Unnamed (Gulf of Alaska beaches, Yakutat quadrangle segment)

Site Name

Primary: Unnamed (Gulf of Alaska beaches, Yakutat quadrangle segment)

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Commodity

Primary: Titanium
Primary: PGE
Primary: Iron
Primary: Gold
Secondary: Zirconium
Secondary: Chromium
Secondary: Tungsten
Secondary: Iron
Secondary: Garnet
Secondary: REE

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Location

State: Alaska
District: Yakutat

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Land Status

Not available

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Holdings

Not available

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Workings

Not available

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Ownership

Not available

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Production

Not available

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Deposit

Record Type: Site
Operation Category: Past Producer
Operation Type: Unknown
Years of Production:
Organization:
Significant:

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Physiography

Not available

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Mineral Deposit Model

Model Name: Placer Au-PGE

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Orebody

Not available

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Structure

Not available

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Alterations

Not available

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Rocks

Not available

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Analytical Data

Not available

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Materials

Ore: Gold
Ore: Magnetite
Ore: Monazite
Ore: Ruthenium
Ore: Rutile
Ore: Scheelite
Ore: Zircon
Ore: Ilmenite
Ore: Palladium
Ore: Rhodium
Ore: Osmium
Ore: Iridium
Ore: Iridium
Ore: Platinum
Gangue: Pyroxene
Gangue: Apatite
Gangue: Garnet
Gangue: Sphene
Gangue: Olivine
Gangue: Hornblende

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Comments

Comment (Deposit): Other Comments = gravity techniques on the recovery of the fine-grained minerals.. The offshore potential is essentially unevaluated. Equipment used for operations offshore, as well as those on the modern beach, needs to be able to withstand, or move quickly from the paths, of major storms.. Some of the deposits, as those in Wrangell-St. Elias National Park, the Logan Beach in the Russell Fiord Wilderness area, and those southeast of Dry Bay in Glacier Bay National Park and Preserve are withdrawn from mineral entry. Placer deposits northwest of Dry Bay, extending westerly to past Yakatut, are in non-wilderness Tongass National Forest or on native-owned lands and might be developed.

Comment (Reserve-Resource): Reserves = Resources have been calculated (Foley and others, 1995) in the Yakutat area, based on an assumption of a placer deposit that is 300 m wide by 24 km long with a wedge shaped beach ranging from 0 to 11 m thick. This volume contains 36 million cubic meters of beach sand equivilent to 57 million metric tons of sand that contains an average of 3.4 percent valuable heavy minerals (ilmenite + rutile + zircon). The range in values found along the beach was from 0.2 to 14.8 percent valuable heavy minerals. The resource contains native gold and PGEs of uncertain amount (Foley and others, 1995).. A less-quantified resource from the Situk River southeasterly to Boussole Bay (the latter bay is in the Mt. Fairweather quadrangle) consists of about 192 million metric tons of sand containing about 3 percent valuable minerals. This segment is fed by glaciers and rivers whose source is in the mafic-ultramafic complex region of the Fairweather Range.

Comment (Deposit): Model Name = High-energy beach sand deposits derived from steep upland terrane.

Comment (Geology): Age = Holocene

Comment (Production): Production Notes = Production of 3700 ounces of gold is reported for the region from Yakutat Bay to Lituya Bay (Reimnitz and Plafker, 1976).

Comment (Reference): Primary Reference = Foley and others, 1995.

Comment (Workings): Workings / Exploration = Workings have been mostly small scale using pans, rockers, and sluices. Some attempts have been made to process the resouce on a larger scale but have not been successful. Exploration work, mostly by the U. S. Bureau of Mines, has been by hand and powered augers and hand-dug cuts and trenches. The studies by Thomas and Berryhill (1962) and Foley and others (1995) have concentrated on the industrial metals iron, titanium, and zirconium instead of the gold or PGEs sought by the small-scale miners. The Bureau demonstrated that significant placer resources exist; probably the most promising deposit is the Yakutat beach. Churn drill testing for heavy mineral concentrates, by private companies, with uncertain results, reportedly occurred in 1957 (Thomas and Berryhill, 1962; Foley and others, 1995, p. 23).

