Unnamed (in Zane Hills, south of upper Caribou Creek) (ARDF #HU016) REE, Th, U

Unnamed (in Zane Hills, south of upper Caribou Creek)

Occurrence, Inactive

Commodities and mineralogy

Main commodities	REE; Th; U
Ore minerals	allanite; betafite; sphene; thorite; uranothorianite; zircon

Geographic location

Quadrangle map, 1:250,000-scale	HU
Quadrangle map, 1:63,360-scale	A-6
Latitude	66.1181
Longitude	-155.9733
Nearby scientific data	Find additional scientific data near this location
Location and accuracy	This occurrence is about 8. 5 miles southwest of Hogatza and four miles south of Caribou Mountain. It is about 0.2 mile south of the center of section 5, T. 8 N., R. 14 E. of the Kateel River Meridian. The location is accurate within 1 mile.

Geologic setting

Geologic description This occurrence consists of radioactive and rare-earth accessory minerals in the border phases of the Cretaceous, Zane Hills pluton. Miller and Ferrians (1968) noted that the quartz monzonitic to monzonitic border phase of the generally granodioritic, Zane Hills pluton showed 5 to 10 times background radioactivity. They also noted that large K-feldspar phenocrysts, as well as tourmaline-bearing aplite dikes, are common in the border phase. Samples of porphyritic quartz monzonite from the border phase contain 20 ppm uranium. Miller and Elliott (1977) described the border phase rocks as monzonite, syenite, quartz monzonite, and hybrid diorite. They indicate an intrusive contact between the border phase and the main Zane Hills granodiorite, and that the monzonitic, border phase is younger. Their samples from the border phase contain 11 to 99 ppm uranium and 46 to 269 ppm, thorium. The uranium and thorium are concentrated in grains of uranothorianite, thorite, betafite, allanite, zircon, and sphene, which occur as disseminated accessory minerals in the monzonite. Although they found no vein-type mineralization, Miller and Elliott (1977) conclude that the border phase intrusives are enriched in U and Th. Sphene from two samples of gneissic monzonite (presumed to be border phase intrusive) from the Zane Hills pluton a few kilometers upstream from the Hogatza placer deposit (HU014) contain 27,890 to 39,180 ppm REE, and 390 to 760 ppm thorium (Staatz and others, 1977). Later investigations, however, suggest that the border phase rocks contain no unusual concentrations of REE (Barker, 1991).
Geologic map unit	(-155.975946762276, 66.117535028293)
Mineral deposit model	Felsic plutonic U-REE (Nokleberg and others, 1987)
Age of mineralization	K-Ar age dating of hornblende from the monzonite at the south end of the Zane Hills pluton gives an age of 81.9 Ma (Miller and others, 1966).
Alteration of deposit	At the contact between border phase monzonite-quartz monzonite and the core granodiorite, the granodiorite is, at least locally, strongly altered to a bleached, fine-grained, sericitic rock. Although the alteration diminishes in intensity away from the contact, all of the original biotite is completely altered to sericite. The granodiorite exhibits cataclastic texture near the contact.

Production and reserves

Workings or exploration	Only surface sampling.
Indication of production	None
Additional comments See also HU011.

References

References Barker, J.C., 1991, Investigations of rare-earth and associated elements, Zane Hills pluton, northwestern Alaska: U.S. Bureau of Mines Open-File Report 36-91, 33 p. Cobb, E.H., and Miller, T.P., 1981, Summaries of data on and lists of references to metallic and selected nonmetallic mineral occurrences in the Hughes, Kotzebue, Melozitna, Selawik and Shungnak quadrangles, west-central Alaska; Supplement to Open-File Report 75-627; Part B, Lists of references to January 1, 1981: U.S. Geological Survey Open-File Report 81-847-B, 14 p. Eakins, G.R., and Forbes, R.B., 1976, Investigation of Alaska's uranium potential: Alaska Division of Geological and Geophysical Surveys Special Report 12, 372 p., 5 sheets, scale 1:1,000,000. Eakins, G.R., Jones, B.K. and Forbes, R.B., 1977, Investigation of Alaska's uranium potential: Alaska Division of Geological and Geophysical Surveys Open-File Report 109, 213 p., 10 sheets, scale 1:40,000. Jones, Brian, 1977, Uranium-thorium bearing rocks of western Alaska: Fairbanks, University of Alaska, M.S. thesis, 80 p. Miller, T.P., 1976, Hardrock uranium potential of Alaska: U.S. Geological Survey Open-File Report 76-246, 5 p. Miller, T.P., and Bunker, C.M., 1975, Uranium, thorium and potassium analyses of selected plutonic rocks from west-central Alaska: U.S. Geological Survey Open-File Report 75-216, 3 p. Miller, T.P., and Elliott, R.L., 1977, Progress report on uranium investigations in the Zane Hills area, west-central Alaska: U.S. Geological Survey Open-File Report 77-428, 12 p. Miller, T.P., and Ferrians, O.J., Jr., 1968, Suggested areas for prospecting in the central Koyukuk River region, Alaska: U.S. Geological Survey Circular 570, 12 p. Nokleberg, W.J., Bundtzen, T.K., Berg, H.C., Brew, D.A., Grybeck, D.J., Robinson, M.S., Smith, T.E., and Yeend, W., 1987, Significant metalliferous lode deposits and placer districts of Alaska: U.S. Geological Survey Bulletin 1786, 104 p., 2 plates, scale 1:5,000,000. Nokleberg, W.J., Bundtzen, T.K., Dawson, K.M., Eremin, R.A., Goryachev, N.A., Koch, R.D., Ratkin, V.V, Rozenblum, I.S., Shpikerman, V.I., Frolov, Y.F., Gorodinsky, M.E., Melnikov, V.D., Diggles, M.F., Ognyanov, N.V., Petrachenko, E.D., Petrochenko, R.I., Pozdeev, A.I., Ross, K.V., Wood, D.H., Grybeck, D., Khanchuck, A.I., Kovbas, L.I., Nekrasov, I.Y., and Sidorov, A.A., 1996, Significant metalliferous and selected non-metalliferous lode mineral deposits and placer districts, and for metallogenesis of the Russian Far East, Alaska, and the Canadian Cordillera: U.S. Geological Survey Open-File Report 96-513-B, 385 p.; U.S. Geological Survey Open-File Report 96-513-B, 385 p. (CD-ROM format). Staatz, M.H., and Miller, T.P., 1976, Uranium and thorium content of radioactive phases of the Zane Hills pluton, in Cobb, E.H., ed., The U.S. Geological Survey in Alaska--Accomplishments during 1975: U.S. Geological Survey Circular 733, p. 39-41. Staatz, M.H., Conklin, N.M., and Brownfield, I.K., 1977, Rare earths, thorium, and other minor elements in sphene from some plutonic rocks in west-central Alaska, in Journal of Research of the U.S. Geological Survey, v. 5, no. 5, p. 623-628.
Reporters	J.M. Britton (Anchorage)
Last report date	8/1/2002