Charlie Creek (lode)

Prospect, Probably inactive

Commodities and mineralogy

Main commodities Bi
Other commodities Au
Ore minerals bismuth; bismuthinite; gold; pyrite
Gangue minerals graphite; quartz; sericite

Geographic location

Quadrangle map, 1:250,000-scale NM
Quadrangle map, 1:63,360-scale D-1
Latitude 64.8458
Longitude -165.4764
Nearby scientific data Find additional scientific data near this location
Location and accuracy The prospect is on the east fork of Charlie Creek, a north-flowing tributary of upper Sinuk River. The prospect is at an elevation of about 1,000 feet and is located within about 1,000 feet. It is locality 4 of Hummel (1962 [MF 248]) and locality 11 of Cobb (1972 [MF 463], 1978 [OFR 78-93]).

Geologic setting

Geologic description

Two bismuth-bearing quartz veins were found prior to 1907 by tracing native bismuth nuggets found during early placer gold mining on Charlie Creek to their souce (Moffit, 1907). These veins are exposed in cuts on both sides of Charlie Creek. As described by Cathcart (1922, p. 223-224), one vein was 5 inches and the other 10 inches wide. They were separated by about 1 foot of schist. The veins strike N80W and dip 50 degrees N. The veins were predominantly vuggy quartz with some white mica, native bismuth, and bismuthinite. Chapin (1914 [B 592-L, p. 397-407]) reported a 4-foot-wide quartz vein with gold-bearing intergrown bismuth and bismuthinite. When the property was visited by Cathcart (1922), there was only about 1 or 2 percent of bismuth minerals in dump material. Some richer material may have been hand-picked and produced earlier. Although platinum had been reported, the U.S. Geological Survey did not find any by assay (Cathcart, 1922). Platinum was again reported in the 1950s but its presence has not been reliably confirmed. The prospect must have been active periodically, because there were buildings and some fairly modern equipment at the site when one of the the compilers (C.C. Hawley) visited the property in about 1995. The veins and widely spaced veinlets in joints are presumably the source of gold, bismuth, and rutile reported in the Charlie Creek placer below the lode (NM047).
The country rock of the Charlie Creek prospect is lower amphibolite facies pelitic schist containing garnet and biotite (Bundzten and others, 1994). The schist strikes east-northeast to east and dips south. North-dipping joints are common and contain thin quartz veinlets at a 1-foot or greater spacing. The country rock could be the older part of the Nome Group and have a Precambrian protolith (Bundzten and others, 1994; Till and Dumoulin, 1994). The Nome Group underwent regional blueschist facies metamorphism in the Late Jurassic or Early Cretaceous (Sainsbury, Coleman and Kachadoorian, 1970; Forbes and others, 1984; Thurston, 1985; Armstrong and others, 1986; Hannula and McWilliams, 1995). The blueschist facies rocks were recrystallized to greenschist facies or higher metamorphic grades in conjunction with regional extension, crustal melting, and magmatism in the mid-Cretaceous (Hudson and Arth, 1983; Miller and Hudson, 1991; Miller and others, 1992; Dumitru and others, 1995; Hannula and others, 1995; Hudson, 1994; Amato and others, 1994; Amato and Wright, 1997, 1998). Lode gold mineralization on Seward Peninsula is mostly related to the higher temperature metamorphism in the mid-Cretaceous (Apodoca, 1994; Ford, 1993 [thesis]; Ford and Snee, 1996; Goldfarb and others, 1997).
Geologic map unit (-165.47902775418, 64.8450395364775)
Mineral deposit model Low-sulfide Au quartz vein (Cox and Singer, 1986; model 36a).
Mineral deposit model number 36a
Age of mineralization Probably mid-Cretaceous, the same age as some gold-quartz veins of southern Seward Peninsula.

Production and reserves

Workings or exploration The prospect was found prior to 1907 by tracing bismuth or bismuthinite nuggets found in sluice boxes in lower Charlie Creek upstream to their source (Moffit, 1907). In 1914, Chapin reported that prospectors had found a 4-foot vein which contained bismuth and gold. Cathcart (1922) reported open cuts on both sides of upper Charlie Creek; evidence of later workings and support facilities were found in 1995.
Indication of production Undetermined
Production notes Possibly some hand-picked bismuth ore was shipped from this prospect.

References

MRDS Number A012787; D001940

References

Apodoca, L.E., 1994, Genesis of lode gold deposits of the Rock Creek area, Nome mining district, Seward Peninsula, Alaska: Boulder, Colorado, University of Colorado, Ph.D. dissertation, 208 p.
Armstrong, R.L., Harakal, J.E., Forbes, R.B., Evans, B.W., and Thurston, S.P., 1986, Rb-Sr and K-Ar study of metamorphic rocks of the Seward Peninsula and southern Brooks Range, Alaska, in Evans, B.W., and Brown, E.H., eds., Blueschists and eclogites: Geological Society of America Memoir 164, p. 184-203.
Ford, R.C., 1993, Geology, geochemistry, and age of gold lodes at Bluff and Mt. Distin, Seward Peninsula, Alaska: Golden, Colorado School of Mines, Ph.D. dissertation, 302 p.
Ford, R.C., and Snee, L.W., 1996, 40Ar/39Ar thermochronology of white mica from the Nome district, Alaska--The first ages of lode sources to placer gold deposits in the Seward Peninsula: Economic Geology, v. 91, p. 213-220.
Goldfarb, R.J., Miller, L.D., Leach, D.L., and Snee, L.W, 1997, Gold deposits in metamorphic rocks in Alaska, in Goldfarb, R.J., and Miller, L.D., eds., Mineral Deposits of Alaska: Economic Geology Monograph 9, p. 151-190.
Hannula, K.A., and McWilliams, M.O., 1995, Reconsideration of the age of blueschist facies metamorphism on the Seward Peninusla, Alaska, based on phengite 40Ar/39Ar results: Journal of Metamorphic Geology, v. 13, p. 125-139.
Hannula, K.A., Miller, E.L., Dumitru, T.A., Lee, Jeffrey, and Rubin, C.M., 1995, Structural and metamorphic relations in the southwest Seward Peninsula, Alaska; Crustal extension and the unroofing of blueschists: Geological Society of America Bulletin, v. 107, p. 536-553.
Hudson, T.L., 1994, Crustal melting events in Alaska, in Plafker, G., and Berg, H. C., eds., The Geology of Alaska: Geological Society of America, DNAG, The Geology of North America, Vol. G-1, p. 657-670.
Hudson, T.L., and Arth, J. G., 1983, Tin granites of Seward Peninsula, Alaska: Geological Society of America Bulletin, v. 94, p. 768-790.
Miller, E.L., Calvert, A.T., and Little, T.A., 1992, Strain-collapsed metamorphic isograds in a sillimanite gneiss dome, Seward Peninsula, Alaska: Geology, v. 20, p. 487-490.
Thurston, S.P., 1985, Structure, petrology, and metamorphic history of the Nome Group blueschist terrane, Salmon Lake area, Seward Peninsula, Alaska: Geological Society of America Bulletin, v. 96, p. 600-617.
Till, A.B., and Dumoulin, J.A, 1994, Geology of Seward Peninsula and St. Lawrence Island, in Plafker, G., and Berg, H.C., eds., The Geology of Alaska: Geological Society of America, DNAG, The Geology of North America, v. G-1, p. 141-152.
Reporters C.C. Hawley and Travis L. Hudson
Last report date 10/22/1999