Io

Prospect, Inactive

Commodities and mineralogy

Main commodities Ag; Cu; Pb; Zn
Other commodities Au
Ore minerals chalcopyrite; galena; magnetite; pyrite; sphalerite

Geographic location

Quadrangle map, 1:250,000-scale CH
Quadrangle map, 1:63,360-scale D-5
Latitude 67.8
Longitude -149.05
Nearby scientific data Find additional scientific data near this location
Location and accuracy The Io prospect is at an elevation of about 4,800 feet just above the headwaters of Robert Creek about 4 1/2 miles south of the confluence of Quartz Creek and the North Fork Chandalar River (SE1/4 sec. 2, T. 34 N., R. 7 W., of the Fairbanks Meridian). The location is accurate within a 1-mile radius.

Geologic setting

Geologic description

The Io prospect is one of a number of skarn deposits in the Chandalar area. Newberry and others (1986) classified this prospect as a Pb-Zn-Ag-Cu skarn and group it with a number of similar prospects that are northwest of and related to the Devonian(?) granitic plutons in the Horace Mountains. Many of these skarns exhibit both garnet and pyroxene prograde and epidote and actinolite retrograde mineral assemblages, and Newberry and others (1986) stated their characteristics place them in the category of continental-margin, porphyry-related copper skarns. They also suggest that the Pb-Zn-rich skarns represent distal concentrations surrounding the porphyry systems in the district. Newberry and others (1997) classify the Io prospect as a calcic Zn-Pb skarn and replacement body. A hand specimen of skarn from Io contains epidote, chlorite, actinolite, pyrite, galena, sphalerite, and magnetite (Newberry and others, 1986). Analysis of this specimen returned values of 12.6 percent Pb, 8.5 percent Zn, 0.04 percent Cu and 83 ppm Ag. In a listing posted on the Ventures Resource Corporation (currently exploring Doyon, Limited lands in the area under an agreement with Doyon, Limited) website (1998, URL http://www.venturesresource.com/) the Io prospect is classified as a Cu-Au prospect, although no supporting data are shown. The prospect is in an area underlain principally by Devonian Skajit Limestone and Hunt Fork Shale (DeYoung, 1978).
Geologic map unit (-149.05276519183, 67.7996064415026)
Mineral deposit model Zn-Pb skarn deposits (Cox and Singer, 1986; model 18c)
Mineral deposit model number 18c
Age of mineralization Devonian(?) based on reported Early Devonian Pb/Pb zircon ages from the associated Baby Creek batholith and Horace Mountain plutons (Dillon and others, 1996).
Alteration of deposit Calc-silicate.

Production and reserves

Indication of production None

Additional comments

See also: Deimos (CH061), Ginger (CH060), Hurricane-Diane (CH062), Venus (CH065), Pilgrim (CH099), Mike (CH100), Vicki (CH097), Cindy (CH098), and Evelyn Lee (CH059).

References

MRDS Number 10307343

References

Newberry, R.J., Allegro, G.L., Cutler, S.E., Hagen-Levelle, D.D., Adams, D.D., Nicholson, L.C., Weglarz, T.B., Bakke, A.A., Clautice, K.H., Coulter, G.A., Ford, M.J., Myers, G.L., and Szumigala, D.J., 1997, Skarn deposits of Alaska, in Goldfarb, R.J., and Miller, L.D., eds., Mineral Deposits of Alaska: Economic Geology Monograph 9, p. 355-395.
Newberry, R.J., Dillon, J.T., and Adams, D.D., 1986, Regionally metamorphosed calc-silicate-hosted deposits of the Brooks Range, northern Alaska: Economic Geology, v. 81, p. 1728-1752.
Ventures Resource Corporation, 1998, 1997 Annual Report and Website (Worldwide Web URL http://www.venturesresource.com/).
Reporters J.M. Britton (Anchorage)
Last report date 11/17/1999