Latitude: 62°28'26"N
Longitude: 152°5'34"W
This area is within Denali National Park and Preserve.
Location: Reed and others (1978, locality 21) locate this occurrence on Cascade Creek, a tributary to East Fork of the Yentna River, in the southeast quarter of Section 32, T. 28 N, R. 15 W., of the Seward Meridian within Denali National Park and Preserve. Also locality 77 of MacKevett and Holloway (1977).
Geology: Reed and others (1978) describe visible gold in pan-concentrate samples from stream gravels at this site. This placer occurrence was apparently unreported prior to MacKevett and Holloway (1977). Curtin, Karlson, Tripp, and Day (1978) show heavy-metal concentrate values in streams draining this area, two of which had an excess of 3000 ppm copper, 50 ppm gold, 100 ppm silver. The country rocks are Mesozoic marine sedimentary rocks (KJs) that are intruded by the Late Cretaceous/early Tertiary Cascade (64.6 m.y.) pluton, one of the composite plutons (Tcp) described by Reed and Nelson (1980). Foley and others (1997) report mean values of 20 ppb gold, 1 ppb palladium, 42 ppb platinum, 139 ppm nickel, and 26 ppm copper from six rock samples of the Cascade pluton. The source of the metal in stream silt and pan concentrate samples at this site is probably related to the Cascade pluton. Anomalous gold, platinum-group elements, copper, chrome, nickel and arsenic are reported from many of the composite plutons in the southern Alaska Range (Curtin, Karlson, Tripp, and Day, 1978; Curtin, Karlson, Tripp, Day, Cooley, and McDougal, 1978; Reed and others, 1978; Nelson and others 1992). Gold and platinum group element placers have been worked at several sites downstream from these bodies (Mertie, 1919; Cobb, 1973). Also see TL020, TL023, TL052, and TL053.
Workings: Reconnaissance mapping, prospecting, stream silt, pan concentrate, and rock sampling by the U.S. Geological Survey (Curtin, Karlson, Tripp, and Day, 1978; Reed and Nelson, 1980) are all that have been published on this site. Reed and others (1978) describe visible gold in pan-concentrate samples from stream gravels at this site. Curtin, Karlson, Tripp, and Day (1978) show heavy-metal concentrate values in streams draining this area, two of which had an excess of 3000 ppm copper, 50 ppm gold, 100 ppm silver. Foley and others (1997) report mean values of 20 ppb gold, 1 ppb palladium, 42 ppb platinum, 139 ppm nickel, and 26 ppm copper from six rock samples of the Cascade pluton. The source of the metal in stream silt and pan concentrate samples at this site is probably related to the Cascade pluton. Anomalous gold, platinum-group elements, copper, chrome, nickel and arsenic are reported from many of the composite plutons in the southern Alaska Range (Curtin, Karlson, Tripp, and Day, 1978; Curtin, Karlson, Tripp, Day, Cooley, and McDougal, 1978; Reed and others, 1978; Nelson and others 1992). Gold and platinum group element placers have been worked at several sites downstream from these bodies (Mertie, 1919; Cobb, 1973).
Age: Pleistocene.
Commodities (Major) - Au, Cu; (Minor) - As
Development Status: None
Deposit Model: Placer Au-PGE (Cox and Singer, 1986; model 39a).
References
Cobb, E.H., and Reed, B.L., 1980, Summaries of data on and lists of reference to metallic and selected nonmetallic mineral deposits in the Talkeetna quadrangle, Alaska: U.S. Geological Survey Open-File Report 80-884, 106 p. Curtin, G.C., Karlson, R.C., O'Leary, R.M., Day, G.W., and McDanal, S.K., 1978, Geochemical and generalized geologic maps showing the distribution and abundance of gold and silver in the Talkeetna quadrangle, Alaska: U.S. Geological Survey Miscellaneous Field Studies Map MF-870-E, 2 sheets, scale 1:250,000. Curtin, G.C., Karlson, R.C., Tripp, R.B., and Day, G.W., 1978, Geochemical and generalized geologic maps showing the distribution and abundance of tin, tungsten, and beryllium in the Talkeetna quadrangle, Alaska: U.S. Geological Survey Miscellaneous Field Studies Map MF-870-F, 2 sheets, scale 1:250,000. Foley, J.Y., Light, T.D., Nelson, S.W., and Harris, R.A., 1997, Mineral occurrences associated with mafic-ultramafic and related alkaline complexes in Alaska, in Goldfarb, R.J., and Miller, L.D., eds., Mineral Deposits of Alaska: Economic Geology Monograph 9, p. 396-449. MacKevett, E.M., Jr., and Holloway, C.D., 1977, Map showing metalliferous and selected non-metalliferous mineral deposits in the eastern part of southern Alaska: U.S. Geological Survey Open-File Report 77-169-A, 99 p., 1 sheet, scale 1:1,000,000. Reed, B.L., and Nelson, S.W., 1980, Geologic map of the Talkeetna quadrangle: U.S. Geological Survey Miscellaneous Investigations Map I-1174, 1 sheet, scale 1:250,000. Reed, B.L., Nelson, S.W., Curtin, G.C., and Singer, D.A., 1978, Mineral resources map of the Talkeetna quadrangle, Alaska: U.S. Geological Survey Miscellaneous Field Studies Map MF-870-D, 1 sheet, scale 1:250,000.
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