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Unnamed (overlooking headwaters of Jones River)

Occurrence, Inactive

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Commodities and mineralogy

Main commodities Cu
Other commodities Pb
Ore minerals chalcopyrite; galena; pyrite
Gangue minerals carbonate; quartz

Geographic location

Quadrangle map, 1:250,000-scale MG
Quadrangle map, 1:63,360-scale B-1
Latitude 62.468
Longitude -153.169
Nearby scientific data Find additional scientific data near this location
Location and accuracy This unnamed occurrence is located on a flattened, south-facing spur overlooking the headwaters of the Jones River; it is at an elevation of 5,200 feet (1,585 m) in the SE1/4 sec. 33, T. 28 N., R. 21 W., of the Seward Meridian. The reporter visited the site in 1984; at station nos. 84BT104 and 84BT147.

Geologic setting

Geologic description

This unnamed occurrence consists of a mineralized quartz-carbonate breccia zone in a small composite pluton of Late Cretaceous (79 Ma) age (Solie and others, 1991). The pluton averages diorite in composition; it covers an equant, one square kilometer area, and intrudes the sandstone, siltstone, and silty limestone of the mid-Silurian Terra Cotta Mountains Sandstone, a unit of the Dillinger subterrane (Bundtzen, Harris, and Gilbert, 1997).
The deposit consists of disseminated chalcopyrite, pyrite, and a trace of galena in an intrusive hosted, quartz-carbonate breccia. Total sulfides amount to no more than 1 percent of the total mineralized zone. No surface measurements of the mineralized area are available. No assay data is available. Metallic content is based on field identification of sulfide minerals.
Geologic map unit (-153.171231384735, 62.4674088336349)
Mineral deposit model Polymetallic replacement? (Cox and Singer, 1986; model 19a?).
Mineral deposit model number 19a?
Alteration of deposit Extensive carbonate alteration.

Production and reserves

Workings or exploration The reporter examined the site in 1984. No assay data is available. Metallic content is based on field identification of sulfide minerals.
Indication of production None
Reserve estimates None.

References

MRDS Number 10307873

References

Bundtzen, T.K., Harris, E.E., and Gilbert, W.G., 1997, Geologic Map of the eastern McGrath quadrangle, Alaska: Alaska Division of Geological and Geophysical Surveys Report of Investigations 97-14, 34 p., 1 sheet, scale 1:125,000.
Solie, D.N., Bundtzen, T.K., and Gilbert, W.G., 1991, K/Ar ages of igneous rocks in the McGrath quadrangle, Alaska: Alaska Division of Geological and Geophysical Surveys Public Data File 91-23, 7 p., 1 sheet, 1:250,000 scale.
Reporters T.K. Bundtzen (Pacific Rim Geological Consulting)
Last report date 12/10/1998