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  3. Alaska Resource Data File (ARDF)

Unnamed (southeast of Driest Point)

Occurrences, Undetermined

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Commodities and mineralogy

Main commodities Ag; barite; Pb; Zn
Ore minerals barite; galena; pyrite; sphalerite
Gangue minerals calcite; hematite; quartz

Geographic location

Quadrangle map, 1:250,000-scale KC
Quadrangle map, 1:63,360-scale A-5
Latitude 55.171
Longitude -131.592
Nearby scientific data Find additional scientific data near this location
Location and accuracy This site represents 5 occurrences along about a half-mile of the south shoreline of the west-trending peninsula that separates Sylburn Harbor from Port Chester. The occurrences are in sections 9 and 29, T. 77 S., R. 92 E., of the Copper River Meridian, between 0.5 and 0.9 mile from Driest Point. The map coordinates are for their approximate midpoint. The site corresponds to loc. 16 in Berg (1972 [I 684]), loc. 135 in Elliott and others (1978), and loc. 23a-e in Karl (1992). The location is accurate within about 0.1 mile.

Geologic setting

Geologic description

The country rocks in the area of this site are recrystallized, Upper Triassic carbonate and clastic rocks, rhyolite, and basalt (Berg, 1972). The rocks are folded and faulted, and intruded by rhyolite dikes. All were regionally metamorphosed to greenschist-grade phyllite and semischist in Late Cretaceous time.
The mineral occurrences consist of quartz-calcite-barite(-hematite) veins up to 6 feet thick that contain galena and sphalerite, and extend at least 60 feet inland from tidewater (Karl, 1992, loc. 23). The veins are hosted by dolomitic conglomerate and brecciated rhyolite. Rhyolite dikes up to 60 feet thick cut the conglomerate and also intrude the veins. Samples of variously mineralized veins and bedded rocks contained up to 20 ppm Ag, more than 2% Pb, 1500 ppm Zn; and more than 5000 ppm Ba (Karl, 1992, loc. 23a-e).
Geologic map unit (-131.593679908967, 55.1706554911236)
Mineral deposit model Polymetallic veins (Cox and Singer, 1986; model 22c)
Mineral deposit model number 22c
Age of mineralization Veins hosted by Upper Triassic strata and cut by a rhyolite dike may be Late Triassic in age; veins that postdate the dike may be Late Cretaceous or younger.

Production and reserves

Workings or exploration Samples of variously mineralized veins and bedded rocks contained up to 20 ppm Ag, more than 2% Pb, 1500 ppm Zn; and more than 5000 ppm Ba (Karl, 1992, loc. 23a-e).
Indication of production None

References

MRDS Number A012377

References

Berg, H.C., 1972, Geologic map of Annette Island, Alaska: U.S. Geological Survey Miscellaneous Geologic Investigations Map I-684, 8 p., 1 sheet, scale 1:63,360.
Elliott, R.L., Berg, H.C., and Karl, S.M.,1978, Map and table describing metalliferous and selected non-metalliferous mineral deposits in the Ketchikan and Prince Rupert quadrangles, Alaska: U.S. Geological Survey Open-File Report 78-73B, 17 p., 1 sheet, scale 1:250,000.
Reporters H.C. Berg, USGS
Last report date 7/6/1999