East Gate Prospect, Fairbanks Mining District, Fairbanks North Star Borough, Alaska, USAi

Regional Level Types
East Gate Prospect	Prospect
Fairbanks Mining District	Mining District
Fairbanks North Star Borough	Borough
Alaska	State
USA	Country

Location: The East Gate prospect extends southwest from the headwaters of Independence Creek and the west branch of Wildcat Creek and covers the ridgetop near mile 3 of Old Murphy Dome Road; it is in the NE1/4 NW1/4 sec. 22, T. 2 N., R. 1 W., Fairbanks Meridian.
Geology: The following geologic description is summarized from a report by Sam Dashevsky (1993) on work done by American Copper and Nickel Company (ACNC) on the Eagle Creek property in the early 1990's. Local zones of anomalous arsenic in soils were first identified on the property in the 1970's by Cantu Minerals Association. In the 1980's, Silverado Gold Mines, Ltd. and Tri-Con Mining delineated a gold anomaly; trenching resulted in the discovery of a narrow, high-grade quartz breccia vein near mile 3 of Old Murphy Dome road. In 1991 and 1992, ACNC conducted a soil sampling program and drilled four reverse circulation holes. Soil sampling identified an irregularly shaped multi-element soil anomaly measuring 5,000 feet long by 500 to 2,500 feet wide that was marked by anomalous arsenic, lead, and bismuth. Three nodes of anomalous gold, antimony, and lead also occur in the area. Silt samples from Independence Creek at the 1,000-, 1,100- and 1,200-foot elevations show anomalous gold. On Wildcat Creek, stream sediment samples contained anomalous gold at the 850-, 900-, 1,000- and 1,150-foot elevations. Drilling and distribution of rock fragments in soil sample pits indicate that the area is predominantly underlain by quartz-mica schist and micaceous quartzite, with subordinate graphitic phyllite and chloritic-biotite schists at depth. Soil samples from the east flank of upper Independence Creek, and several other nearby sites have abundant felsic intrusive rocks mixed with schist chips and regolith. Rock fragments are commonly altered and limonitic, and vein quartz fragments are broadly distributed throughout the zone. Drilling intersected sporadic pegmatite veinlets. Directly east of the gate to the East Scrafford prospect, limonite-stained finely fractured schist without quartz veining contains 5,000-6,000 ppb gold (0.14-0.18 ounce of gold per ton). Five hundred feet farther east, pieces of quartz-sulfide float as much as 18 inches thick contain 11,000 to 19,000 ppb gold (0.32 to 0.55 ounce of gold per ton). Isolated fragments of silicified felsic intrusive breccia contain 6,850 ppb gold. Four drill holes indicate broad zones of weakly mineralized schist in sparsely veined, weakly pyritic, silicified zones that are at depths exceeding 400 feet. The high-grade veins at the surface were intercepted in the drilling program; one 110-foot intercept ran 0.026 ounce of gold per ton, and one 5-foot interval ran 0.068 ounce of gold per ton. Rock fragments in soils show much evidence of silicification, clay alteration, and limonite. Drilling identified broad zones of pyritic silicification at a depth of more than 400 feet; argillation, patchy silicification, and chloritic alteration were confined to sheared zones at higher levels.
Workings: In the 1970's, Cantu Minerals Association conducted soil sampling in the area. In the 1980's, Silverado Gold Mines, Ltd. and Tri-Con Mining completed a small soil grid and identified a gold anomaly. In 1991 and 1992, American Copper and Nickel Company conducted silt and soil sampling and in 1993 drilled four holes that totaled 2,335 feet (Dashevsky, 1993).
Alteration: Rock fragments in soils show much evidence of silicification, clay alteration, and limonite. Drilling identified broad zones of pyritic silicification at depths of more than 400 feet; argillation, patchy silicification, and chloritic alteration occured in shallower rocks (Dashevsky, 1993).

Commodities (Major) - Au
Deposit Model: Schist-hosted gold-quartz vein

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Link to USGS - Alaska:	FB081

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References