic Field (RTP); 3. First Vertical Derivative of the Reduced-to-Pole Magnetic Field (RTP_VD); and 4. Tilt Derivative of the Reduced-to-Pole Magnetic Field (RTP_TDR). These maps are provided as pdfs, geotiffs and Geosoft grid files. Colour ramps/legends are provided for each map.