Unnamed Prospect (ARDF - EA005; near Granite Creek), Eagle Mining District, Southeast Fairbanks Census Area, Alaska, USAi

Regional Level Types
Unnamed Prospect (ARDF - EA005; near Granite Creek)	- not defined -
Eagle Mining District	Mining District
Southeast Fairbanks Census Area	Census Area
Alaska	State
USA	Country

The Granite Creek prospect is located within Doyon, Ltd. selected or conveyed land. For more information contact Doyon, Ltd., Fairbanks, Alaska.
Location: This prospect is the probable source of tungsten anomalies in the north fork of Granite Creek; the prospect coordinates are in the center of the prospect area, in section 11, T. 1 S., R. 25 E., of the Fairbanks Meridian. Tungsten anomalies occur in a northwest-trending zone about 3.5 miles long by 0.5 mile wide. The location is only accurate within 2 miles. The Granite Creek prospect is located within Doyon, Ltd. selected or conveyed land.
Geology: Upper Granite Creek drains a Late Cretaceous granitic batholith that underlies much of the northern Eagle quadrangle (Foster, 1976; Dashevsky and others, 1986). Biotite from granite adjacent to a gold-bearing quartz-arsenopyrite vein on upper Granite Creek gives a 40Ar/39Ar plateau age of 93.3 +/- 0.5 Ma (Newberry and others, 1996). Elevated tungsten was found in panned heavy-mineral concentrates for 16 miles of Granite Creek near the contact with the granitic batholith (Dashevsky and others, 1986). Portions of the tungsten anomaly were traced to quartz-scheelite-chalcopyrite-molybdenite veinlets in west-northwest-trending joint sets in unaltered quartz monzonite and quartz diorite. A 30 foot-long chip sample from one of these zones contains 1,750 ppm copper, 125 ppm tungsten, and 200 ppm tin. Panned heavy-mineral samples downstream of this zone contain 630 ppm tungsten and 1,590 ppm tin. Molybdenite was found along hairline fractures and in float of phyllic-altered monzonite near high-angle breccia zones. Alteration is generally restricted to vein selvages. One float sample with 4,060 ppm molybdenum contains visible molybdenite and ferrimolybdenite. There are also quartz veins without tungsten or molybdenum that contain as much as several percent copper and several ounces of silver per ton, as well as elevated lead, zinc, arsenic, gold, and tin. Stream-sediment samples and panned-concentrate samples from lower Granite Creek contain elevated gold, mercury, tin, and tungsten. The Ole Creek prospect (EA007) is located nearby at the head of the south fork of Granite Creek. WGM Inc. conducted stream-sediment sampling along Granite Creek in 1975 and 1976 (Dashevsky and others, 1986). In 1979, WGM Inc. panned heavy-mineral concentrates and sampled rocks in the Granite Creek area and discovered a lode source for the tungsten sediment and pan concentrate anomalies. In 1982, Doyon, Ltd. sampled rocks and stream sediments, and discovered breccia zones in the Granite Creek area.
Workings: WGM Inc. conducted stream-sediment sampling along Granite Creek in 1975 and 1976 (Dashevsky and others, 1986). In 1979, WGM Inc. panned heavy-mineral concentrates and sampled rocks in the Granite Creek area, and discovered a lode source for the tungsten sediment and pan concentrate anomalies. In 1982, Doyon, Ltd. sampled rocks and stream sediments and discovered breccia zones in the Granite Creek area.
Age: Biotite from granite adjacent to a gold-bearing quartz-arsenopyrite vein on upper Granite Creek gives a 40Ar/39Ar plateau age of 93.3 +/- 0.5 Ma (Newberry and others, 1996). Mineralization in the Granite Creek area is probably this age or younger.
Alteration: Molybdenite was found along hairline fractures and in phyllic-altered monzonite float near high-angle breccia zones (Dashevsky and others, 1986). Alteration is generally restricted to vein selvages.

Commodities (Major) - Ag, Au, Cu, Hg, Mo, Pb, Sn, W
Development Status: None
Deposit Model: Possibly a porphyry Mo deposit (Cox and Singer, 1986; model 21b?).

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Link to USGS - Alaska:	EA005

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References