Fish Prospect, Fortymile District, Southeast Fairbanks Borough, Alaska, USA

This prospect is located on Doyon, Ltd. selected or conveyed land. For more information contact Doyon, Ltd., Fairbanks, Alaska.
Location: This prospect covers the drainages of several tributaries of Fish Creek. The prospect is about 0.6 mile northwest of hill 4280 near the center of the southern boundary of the Eagle B-4 quadrangle. The coordinates are the location of a quartz-carbonate vein and gossan zone at the headwaters of Texas Creek in the NE1/4 section 1, T. 8 S., R. 25 E., of the Fairbanks Meridian. Texas Creek, a small tributary of Fish Creek, is not labeled on the U.S. Geological Survey topographic map of the Eagle B-4 quadrangle (1956); its mouth is located in the NE1/4 section 24, T. 7 S., R. 25 E. The location is accurate.
Geology: In upper Fish Creek, Paleozoic metasedimentary and metavolcanic rocks are intruded by Mesozoic to early Tertiary(?) biotite-hornblende quartz monzonite and granodiorite stocks (Dashevsky and others, 1986). Hornfelsed metamorphic rocks are common near the contact of a quartz monzonite pluton. Quartz-carbonate veins and a gossan zone are present in the headwaters of Texas Creek (see EA061). Mineralization in one drainage appears to be associated with a 5- to 10-foot-wide gossan zone along a north-south-trending fault zone at a contact of granodiorite and metasedimentary rock. Gossan samples from the fault zone contain 8 to 24 percent zinc, as much as 2,000 parts per million lead, and as much as 200 ppm copper. Gossan samples and silicified zones contain greater than 30,000 ppm zinc, as much as 6,424 ppm lead, and 12 ppm silver (U.S. Bureau of Mines, 1995). Five VLF lines run at right angles to the trend of the fault zone showed 'crossovers' probably related to the fault. The geology in the prospect area is considered permissive for skarn, structurally controlled, or stratabound deposits (Dashevsky and others, 1986). There has been placer gold prospecting on Fish Creek (EA059) and Texas Creek (EA061) to the north and west of this prospect. Sulfides in the area were first noted by Foster (1976). Reconnaissance stream-sediment sampling was done in the upper Fish Creek drainage in 1976 by WGM Inc. (Dashevsky and others, 1986). Initial reconnaissance sampling detected elevated zinc and lead in stream sediments (600 to 1,000 ppm zinc, and 60 to 150 ppm lead) in several tributaries to Fish Creek. In 1977, WGM Inc. conducted reconnaissance traverses and soil and rock sampling, and fill-in stream sediment sampling. In 1981, Arctic Resources Inc. conducted ridge line traverses and ran a soil sampling line across the north-south-trending fault zone. Soils with elevated lead and zinc were found west of the fault in hornfels and quartzite, but no mineralization was observed. In 1991, Central Alaska Gold Co. conducted rock sampling in the area; no gold was detected in any samples (WGM Inc., 1998 [DLR 98-10]). The U.S. Bureau of Mines briefly examined the Fish Creek area in 1994. Soil sampling and mapping by WGM Inc. in 2001 resulted in defining a steeply dipping metal-enriched shear zone that extends uninterrupted for 4,800 feet across a high ridge crest to the edge of the soil grid. The zone is defined by zinc, lead, silver, copper, bismuth, arsenic, antimony, cadmium, and manganese anomalies. All zinc values exceed 1,000 ppm for the entire 4,800 feet. In mirror-image 1,200-foot segments on opposite sides of the ridge, all zinc values exceed 5,000 ppm. Near the south end of the soil grid a second polymetallic anomaly appears and is also open off the grid to the south. Gossan float extends 1,200 feet down the north and south slopes from the ridge crest. Twenty-eight grab samples average 11.6 percent zinc, 0.13 percent lead, and 18.7 ppm silver. Highest values are 28 percent zinc and 215 ppm (6.3 ounces per ton) silver. The mineralized zone thickness is estimated at 50 to 75 feet, based on gossan distribution (Swainbank and others, 2002; Ventures Resource Corp., 2002). Under an agreement with Doyon Ltd., Full Metal Minerals began work on the prospect in 2006 and drilled 7 holes (Full Metals, 2008, 40 mile). They described the mineralization as strongly oxidized massive sulfides up to 44 meters thick; they drilled on a gossan 15 to 23 meters thick derived from intensely weathered massive to semi-massive sulfides. The zinc in the gossan occurs mainly as smithsonite. The gossan has been traced 1,500 meters along strike and 250 meters down dip; the drilling tested about 500 meters of strike length and 175 meters down dip. Some of the highest grade drill intercepts include 11 meters with 205.2 grams of silver per ton, 0.11 percent copper, 0.20 percent lead, and 4.2 percent zinc; 12.8 meters with 181.3 grams of silver per ton, 0.09 percent copper, 0.41 percent lead, and 4.0 percent zinc; 44.4 meters with 34.1 grams of silver per ton, 0.10 percent copper, 0.09 percent lead, and 3.3 percent zinc; 28.1 meters with 0.27 gram of gold per ton, 8.3 gram of silver per ton, 0.08 percent copper, and 4.9 percent zinc; and 20.6 meters with 52.0 grams of silver per ton, 0.06 percent copper, 0.08 percent lead, and 1.7 percent zinc. Twenty-eight of the 71 rock samples taken along 760 meters of the mineralized zone averaged 11.6 percent zinc, 0.13 percent lead, and 18.7 grams of silver per ton. As of early 2008, Full Metal completed 10 holes at Fish; they continued to cut encouraging intercepts and the mineralization remains open in depth and in both directions along strike.
Workings: Sulfides in the area were first noted by Foster (1976). Reconnaissance stream-sediment sampling was done in the upper Fish Creek drainage in 1976 by WGM Inc. (Dashevsky and others, 1986). In 1981, Arctic Resources Inc. conducted ridge line traverses and ran a soil sampling line across the north-south-trending fault zone. In 1991, Central Alaska Gold Co. conducted rock sampling in the area; no gold was detected in any samples (WGM Inc., 1998 [DLR 98-10]). The U.S. Bureau of Mines briefly examined the Fish Creek area in 1994. WGM carried out soil sampling and mapping. Under an agreement with Doyon Ltd., Full Metal Minerals began work on the prospect in 2006, drilled 7 holes, and carried out surface mapping and sampling (Full Metals, 2008, 40 mile). They drilled 3 more holes in 2008.
Age: Paleozoic metasedimentary and metavolcanic rocks are intruded by Mesozoic to early Tertiary(?) biotite-hornblende quartz monzonite and granodiorite stocks in the upper Fish Creek drainage (Dashevsky and others, 1986).
Reserves: None.

Commodities (Major) - Ag, Cu, Pb, Zn
Development Status: None
Deposit Model: As of 2008, considered to be a weathered massive sulfide deposit (Full Metals M

Mineral List

14 entries listed. 11 valid minerals.

References