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Unnamed

Occurrence in Alaska, United States with commodities Silver, Gold, Copper
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Sections on this page
  1. Identification information
  2. Geographic coordinates
  3. Site location context
  4. Geographic areas
  5. Commodities
  6. Materials information
  7. Alteration
  8. Mineral occurrence model information
  9. Host and associated rocks
  10. Nearby scientific data
  11. Economic information about the deposit and operations
  12. Mining district
  13. Links to other databases
  14. Bibliographic references
  15. General comments
  16. Reporter information

Geologic information

Identification information

Deposit ID 10000908
MRDS ID A011566
Record type Site
Current site name Unnamed

Geographic coordinates

Geographic coordinates: -152.19976, 62.55341 (WGS84)
Relative position C.C. Hawley and Associates, Inc. (1978, locality C, Fig. 4.1-C(3)) show this occurrence 3.4 miles from the peak of Dall Mt. on a bearing of S61E in the southwest quarter of Section 36, T. 29 N., R. 16 W., of the Seward Meridian at about 3600 feet within Denali National Park and Preserve.

Site location context

Political divisions (FIPS codes)

Matanuska-Susitna(Borough)

Alaska(state)

United States(country)

North America(continent)

Land(continent)

USGS map quadrangles

Talkeetna C-5(quadrangle 1:63,360 scale)

Talkeetna NW(quadrangle 1:100,000 scale)

Talkeetna(quadrangle 1:250,000 scale)

Hydrologic units (watersheds)

Yentna River(hydrologic unit)

Susitna River(hydrologic accounting unit)

South Central Alaska(hydrologic subregion)

Alaska(hydrologic region)

Geographic areas

Country State
United States Alaska

Commodities

Commodity Importance
Silver Primary
Gold Primary
Copper Primary

Comments on the commodity information

  • Ore Material = unknown platinoid
  • Ore Material = unknown silver mineral
  • Ore Material = unknown platinoid
  • Ore Material = unknown silver mineral

Materials information

Materials Type of material
Bornite Ore
Chalcopyrite Ore
Gold Ore
Calcite Gangue
Diopside Gangue
Garnet Gangue
Wollastonite Gangue

Alteration

  • (Local) Development of calc-silicate mineral assemblages in tactitized limestone, and silicification of argillite and siltstone (C.C. Hawley and Associates, Inc., 1978).

Mineral occurrence model information

Model code 59
USGS model code 18b
Deposit model name Skarn Cu
Mark3 model number 8

Host and associated rocks

  • Host or associated Associated
    Rock type Plutonic Rock > Mafic Intrusive Rock > Diorite
    Rock unit name Dall Stock
    Rock description Dall Stock
    Stratigraphic age (youngest) Pliocene
    Stratigraphic age (youngest) Pliocene
  • Host or associated Host
    Rock type Sedimentary Rock > Carbonate > Limestone

Nearby scientific data

(1) -152.19976, 62.55341
ListMap

Economic information

Comments on the geologic information

  • Geologic Description = At this occurrence massive Middle or Upper Devonian limestone (Dl), Paleozoic siliceous black argillite, and minor siltstone (Pzus) are intruded by the Cascade pluton, a 64.6 m.y. old composite pluton (Tcp) which consists of granite-porphyry, intermediate phase rocks and lamprophyre (Reed and Nelson, 1980). The mineral occurrence is separated from the intrusion by a few feet of pyritic, silicified black argillite. Massive bornite and chalcopyrite occur in a replacement band 0.3 to 3 feet wide, with free gold in thin calcite-diopside seams within banded tactite. One sample contained 25% copper, 41 oz/ton silver and 0.7 oz/ton gold over a three foot width (C.C. Hawley and Associates, Inc., 1978). Foley and others (1997) report locally abundant bornite within the pluton and anomalous gold in the lamprophyre (31 ppb) and in granite-porphyry (88 ppb). They also note anomalous platinum (300 ppb) in pan concentrate samples at the eastern margin of the pluton. The pluton has converted the country rocks to a tactite assemblage which includes diopside and wollastonite.? This occurrence is part of 10-mile-long tactite zone related to Cascade pluton; another anomalous area lies about three quarters of a mile southwest of this site (TL066) where bleached tactite zone in pebble conglomerate and extends for hundreds of yards between Cascade pluton and a small outlying stock.? the Cascade pluton has a composition similar to the Kohlsaat pluton (Reed and Nelson, 1980; Nelson and others, 1992). Foley and others (1997) report mean values of 20 ppb gold, 1 ppb palladium, 42 ppb platinum, 139 ppm nickel, and 26 ppm copper from six rock samples of the Cascade pluton. Anomalous gold, platinum-group elements, copper, chrome, nickel and arsenic are reported from the composite plutons mapped by Reed and Nelson (1980) in the southern Alaska Range (Reed and others, 1978; Nelson and others 1992). Gold and platinum group element placers have been worked at sites downstream from these bodies (Mertie, 1919; Cobb, 1973). See also TL020, TL023, TL052, and TL053.
  • Age = Late Cretaceous/early Tertiary; mineralization is interpreted to be linked to the Cascade pluton dated as 64.6 +/- 1.8 m.y. by K/Ar methods (Reed and Lanphere, 1972).

