Unnamed (between Balboa Bay and Dorenoi Bay)

Prospect, Inactive

Commodities and mineralogy

Main commodities Ag; Au; Cu; Pb; Zn
Other commodities As; Hg; Mo; Sb
Ore minerals arsenopyrite; chalcopyrite; galena; gold; magnetite; molybdenite; pyrite; sphalerite; tetrahedrite
Gangue minerals barite; calcite; quartz

Geographic location

Quadrangle map, 1:250,000-scale PM
Quadrangle map, 1:63,360-scale C-2
Latitude 55.62
Longitude -160.49
Nearby scientific data Find additional scientific data near this location
Location and accuracy This site is located on the Alaska Peninsula and represents an area of over 24 square miles between Balboa and Dorenoi Bays (Christie, 1974, color anomaly 76; MacKevett and Holloway, 1977, locality 21; Wilson and others, 1988, locality 21). The site location is plotted near the center of the area, in the SE1/4 of sec. 5, T. 53 S., R. 73 W., of the Seward Meridian.

Geologic setting

Geologic description

This site represents a 24-square-mile color anomaly (Christie. 1974, number 76) that contains numerous areas of mineralization. The anomaly occurs in rocks mapped as Miocene volcanics (Wilson and others, 1995) which here include andesite to dacite tuff, breccia, agglomerate, tuffaceous sedimentary rocks, some flow rocks, and minor sandstone and shale. These have been intruded by diorite stocks and rhyolite dikes. The anomaly is caused by the oxidation of as much as 5 percent pyrite disseminated in propylitically altered andesite.
An Aleut-Quintana-Duval joint venture in 1975 mapped, sampled, conducted a magnetic survey, and drilled two holes on a narrow zone of copper-molybdenum mineralization in fine-grained diorite containing as much as 0.25 percent copper (Christie, 1976). The diorite contains chalcopyrite, magnetite, pyrite, and quartz in fractures. It exhibits pervasive propylitic alteration. The mineralized zone trends southeast beneath a large covered area in which the holes were drilled. These drill holes intersected as much as 183 feet of oxidized capping and bottomed in weakly mineralized diorite containing 5 to 10 percent pyrite and as much as 0.015 percent copper.
Resource Associates of Alaska explored the color anomaly for precious metals in 1979, 1980, and 1983. They mapped, sampled, and hand trenched and discovered many discontinuous, narrow zones of silicification and brecciation that appear to be associated with regional faults (Anderson and others, 1980). They also noted areas of strongly developed stockwork veining. Some of the altered zones contain narrow quartz-barite or quartz-carbonate veins with metal values of as much as 4.45 ppm gold, 500 ppm silver, 23,975 ppm copper, 30,000 ppm lead, and 14,700 ppm zinc. Mercury and antimony are also present (Trujillo and others, 1983).
During this period of exploration three other areas of silica-flooded rock were discovered in a variety of host rocks and structural settings. These occurrences are subhorizontal bodies as much as 200 feet thick and 2,000 feet long. Some contain iron oxides and pyrite as disseminations and as fracture fillings. Silica replacement of the hostrocks ranges from partial to total. Zones of intense argillization tend to partially surround the silicified zones, especially at their base (Trujillo and others, 1983). Base metal sulfides occur in the silicified rocks in voids, in quartz veins, and in gouge and breccia zones. Gold values are generally low; a few of the quartz veins contain as much as 0.28 ppm gold and 1.3 ppm silver.
Geologic map unit (-160.49202091102, 55.6191788789218)
Mineral deposit model Epithermal gold veins, Porphyry Cu, Porphyry Cu-Mo, Polymetallic veins (Cox and Singer, 1986; models 17, 21a, 22c)
Mineral deposit model number 17, 21a, 22c
Age of mineralization Miocene or younger.
Alteration of deposit All volcanic units exhibit pervasive propylitization. Silicification is present along mineralized shears and in zones of fracturing and brecciation. Argillization is associated with silica-flooded areas.

Production and reserves

Workings or exploration In 1975 an Aleut-Quintana-Duval joint venture sampled, mapped, made magnetic surveys, and drilled two core holes for a total of 1,503 feet. Resource Associates of Alaska explored the area in 1979, 1980, and 1983. They did detailed mapping, collected some 2,000 samples for assay, and hand dug trenches. Freeport Exploration Company briefly mapped and sampled the area in 1984. The U.S. Geological Survey sampled the prospect in the mid-1980s.
Indication of production None

Additional comments

This prospect is located on land selected or patented by, or interim-conveyed to, the Aleut Corporation.

References

MRDS Number 10308102

References

Andersen, G.D., Butherus, D.L., Fankhauser, R.E., Pray, J.C., Lindberg, P.A., and Hoffman, B.L., 1980, Exploration and evaluation of lands leased from Aleut Native Corporation 1980: Resource Associates of Alaska Report, 84 p, 16 map sheets, various scales. (Report held by the Aleut Corporation, Anchorage, Alaska.)
Butherus, D. L., Gressitt, E.E., Pray, J., Corner, N.G., Lindberg, P.A., Fankhauser, R.E., 1979, Exploration and evaluation of the Aleut Native Corporation lands: Resource Associates of Alaska Report, 69 p, 90 map sheets, various scales. (Held by the Aleut Corporation, Anchorage)
Christie, J.S., 1974, Aleut-Quintana-Duval 1974 joint venture, final report: Unpublished Quintana Minerals Corporation report, 24 p., 3 appendices, 2 maps. (Report held by the Aleut Corporation, Anchorage, Alaska.)
Christie, J.S., 1976, Aleut-Quintana-Duval joint venture, 1975. Report on drill programs at the Tarasof and San Diego prospects and additional exploration Rootok Island and Unalaska Island: Quintana Minerals Report, 20 p., 11 map sheets, various scales. (Report held by the Aleut Corporation, Anchorage, Alaska.)
Freeport Exploration Company, 1985, 1984 report of activities, Canoe Bay joint venture: Freeport Exploration Company, 25 p. (Report held by the Aleut Corporation, Anchorage, Alaska.)
Trujillo, R.S., Farnham, S., and Andersen, G.D., 1983, Exploration and evaluation of precious metal potential of the Aleut Corporation 14(h)8 lands, southwest Alaska: Resource Associates of Alaska report, 25 p., 11 map sheets, various scales. (Report held by the Aleut Corporation, Anchorage, Alaska.)
Trujillo, R.S., Tapper, C.J., Alvarez, T.J., Porterfield, Ben, and Toupe, W.M., 1982, Exploration and evaluation of precious metal potential of portions of Aleut Corporation lands, southwest Alaska 1982: Resource Associates of Alaska unpublished report, 91 p, 33 maps, various scales. (Report held by the Aleut Corporation, Anchorage, Alaska.)
Reporters S.H. Pilcher
Last report date 1/8/2001