Bluff

Site Name

Primary: Bluff

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Commodity

Primary: Zinc
Primary: Lead

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Location

State: Alaska
District: Fortymile

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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: Prospect
Operation Type: Unknown
Years of Production:
Organization:
Significant:

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Physiography

Not available

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Mineral Deposit Model

Model Name: Porphyry Cu-Mo

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Orebody

Not available

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Structure

Not available

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Alterations

Alteration Type: L
Alteration Text: Strong hydrothermal alteration (Singer and others, 1976).

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Rocks

Not available

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Analytical Data

Not available

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Materials

Ore: Sphalerite
Ore: Chalcopyrite
Ore: Galena
Ore: Magnetite
Ore: Molybdenite
Ore: Pyrite
Gangue: Tourmaline

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Comments

Comment (Deposit): Model Name = Porphyry Cu (Cox and Singer, 1986; model 21a)

Comment (Geology): Age = Mid-Cretaceous to early Tertiary, based on other deposits in the area (Mosquito: TC015).

Comment (Reference): Primary Reference = Eberlein and others, 1977

Comment (Deposit): Other Comments = See also Mosquito (TC015) and Peternie (TC022) prospects.

Comment (Geology): Geologic Description = The Bluff prospect contains disseminated pyrite, chalcopyrite, molybdenite, tourmaline, and magnetite within high-level porphyritic quartz monzonite and granodiorite intrusions. The intrusions are of mid-Cretaceous to early Tertiary age (Foster, 1970). The intrusions also show evidence of strong hydrothermal alteration. Numerous faults and dikes are found in the area (Singer and others, 1976). The prospect was explored by surface sampling, diamond drilling, and geophysics in the early 1970's by Cities Services Mineral Corp. (David Hedderly-Smith, oral communication, 1998). The regional geology of the prospect consists of Precambrian-Paleozoic biotite gneiss and schist of amphibolite grade (Foster, 1970). The prospect also lies within the eastern portion of the Y1 subterrane of the Yukon-Tanana terrane (Foster and others, 1994).

Comment (Workings): Workings / Exploration = Explored by surface sampling, diamond drilling, and geophysics by Cities Services Mineral Corp. in the early 1970's (Singer and others, 1976). There has probably been more exploration in recent years. The Bluff prospect was also staked in 1987 by Resource Associates of Alaska, but was dropped two years later.

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References

Reference (Deposit): Foster, H.L., and Keith, T.E.C., 1994, Geology of the Yukon-Tanana area of east-central Alaska: in Plafker, G. and Berg, H.C., eds, The geology of North America, vol. G-1, The geology of Alaska: Geological Society of America, p. 205-240.

Reference (Deposit): Cobb, E.H., and Eberlein, G.D., 1980, Summaries of data on and lists of references to metallic and selected nonmetallic mineral deposits in the Big Delta and Tanacross quadrangles, Alaska: U.S. Geological Survey Open-File Report 80-1086, 77 p.

Reference (Deposit): Singer, D.A., Csejtey, Bela, Jr., and Miller, R.J., 1978, Map and discussion of the metalliferous and selected nonmetalliferous mineral resources of the Talkeetna Mountains quadrangle, Alaska: U.S. Geological Survey Open-file Report 78-588-Q, 33 p., 1 plate, scale 1:250,000.

Reference (Deposit): Nokleberg, W.J., Bundtzen, T.K., Berg, H.C., Brew, D.A., Grybeck, D.J., Robinson, M.S., Smith, T.E., and Yeend, W., 1987, Significant metalliferous lode deposits and placer districts of Alaska: U.S. Geological Survey Bulletin 1786, 104 p.

Reference (Deposit): Foster, H.L., 1970, Reconnaissance geologic map of the Tanacross quadrangle, Alaska: U.S. Geological Survey Miscellaneous Geological Investigations Map I-593, 1 sheet, scale 1:250,000.

Reference (Deposit): 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, scale 1:1,000,000.

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