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Cache Creek Area Mine, Yentna District, Matanuska-Susitna Borough, Alaska, USA
Latitude: 62°29'23"N
Longitude: 150°59'2"W
Longitude: 150°59'2"W
Location: The Cache Creek area, in the Yentna District, is a productive placer area covering approximately 50 square miles, including streams draining the northwest flank of Peters Hills and the southeast flank of Dutch Hills, as well as tributaries to Cache Creek. Reference coordinates are the approximate center of the most productive area on Cache Creek in the northwest quarter of Section 29, T. 28 N., R. 9 W., of the Seward Meridian. Dredging operations mined stream placers from Windy Creek to Nugget Creek, tributaries to Cache Creek. Mining claims extend, or have extended, from the headwaters to below Spruce Creek (C.C. Hawley and Associates, Inc., 1978, Fig. 4.2-B(3))., including Spruce Creek;Short Creek; Rambler Creek; Lucky Creek; Pineo Bar; Bradley; Cache Creek Dredging Company; Cache Creek Mining Company; Erickson; Gold; Ltd.; Morgan; Murray; Murray And Harper; Obermiller And Eaglehorn; Peterson; T
Geology: The Cache Creek area is a productive placer area in the Yentna District encompassing approximately 50 square miles including streams draining the northwest flank of Peters Hills and the southeast flank of Dutch Hills, as well as tributaries to Cache Creek. Dredging operations mined stream placers from Windy Creek to Nugget Creek, tributaries to Cache Creek. Mining claims extend, or have extended, from the headwaters to below Spruce Creek (C.C. Hawley and Associates, Inc., 1978, Fig. 4.2-B(3)). Collectively the placer mines in the Yentna district have produced over 3.58 million grams of gold from 1906 to the present (Cobb and Reed, 1980; Nokelberg and others, 1994) with most of the area's production from dredging on Cache and Peters Creeks. The largest operation used two floating dredges supported by three backhoes. This huge region contains many placer prospects and mines in Pleistocene stream and bench deposits of well-washed gravels derived from glacial debris, transitional with deposits of glaciofluvial origin (Clark and Hawley, 1968). Pleistocene sediments are deposited on Mesozoic marine slates and graywackes (KJs), although areas underlain by continentally derived Tertiary sediments of the Kenai group also occur (Reed and Nelson, 1980). Mesozoic rocks are cut by small granite bodies, diabase, and felsic dikes presumed to be early Tertiary in age (Clark and Hawley, 1968; Reed and Nelson, 1980). C.C. Hawley and Associates, Inc. (1978) describe shallow stream gravels, 3 to 10 feet deep, average 4.5 feet, with well-defined, discontinuous pay streaks 150 to 300 feet wide and bench placers 7 to 35 feet deep with gold throughout, but mostly concentrated on bedrock of Mesozoic graywacke and argillite. Cobb and Reed (1980) report arsenopyrite, cassiterite, copper, ilmenite, magnetite, unknown platinoids, platinum, pyrite, scheelite, uranothorianite, garnet, monazite, rutile, quartz, and zircon in the concentrates. Grades in the more productive parts of pay streaks mined during productive periods were $2 to $3 per bedrock foot or $1.50 per cubic yard when gold was valued at $20.67 an ounce (Capps, 1913, p. 57). In 1919 Martin (p. 247) reported platinum contents equal to about 0.003% of gold by weight. Concentrate samples contain 0.07% U and 0.035% ThO2 with eU content of 0.19% (Robinson and others, 1955, p.2). The average fineness of the gold from Cache Creek is 866, with a range of 850.75 to 871 (Smith, 1941; Clark and Hawley,1968). In their 1978 report C.C. Hawley and Associates, Inc. indicate that probably more than half of the gold in Cache Creek has been mined. Ground down to about 10 cents per bedrock foot has been mined profitably in both Cache and lower Falls Creek in the 1970s. This record refers to the Cache Creek region generally, and encompasses many specific occurrences and former producers. Mining claims on Cache Creek extend, or have extended, from its headwaters to below Spruce Creek. Placer mining took place on the following secondary drainages to Cache Creek: Spruce Creek, Dollar Creek, Windy Creek, Short Creek, Cheechako Gulch, Falls Creek, Thunder Creek, Rambler Creek, Lucky Creek, Nugget Creek, and Gold Creek (C.C. Hawley and Associates, Inc., 1978, Fig. 4.2-B(3)).
