| GMRAP ID | 7 |
|---|---|
| Tract name | Alaska Peninsula and Aleutian Islands (003pCu5006) |
| Site status | deposit |
| Country | United States |
|---|---|
| State or province | Alaska |
| Geographic location | -160.6753, 55.6298 |
| Geologic map unit | -160.6753, 55.6298 |
| Nearby data |
| Deposit type | Porphyry copper |
|---|---|
| Age (Ma) | 6.4Ma |
| Age determination method | Re-Os molybdenite |
| Age range | 6.4 Ma |
| Age reference | Singer and others (2008); Wilkins (2011) |
| Minerals | apatite, biotite, chalcocite, chalcopyrite, chlorite, chrysocolla, covellite, cuprite, epidote, fluorite, goethite/limonite, hematite, kaolinite, magnetite, molybdenite, pyrite, rhodochrosite, rutile, sericite |
| Associated rocks | dacite porphyry, hornfels, quartz diorite porphyry, andesite, carbonaceous shale, sandstone, volcaniclastic sedimentary rocks |
| Tectonic setting | mixed |
| Stratigraphic age | Miocene |
| Development status | Prospect |
|---|---|
| Major commodities | Cu, Mo |
| Minor commodities | Ag, Au, Pb, Sb, Zn |
| Tonnage (Mt) | 159Mt |
| Cu grade (%) | 0.372% |
| Mo grade (%) | 0.018% |
| Au grade (g/t) | 0.05g/t |
| Contained copper | 591,000t |
| Gold-Moly ratio | 3 |
| Comments | Associated with a quartz diorite pluton that cuts Paleocene- to Eocene-age sedimentary rock of the Tolstoy Formation; the stock and Mo mineralization have been dated at 6 million years (Wilson and others, 1996; Wilkins, 2011). The alteration consists of a barren, potassically-altered core zone, an intermediate zone characterized by pervasive quartz and sericite, and a propylitic outer zone. In 1975, the resource was estimated to be 126 million tons with a grade of 0.403 percent copper and 0.025percent molybdenum; there was said to be potential for an additional 49 million tons of chalcocite-enriched ore. In 2013, the resource was estimated to be 173 million metric tons with a grade of 0.088 g/t Au, 0.35% copper, and 0.02% molybdenum (based on 49 drill holes totaling 9,177 m). |
|---|---|
| Study area name | United States |
| References | U.S. Geological Survey (2014a); Wilkins (2011); Wilson and others (1996); Farrow and Arseneau (2013); Nokleberg and others (1987); Young and others (1997); Singer and others (2008) |
| Site reference | U.S. Geological Survey National Mineral Resource Assessment Team (2002) |