Geologic descriptionAn unpublished National Park Service map and accompanying database identify this locality as a copper-silver porphyry prospect. Eleven mining claims were once located here and there are numerous surface diggings and short shafts. The bedrock in this area is dominantly granitic rocks of the mid-Cretaceous Nabesna pluton (Richter, 1973). This pluton is locally intruded by dikes, small irregular bodies, and stocks of hornblende-plagioclase porphyry. This porphyry is considered to be Tertiary in age (Richter, 1973). |
Geologic map unit |
(-142.76242817747, 62.2185131300161) |
Mineral deposit model |
Porphyry Cu-Mo (Cox and Singer, 1986; model 21a) |
Mineral deposit model number |
21a |
Age of mineralization |
Mid-Cretaceous? K/Ar ages for the Nabesna pluton range from 105 +/- 4.0 to 114 +/- 3.4 Ma (Richter and others, 1975; Richter, Lanphere, and Matson, 1975). Many varieties of hornblende-plagioclase porphyry form irregular intrusive bodies into the Nabesna pluton and other regional bedrock units in the area; the porphyry is considered to be Tertiary in age (Richter, 1973). |
Alteration of deposit |
Hydrothermal alteration like that at other porphyry copper prospects in the area (e.g. NB043) may be present. |