Geologic descriptionThe entire island has been mapped as a color anomaly (Cox and others, 1981). A mineralization system on the island has been classified by Wilson (1980) as a volcanic porphyry deposit, although no mention is made of ore or gangue minerals present. Rocks consist of andesite flows and sills of Oligocene to Pliocene age and sedimentary rocks of the Paleocene and Eocene Tolstoi Formation (Detterman and others, 1981). A hornblende andesite sill has been dated at approximately 36 m.y. and sericitic alteration at approximately 30 m.y. (Wilson, 1980). |
Geologic map unit |
(-157.722047548756, 56.4892350563923) |
Mineral deposit model |
Porphyry copper (Cox and Singer, 1986, model 17) |
Mineral deposit model number |
17 |
Age of mineralization |
Tertiary. |
Alteration of deposit |
A small zone of sericitic alteration in undescribed rocks lies near the northern part of the island (Wilson, 1980). Propylitic and argillic types may also be present. |