Myers Fork Mine, Fortymile District, Southeast Fairbanks Borough, Alaska, USA

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Location: Myers Fork is a small creek about a mile north of Chicken that drains southeast into Chicken Creek. Placer tailings on Myers Fork are shown on the U.S. Geological Survey 1:63,360-scale topographic map of the Eagle A-2 quadrangle (1956; revised in 1971). The coordinates for this mine correspond to the approximate midpoint of these tailings in section 29, T. 27 N., R. 18 E., of the Copper River Meridian; the location is accurate. This site is locality 77 and 80 of Burleigh and Lear (1994), locality 43 of Eberlein and others (1977), and locality 51 of Cobb (1972 [MF-393]).
Geology: Myers Fork, a tributary of Chicken Creek, flows through a high-angle-fault bounded, structurally down-dropped basin that preserves a wedge of Tertiary gabbro and sedimentary rocks (Werdon and others, 2001). Intra-basin, high-angle faults are rarely exposed in outcrop but are inferred from the distribution of the geologic units, stratigraphic relations, and airborne resistivity and magnetic data (Alaska Division of Geological and Geophysical Surveys and others, 1999). The structural basin is bounded to the south and east by the Taylor Mountain batholith of Triassic age and to the north and west by upper Paleozoic greenschist-facies metasedimentary and metavolcanic rocks (Foster, 1969); Werdon and others, 2001). In the headwaters of Myers Fork, the upper Paleozoic metamorphic rocks are in high-angle fault contact with the Chicken pluton of Jurassic age to the north. Quaternary alluvium and colluvium deposits are extensive within the Myers Fork area and Chicken Creek valley. They largely consist of gravel and lesser silt and sand overlain by muck. Placer mining of the sedimentary deposits in Chicken Creek (see EA128) has exposed numerous Pleistocene mammalian fossils, including mammoth, horse, caribou, and bison (Pinney, 2001). Many Quaternary terrace gravel benches of possible glaciofluvial origin occur up to 600 feet above the creek (Pinney, 2001). Along Myers Fork, at least four bedrock benches are recognized below the stream gravels. Near the lower part of Myers Fork, the alluvium is as much as 15 feet thick, and silt and muck over it is about 11 feet thick (Mertie, 1938). Most of the gold on the east side of the creek occurs on top of a clay- and silt-rich layer and in fine gravels just below it, a few inches above bedrock. Very little gold is present within or on top of bedrock. The gold is not coarse, but one 1.5-ounce nugget was found. The fineness of gold mined from benches from 1925 to 1935 ranged from 827 to 842 parts of gold per thousand and from 148 to 171 parts of silver per thousand (Mertie, 1938). The average gold fineness was 833 parts of gold per thousand and 160 parts of silver per thousand. The fineness of gold from a high bench on the southwest side of Myers Fork was 819 parts of gold per thousand and 176 parts of silver per thousand. Placer concentrates contain mostly magnetite and ilmenite, as well as minor garnet, barite, scheelite, and zircon. A potential source for placer gold in Myers Fork is the Purdy lode gold prospect (EA121), which is located on the ridge just north of the creek. Myers Fork has been mined by drifting, sluicing, bulldozer, and hydraulic methods. Placer gold was produced from about 1903 to at least 1940, and intermittently in the 1970's. Two hydraulic plants were operating on Myers Fork in 1936 (Mertie, 1938). The estimated value of the cut that was mined in 1936 is about 30 cents to the square foot of bedrock (Mertie, 1938). In 1990, there was an active placer mine on Myers Fork (Yeend, 1992).
Workings: Myers Fork has been mined by drifting, sluicing, bulldozer, and hydraulic methods. Placer gold was produced from about 1903 to at least 1940 and intermittently in the 1970's. Two hydraulic plants were operating on Myers Fork in 1936 (Mertie, 1938).
Age: Quaternary.
Production: The estimated value of the cut that was mined in 1936 is about 30 cents to the square foot of bedrock (Mertie, 1938). Production in 1904-1907 that included that from Myers Fork (EA124), Lost Chicken Creek (EA131), Stonehouse Creek (EA122), and Ingle Creek (EA111) totaled about 18,835 fine ounces (Eberlein and others, 1977).

Commodities (Major) - Au; (Minor) - W
Development Status: Yes; small
Deposit Model: Placer Au (Cox and Singer, 1986; model 39a).