Comment (Deposit): Other Comments = the titanium resource is relatively low grade and consists mostly of ilmenite rather than rutile. The placer deposits were formed by high-energy single pass systems rather than by complex transgressions and regressions that produced the rutile-based titanium placers characteristic of beach placers derived from the erosion of stable regions. Nevertheless, the resources are significant, and could be important if the high-titanium placer deposits are depleted. Clifton and Luepke (1987) have studied the Yakutat beach placers as part of their comprehensive study of the Pacific beach placers from Alaska to Baja California.. Other minerals and metals, such as gold and PGEs will add value, as could garnet, now not considered as a valuable mineral. Large-scale mining might also produce tungsten (scheelite), REEs (from monazite), and chromite. Some of the gold and PGEs and other valuable minerals are very fine-grained; Cook (1969) has studied flotation and ultrafine

Comment (Geology): Geologic Description = The Yakutat beaches in general are well sorted sandy to gravelly sand to sandy boulder beaches with abrupt back beaches bounded by wave-cut cliffs. Economic beach placer deposits of the system are formed in a high- energy beach environment changing significantly on a seasonal, or occasionally, on a daily basis (Foley and others, 1995). There are several sources for the heavy minerals contained in the placer deposits. The westernmost beaches of the system are cut in glacial moraine and outwash brought down by Malaspina Glacier. Placer sources are also in the streams arising from the glacier, examples named west to east--Fountain, Alder, Manby, Kame, and Grand Wash--which bring down tremendous quantities of alluvium which is then density-separated by beach and long shore currents. Tertiary rocks of the Malaspina area are also a secondary source of heavy-minerals incorporated in the placer deposits (Plafker and Miller, 1957, 1958). The placers on the east side of Yakutat Bay, the Logan Beach and Khantaak, and the deposits further east, such as the major Yakutat beach, are developed on unconsolidated deposits of Holocene age. These sediments, in turn, derived some of their heavy minerals from poorly consolidated rocks of Tertiary age (Reimnitz and Plafker, 1976; Tarr, 1909; Miller, 1961; and Wright, 1969 and 1972) . The ultimate sources of most of the placer minerals are the crystalline and intrusive rocks that lie northeast of the Gulf of Alaska Tertiary province (Hudson, Plafker, and Lanphere, 1977; Hudson, Plafker, and Turner, 1977), and this material is distributed and locally concentrated by alluvial and marine processes. In the southeast part of the system, the Alsek River could intersect mafic-ultramafic source materials that would furnish Ti, Fe, Cr, and PGE to the system. Production from the beaches has been small, but has occurred over a long interval of time, dating back to before 1890 (Spencer and Schrader, 1901; Brooks, 1904; Blackwelder, 1907; Tarr, 1906; Tarr and Butler, 1909; Brooks, 1918; Brooks, 1923). Most of the production has come from small-scale placer operations operating on heavy-mineral concentrate layers less than a foot to several feet thick, but the beaches contain concentrations of up to several percent of 'valuable heavy minerals' defined as ilmenite + rutile + zircon, that constitute a medium- to large-scale resource (Thomas and Berryhill, 1962; Foley and others, 1995) which could be exploited on a larger scale. Locally, the deposits contain concentrations of monazite and scheelite, sources respectively of REEs and tungsten. PGEs are local trace components of some of the heavy-mineral placers (Foley and others, 1989). Offshore concentrates almost certainly exist, as do onshore inland concentrations produced at varying seastands. Some indication of the extent of the fossil beaches preserved on the upland is given in the Yakutat and Akwe River drainage areas where MacKevett and Plafker (1970, p. 1) locally show the preserved upland beaches. Some of the placer deposits have magnetic signatures (Johnson and Plafker, 1969). Some of the beach placer system, as at Yakutat, is on native-owned or U.S. Forest Service land where it might be exploited commercially.

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References

Reference (Deposit): 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.

Reference (Deposit): Tarr, R.S., and Butler, B.S., 1909, Area geology, in Tarr, R. S. and Butler, B. S, The Yakutat Bay region, Alaska: U.S. Geological Survey Professional Paper 64, p. 145-178.

Reference (Deposit): Cobb, E.H., 1972, Metallic mineral resources map of the Yakutat quadrangle, Alaska: U.S. Geological Survey Miscellaneous Field Studies Map MF-408, 1 sheet, scale 1:250,000.

Reference (Deposit): Cook, D.J., 1969, Heavy minerals in Alaskan beach sand deposits: University of Alaska, Mineral Industry Research Laboratory Report 20, 114 p.

Reference (Deposit): Cobb, E.H., 1973, Placer deposits of Alaska: U.S. Geological Survey Bulletin 1374, 213 p.

Reference (Deposit): Tarr, R.S., 1909, Physiography and glacial geology, in Tarr, R. S. and Butler, B. S, The Yakutat Bay region, Alaska: U.S. Geological Survey Professional Paper 64, p. 11-144.

