Goss Gulch Prospect, Innoko Mining District, Yukon-Koyukuk Census Area, Alaska, USAi

Regional Level Types
Goss Gulch Prospect	Prospect
Innoko Mining District	Mining District
Yukon-Koyukuk Census Area	Census Area
Alaska	State
USA	Country

Location: The Goss Gulch prospect is on a high level terrace at an elevation of 1,500 feet, about 1.5 kilometers southeast of the Yankee Creek 'placer mine' shown on the USGS 1:63,360-scale topographic The prospect is about 0.4 mile west of the northeast corner of section 6, T. 33N., R. 37W., of the Seward Meridian. The location is accurate.
Geology: The Goss Gulch prospect is in a mineralized quartz-feldspar dike or sill that intrudes sandstone and shale of the Upper Cretaceous Kuskokwim Group and chert of the Late Paleozoic to Mesozoic, Innoko Terrane (Bundtzen and Laird, 1983; Miller and Bundtzen, 1994). The mineralized intrusion is about 160 feet thick. A 800-foot -thick, fine-grained, biotite quartz monzonite sill cuts the sediments about 650 feet southeast of southeast of Goss Gulch. This intrusion has a 40Ar/39Ar age of 71.3 Ma (Bundtzen, unpublished data, 1999). The Goss Gulch prospect lies directly over the trace of the Ganes-Yankee Creek fault zone (Bundtzen and Miller, 1997). At the prospect, fault-controlled lensoid veins of nearly pure stibnite from 0.4 to 8 inches thick can be traced in rubble crop for 100 feet. The veins are oriented in two planes. One has a strike of N70E and a vertical dip; the other strikes N10-15E strike and dips 80SE. Samples of the vein contained as much as 35.0 percent antimony, 2.40 parts per million (ppm) gold, and 1,500 ppm arsenic (Bundtzen and others, 2000). Despite the conspicuous presence of stibnite, the correlation coefficient between gold and antimony is only 44; the coefficient between gold and arsenic is about 92 (Bundtzen and others, 2000; T.K. Bundtzen, unpublished data, 2002). In 2001, two reconnaissance diamond drill holes totaling 1,214 feet were completed at the prospect (EMEX Corporation press release, February 14, 2002). Drill Hole GG01-01 did not penetrate significant mineralization. Drill hole GG-01-02 intersected three auriferous zones. Core from 277.6 to 279.9 feet contained 1,045 parts per billion (ppb) gold, 2,020 parts per million (ppb) arsenic, and 55 ppm antimony; core from 282.5 to 285.4 feet contained 750 ppb gold, 2,180 ppm arsenic, and 75 ppm antimony; and core from 650.0 to 665.0 feet contained 4,100 ppb gold,1,000 ppb silver, 220 ppm arsenic, and 60 ppm antimony. The upper auriferous intercepts are in dike rock; the lower gold-bearing intercept is at the contact between quartz porphyry and quartz-veined sedimentary rocks.
Workings: The prospect was discovered in 1998 during a soil and rock-chip geochemical survey for North Star Exploration, Inc. on land optioned from Doyon Limited (Hinderman and others, 1999). In 2001, two reconnaissance diamond drill holes totaling 1,214 feet were completed at the prospect (Galey and others, 2002; EMEX Corporation press release, February 14, 2002).
Age: Quartz monzonite on nearby French Joe Mountain (ID040) has a 40Ar/39Ar age of 71.3 Ma (T.K. Bundtzen, unpublished data, 1999).
Alteration: Phyllic alteration in sedimentary rocks; potassic alteration with secondary biotite in quartz monzonite.

Commodities (Major) - Au, Sb; (Minor) - Ag, As
Development Status: None
Deposit Model: Low sulfide gold-quartz vein or Simple antimony vein; (Cox and Singer, 1986; mo

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Link to USGS - Alaska:	ID039

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References