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Landmark Gap

Prospect, Inactive

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Commodities and mineralogy

Main commodities Cu
Ore minerals bornite; chalcopyrite; pyrite
Gangue minerals quartz

Geographic location

Quadrangle map, 1:250,000-scale MH
Quadrangle map, 1:63,360-scale A-5
Latitude 63.1375
Longitude -146.0964
Nearby scientific data Find additional scientific data near this location
Location and accuracy The Landmark Gap prospect is at an elevation of about 3,950 feet and west of Landmark Gap Lake. It is about at the center of section 31, T. 20 S., R. 9 E., Fairbanks Meridian. The location is accurate within about 800 feet.

Geologic setting

Geologic description

The prospect is in metabasalt of the Nikolai Greenstone of Late Triassic age (Nokleberg and others, 1991). Mineralization at the site is stratiform; it ranges from 1 inch to 3 feet thick and consists of disseminated to massive chalcopyrite, pyrite, and minor bornite. The sulfides occur in cherty bands and in irregular quartz veins that surround pillows and breccia clasts. The prospect was discovered in 1996 by American Copper and Nickel Company; samples contained as much as 3.5 percent copper (W.T. Ellis, unpublished data, 1996). The deposit probably is syngenetic and possibly of Cyprus type.
Geologic map unit (-146.098646345096, 63.1370739655411)
Mineral deposit model Although most of the deposits in the Nikolai Greenstone are of basaltic copper type (Cox and Singer, 1986; model 23), the Landmark Gap deposit is stratiform and possibly of Cyprus type? (model 24a?).
Mineral deposit model number 23, 24a?
Age of mineralization Late Triassic, the age of the host rock.
Alteration of deposit Silicification.

Production and reserves

Workings or exploration American Copper and Nickel Company discovered the site in 1996 and collected samples as rich as 3.5 percent copper (W.T. Ellis, unpublished data, 1996). The area is on active MAN Resources claims.
Indication of production None

Additional comments

The mineralization is characterized by abundant vermilion so-called copper lichen.

References

References

Nokleberg, W.J., Lange, I.M., Roback, R.C., Yeend, Warren, and Silva, S.R., 1991, Map showing locations of metalliferous lode and placer mineral occurrences, mineral deposits, prospects, and mines, Mount Hayes quadrangle, eastern Alaska Range, Alaska: U.S. Geological Survey Miscellaneous Field Studies Map MF-1996-C, 42 p., 1 sheet, scale 1:250,000.
Reporters W.T. Ellis (Alaska Earth Science), C.C. Hawley (Hawley Resource Group), and W.J. Nokleberg (USGS)
Last report date 6/18/2001