The Granite Creek map area includes the southwestern section of the Gustavus Range. This area hosts summits approximately 2000 m in elevation. Granite and Albert creeks drain into Roop Lakes, through the wide, u-shaped lower Granite Creek valley. Keystone Creek flows in a narrow, bedrock-controlled valley. Lower Granite creek flows through the middle of the valley, depositing modern fluvial gravel and a blanket of organic material on the floodplain. Till from four alpine sources, as well as from the Cordilleran Ice Sheet (CIS), blanket the lower valley and intermix with glaciolacustrine sand and silt. Glaciolacustrine sediment can also be found capping moraines, and on valley walls above lateral moraines deposited when the CIS advanced up lower Granite Creek valley. Glaciofluvial gravel forms a proglacial fan where the former Granite Creek alpine glacier terminated and meltwater channels mark most former ice margins of the CIS. Till from the most recent glaciation is found in alpine glacier and Cordilleran Ice Sheet moraines, as well as in cirque valleys as blankets and veneers where preserved. Loess forms blankets on most gentle slopes, which allows for its preservation. Colluvium veneers, blankets, and fans form below steep slopes with active rockfall. Bedrock outcrops along steep cirque headwalls and in cirque valleys, as well as in Keystone Creek where fluvial downcutting processes are active. Stone stripes formed by frost heaving are found on gentle slopes. Flat upland surfaces host weathered bedrock and mud boils.

Quantitative gamma-ray spectrometric and aeromagnetic helicopter-borne geophysical survey was completed by Fugro Airborne Surveys. The survey was flown from September 10 to October 14, 2008. The nominal traverse and control line spacings were 400 m and 2400 m respectively, and the aircraft flew at a nominal terrain clearance of 125 m. Traverse lines were oriented at 0 degrees with orthogonal control lines.

This map of the total magnetic field was derived from data acquired during an aeromagnetic survey carried out by EON Geosciences Inc. in the period between April 10, 2009 and September 16, 2009. The data were recorded using split-beam cesium vapour magnetometers (sensitivity =0.005 nT) mounted in each of the tail booms of a Piper Navajo and a Cessna 206 aircraft. The nominal traverse and control line spacings were, respectively, 800 m and 2 400 m, and the aircraft flew at a nominal terrain clearance of 250 m. Traverse lines were oriented N90°E with orthogonal control lines. The flight path was recovered following post-flight differential corrections to the raw Global Positioning System data and inspection of ground images recorded by a vertically-mounted video camera. The survey was flown on a pre-determined flight surface to minimize differences in magnetic values at the intersections of control and traverse lines. These differences were computer-analysed to obtain a mutually levelled set of flight-line magnetic data. The levelled values were then interpolated to a 200 m grid. The International Geomagnetic Reference Field (IGRF) was not removed from the magnetic field.

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This aeromagnetic survey was carried out by Goldak Airborne Surveys from February 17, 2014 to March 21, 2014. The data were collected using split-beam cesium vapour magnetometers mounted in each of the tail booms of 2 Piper Navajo aircraft. Nominal traverse and control line spacings were 400 and 1400 m, and the nominal terrain clearance was 125 m.

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.

The aeromagnetic survey was carried out by Goldak Airborne Surveys and data were acquired from March 10 to July 6, 2017. Spacing for the nominal traverse and control lines were 400 m and 2400 m, respectively. Nominal terrain clearance was 150 m.

Aurora Geosciences Ltd was contracted to perform a review of publicly available digital magnetic geophysical data submitted with assessment reports to develop standardized products and compilations. Data submitted prior to March 2015 were considered. Individual assessment report data were levelled and integrated with 1:250 000 compilations. Four gridded PDFs have been produced (residual total magnetic field, reduced to pole, vertical derivative and tilt derivative). Original 250k geophysical data can be found in YGS Open File 2017-36.

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.