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Unnamed (near O'Brien Creek)

Occurrence, Inactive

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Commodities and mineralogy

Main commodities Ba; Pb; Zn
Ore minerals galena; pyrite; sphalerite
Gangue minerals celsian

Geographic location

Quadrangle map, 1:250,000-scale EA
Quadrangle map, 1:63,360-scale B-1
Latitude 64.4196
Longitude -141.3817
Nearby scientific data Find additional scientific data near this location
Location and accuracy This occurrence is located along the Taylor Highway and O'Brien Creek, about 1.2 miles southeast of the mouth of Columbia Creek. The occurrence is in section 3, T. 5 S., R. 32 E., of the Fairbanks Meridian. The location is accurate within 1,000 feet.

Geologic setting

Geologic description

The rocks in the vicinity of this occurrence are predominantly Paleozoic greenschist-facies black carbonaceous quartzite (Dusel-Bacon and others, 1998). Approximately three-quarters of a mile to the south, these rocks are in fault contact with Paleozoic amphibolite-facies metamorphic rocks (Foster, 1976). Sulfides occur within buff-colored, celsian (barium-silicate) -bearing quartzite. The sulfides, in decreasing order of abundance, are sphalerite, pyrite, galena, and chalcopyrite (Dusel-Bacon and others, 1998). Celsian-bearing quartzite from this site and another nearby occurrence (EA076) contain between 1.6 and 3.6 percent barium, 1.8 and 2.7 percent zinc, and 1,040 ppm and 3,980 ppm lead (Dusel-Bacon and others, 1998). Dusel-Bacon and others (1998) interpret this occurrence is interpreted to be a sedimentary-exhalative massive sulfide occurrence.
Geologic map unit (-141.38400066344, 64.4192935568101)
Mineral deposit model Sedimentary exhalative massive sulfide (Cox and Singer, 1986; model 31a).
Mineral deposit model number 31a
Age of mineralization Paleozoic or younger.

Production and reserves

Indication of production None

References

References

Dusel-Bacon, Cynthia, Bressler, J.R., Takaoka, H., Mortensen, J.K., Oliver, D.H., Leventhal, J.S., Newberry, R.J., and Bundtzen, T.K., 1998, Stratiform zinc-lead mineralization in Nasina assemblage rocks of the Yukon-Tanana Upland in east-central Alaska: U.S. Geological Survey Open-File Report 98-340, 26 p. (World Wide Web URL, http://caldera.wr.usgs.gov/syngenms/OF98-340.html).
Foster, H.L., 1976, Geologic map of the Eagle quadrangle, Alaska: U.S. Geological Survey Miscellaneous Investigations Series, Map 922, 1 sheet, scale 1:250,000.
Reporters M.B. Werdon
Last report date 5/1/2002