Workings: Sluice box-CAT or dredge methods for almost 10 miles. Large volume, low grade and the overall coarseness of the gold favor large-scale, high capacity operations such as dredging (C.C. Hawley and Associates, Inc., 1978).
Age: Pleistocene and Tertiary (?) (Clark and Hawley, 1968).
Production: Large volume, low grade and the overall coarseness of the gold favor large-scale, high capacity operations such as dredging. Most of area's production from dredging on Cache & Peters Creeks. Ground down to about 10 cents per bedrock foot has been mined profitably in both Cache and lower Falls Creek in the 1970s (C.C. Hawley and Associates, Inc., 1978. Grades in the more productive parts of pay streaks mined during productive periods were $2 to $3 per bedrock foot or $1.50 per cubic yard when gold was valued at $20.67 an ounce (Capps, 1913, p. 57). Platinum content is equal to about 0.003% of gold by weight (Martin, 1919, p. 247). Concentrate sample contained 0.07% U and 0.035% ThO2 with eU content of 0.119% (Robinson and others, 1955, p.2). Clark and Hawley (1968) report the average fineness of the gold from Cache Creek is 866, with a range of 850.75 to 871.
Reserves: C.C. Hawley and Associates, Inc. (1978) indicate that probably more than half of the gold in Cache Creek has been mined.
Commodities (Major) - Au; (Minor) - As, Pt, Sn, Th, U, W
Development Status: Yes
Deposit Model: Placer Au-PGE (Cox and Singer, 1986; model 39a).
Mineral List
| Arsenopyrite Cassiterite Copper 'Garnet' | Gold Ilmenite Magnetite 'Monazite' | Platinum Pyrite Quartz Rutile | Scheelite Thorianite var: Uranothorianite Zircon |
15 entries listed. 12 valid minerals.
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References
Brooks, A.H., 1910, The mining industry in 1909: U.S. Geological Survey Bulletin 442, p. 20-46. Brooks, A.H., 1911, The Mount McKinley region Alaska, with descriptions of the igneous rocks and of the Bonnifield and Kantishna districts, by L. M. Prindle: U.S. Geological Survey Professional Paper 70, 234 p. Brooks, A.H., 1911, The mining industry in 1910: U.S. Geological Survey Bulletin 480, p. 21-42. Brooks, A.H., 1914, The mining industry in 1913: U.S. Geological Survey Bulletin 592, p. 45-74. Brooks, A.H., 1915, The mining industry in 1914: U.S. Geological Survey Bulletin 622, p. 11-62. Brooks, A.H., 1918, The mining industry in 1914: U.S. Geological Survey Bulletin 662, p. 89-62. Brooks, A.H., 1921, The future of Alaska mining: U.S. Geological Survey Bulletin 714, p. 5-57. Brooks, A.H., 1922, The Alaska mining industry in 1920: U.S. Geological Survey Bulletin 722, p. 7-67. Brooks, A.H., 1923, The Alaska mining industry in 1921: U.S. Geological Survey Bulletin 739, p. 1-44. Brooks, A.H., 1925, Alaska's mining resources and production, 1923: U.S. Geological Survey Bulletin 773, p. 3-52. Brooks, A.H. and Capps, S.R., 1924, The Alaska mining industry in 1919: U.S. Geological Survey Bulletin 714, p. 3-49. Brooks, A.H. and Martin, G.C., 1921, The Alaska mining industry in 1922: U.S. Geological Survey Bulletin 755, p. 59-95. C.C. Hawley and Associates, Inc., 1978, Mineral appraisal of lands adjacent to Mt. McKinley National Park, Alaska: U.S. Bureau of Mines Open-File Report 24-78, 277 p., 12 sheets. Capps, S.R., 1912, Gold placers of the Yentna district: U.S. Geological Survey Bulletin 520, p. 174-200. Capps, S.R., 1913, The Yentna district, Alaska: U.S. Geological Survey Bulletin 534, 75 p. Capps, S.R., 1924, Geology and mineral resources of the region traversed by the Alaska Railroad: U.S. Geological Survey Bulletin 775, p. 73-150. Clark, A.L., and Cobb, E.H., 1972, Metallic mineral resources map of the Talkeetna quadrangle, Alaska: U.S. Geological Survey Miscellaneous Field Studies Map MF-369, 1 sheet, scale 1:250,000. Clark, A.L., and Hawley, C.C., 1968, Reconnaissance geology, mineral occurrences, and geochemical anomalies of the Yentna district, Alaska: U.S. Geological Survey Open-File Report 68-35, 64 p. Cobb, E.H., 1973, Placer deposits of Alaska: U.S. Geological Survey Bulletin 1374, 213 p. 