Nunatak; Saksaia Glacier Prospect, Skagway District, Juneau District, Haines Borough, Alaska, USA
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Geology: According to Still (1984 [OF 21-84]), the prospect consists of an iron-stained zone of quartz-sericite schist and altered volcanic rocks exposed for 1,500 feet across the face of a nunatak. Barite lenses and beds containing interbedded and remobilized sulfides occur within this zone. The mineral assemblage and field relationships are similar to the Main Zone/Palmer prospect (SK066) (MacKevett and others, 1974). Rubblecrop indicates that some of the baritic beds may be up to 20 feet thick. Samples of the baritic rock contain up to 2.58 ppm gold, 335.3 ppm silver, 2.38% zinc, 1,820 ppm copper, 2.0% lead, 48% barite, and 1,000 ppm arsenic. A 200-pound sample collected by Merrill Palmer was divided into 13 separate samples and analyzed by Newmont Gold Company. The samples averaged 11.84 ounces of silver per ton and 0.092 ounces of gold per ton. This prospect lies along a northwesterly mineral trend that extends through the Cap prospect (SK060) to the Mount Henry Clay prospect (SK068). Rubicon Minerals considers these prospects to all occur at the same mineralized stratigraphic horizon and attributes their distribution to a northwest-trending, shallowly plunging antiform that brings the massive-sulfide horizon close to the surface (Rubicon Minerals, 1998). The Nunatak prospect and other similar prospects in the Mt. Henry Clay area are probably correlative with the Windy Craggy deposit in Canada and the Greens Creek deposit on Admiralty Island and are therefore Late Triassic (Still, 1984 [OF 118-84]; Newberry and others, 1997).
Age: The Nunatak prospect and other similar prospects in the Mt. Henry Clay area are probably correlative with the Windy Craggy deposit in Canada and the Greens Creek deposit on Admiralty Island and are, therefore Late Triassic (Still, 1984 (OFR 118-84); Newberry and others, 1997).
Alteration: Phyllic.
Commodities (Major) - Ag, Au, Ba, Cu, Pb, Zn
Development Status: None
Deposit Model: Besshi- or Kuroko-type volcanogenic massive sulfide deposit (Cox and Singer, 19
Mineral List
6 entries listed. 6 valid minerals.
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References
Berg, H.C., 1984, Regional geologic summary, metallogenesis, and mineral resources of southeastern Alaska: U.S. Geological Survey Open-file Report 84-572, 298 p., 1 plate, scale 1:600,000. Cobb, E.H., 1972, Metallic mineral resources map of the Skagway quadrangle, Alaska: U.S. Geological Survey Miscellaneous Field Studies Map MF-424, 1 sheet, scale 1:250,000. Cobb, E.H., 1978, Summary of references to mineral occurrences (other than mineral fuels and construction materials) in the Mt. Fairweather and Skagway quadrangles, Alaska: U.S. Geological Survey Open-File Report 78-316, 123 p. Gilbert, W.G., and Redman, E.C., 1989, Lode deposits, prospects, and occurrences of the Porcupine mining area, southeast Alaska: U.S. Bureau of Mines Open-File Report 17-89, 1 sheet, scale 1:39,600. MacKevett, E.M., Jr., 1971, Analyses of samples and preliminary geologic summary of barite-silver-base metal deposits near Glacier Creek, Skagway B-4 quadrangle, southeastern Alaska: U.S. Geological Survey Open-File Report 71-195, 8 p. MacKevett, E.M., Jr., Robertson, E.C., and Winkler, G.R., 1974, Geology of the Skagway B-3 and B-4 quadrangles, southern Alaska: U.S. Geological Survey Professional Paper 832, 33 p., 1 plate. Newberry, R.J., Crafford, T.C., Newkirk, S.R., Young, L.E., Nelson, S.W., and Duke, N.A., 1997, Volcanogenic massive sulfide deposits of Alaska, in Goldfarb, R.J. and Miller, L. D., eds., Mineral deposits of Alaska: Economic Geology Monograph 9, p. 120-150. Rubicon Minerals, 1998, Palmer VMS Project, southeast Alaska, Executive Summary: Unpublished report by Rubicon Minerals Corporation, Vancouver, British Columbia, 25 p. Still, J.C., 1984, Stratiform massive sulfide deposits in the Mt. Henry Clay area, southeast Alaska: U.S. Bureau of Mines Open-File Report 118-84, 65 p. Still, J.C., 1991, Bureau of Mines mineral investigations in the Juneau mining district, Alaska, 1984-1988; Volume 2, Detailed mine, prospect, and mineral occurrence descriptions, Section A, Haines-Klukwan-Porcupine subarea: U.S. Bureau of Mines of Mines Special Publication, 214 p. Still, J.C., Hoekzema, R.B., Bundtzen, T.K., Gilbert, W.G., Wier, K.R., Burns, L.E., and Fechner, S.A., 1991, Economic geology of Haines-Klukwan-Porcupine area, southeastern Alaska: Alaska Division of Geological and Geophysical Surveys Report of Investigations 91-4, 156 p., 5 sheets, scale 1:63,360. Winkler, G.R., and MacKevett, E.M., Jr., 1970, Analyses of bedrock and stream-sediment samples from the Haines-Porcupine region, southeastern Alaska: U.S. Geological Survey Open-File Report 369, 91 p., 1 sheet, scale 1:125,000.