Eva Creek; Ruby Silver Prospect, Fortymile District, Southeast Fairbanks Borough, Alaska, USA

The Eva Creek prospect is located within Doyon, Ltd. selected or conveyed land. For more information contact Doyon, Ltd., Fairbanks, Alaska.
Location: The center of the Eva Creek prospect is at an elevation of about 3,900 feet on the ridge north of Eva Creek. The prospect area extends several miles to the north and south into the Norvell Creek and Iron Creek drainages. The coordinates are the location of trenches, in the central part of the Eva Creek prospect in section 23, T. 27 N., R. 11 E., of the Copper River Meridian. The location is accurate. The Eva Creek prospect is locality 9 of Cobb (1972 [MF-393]) and locality 52 of Eberlein and others (1977). The Eva Creek prospect is located within Doyon, Ltd. selected or conveyed land.
Geology: The Eva Creek prospect is in Paleozoic gneiss, schist, quartzite, and marble, that have been intruded by the Mount Veta syenite of Jurassic age (Foster, 1976). Other Tertiary to Mesozoic monzonite and granite intrusions are located about 1 mile east of the prospect, and there are felsic and mafic dikes in the area (Dashevsky and others, 1986). The granitic intrusion to the east is epidotized and contains local altered zones near the contact (Foster and Clark, 1970). Several other prospects are spatially associated with the Mount Veta intrusive complex, including East Eva (EA098), Oscar (EA096), Oscar West (EA097), Little Enchilada (EA103), unnamed (north of Fish Creek) (EA062), Molly Creek (EA100), Little Whiteman Creek (EA060), and Mitchell (EA101). At the Eva Creek prospect, pyrite and pyrrhotite occur as disseminated grains within gneiss and schist. There are scattered highly mineralized marble units that contain argentiferous galena, cerussite, sphalerite, azurite, and malachite filling vugs, boxworks, and quartz veinlets (Carter, 1981 [DLR 81-27]). Wedow and others (1954) reported quartz veins as much as several feet thick, most of which are highly fractured and stained with hematite. These veins contain pods of galena, partly altered to cerrusite, and calcite. Rock samples from the Eva Creek prospect with galena, sphalerite, and malachite contain as much as 9.24 ounces of silver per ton, 29.13 percent lead, and 0.61 percent copper (Saunders, 1962 [PE 60-10]). Rock samples from trenches contain 0.4 to 2 percent copper, 7 to 52 percent lead, 0.6 to 21 percent zinc, and 31 to 99 ounces of silver per ton. Other samples of vein material and gossan in trenches contain as much as 32.4 ounces of silver per ton, 0.18 percent copper, 896 ppm antimony, 9.5 percent zinc, and 6.6 percent lead (U.S. Bureau of Mines, 1995). A vein that strikes at least 1,800 feet contains as much as 28.7 percent lead, 9.4 percent zinc, 0.28 percent copper, 0.003 ounce of gold per ton, and 19.4 ounces of silver per ton (Swainbank and others, 1998). Metal anomalies in soils at the Eva Creek prospect are elongated northeast-southwest, and there is a subtle base-metal anomaly that extends to the northeast (Dashevsky and others, 1986). Both CEM and VLF-EM geophysical surveys detected narrow conductors striking north to northwest for 400 feet or less. Seven-hundred feet northwest of the trenches at the Eva Creek prospect, soils have elevated copper in an area of strong response to IP and ground magnetic surveys. A drill hole at the Eva Creek prospect penetrated pyrite- and magnetite-bearing, biotite schist, and calcite-filled breccia zones as much as 58 feet thick. At the head of Iron Creek, two core holes totaling 404 feet were drilled in an area with anomalous magnetite and zinc; these holes intersected disseminated pyrite and chalcopyrite, iron oxides, and rare galena in banded marble and dolomite (Dashevsky and others, 1986). About 18 miles of traverses were conducted in the area in 1949 (Wedow and others, 1954), but no significant radioactivity was detected in panned heavy-mineral concentrates. Saunders (1962 [PE 60-10]) examined prospects in the My Creek and Eva Creek area in 1960. Rock and stream-sediment samples were collected from the Molly Creek drainage in 1968 (Foster and Clark, 1970). Apex Exploration, Ltd. conducted exploration in the Eva Creek area in the early 1970's (Dashevsky and others, 1986). Placid Oil Company explored in the area from 1975 to 1978, which included float mapping, soil sampling on a grid, and ground magnetic, CEM, and VLF-EM geophysical surveys. Three core holes were drilled in trenches at Eva Creek in 1977, and two core holes were drilled on Iron Creek in 1978. In 1981, Arctic Resources Inc. conducted soil and high-grade rock sampling at the Eva Creek prospect, and work by Doyon Ltd. in 1982 included two lines of IP-resistivity and magnetometer surveys.
Workings: About 18 miles of traverses were conducted in the area in 1949 (Wedow and others, 1954), but no significant radioactivity was detected in panned heavy-mineral concentrates. Saunders (1962 [PE 60-10]) examined prospects in the My Creek and Eva Creek area in 1960. Rock and stream-sediment samples were collected from the Molly Creek drainage in 1968 (Foster and Clark, 1970). Apex Exploration, Ltd. conducted exploration in the Eva Creek area in the early 1970's (Dashevsky and others, 1986). Placid Oil Company explored in the area from 1975 to 1978, which included float mapping, soil sampling on a grid, and ground magnetic, CEM, and VLF-EM geophysical surveys. Three core holes were drilled in trenches at Eva Creek in 1977, and two core holes were drilled on Iron Creek in 1978. In 1981, Arctic Resources Inc. conducted soil and high-grade rock sampling at the Eva Creek prospect, and work by Doyon Ltd. in 1982 included two lines of IP-resistivity and magnetometer surveys.
Age: Jurassic or younger.

Commodities (Major) - Ag, Cu, Pb, Zn; (Minor) - Au, Sb
Development Status: None
Deposit Model: Cu skarn, Zn-Pb skarn, or kuroko massive sulfide (Cox and Singer, 1986; models

Mineral List

16 entries listed. 15 valid minerals.

References