Unnamed (west of the Middle Fork Chandalar River)

The Unnamed (west of the Middle Fork Chandalar River) is a zinc and lead mine located in Alaska.

About the MRDS Data:

All mine locations were obtained from the USGS Mineral Resources Data System. The locations and other information in this database have not been verified for accuracy. It should be assumed that all mines are on private property.

Mine Info

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Site Name

Primary: Unnamed (west of the Middle Fork Chandalar River)

Commodity

Primary: Zinc
Primary: Lead
Secondary: Copper
Secondary: Silver

Location

State: Alaska
District: Chandalar

Land Status

Not available

Holdings

Not available

Workings

Not available

Ownership

Not available

Production

Not available

Deposit

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

Physiography

Not available

Mineral Deposit Model

Model Name: Mississippi Valley, S.E. Missouri Pb-Zn

Orebody

Not available

Structure

Not available

Alterations

Not available

Rocks

Not available

Analytical Data

Not available

Materials

Ore: Galena
Ore: Pyrite
Ore: Sphalerite
Ore: Tetrahedrite
Ore: Chalcopyrite
Gangue: Quartz

Comments

Comment (Exploration): Status = Inactive

Comment (Deposit): Model Name = Mississippi Valley Zn-Pb (?) (Cox and Singer, 1986; model 32a).

Comment (Deposit): Other Comments = See also locations PS007 and PS008. Area has potential for stratabound lead-zinc deposits.

Comment (Workings): Workings / Exploration = Two blocks of claims staked in 1977 (19 by Noranda, 6 by RAA). Semi-quantitative spectrographic data for sample 76ARR46 (Detra, 1977, Table 1): Ag (70 ppm), Cu (1,000 ppm), Pb (3,000 ppm), Sb (700 ppm), Zn (greater than 20,000 ppm); Zn by wet chemical analysis (340,000 ppm).

Comment (Reference): Primary Reference = Detra, 1977

Comment (Geology): Geologic Description = One of two mineralized areas with small outcrops within which lead-zinc-silver-(copper?) mineralization is found (Detra, 1977). Sphalerite, galena and pyrite are found in crosscutting veins in a chert breccia with quartz veins. Samples from the veins are reported to contain galena, sphalerite and chalcopyrite as well as iron sulfides. An analysis of mineralized material returned a value of 34 percent Zn and 70 ppm Ag (Detra, 1977). Exposures of mineralization are less than 3 meters in length and not much wider than the streams (approximately 1 to 2 meters) in which they are exposed. The mineralization is described as occurring in a chert cap at an unconformable paleokarst surface at the top of the Devonian Skajit Limestone at the base of a 1,200-meter-thick Frasnian fine clastic marine sequence (Dutro, 1978). This marine sequence grades upward from basal black shales and dark laminated limestones through cycles of fine clastics and into reef limestones. The clastics contain volcaniclastics and mafic volcanic rocks. The overlying clastics are yellow-weathering phyllitic shales and sandstones, which in turn are overlain by black shales of the Hunt Fork Shale. This is purportedly the only carbonate-hosted prospect in Alaska genetically linked to a karst or paleokarst event (Schmidt, 1997). The surrounding area is mapped as Devonian shale, sandstone and conglomerate with scattered bodies of mafic rocks of uncertain age.

References

Reference (Deposit): Maas, K.M., 1987, Availability of land for Mineral exploration and development in northern Alaska, 1986: U.S. Bureau of Mines Special Publication, 34 p., 33 sheets.

Reference (Deposit): Schmidt, J.M., 1997, Shale-hosted Zn-Pb-Ag and barite deposits of Alaska, in Goldfarb, R.J., and Miller, L.D., eds., Mineral Deposits of Alaska, 1997: Economic Geology Monograph 9, p. 35-65.

Reference (Deposit): Menzie, W.D., Reiser, H.N., Brosgi, W.P., and Detterman, R.L., 1985, Map showing distribution of mineral resources (excepting oil and gas) in the Philip Smith Mountains quadrangle, Alaska: U.S. Geological Survey Miscellaneous Field Investigations Map MF-879-C, 2 sheets, scale 1:250,000.

Reference (Deposit): Dutro, J.T., Jr., 1978, Potential stratabound lead-zinc mineralization, Philip Smith Mountains quadrangle, Alaska, in Johnson, K. M., ed., The United States Geological Survey in Alaska, Accomplishments during 1977: U.S. Geological Survey Circular 772-B, p. B9-B11.

Reference (Deposit): Barker, J.C., 1978, Mineral Investigations of certain lands in the eastern Brooks Range: a summary report: US Bureau of Mines Open-File No. 63-78

Reference (Deposit): Cathrall, J.B., Cooley, E.F., Detra, D.E., and O'Leary, R.M., 1977, A listing and statistical summary of spectrographic and chemical analysis of stream-sediment and rock samples from the Philip Smith Mountains quadrangle, Alaska: U.S. Geological Survey Open-File Report 77-244, 79 p.

Reference (Deposit): Detra, D.E., 1977, Delineation of an anomalous lead-zinc area in the Philip Smith Mountains A-2 quadrangle, Alaska: U.S. Geological Survey Open-File Report 77-223, 11 p.

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