Cascade Creek

Occurrence, Inactive

Commodities and mineralogy

Main commodities Au; Cu
Other commodities As
Ore minerals gold

Geographic location

Quadrangle map, 1:250,000-scale TL
Quadrangle map, 1:63,360-scale B-5
Latitude 62.474
Longitude -152.093
Nearby scientific data Find additional scientific data near this location
Location and accuracy 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).

Geologic setting

Geologic description

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.
Geologic map unit (-152.09523546884, 62.4734438068089)
Mineral deposit model Placer Au-PGE (Cox and Singer, 1986; model 39a).
Mineral deposit model number 39a
Age of mineralization Pleistocene.

Production and reserves

Workings or exploration 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).
Indication of production None

Additional comments

This area is within Denali National Park and Preserve.

References

MRDS Number A011551

References

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.
Reporters Madelyn A. Millholland (Millholland & Associates)
Last report date 8/10/1998