Reference (Deposit): Blackwelder, Eliot, 1907, Reconnaissance on the Pacific Coast from Yakutat to Alsek River: U.S. Geological Survey Bulletin 314, p. 82-88.

Reference (Deposit): Tarr, R.S., 1906, The Yakutat Bay region: U.S. Geological Survey Bulletin 284, p. 61-64.

Reference (Deposit): Hudson, T.L., Plafker, George, and Lanphere, M. A., 1977, Intrusive rocks of the Yakutat-St. Elias area, south-central Alaska: U.S. Geological Survey Journal of Research, v. 5, no. 2, p. 155-172.

Reference (Deposit): Plafker, George, and Miller, D. J., 1957, Reconnaissance geology of the Malaspina district, Alaska: U.S. Geological Survey Oil and Gas Investigations Map OM-189, 1 sheet, scale 1:125,000

Reference (Deposit): Foley, J.Y., La Berge, R.D., Grosz, A.E., Oliver, F.S., and Hirt, W.C., 1995, Onshore titanium and related heavy mineral investigations in the eastern Gulf of Alaska region, southern Alaska: U.S. Bureau of Mines Open-File Report 10-95, 125 p.

Reference (Deposit): Johnson, G.R. and Plafker, George, 1969, Preliminary geologic interpretation of aeromagnetic data in the Yakutat district, Alaska: U.S. Geological Survey Open-File Report 379, 10 p.

Reference (Deposit): Plafker, George, and Miller, D. J., 1958, Glacial features and surficial deposits of the Malaspina district, Alaska: U.S. Geological Survey Miscellaneous Geological Investigations Map I-271, 1 sheet, scale 1:125,000

Reference (Deposit): Wright, F.F., 1972, Marine geology of Yakutat Bay, Alaska: U.S. Geological Survey Professional Paper 800-B, p. B9-B15.

Reference (Deposit): Wright, F.F., 1969, Sedimentation and gold distribution, Yakutat Bay, Alaska: University of Alaska Marine Science Report R69-9, 12p.

Reference (Deposit): Schrader, F.C., and Spencer, A.C., 1901, The geology and mineral resources of a portion of the Copper River district, Alaska: U.S. Geological Survey Special Publication, 94 p.

Reference (Deposit): Brooks, A.H., 1904, Placer mining in Alaska in 1903: U.S. Geological Survey Bulletin 225, p. 43-59.

Reference (Deposit): Reimnitz, Erk, and Plafker, George, 1976, Marine gold placers along the Gulf of Alaska margin: U.S. Geological Survey Bulletin 1415, 16 p.

Reference (Deposit): Thomas, B.I., and Berryhill, R. V., 1962, Reconnaissance studies of Alaskan beach sands, eastern Gulf of Alaska: U.S. Bureau of Mines Report of Investigations 5986, 40 p.

Reference (Deposit): Miller, D. J., 1961, Geology of the Lituya district, Alaska, Gulf of Alaska Tertiary Province, Alaska: U.S. Geological Survey Open-File Report 210, 1 map, scale 1:96,000.

Reference (Deposit): MacKevett, E.M., Jr., and Plafker, G., 1970, Geochemical and geophysical reconnaissance of parts of the Yakutat and Mount St. Elias quadrangles, Alaska: U.S. Geological Survey Bulletin 1312-L, 12 p.

Reference (Deposit): Brooks, A.H., 1923, The Alaska mining industry in 1921: U.S. Geological Survey Bulletin 739, p. 1-50.

Reference (Deposit): Foley, J.Y., Burns, L.E., Schneider, C.L., and Forbes, R.B., 1989, Preliminary report of platinum group element occurrences in Alaska: Alaska Division of Geological and Geophysical Surveys Public Data File 89-20, 32 p., 1 map sheet, scale 1:2,500,000.

Reference (Deposit): Hudson, T.L., Plafker, George, and Turner, D. L., 1977, Metamorphic rocks of the Yakutat-St. Elias Area, South-central Alaska: U.S. Geological Survey Journal of Research, v. 5, no. 2, p. 173-184.

Reference (Deposit): Brooks, A.H., 1918, Mineral resources of Alaska, 1916: U.S. Geological Survey Bulletin 662, 469 p.

Reference (Deposit): Clifton, H.E., and Luepke, G., 1987, Heavy-mineral placer deposits of the continental margin of Alaska and the Pacific Coast States, in Geology and resource potential of the continental margin of western North America and adjacent ocean basins, Beaufort Sea to Baja California: Circum-Pacific Council for Energy and Mineral Resources, Earth Science Series, v. 6, p. 691-738.

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