Notch

Prospect, Active

Alternative names

Golden Range

Commodities and mineralogy

Main commodities Ag; As; Au
Ore minerals arsenopyrite; gold
Gangue minerals carbonate minerals; quartz

Geographic location

Quadrangle map, 1:250,000-scale GU
Quadrangle map, 1:63,360-scale D-1
Latitude 62.8914
Longitude -143.9986
Nearby scientific data Find additional scientific data near this location
Location and accuracy The Notch prospect is about 13.0 miles north of Slana. It is 3.1 mile northwest of VABM 6677 'Ahtell', near the center of section 24, T. 3 S., R. 7 E. The location is accurate.

Geologic setting

Geologic description

The rocks in the area of the Notch prospect are diorite and quartz diorite of the Permian to Pennsylvania Ahtell pluton (Richter, 1966; Richter and others, 1975; Wilson and others, 1998; Corvus Gold Inc., 2012). The rocks are cut by extensive dike swarms and faults. The mineralization is on the northeast side of a regional-scale northwest-striking fault.
The Notch prospect may have been sampled in 1980 when WGM Inc. on behalf of the Ahtna Native Corporation searched for the source of geochemical anomalies in gold that outlined a northwest-trending area several miles long that WGM had identified in 1979 (WGM Inc., 1979, 1980). In 1980, they collected several rock samples at scattered locations along the trend that contained up to 3,260 parts per billion (ppb) gold.
In 2010, Corvus Gold Inc. revisited the area, outlined an area of mineralization 2 by 9 kilometers in size, and called it the Golden Range target. They collected more than 300 rock and soil samples in the area. The 151 rock samples averaged 0.6 gram of gold per tonne; 29 of the 151 had more than 0.10 gram of gold per tonne, and the best had 50.4 grams of gold per tonne.
By 2011, Corvus had identified at least 5 prospects in the Golden Range target area that they had sampled and drilled (Corvus Gold, Inc., 2012). One is the Notch prospect where they drilled 7 holes totaling 1,674 meters and dug 4 trenches that totaled 104 meters.
The Notch drilling defined a mineralized, east-west striking shear zone that can be traced for more than a kilometer; it is 40-60 meters thick and dips south. The shear zone is highly altered. The alteration consists of pre- to syn-mineralization sericitic alteration followed by syn- and postmineral carbonate and iron-carbonate alteration. The shear zone hosts arsenopyrite-quartz veins which commonly are folded and disarticulated. The hanging wall of the zone is quartz diorite; the footwall is diorite. The mineralized shear zone is offset by a steep north-dipping fault that offsets the zone for about 40 meters. The drilling indicates that the mineralization continues down dip for at least 250 meters. Some notable intercepts are: 1)15.8 meters with 23.19 grams of gold per tonne and 1.93 grams of silver per tonne; 2) 12.3 meters with 1.60 grams of gold per tonne and 1.93 grams of silver per tonne; 3) 44.9 meters with 0.34 grams of gold per tonne and 0.68 grams of silver per tonne; 4) 16.9 meters with 1.99 grams of gold per tonne, and 5) 5.1 meters with 4.57 grams of gold per tonne.
Geologic map unit (-144.00080651273, 62.8910142167738)
Mineral deposit model Mineralized zone with arsenopyrite-quartz veins (Cox and Singer, 1986; model 22c).
Mineral deposit model number 22c
Age of mineralization Younger than the Permian to Pennsylvanian host rocks.
Alteration of deposit Pre- to syn-mineralization sericitic alteration followed by syn- and postmineral carbonate and iron-carbonate alteration.

Production and reserves

Workings or exploration
The Notch prospect may have been sampled in 1980 when WGM Inc. on behalf of the Ahtna Native Corporation searched for the source of geochemical anomalies in gold that outlined a northwest-trending area several miles long that WGM had identified in 1979 (WGM Inc., 1979, 1980). In 1980, they collected several rock samples at scattered locations along the trend that contained up to 3,260 parts per billion (ppb) gold.
In 2010, Corvus Gold Inc. revisited the area, outlined an area of mineralization 2 by 9 kilometers in size, and called it the Golden Range target. They collected more than 300 rock and soil samples in the area. By 2011, Corvus had identified at least 5 prospects in the Golden Range target area that they had sampled and drilled (Corvus Gold, Inc., 2012). One is the Notch prospect where they drilled 7 holes totaling 1,674 meters and dug 4 trenches that totaled 104 meters.
Indication of production None
Reserve estimates None.
Production notes None.

References

MRDS Number 10307496

References

Corvus Gold Inc., 2012, Chisna: http://www.corvusgold.com/projects/alaska/chisna/ (as of March 1, 2012).
Myers, Russell, Brown, Chris, Taylor Christ, Wilkins, Andres, Burnett, Bill, Stroup, Caleb, Keeley Josh, Benchley, Kristen, Robinson, John, Van Wyck Nick, and Jacobs, Joe, 2011, Golden Range- A new high grade gold discovery in Alaska: Alaska Miners Association, 2011 Annual Convention Abstracts, p. 37.
Richter, D.H., Lanphere, M.A., and Matson, N.A., Jr., 1975, Granite plutonism and metamorphism, eastern Alaska Range, Alaska: Geological Society of American Bulletin, v. 86, p. 819-820.
WGM Inc., 1979, 1978 Annual Progress Report, Uranium Exploration, Ahtell Creek Area, Volume I: WGM Inc., 39 p., appendices, 4 maps. (Report available, Ahtna Mineral Co., Anchorage, Alaska).
WGM Inc., 1980, 1979 Summary report of gold potential, Slana District, Ahtna project: WGM Inc., 10 p., map, scale 1:63,360. (Report held by Ahtna Mineral Co., Anchorage, Alaska).
Reporters W.T. Ellis (Alaska Earth Sciences), C.C. Hawley (Hawley Resource Group), and W.J. Nokleberg (U.S. Geological Survey); D.J. Grybeck (Contractor, USGS)
Last report date 4/1/2012