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. Hawley, C.C., and Clark, A.L., 1973, Geology and mineral deposits of the Chulitna -Yentna mineral belt, Alaska: U.S. Geological Survey Professional Paper 758-A, p. A1-A10, 2 plates, scale 1:250,000 and 1:500,000. Joesting, H.R., 1942, Strategic mineral occurences in interior Alaska: Alaska Territorial Department of Mines Pamphlet 1, 46 p. Koschmann, A.H., and Bergendahl, M.H., 1968, Principal gold producing districts of the United States: U.S. Geological Survey Professional Paper 610, 283 p. 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. Martin, G.C., 1919, Alaska Mining Industry in 1917: U.S. Geological Survey Bulletin 692-A, p. 11-42. Martin, G.C., 1920, The Alaska mining industry in 1918: U.S. Geological Survey Bulletin 712-A, p. 1-52. Mertie, J.B., Jr., 1919, Platinum-bearing gold placers of the Kahiltna Valley: U.S. Geological Survey Bulletin 692-D, p. 233-264. Mertie, J.B., Jr., 1969, Economic geology of platinum minerals: U.S. Geological Survey Professional Paper 630, 120 p. Moffit, F.H., 1927, Mineral industry in Alaska in 1925: U.S. Geological Survey Bulletin 792-A, p. 1-39. Nokleberg, W.J., and (seven) others, 1994, Metallogeny and major mineral deposits of Alaska and Metallogenic map of significant metalliferous lode deposits and placer districts of Alaska, in Plafker, G. and Berg, H.C., eds., The Geology of Alaska: Geological Society of America, DNAG, The Geology of North America, Vol.. G1, p. 855-904, Plate 11, scale 1:2,500,000. 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. Robinson, G. D., Wedow, Helmuth, Jr., and Lyon, J. B., 1955, Radioactivity investigations in the Cache Creek area, Yentna district, Alaska 1945: U.S. Geological Survey Bulletin 1024-A, p. 1-23. Smith, P.S., 1926, Mineral industry of Alaska in 1924: U.S. Geological Survey Bulletin 783-A, p. 1-30. Smith, P.S., 1929, Mineral industry of Alaska in 1926: U.S. Geological Survey Bulletin 797, p. 1-50. Smith, P.S., 1930, Mineral industry of Alaska in 1927: U.S. Geological Survey Bulletin 810-A, p. 1-64. Smith, P.S., 1930, Mineral industry of Alaska in 1928: U.S. Geological Survey Bulletin 813-A, p. 1-72. Smith, P.S., 1932, Mineral industry of Alaska in 1929, in Smith, P.S., and others Mineral resources of Alaska, report on progress of investigations in 1929: U.S. Geological Survey Bulletin 824-A, p. 1-81. Smith, P.S., 1933, Mineral industry of Alaska in 1930: U.S. Geological Survey Bulletin 836-A, p. 1-83. Smith, P.S., 1933, Mineral industry of Alaska in 1931: U.S. Geological Survey Bulletin 844-A, p. 1-81. Smith, P.S., 1934, Mineral industry of Alaska in 1932: U.S. Geological Survey Bulletin 857-A, p. 1-91. Smith, P.S., 1934, Mineral industry of Alaska in 1933: U.S. Geological Survey Bulletin 864-A, p. 1-94. Smith, P.S., 1936, Mineral industry of Alaska in 1934: U.S. Geological Survey Bulletin 868-A, p. 1-91. Smith, P.S., 1937, Mineral industry of Alaska in 1935: U.S. Geological Survey Bulletin 880-A, p. 1-95. Smith, P.S., 1938, Mineral industry of Alaska in 1936: U.S. Geological Survey Bulletin 897-A, p. 1-107. 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. Wedow, Helmuth, Jr., White, M.G. and Moxham, R.M., 1952, Interim report on an appraisal of the uranium possibilities of Alaska: U.S. Geological Survey Open-File Report 51, 123 p.
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