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Unnamed (northwest shore of outer Adams Inlet)

Occurrence, Inactive

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Commodities and mineralogy

Main commodities Cu
Other commodities Ag; Co; Mo; Sn
Ore minerals chalcopyrite; ilmenite; magnetite; pyrite; pyrrhotite

Geographic location

Quadrangle map, 1:250,000-scale JU
Quadrangle map, 1:63,360-scale D-6
Latitude 58.8654
Longitude -135.9825
Nearby scientific data Find additional scientific data near this location
Location and accuracy This occurrence is on the north shore of Adams Inlet, approximately 3 miles from its entrance. It is in the NW1/4 section 6, T. 35 S., R. 57 E. of the Copper River Meridian. The location is accurate within 1/4 mile.

Geologic setting

Geologic description

The rocks in the area consist of deformed and metamorphosed Silurian or Devonian carbonate, clastic and volcanic clastic units that have been intruded by Upper Jurassic and Lower Cretaceous granitic and dioritic rocks (Brew and others, 1992). Lava flows of amygdaloidal, vesicular, altered basalt up to 15 feet thick are exposed for 500 feet along the shore at this site. Pyrite, chalcopyrite, and pyrrhotite occur along fractures in the basalt and near altered basalt dikes which intrude the flows. Pyrite, ilmenite, and magnetite are disseminated throughout the dikes (Brew and others, 1978). The groundmass of the altered basalt consists of epidote, actinolite, and lesser amounts of calcite, dolomite, and chlorite. All samples collected contained anomalous amounts of copper; one sample contained 300 ppm cobalt. Most samples contained trace amounts of molybdenum; one contained silver and tin (MacKevett and others, 1971).
Geologic map unit (-135.984375874145, 58.8650159820108)
Mineral deposit model Volcanic-hosted Cu (Cox and Singer, 1986; model 22a)
Mineral deposit model number 22a
Alteration of deposit Propylitization of basalt hostrock.

Production and reserves

Workings or exploration Surface sampling only.
Indication of production None

References

MRDS Number A012112

References

Brew, D.A., Himmelberg, G.R., Loney, R.A., and Ford, A.B., 1992, Distribution and characteristics of metamorphic belts in the southeastern Alaska part of the North American Cordillera--Metamorphic styles in young and ancient orogenic belts: Journal of Metamorphic Geology, v. 10, no. 3, p. 465-482.
Brew, D.A., Johnson, B.R., Grybeck, D., Griscom, A., Barnes, D.F., Kimball, A.L., Still, J.C., and Rataj, J.L., 1978, Mineral resources of the Glacier Bay National Monument Wilderness Study Area, Alaska: U.S. Geological Survey Open-File Report 78-494, 670 p., 7 sheets.
MacKevett, E.M., Jr., Brew, D.A., Hawley, C.C., Huff, L.C., and Smith, J.G., 1971, Mineral resources of Glacier Bay National Monument, Alaska: U.S. Geological Survey Professional Paper 632, 90 p., 12 plates, scale 1:250,000.
Reporters J.C. Barnett and L.D. Miller (Juneau, Alaska )
Last report date 12/15/2001