Venus

Prospect, Active

Commodities and mineralogy

Main commodities Ag; Au; Cu
Other commodities Mo
Ore minerals bornite; chalcopyrite; magnetite; molybdenite; pyrite
Gangue minerals amphibole; calcite; chlorite; diopside; epidote; garnet; quartz

Geographic location

Quadrangle map, 1:250,000-scale CH
Quadrangle map, 1:63,360-scale C-5
Latitude 67.6303
Longitude -149.3223
Nearby scientific data Find additional scientific data near this location
Location and accuracy The Venus prospect is exposed on the west bank of Spruce Creek about 3.1 miles north of its mouth on the Bettles River. It is in the northwest part of section 3 and the northeast part of section 4, T. 32 N., R. 8 W. The location is accurate. Kurtak and others (2002) include a detailed map of the prospect and a map showing the regional geology of the area and the location of this and the other deposits of the Chandalar Copper Belt.

Geologic setting

Geologic description

The Venus prospect was discovered by Bear Creek Mining Company in 1967 along what would would become known as the Chandalar Copper Belt (Kurtak and others, 2002). Bear Creek and several other companies (Midwest Oil Company, WGM Inc., Arctic Resources Inc., and Ventures Resource Corp.) explored the property into the 1990s. The work consisted mainly of mapping, geochemical and geophysical surveys, and sampling; 5 holes were drilled in 1973 and 1974 by WGM Inc. that totaled 2,466 feet.
The Venus prospect is a porphyry copper deposit associated with copper-gold-silver skarn (Kurtak and others, 2002). The Venus prospect and others along the Chandalar Copper Belt were described by Newberry and others (1986) as continental-margin, porphyry-related copper skarns; many exhibit both prograde and retrograde mineral assemblages. Ventures Resource Corporation (1998) and Dillon and others (1996) described the geology of the Venus prospect as an elongated, altered and foliated, Devonian granodiorite pluton bounded on the east by overthrust Silurian or Devonian, Skajit Limestone and on the west by Skajit Limestone and gray phyllite, felsic calc-schist, and chloritic schist.
The porphyry mineralization at Venus prospect consists of disseminations and fracture fillings of pyrite, chalcopyrite, and minor molybdenite in schistose Devonian meta-granodiorite porphyry (Kurtak and others, 2002). The meta-granodiorite porphyry is extensively propylitized and pyritized, with local zones of sericitic to potassic alteration. The intrusion-hosted mineralization contains about 0.1 to 0.2 percent copper Cu, and generally less than 0.01 ounce of gold per ton (Ventures Resource Corporation, 1999). A hand specimen described by Newberry and others (1986) as porphyry contains quartz, sericite, pyrite, chalcopyrite, chlorite, and molybdenite; the specimen contained 0.38 percent copper, 1 part per million (ppm) silver, less than 0.1 ppm gold, 0.002 percent zinc, and 0.001 percent lead. Three drill holes averaged 0.15 to 0.2 percent copper, but one averaged only 0.08 percent copper (WGM Inc., 1973; Nicholson, 1990).
The skarns form irregular masses in Skajit Limestone and calc-schist adjacent to, and as xenoliths in the meta-granodiorite. The skarns are principally garnet-magnetite-diopside bodies that show retrograde vein and replacement, epidote, amphibole, chlorite, calcite, and quartz. The mineralization consists of irregular masses of pyrite and chalcopyrite. The grade of the skarn deposits is variable but generally is about 1.5 percent to 6 percent copper, less than 0.01 ounce of gold per ton, and up to 1 ounce of silver per ton (Newberry and others, 1986; Nicholson, 1990; Ventures Resource Corporation, 1999; Kurtak and others, 2002).
Based on limited data, Nicholson (1990) estimated that the deposit has a resource of 300,000 tons with an average grade of 0.3 percent copper. Ventures Resource (1990) estimated a resource of 495 million pounds of copper.
Geologic map unit (-149.325055966387, 67.6298971424667)
Mineral deposit model Porphyry copper and copper-skarn-related deposits (Cox and Singer, 1986; models 17 and 18a).
Mineral deposit model number 17 and 18a
Age of mineralization Devonian(?) based on Early Devonian Pb/Pb zircon ages from the nearby Baby Creek batholith and Horace Mountain plutons (Dillon and others, 1996).
Alteration of deposit Extensive propylitic alteration of the meta-granodiorite, with local areas of sericitic to potassic alteration. Hornfels and skarn developed in adjacent calcareous rocks.

