Three Cub

Occurrence, Inactive

Commodities and mineralogy

Main commodities Ag; Au; Cu; Pb; Sb; W; Zn
Ore minerals arsenopyrite; chalcopyrite; galena; pyrite; scheelite; sphalerite; stibnite
Gangue minerals barite; carbonate; quartz

Geographic location

Quadrangle map, 1:250,000-scale LH
Quadrangle map, 1:63,360-scale D-2
Latitude 61.7659
Longitude -153.6342
Nearby scientific data Find additional scientific data near this location
Location and accuracy
This occurrence is on the north side of a hanging-glacier moraine in the headwaters of an unnamed south tributary to uppermost Fish Creek. It is at an elevation of about 4,800 feet, 0.9 mile north of peak 6590. The map site is in the NE1/4 section 4, T 19 N, R 24 W, of the Seward Meridian.
This occurrence is sample locations 823 and 824 of Allen and others (1990), Allen and Slaughter (1990), and Allen (1991).

Geologic setting

Geologic description

Thin, sulfide-bearing quartz veins, generally less than 15 cm wide, locally crosscut Jurassic or Lower Cretaceous graywacke and Upper Cretaceous or Tertiary granitic rocks at this locality (Allen, 1990; Allen and others, 1990; Allen and Slaughter, 1990). The veins consist dominantly of quartz, carbonate, pyrite, and arsenopyrite, and less commonly contain barite, chalcopyrite, stibnite, galena, and sphalerite. Some aplite dikes, quartz veins, and pyrite-bearing fracture surfaces in the granitic rocks contain scheelite and arsenopyrite. Calc-silicate skarn is very locally developed in sedimentary rocks adjacent to the granitic rock contacts. Quartz veins in graywacke contain as much as 1.3 ppm gold, 70 ppm silver, 3,000 ppm copper, and 500 ppm zinc. A sample from a sulfide-rich quartz-carbonate vein at a granitic rock contact contained 1.9 ppm gold, 150 ppm silver, 2,000 ppm arsenic, 150 ppm bismuth, 1,000 ppm lead, 1,000 ppm antimony, 50 ppm tin, and 3,000 ppm zinc. Although scheelite has been reported in quartz veins from the general area, samples at this locality contained less than 20 ppm tungsten. The granitic rocks are part of the Alaska-Aleutian Range batholith (Reed and Lanphere, 1973).
Geologic map unit (-153.636441201793, 61.76526314877)
Mineral deposit model Polymetallic veins (Cox and Singer, 1986, model 22c)
Mineral deposit model number 22c
Age of mineralization Late Cretaceous or Tertiary. The veins crosscut Upper Cretaceous or Tertiary granitic rocks of the Alaska-Aleutian Range batholith.
Alteration of deposit Silicification and local calc-silicate skarn.

Production and reserves

Workings or exploration Surface observation and sampling has occurred at this locality.
Indication of production None

References

MRDS Number 10307756

References

Nokleberg, W.J., and (seven) others, 1994, Metallogeny and major mineral deposits of Alaska and Metallogenic map of significant metalliferous lode deposits and placer districts of Alaska, in Plafker, G. and Berg, H.C., eds., The Geology of Alaska: Geological Society of America, DNAG, The Geology of North America, Vol.. G1, p. 855-904, Plate 11, scale 1:2,500,000.
Reed, B.L., and Lanphere, M.A., 1973, Alaska-Aleutian Range batholith--Geochronology, chemistry, and relation to circum-Pacific plutonism: Geological Society of America Bulletin, v. 84, no. 8, p. 2583-2610.
Reporters Travis L. Hudson and Madelyn A. Millholland
Last report date 6/10/2001