Nebraska Prospect, Nizina District, Valdez-Cordova Borough, Alaska, USA
This page is currently not sponsored. Click here to sponsor this page.
Location: This prospect is in the valley of Glacier Gulch, a south tributary to Hidden Creek. It is at an elevation of about 4,300 feet, 4,000 feet south-southeast of elevation 6610 and 3,300 feet northeast of the center of section 11, T. 4 S., R. 12 E. of the Copper River Meridian. This is locality 100 of MacKevett (1976). It is accurate to within about 1,000 feet.
Geology: This prospect consists of veins and fracture coatings of malachite and rare bornite in fractured Triassic Nikolai Greenstone (Moffit and Maddren, 1909; MacKevett, 1976). The prospect was explored by a short adit and surface pits and trenches. The widespread deposition of copper in Triassic greenstone and limestone of the area is thought to have accompanied regional deformation and low-grade metamorphism in the Late Jurassic or Early Cretaceous (MacKevett and others, 1997). Copper-bearing minerals were deposited in the underlying Nikolai Greenstone at about 112 Ma (Silberman and others, 1980).
Workings: The prospect was explored by a short adit and surface pits and trenches.
Age: Cretaceous? The widespread deposition of copper in Triassic greenstone and limestone of the area is thought to have accompanied regional deformation and low-grade metamorphism in the Late Jurassic or Early Cretaceous (MacKevett and others, 1997). Copper-bearing minerals were deposited in the underlying Nikolai Greenstone at about 112 Ma (Silberman and others, 1980).
Alteration: Oxidation.
Commodities (Major) - Cu
Development Status: None
Deposit Model: Basaltic Cu (Cox and Singer, 1986; model 23)
Mineral List
2 entries listed. 2 valid minerals.
The above list contains all mineral locality references listed on mindat.org. This does not claim to be a complete list. If you know of more minerals from this site, please register so you can add to our database. This locality information is for reference purposes only. You should never attempt to
visit any sites listed in mindat.org without first ensuring that you have the permission of the land and/or mineral rights holders
for access and that you are aware of all safety precautions necessary.
References
MacKevett, E.M., Jr., 1976, Mineral deposits and occurrences in the McCarthy quadrangle, Alaska: U.S. Geological Survey Miscellaneous Field Studies Map MF-773-B, 2 sheets, scale 1:250,000. MacKevett, E.M., Jr., Cox, D.P., Potter, R.W., III, and Silberman, M.L., 1997, Kennecott-type deposits in the Wrangell Mountains, Alaska--High-grade copper ores near a basalt-limestone contact, in Goldfarb, R.J., and Miller, L.D., eds., Mineral deposits of Alaska: Economic Geology Monograph 9, p. 66-89. Moffit, F.H., and Maddren, A.G., 1909, Mineral resources of the Kotsina-Chitina region, Alaska: U.S. Geological Survey Bulletin 374, 103 p. Silberman, M.L., MacKevett, E.M., Jr., Connor, C.L., and Mathews, A., 1980, Metallogenic and tectonic significance of oxygen isotope data and whole-rock potassium-argon ages of Nikolai Greenstone, McCarthy quadrangle, Alaska: U.S. Geological Survey Open-File Report 80-2019, 31 p.