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Road Cut II

Prospect in Alaska, United States with commodities Copper, Zinc, Silver, Gold
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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. Host and associated rocks
  9. Nearby scientific data
  10. Economic information about the deposit and operations
  11. Mining district
  12. Links to other databases
  13. Bibliographic references
  14. General comments
  15. Reporter information

Geologic information

Identification information

Deposit ID 10308236
Record type Site
Current site name Road Cut II

Geographic coordinates

Geographic coordinates: -135.43209, 59.18975 (WGS84)
Relative position This prospect occurs along the Mud Bay Road between mileposts 4 and 5 (from Haines). It is approximately 1 mile south of the Road Cut prospect (SK006) along the Mud Bay Road (Still, 1988). It is in the SE1/4, section 11, T. 31 S., R. 59 E. of the Copper River Meridian.

Site location context

Political divisions (FIPS codes)

Alaska(state)

United States(country)

North America(continent)

Land(continent)

USGS map quadrangles

Skagway A-2 NE(quadrangle 1:24,000 scale)

Skagway SE(quadrangle 1:100,000 scale)

Skagway(quadrangle 1:250,000 scale)

Hydrologic units (watersheds)

Chilkat-Skagway Rivers(hydrologic unit)

Northern Southeast Alaska(hydrologic accounting unit)

Southeast Alaska(hydrologic subregion)

Alaska(hydrologic region)

Geographic areas

Country State
United States Alaska

Commodities

Commodity Importance
Copper Primary
Zinc Critical Primary
Silver Secondary
Gold Secondary

Materials information

Materials Type of material
Chalcopyrite Ore
Pyrite Ore
Sphalerite Ore
Epidote Gangue

Alteration

  • (Local) Epidotization.

Host and associated rocks

  • Host or associated Host
    Rock type
    Stratigraphic age (youngest) Late Triassic

Nearby scientific data

(1) -135.43209, 59.18975
ListMap

Economic information

Comments on the geologic information

  • Geologic Description = According to Still (1988), spotty gold-copper-zinc mineralization extends for at least a mile, between mileposts 4 and 5 on the Mud Bay Road. Mineralization consists of epidote-altered metabasalt and epidote bands up to 2 feet thick that contain pyrite, chalcopyrite, and locally sphalerite. Samples contain up to 0.21 ppm gold, 2.5 ppm silver, 0.69% copper, and 1.83% zinc. This mineralization may be continuous with the Road Cut prospect (SK006). From the descriptions of Still (1988), it appears that mineralization at both prospects occurs along fault and shear zones that are subsidiary shears and splits of the Chilkat fault. If so, then the age of the mineralization is probably Tertiary or youngersince most movement along the Chilkat Fault has probably been post-Mesozoic (Lanphere, 1978). Plafker, Hudson and Silberling (1979) and Plafker and Hudson (1980) cite fossil evidence for a Late Triassic (Karnian) age for the metabasalts on the Chilkat Peninsula. The age of a nearby ultramafic body is probably 108-109 m.y. based on potassium-argon ages from a pyroxenite at Battery Point (MacKevett and others, 1974).
  • Age = the age is not well established. It can be no older than the Late Triassic age of the metabasalt that hosts the prospect (Plafker, Hudson and Silberling, 1979; Plafker and Hudson, 1980). If the structures that localize the mineralization are related to the Chilkat Fault, then the age of the mineralization is probably Tertiary or younger as most movement on the Chilkat Fault has been post-Mesozoic (Lanphere, 1978).

Economic information about the deposit and operations

Development status Prospect

Comments on exploration

  • Status = Inactive

Mining district

District name Juneau (Skagway subdistrict)

Comments on the workings information

  • Workings / Exploration = In 1986-1987 the U.S. Bureau of Mines made shallow excavations and sampled the bedrock and rubble. They also ran two 440-foot-long magnetometer lines across the beach and road and up the escarpment that forms the eastern edge of the Chilkat Fault near milepost 5 of the Mud Bay Road. A prominent magnetic low indicates a fault zone that strikes N37W about 35 feet east of the Mud Bay road (Still, 1988). An approximately 30-foot-long adit in metabasalt is located several hundred feet southeast of milepost 4 on the Mud Bay road. No mineralization was seen in the adit, but a band of metabasalt adjacent to the adit contains chalcopyrite (Still, 1988).

Reference information

Bibliographic references

Comments on the references

  • Primary Reference = Still, 1988

General comments

Subject category Comment text
Deposit Model Name = Base metal sulfides with some precious metal values along a shear zone in metabasalt.
Deposit Other Comments = This prospect is within a mile of the Chilkat State Park.

Reporter information

Type Date Name Affiliation Comment
Reporter 04-FEB-01 T.C. Crafford T. Crafford & 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.