Telephone Prospect (Tele) Hill, Iditarod District, Yukon-Koyukuk Borough, Alaska, USA
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Geology: The Telephone (Tele) Hill prospect consists of arsenical gold deposits in hornfels, deformed sedimentary rocks of the Upper Cretaceous, Kuskokwim Group, and in fine-grained quartz-feldspar and granite porphyry and somewhat coarser-grained biotite-pyroxene monzonite (Bundtzen and Miller, 1997). The prospect is within 500 feet of the trace of the Ganes-Yankee Creek fault zone (Bundtzen and Laird, 1983, Miller and Bundtzen, 1994). The mineralized intrusions at the prospect are elongated in a north-south direction. The deposit consists of: 1) arsenopyrite-rich, quartz-iron carbonate, crackle breccias in hornfels and deformed shale; 2) disseminated arsenopyrite in quartz-feldspar porphyry; 3) disseminated pyrite and arsenopyrite in sericitized monzonite; and 4) thin, 0.4- to 1-inch-thick sulfide-sulphosalt-quartz veins in monzonite and quartz-feldspar porphyry. Surface samples locally contained stibnite and unidentified sulfosalts. The richest material found during sampling at the surface was in arsenic-rich, iron-carbonate-bearing crackle breccia in hornfels and deformed shale. Mineralized grab samples contained from 6.6 parts per million (ppm) to 13.8 ppm gold and from 2,500 to 5,500 ppm arsenic (North Star Exploration, Inc. unpublished brochure, 1999; T.K. Bundtzen, unpublished data, 2002). The correlation coefficients between gold and arsenic in samples averaged 0.90 (Bundtzen and others, 2000). Biotite from the Telephone Hill prospect has a 40Ar/39Ar age of 70.6 Ma (T.K. Bundtzen, unpublished data, 1999). Three reconnaissance diamond drill holes tested the prospect in 2001. Drill hole TH-01-01 intersected three main mineralized intervals. From 90.0 to 106.0 feet, the core contained 1,970 parts per billion (ppb) gold, 350 ppb silver, and 2,988 parts per million (ppm) arsenic. From 170.0 to 179.8 feet, the core contained 1,233 ppb gold, 750 ppb silver, and 2,770 ppm arsenic. And from 230.0 to 273.0 feet, the core contained 1,166 ppb gold and 1,070 ppm arsenic. The core from drill hole TH-01-02 contained 3,050 ppb gold, 1,220 ppb silver, and 4,468 ppm arsenic from 586.6 to 594.5 feet. The core from 410.1 to 435.0 feet in drill hole TH-01-03 contained 598 ppb gold and 1,220 ppb gold. (Galey and others, 2002; EMEX Corporation press release, February 14, 2002). Anomalous antimony values were also present in the drill holes. The highest gold values in the drill holes were in zone of quartz-carbonate veins and in altered sedimentary rocks near intrusive contacts. The geology and age of the Telephone Hill prospect is similar to the Vinasale Mountain (see McGrath ARDF report) and the Donlin Creek gold-arsenic-antimony deposit (ID167) of the Kuskokwim mineral belt (Bundtzen and Miller, 1997; Bundtzen, 1999).
Workings: Westgold, Inc. analyzed soils and rocks over the Telephone Hill prospect in 1989. Placer Dome Exploration also collected soils and rock samples in the Telephone Hill prospect area in 1996 and 1997 (St. George, 1998). North Star Exploration, Inc., which held a minerals option agreement with the landowner, Doyon Limited, collected rock and soil samples over Telephone Hill prospect in 1998 (Hinderman and others, 1999). In 2001, North Star Exploration, Inc. explored the Telephone Hill prospect with three diamond drill holes totaling about 1,720 feet. All three drill holes intersected zones with anomalous gold, silver, antimony, and arsenic.
Age: Secondary biotite in altered monzonite at the Telephone Hill prospect has 40Ar/39Ar age of 70.6 Ma (Bundtzen and others, 2000).
Alteration: Alteration assemblages include: 1) pervasive clay alteration in brecciated quartz-feldspar porphyry; 2) ubiquitous sericite alteration in monzonite; 3) dolomite replacement of monzonite; and 4) mariposite in altered intermediate dikes near porphyritic intrusions.
Production: None; the gold deposits at Telephone Hill and nearby prospects along the Ganes-Yankee Creek fault zone are likely to be the lode source for the more than 70,000 ounces of gold that has been produced in Yankee Creek (ID037).
Reserves: No reserve or resource estimates have been made.
Commodities (Major) - Au; (Minor) - Ag, As, Sb
Development Status: None
Deposit Model: Low sulfide gold-quartz vein or Porphyry gold-copper deposit; (Cox and Singer,
8 entries listed. 6 valid minerals.
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Bundtzen, T.K., and Laird, G.M., 1983, Geologic map of the Iditarod D-1 quadrangle, Alaska: Alaska Division of Geological and Geophysical Surveys Professional Report 78, scale 1:63,360. Bundtzen, T.K., and Miller, M.L., 1997, Precious metals associated with Late Cretaceous-early Tertiary igneous rocks of southwestern Alaska, in Goldfarb, R.J., and Miller, L.D., eds., Mineral Deposits of Alaska: Economic Geology Monograph 9, p. 242-286. Bundtzen, T.K., Bouley, B.A., Noyes, H.J., and Nokleberg, W.J., 2000, Regional metallogenesis of central Alaska: Society of Mining, Metallurgy, and Exploration Annual Meeting, Salt Lake City, Utah, February 28-March 1, 2000, p.1-29. Galey, J., Retherford, R., Ellis, W., Harris, R., Deane, S., and Hinderman, T., 2002, 2001 Annual report, Takotna village block: Lakewood, Colorado, North Star Exploration, Inc., AR-01-Takotna, to Doyon Limited: 29 p. 9 sheets and 4 appendices. Hinderman, T., Retherford, R., Bull, K.F., Vanderpool, T., and Bundtzen, T.K., 1999, 1998 annual report, Takotna village block: Lakewood, Colorado, North Star Exploration, Inc., AR-98-Takotna, to Doyon Limited, 57 pages, 4 sheets and 3 appendices. Hollister, V.F., 1992, On a proposed plutonic porphyry gold deposit model: Nonrenewable Resources, vol. 1, p. 293-302. Miller, M.L., and Bundtzen, T.K., 1994, Generalized geologic map of the Iditarod quadrangle, Alaska showing potassium-argon, major oxide, trace element, fossil, paleocurrent, and archeological sample localities: U.S. Geological Survey Miscellaneous Field Studies Map MF-2219-A, 48 pages; 1 sheet, scale 1:250,000. St. George, P., 1998, Progress report for 1997, Ganes Creek project A326, southwest Alaska: Anchorage, Alaska, unpublished Placer Dome Exploration report, 13 pages, plus plates and appendices.