Economic information about the deposit and operations

Development status Occurrence
Commodity type Metallic

Comments on exploration

  • Status = Inactive

Mining district

District name Yentna

Comments on the workings information

  • Workings / Exploration = Reconnaissance mapping, prospecting, stream silt, pan concentrate and rock sampling are all that have been done here. Foley and others (1997) report mean values of 20 ppb gold, 1 ppb palladium, 42 ppb platinum, 139 ppm nickel, and 26 ppm copper from six rock samples of the Cascade pluton. Anomalous gold, platinum-group elements, copper, chrome, nickel and arsenic are reported from the composite plutons mapped by Reed and Nelson (1980) in the southern Alaska Range (Reed and others, 1978; Nelson and others 1992). Gold and platinum group element placers have been worked at sites downstream from these bodies (Mertie, 1919; Cobb, 1973).

Reference information

Bibliographic references

  • Deposit

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

  • Deposit

    Reed, B.L., and Lanphere, M.A., 1972, Generalized geologic map of the Alaska-Aleutian range batholith showing potassium-argon ages of the plutonic rocks: U.S. Geological Survey Miscellaneous Field Studies Map MF-372, 2 sheets, scale 1:1,000,000.

  • Deposit

    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, 275 p., 7 plates.

  • Deposit

    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.

  • Deposit

    Cobb, E.H., and Reed, B.L., 1980, Summaries of data 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.

  • Deposit

    Reed, B.L., and Nelson, S.W., 1980, Geologic map of the Talkeetna quadrangle: U.S. Geological Survey Miscellaneous Investigations Map I-1174, scale 1:250,000.

  • Deposit

    Nelson, S.W., Foley, J.Y., and Nelson, B.K., 1992, Metal-rich lamprophyric and associated alkaline mafic, ultramafic and intermediate to felsic rocks from composite plutons, central Alaska Range, Alaska [abs.]: International Conference on Arctic Margins, Anchorage, Alaska, September 2-4, 1992, Abstracts with Program.

  • Deposit

    Foley, J.Y., Light, T.D., Nelson, S.W., and Harris, R.A., 1997, Mineral occurrences associated with mafic-ultramafic and related alkaline complexes in Alaska: Economic Geology, Monograph 9, p. 396-449.

  • Deposit

    Mertie, J.B., Jr., 1919, Platinum-bearing gold placers of the Kahiltna Valley: U.S. Geological Survey Bulletin 692-D, p. 233-264.

  • 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.

Comments on the references

  • Primary Reference = C.C. Hawley and Associates, Inc., 1978

General comments

Subject category Comment text
Deposit Model Name = Cu skarn deposits (Cox and Singer, 1986; model 18b).
Deposit Other Comments = the Cascade pluton has also been called the Dall Stock (C.C. Hawley and Associates, 1978). This occurrence is part of a 10-mile-long tactite zone related to Cascade pluton; another anomalous area lies 1 mile southwest of this site: bleached tactite zone in Dall Limestone pebble conglomerate extends for hundreds of yards between Cascade pluton and small outlying stock. This site is located within Denali National Park and Preserve.

Reporter information

Type Date Name Affiliation Comment
Reporter 10-AUG-1998 Madelyn A. Millholland Millholland & Associates

Beyond USGS

Supplemental information added by qvyshift.com. Not part of the original USGS MRDS record.

Maps centered on this site

Authoritative Alaska resources

These are landing pages for further research — the state agencies don't currently expose per-mine deep links.