Kasna Creek

Prospect, Inactive

Alternative names

Barnes
Gilt Edge

Commodities and mineralogy

Main commodities Cu; Fe
Other commodities Au; Ag; Pb; Zn
Ore minerals chalcopyrite; pyrite; specular hematite; sphalerite
Gangue minerals calcite; chlorite; fibrous amphibole; garnet; quartz

Geographic location

Quadrangle map, 1:250,000-scale LC
Quadrangle map, 1:63,360-scale A-3
Latitude 60.161
Longitude -154.051
Nearby scientific data Find additional scientific data near this location
Location and accuracy About 2.4 km upstream from mouth of Kasna Creek, on the southern edge of Kontrashibuna Lake. Locality 31 of Nelson and others (1985), locality 4 of MacKevett and Holloway (1977), locality 5 of Cobb (1972), and samples 169-184 of Eakins (1970). NE1/4SE1/4 sec. 24, T. 1 N., R. 28 W., of the Seward Meridian. Locality accurate within 300 m.

Geologic setting

Geologic description

The prospect occurs in lenticular contact-metamorphosed Upper Triassic limestone and dolomite. It consists of bedding parallel bands of skarn containing specular hematite, chalcopyrite, and lesser magnetite veinlets in amphibole-chlorite-calcite-quartz gangue. Tuffs, mafic volcanic rocks, and agglomerate occur within the limestone. Capps (1935) reported stringers of solid chalcopyrite several inches thick. The prospect consists of two ore bodies: Gilt Edge, 320 m x 76 m, to the north; and Barnes, 408 m x 12 m, to the south. The limestone and included lodes strike NE and dip NW (Berg and Cobb, 1967). Numerous trenches were dug and sampled by USBM in both ore bodies for assay analysis. Ore bodies average 0.95 percent Cu, 27.5 percent Fe, and 30.1 percent SiO2 (Warfield and Rutledge, 1951).
A Tertiary, medium- to fine-grained hornblende-biotite quartz monzodiorite is nearby (Nelson and others, 1983; unit Ti2). The pluton yields concordant potassium-argon ages for hornblende and biotite of about 61 m.y. (Reed and Lanphere, 1972; 1973)
Geologic map unit (-154.053197518299, 60.1603386885255)
Mineral deposit model Fe skarn; Cu skarn (Cox and Singer, 1986; models 18d and 18b)
Mineral deposit model number 18d and 18b
Age of mineralization Paleocene or younger. A quartz monzodiorite which is probably related to the deposit yields concordant potassium-argon ages for hornblende and biotite of about 61 m.y. (Reed and Lanphere, 1972; 1973).

Production and reserves

Workings or exploration One adit each in Gilt Edge and Barnes deposits. Numerous trenches were dug and sampled by USBM in both ore bodies for assay analysis. Ore bodies average 0.95 percent Cu, 27.5 percent Fe, and 30.1 percent SiO2 (Warfield and Rutledge, 1951). Eakins (1970) reports stream sediments samples that yield up to 2,810 ppm Cu, 150 ppm Pb, and 1,200 ppm Zn.
Indication of production None
Reserve estimates Swainbank and others (1997) report reserves of over 9,070,000 tonnes of ore that grade more than 1 percent Cu.
Production notes No production.

Additional comments

Claims currently inactive, but diamond drilling between 1965 and 1970 has proved the presence of copper and iron in significant quantities (Detterman and Reed, 1980). Site is in Lake Clark National Park and Preserve.

References

MRDS Number A010656; A013001

References

Reed, B.L., and Lanphere, M.A., 1973, Alaska-Aleutian Range batholith: Geochronology, chemistry, and relation to circum-Pacific plutonism: Geological Society of America Bulletin, v. 84, no. 8, p. 2583-2609.
Reporters M.L. Miller (USGS); D.P. Bickerstaff (USGS)
Last report date 6/15/1998