References

Alaska Division of Geological and Geophysical Surveys, Geoterrex-Dighem, and Stevens Exploration Management Corporation, 1999, CD-ROM containing profile and gridded data and section lines of 1997 geophysical survey data for part of the Fortymile mining district, Alaska, southern Eagle and northern Tanacross quadrangles: Alaska Division of Geological and Geophysical Surveys Public-Data File 99-9, 2 CD-ROMs. Brooks, A.H., 1909, The Alaskan mining industry in 1908: U.S. Geological Survey Bulletin 379-A, p. 21-62. Burleigh, R.E., and Lear, K.G., 1994, Compilation of data for phase 1 of the mineral resource evaluation of the Bureau of Land Management Black River and Fortymile River subunits: U.S. Bureau of Mines Open-File Report 48-94, 116 p. Cobb, E.H., 1972, Metallic mineral resources map of the Eagle quadrangle, Alaska: U.S. Geological Survey Miscellaneous Field Studies Map MF-393, 1:250,000 scale, 1 sheet. Cobb, E.H., 1973, Placer deposits of Alaska: U.S. Geological Survey Bulletin 1374, 213 p. Cobb, E.H., 1977, Summary of references to mineral occurrences in the Eagle quadrangle, Alaska: U.S. Geological Survey Open-File Report 77-845, 122 p. Eberlein, G.D., Chapman, R.M., Foster, H.L., and Gassaway, J.S., 1977, Map and table describing known metalliferous and selected nonmetalliferous mineral deposits in central Alaska: U.S. Geological Survey Open-File Report 77-168-D, 132 p., 1 map sheet, scale 1:1,000,000. Ellsworth, C.E., and Parker, G.L., 1911, Placer mining in the Yukon-Tanana region: U.S. Geological Survey Bulletin 480-F, p. 153-172. Foster, H.L., 1969, Asbestos occurrence in the Eagle C-4 quadrangle, Alaska: U.S. Geological Survey Circular 611, 7 p. Foster, H.L., 1976, Geologic map of the Eagle quadrangle, Alaska: U.S. Geological Survey Miscellaneous Investigations Series, Map 922, 1 sheet, scale 1:250,000. Joesting, H.R., 1943, Strategic mineral occurrences in interior Alaska--Supplement to Pamphlet No. 1: Alaska Department of Mines Pamphlet 2, 28 p. Mertie, J.B., Jr., 1930, Mining in the Fortymile district: U.S. Geological Survey Bulletin 813-C, p. 125-142. Mertie, J.B., Jr., 1937, The Yukon-Tanana region, Alaska: U.S. Geological Survey Bulletin 872, 276 p. Mertie, J.B., Jr., 1938, Gold placers of the Fortymile, Eagle, and Circle districts, Alaska: U.S. Geological Survey Bulletin 897-C, p. 133-261. Pinney, D.S., 2001, Surficial-geologic map of the Eagle A-2 quadrangle, Fortymile mining district, Alaska: Alaska Division of Geological and Geophysical Surveys Preliminary Interpretive Report 2001-3c, 1 sheet, scale 1:63,360. Powers, J.B., 1935, Brief history of the Fortymile and Eagle Mining Districts to 1935: Alaska Territorial Department of Mines Mineral Report MR 60-2, 19 p. Prindle, L.M., 1905, The gold placers of the Fortymile, Birch Creek, and Fairbanks regions, Alaska: U.S. Geological Survey Bulletin 251, 89 p. Prindle, L.M., 1908, The Fortymile gold-placer district, in Brooks, A.H., ed., Mineral Resources of Alaska, Report on progress of investigations in 1907: U.S. Geological Survey Bulletin 345, p. 187-197. Roehm, J.C., 1949, Report of investigations and itinerary of J.C. Roehm[, associate mining engineer, Territorial Department of Mines] in the Fortymile Precinct, Alaska: Alaska Territorial Department of Mines Investigation Report IR 60-1, 9 p. Saunders, R.H., 1955, Report on the examination of the Copper Creek copper prospect: Alaska Territorial Department of Mines Mineral Investigations 60-1, 10 p. Smith, P.S., 1929, Mineral industry of Alaska in 1926: U.S. Geological Survey Bulletin 797, p. 1-50. Smith, P.S., 1937, Mineral industry of Alaska in 1935: U.S. Geological Survey Bulletin 880-A, p. 1-95. Smith, P.S., 1939, Mineral industry of Alaska in 1937: U.S. Geological Survey Bulletin 910-A, p. 1-113. Smith, P.S., 1939, Mineral industry of Alaska in 1938: U.S. Geological Survey Bulletin 917-A, p. 1-113. Smith, P.S., 1941, Mineral industry of Alaska in 1939: U.S. Geological Survey Bulletin 926-A, p. 1-106. Smith, P.S., 1942, Mineral industry of Alaska in 1940: U.S. Geological Survey Bulletin 933-A, p. 1-102. Thorne, R.L., Muir, N.M., Erickson, A.W., Thomas, B.I., Heide, H.E., and Wright, W.S., 1948, Tungsten deposits in Alaska: U.S. Bureau of Mines Report of Investigations 4174, 22 p. Werdon, M.B., Newberry, R.J., and Szumigala, D.J., 2001, Bedrock geologic map of the Eagle A-2 quadrangle, Fortymile mining district, Alaska: Alaska Division of Geological and Geophysical Surveys Preliminary Interpretive Report 2001-3b, 1sheet, scale 1:63,360. Williams, J.A., 1950, Mining operations in the Fortymile district, Fairbanks Recording District: Alaska Territorial Department of Mines Mineral [Miscellaneous] Report MR 60-3, 5 p.

Mineral List

Gold

Scheelite

2 entries listed. 2 valid minerals.