Evelyn Lee

Prospect, Undetermined

Commodities and mineralogy

Main commodities Ag; Au; Cu
Ore minerals bornite; chalcopyrite; gold; pyrite

Geographic location

Quadrangle map, 1:250,000-scale CH
Quadrangle map, 1:63,360-scale C-5
Latitude 67.6587
Longitude -149.2571
Nearby scientific data Find additional scientific data near this location
Location and accuracy The Evelyn Lee prospect is about 2.4 miles northwest of the mouth of Sheep Creek on Robert Creek. It is about 0.2 mile northwest of the center of section 25, T. 33 N., R. 8 W. 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 Evelyn Lee 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. Bear Creek diamond drilled two holes, 512 and 183 feet deep, and drilled two core holes, 18 and 23 feet deep, with a packsack drill.
The Evelyn Lee prospect is one of a number of copper skarn deposits in the Chandalar area which have been described by Newberry and others (1986). They are located northwest of Devonian(?) Horace Mountain belt of metamorphosed granitic rocks, which are probably genetically related to the deposits. Many of the copper skarns exhibit both prograde garnet/pyroxene and retrograde epidote and actinolite mineral assemblages. Newberry and others (1986) concluded that the deposit's mineralogy, mineralization, and alteration suggested continental-margin, porphyry-related copper skarns.
Dillon and others (1996) mapped the area as Devonian, Horace Mountain granite gneiss and Devonian felsic schists with proximal tactite and calcareous hornfels. They interpreted the Devonian felsic schists as hypabyssal to plutonic in origin. The Evelyn Lee deposit consists of chalcopyrite, bornite, and pyrite in isolated skarn bodies intercalated with marble of the Skajit Limestone, argillite, and quartz-mica schist, near or at the contact with weakly mineralized Devonian hornblende-granodiorite porphyry that covers an area about 1,000 feet wide and 4,000 feet long (Kurtak and others, 2002). The skarn bodies reportedly are up to 300 feet long and 30 feet wide. Outcrop samples contain as much as 10 percent copper. The meta-granodiorite is altered and pyritized near the skarns. One of the drill holes cut 18 feet of skarn with 2.0 percent copper; another cut 23.5 feet of skarn with 3.5 percent copper. A notable 7-foot-thick zone of sulfides in skarn contained 9.9 percent copper and 8.17 ounces of silver per tonne, and a 5-foot-long surface sample contained 5.6 percent copper and 0.04 ounce of gold per ton. Kurtak and others (2002) sampled 700 feet of outcrop with prominent copper staining on the south-southwest side of the prospect; eight select samples averaged 4.06 percent copper and 11.9 ppm silver.
DeYoung (1978) estimated that the Evelyn Lee deposit has a resource of about 1 million metric tons with an average grade of 5 percent copper. Ventures Resource Corp. (1999) estimated the resource as 'tens of million of tons that graded 2 percent to 5 percent copper with gold and silver credits'.
Geologic map unit (-149.259857174106, 67.6582989862517)
Mineral deposit model Porphyry copper and related copper-skarn 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 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 Evelyn Lee 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 early 1990s. The work consisted mainly of mapping. geochemical and geophysical surveys, and sampling. Bear Creek diamond drilled two holes, 512 and 183 feet deep, and drilled two core holes, 18 and 23 feet deep, with a packsack drill.
Indication of production None
Reserve estimates DeYoung (1978) estimated that the Evelyn Lee deposit has a resource of about 1 million metric tons with an average grade of 5 percent copper. Ventures Resource Corp. (1999) estimated the resource as 'tens of million of tons grading 2 percent to 5 percent copper with gold and silver credits'.
Production notes None.

Additional comments

This prospect is on Doyon Ltd. selected lands; for more information, contact Doyon Ltd., Fairbanks, Alaska.
MAS No. 0020310062

References

MRDS Number A012138

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