Dome

Prospect, Active

Commodities and mineralogy

Main commodities Au; Cu
Other commodities Ag; As; Bi; Hg; Sn
Ore minerals arsenopyrite; chalcopyrite; magnetite
Gangue minerals quartz

Geographic location

Quadrangle map, 1:250,000-scale ID
Quadrangle map, 1:63,360-scale A-5
Latitude 62.07378
Longitude -158.15618
Nearby scientific data Find additional scientific data near this location
Location and accuracy The Dome prospect is on hill 1234 which is souhwest of Dome Creek and northwest of Quartz Gulch; in the NW1/4 of section 19, T. 23 N., R. 48 W., of the Seward Meridian. Cobb (1972 [MF 363]; 1976 [OFR 76-576]).

Geologic setting

Geologic description

The Dome prospect is on a large, generally untested, gold anomaly in soils at the northeast end of the Donlin Creek swarm of dikes and sills. Quartz-sulfide veins and veinlets cut granite porphyry and quartz-feldspar porphyry dikes and sills as well as hornfels derived from the Upper Cretaceous, Kuskokwim Group (Miller and Bundtzen, 1994; Szumigala, Dodd, and Arribas, 2000). The greater extent of hornfels here relative to its general absence near the Donlin Creek lode (ID167) suggests that a larger intrusion might underlie this area. Quartz-feldspar porphyry and igneous breccias were identified in drill core (McCoy and others, 1999).
Gold appears to be associated with widespread arsenopyrite (McCoy and others, 1999). Chalcopyrite occurs sparsely. Samples by the U.S. Geological Survey and by the Alaska Division of Geological and Geophysical Surveys in the early 1980s contained up to 1.0 parts per million (ppm) silver, 5.1 ppm mercury, 70 ppm tin, 3.0 ppm bismuth, and 1,000 ppm arsenic in addition to gold (McGimsey and others, 1988). Szumigala, Dodd, and Arribas (2000) believe that the intrusive and sediment -hosted, gold and copper mineralization represent a porphyry-type deposit. They also report fluid inclusion temperatures of 400 degrees C which suggests a magmatic source for the hydrothermal fluids and further supports the idea of porphyry-type mineralization here.
Geologic map unit (-158.158589578752, 62.0730875828244)
Mineral deposit model Porphyry gold-copper deposit; (Cox and Singer, 1986; model 20c); possibly the porphyry gold type deposit of Hollister (1992); or the peraluminous granite, porphyry gold-polymetallic type deposit of Bundtzen and Miller (1997).
Mineral deposit model number 20c
Age of mineralization The mineralization is 65.0 Ma based on 40K/40Ar age date reported by Miller and Bundtzen (1994).
Alteration of deposit Development of secondary biotite and sericite.

Production and reserves

Workings or exploration The prospect was sampled by the U.S. Geological Survey and by the Alaska Division of Geological and Geophysical Surveys in the early 1980s (McGimsey and others, 1988). Westgold explored the Dome prospect from 1988 to 1990 but did not drill it (Retherford and McAtee, 1994). Placer Dome drilled the prospect in 1996 and 1997 but the total footage has not been released (McCoy and others, 1997).
Indication of production None

References

References

Bundtzen, T.K., and Miller, M.L., 1997, Precious metals associated with Late Cretaceous-early Tertiary igneous rocks of southwestern Alaska, in Goldfarb, R.J., and Miller, L.D., eds., Mineral Deposits of Alaska: Economic Geology Monograph 9, p. 242-286.
McCoy, D.T., Dodd, S.P., Arribas, A. Jr., Miller, M.L., Goldfarb, R.J., and Szumigala, D.J., 1999, Geology and geochemistry of the Donlin Creek gold deposit, southwest Alaska: Geological Society of America Abstracts with Programs, v. 31, no. 6, p. A-78.
McCoy, D.T., Newberry, R.J., Layer, P.W., DiMarchi, J.J., Bakke, A.A., Masterman, J.S., and Minehane, D.L., 1997, Plutonic-Related Gold Deposits of Interior Alaska, in, Goldfarb, R.J., and Miller, L.D., eds., Mineral Deposits of Alaska: Economic Geology Monograph 9, p. 191-241.
Retherford, R.M., and McAtee, June, 1994, Donlin Creek property, southwest Alaska: Anchorage, Calista Corporation Land Department unpublished report, 27 p., one sheet, scale 1:10,000
Reporters T.K. Bundtzen (Pacific Rim Geological Consulting, Inc.), M.L. Miller (U.S. Geological Survey); and C.C. Hawley (Hawley Resource Group)
Last report date 5/26/2003