Twin Lakes West

Occurrence, Inactive

Commodities and mineralogy

Main commodities Cu; Pb; Zn
Ore minerals chalcopyrite; galena; hematite; pyrite; sphalerite
Gangue minerals calcite; chlorite; epidote

Geographic location

Quadrangle map, 1:250,000-scale LC
Quadrangle map, 1:63,360-scale C-3
Latitude 60.68
Longitude -153.83
Nearby scientific data Find additional scientific data near this location
Location and accuracy About 2.1 km north of the eastern arm of Twin Lakes on peak 5,280. The 1.3 km wide, oval-shaped occurrence extends approximately 7.3 km S-SE across Twin Lakes, terminating near peak 5,570. Corresponds with locality 11 of Nelson and others (1985) and locality 21 of MacKevett and Holloway (1977). Sec. 22, T. 7 N., R. 26 W., of the Seward Meridian. Longitude and latitude of occurrence is accurate within 1,200 m.

Geologic setting

Geologic description

Mineralization occurs as fine-grained disseminations and hairline fracture fillings of pyrite and lesser chalcopyrite, sphalerite, and galena in silicified rhyolite and rhyolite-dacite volcanic rocks and breccias (Nelson and others, 1983). Resource Associates of Alaska (1976) considered the setting as a possible volcanic vent center. These rocks have undergone epidote and chlorite alteration, silicification, and lesser sericitization. The volcanic rocks have potassium-argon ages that range from 56.2 to 62.7 m.y. (Eakins and others, 1978).
Geologic map unit (-153.832258701794, 60.6793369735209)
Mineral deposit model Polymetallic vein? (Cox and Singer, 1986; model 22c?).
Mineral deposit model number 22c?
Age of mineralization The volcanic rocks that host the mineralization have potassium-argon ages that range from 56.2 to 62.7 m.y. (Eakins and others, 1978).
Alteration of deposit The volcanic rocks have undergone epidote and chlorite alteration, silicification, and lesser sericitization.

Production and reserves

Indication of production None
Reserve estimates No reserves
Production notes No production

Additional comments

Site is in Lake Clark National Park and Preserve.

References

MRDS Number A013025; A013026

References

Resource Associates of Alaska, Inc., 1976, Geology and geochemistry of certain land within the Lake Clark National Park: Contract report for U.S. Bureau of Mines, Contract JO166108, 7 v.
Reporters M.L. Miller (USGS); D.P. Bickerstaff (USGS)
Last report date 6/15/1998