Evelyn Lee Prospect, Koyukuk Mining District, Yukon-Koyukuk Census Area, Alaska, USAi

Regional Level Types
Evelyn Lee Prospect	Prospect
Koyukuk Mining District	Mining District
Yukon-Koyukuk Census Area	Census Area
Alaska	State
USA	Country

See also: Venus (CH065), Victor (CH064), Eva (CH063), and Geroe Creek (CH053) prospects. Alaska Kardex No. KX-31-53H (Kardex is a card file mining claim information system located at the State of Alaska DNR Public Information Center in Fairbanks).
Location: This site is at an elevation of about 4,400 feet on a ridge between Sheep Creek and Spruce Creek west of Horace Mountain (NW1/4 sec. 25, T. 33 N., R. 8 W., of the Fairbanks Meridian). Its location is taken from maps published on the Internet website of the current operator, Ventures Resource Corp. (URL http://www.venturesresource.com/). The known mineralized area extends approximately 1/2 mile northeast and southwest of the reference point. The location is accurate within a 1/2-mile radius.
Geology: The Evelyn Lee prospect is one of a number of Cu skarn deposits in the Chandalar area which have been described in general by Newberry and others (1986). They are all located northwest of the belt of the Devonian(?) Horace Mountain granitic rocks. Many of the Cu skarns exhibit both prograde garnet/pyroxene and retrograde epidote and actinolite mineral assemblages. Newberry and others (1986) stateed that the mineralogy, mineralization, and alteration of these skarns tend to place them in the category of 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. The Devonian felsic schists are interpreted by Dillon and others (1996) as hypabyssal to plutonic in origin, but they are not included in the Horace Mountain plutonic assemblage. Early descriptions (early to mid-1970s) of the Evelyn Lee prospect described chalcopyrite, bornite, and pyrite in isolated skarn bodies that occur in marble in the Skajit Limestone near or at the contact with Devonian hornblende granodiorite porphyry. Skarn bodies were reported to be as much as 100 m long and 10 m wide. Copper grades as high as 10 percent Cu were obtained from outcrops. Altered and pyritized meta-granodiorite bodies are spatially associated with the mineralized skarns. Mineralization on the property has been described by Ventures Resource Corp. as consisting of pyrite, chalcopyrite, and bornite with silver and gold found in metamorphosed VMS, skarn, and sheared granitic-hosted deposits. Ventures Resource considers the target model for this prospect to be copper-gold skarn mineralization related to copper porphyry-type intrusives. The host rocks are volcanogenic calc-schist, chloritic calc-schist, limestone and dolomite, and intensely sheared granitic intrusive. Structurally, the host rocks form a broad syncline intruded along the keel by granodiorite. Assays include grades of 9.9 percent Cu and 8.17 ounces of silver per ton from a 7-foot-thick zone of sulfides in skarn, and a 5-foot surface sample which grades 5.6 percent Cu and 0.04 ounce of gold per ton. A core sample assayed 3.5 percent Cu over a 23.5-foot drill intercept.
Workings: Claims were staked in 1969 and 1970. The property was selected by Doyon, Limited (an Alaska Native Corporation) in the early 1970s as part of Alaska Native Claims Settlement Act (ANCSA) settlement. In 1998 the Evelyn Lee property was being explored by Ventures Resource Corporation under the terms of an exploration agreement with the owner, Doyon, Limited. Sampling results from a large soil sample grid (approximately 5,000 feet x 2,500 feet ) shows extensive areas of more than 500 ppm Cu in soil (Ventures Resource Corporation,1998). A grade 9.9 percent Cu and 8.17 ounces of Ag per ton of was obtained from sampling of a 7-foot-thick sulfide layer in skarn. Two shallow core drill holes have explored one of the copper soil anomalies. This drilling encountered mineralization that assayed 3.5 percent copper from surface to 23.5 feet and 2 percent copper from surface to 18 feet.
Age: 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: Potassic and sericitic alteration in the meta-igneous rocks. Calc-silicate hornfels.
Reserves: Estimates of potential for this property ranges from about 1 million metric tons of 5 percent Cu (DeYoung, 1978) to 'tens of million of tons grading 2 percent to 5 percent Cu with gold and silver credits' (Ventures Resource Corporation website, 1998, URL http://www.venturesresource.com/).

Commodities (Major) - Ag, Au, Cu
Development Status: None
Deposit Model: Porphyry Cu, skarn-related deposits (Cox and Singer, 1986; model 18a)

Other Databases

Link to USGS - Alaska:	CH059

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References