Production and reserves

Workings or exploration The Venus prospect was discovered by Bear Creek Mining Company in 1967 along what would become known as the Chandalar Copper Belt (Kurtak and others, 2002). Bear Creek and several other companies (Midwest Oil Company, WGM Inc., Arctic Resources Inc., and Ventures Resource Corp.) explored the property into the 1990s. The work consisted mainly of mapping, geochemical and geophysical surveys, and sampling; 5 holes were drilled in 1973 and 1974 that totaled 2,466 feet.
Indication of production None
Reserve estimates Based on limited data, Nicholson (1990) estimated that the porphyry deposit has a resource of 300,000 tons with an average grade of 0.3 percent copper. Ventures Resource Corp. (1999) estimated a resource of 495 million pounds of copper.
Production notes None.

Additional comments

This prospect is on Doyon Ltd. selected lands; for more information, contact Doyon Ltd., Fairbanks, Alaska.
MAS No. 0020310060

References

MRDS Number A012153

References

Kurtak, J.M., Klieforth, R.F., Clark, J.M., and Maclean, E.A., 2002, Mineral investigations in the Koyukuk mining district, northern Alaska, 2 vols.: Bureau of Land Management, Alaska Technical Report 50, 845 p.
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.
Nichol, D.L., 1983, Evaluation of the mineral potential of Doyon Ltd.'s Blocks 5 and 22: Unpublished report for Doyon Ltd. (on file at Doyon Ltd., Fairbanks, Alaska).
Nicholson, L.M., 1990, Porphyry copper, copper skarn, and volcanogenic massive sulfide occurrences in the Chandalar copper district, Alaska: Fairbanks, University of Alaska, M.Sc. thesis, 164 p.
Ventures Resource Corp., 1999, 1999 Annual report: Ventures Resource Corporation, 36 p.
WGM Inc., 1973, Progress report 1973, Chandalar district: Unpublished report for Midwest Oil Corporation, 46 p.
WGM inc., 1974, Chandalar district progress report 1974: Unpublished report for AMOCO Minerals, 37 p.
WGM Inc., 1978, 1977 Annual progress report, Doyon Ltd. project, v. II, Luna area: Unpublished report 78-04 for Doyon Ltd., 15 p. (on file at Doyon Ltd., Fairbanks, Alaska).
WGM Inc., 1979, 1978 Doyon Ltd. annual progress report, Block 5 Luna volcanogenic massive sulfide and associated base-metal deposits and anomalies of the Chandalar Copper Belt: Unpublished report 79-21 for Doyon Ltd., 35 p. (on file at Doyon Ltd., Fairbanks, Alaska)
WGM Inc., 1980, 1979 annual profess report, Block 5-Wiseman Chandalar Cop[er Belt: Unpublished report 80-06 for Doyon Ltd., 28 p. (on file at Doyon Ltd., Fairbanks, Alaska).
Young, L.E., St. George, P., and Bouley, B., 1997, Porphyry copper deposits in relation to the magmatic history and palinspastic restoration of Alaska, in Goldfarb, R.J., and Miller, L.D., eds., Mineral deposits of Alaska: Economic Geology Monograph 9, p. 306-333.
Reporters J.M. Britton (Anchorage, Alaska); D.J. Grybeck (Contractor, U.S. Geological Survey)
Last report date 4/18/2010