Geologic descriptionAt this prospect, Cretaceous volcanic and volcaniclastic rocks contain disseminated pyrite; the rocks are locally cut by pyrite-bearing dikes (Moffit, 1943; Richter and Jones, 1973). Small pyrite and quartz veins in volcanic rock and in a dike that strikes N 20 W and dips 75 N contain free gold and galena with up to 22 ounces silver per ton (Capps, 1916). A grab sample of massive, green fragmental volcanic rock contained 1,500 parts per million (ppm) copper and 500 ppm lead (Richter and Matson, 1970 [OFR 70-275]). Short adits have been driven to explore this prospect. This mineralized zone is on the southeast flank of Gold Hill, where intrusive rocks of the Chisana pluton intrude volcanic rocks of the Cretaceous, Chisana Formation. |
Geologic map unit |
(-141.869530057819, 62.0805377314687) |
Mineral deposit model |
Polymetallic veins? (Cox and Singer,1986; model 22c) |
Mineral deposit model number |
22c? |
Age of mineralization |
Mid-Cretaceous? The deposit may be related to emplacement of the Chisana pluton which has a K/Ar age of 110 +/- 3.0 Ma (Richter, Lanphere, and Matson, 1975). |
Alteration of deposit |
Disseminated pyrite and quartz-sulfide veining. Oxidation has produced iron-staining. |