Gulch Creek No. 1

Occurrence, Inactive

Commodities and mineralogy

Main commodities Ag; Au
Other commodities Cu; Pb; Sb; Zn
Ore minerals arsenopyrite; chalcopyrite; galena; gold; sphalerite; stibnite
Gangue minerals quartz

Geographic location

Quadrangle map, 1:250,000-scale SR
Quadrangle map, 1:63,360-scale D-7
Latitude 60.7633
Longitude -149.3056
Nearby scientific data Find additional scientific data near this location
Location and accuracy This occurrence is located in the SE1/4 section 20, T. 8 N., R. 1 E., of the Seward Meridian. It is at an elevation of 3,700 to 4,200 feet, on a ridge above the head of a small, northwest-flowing tributary to Gulch Creek. This is location S-281 of Jansons and others (1984). The location is accurate to within a quarter of a mile.

Geologic setting

Geologic description

This occurrence consists of two narrow quartz veins, averaging 3 inches wide, that strike N35-50W and dip 40-55NE. The veins contain arsenopyrite, chalcopyrite, galena, sphalerite, stibnite, and gold. One vein can be traced along strike for 200 feet (Jansons and others, 1984). The veins are hosted in complexly folded and faulted, interbedded, locally iron-stained, slightly metamorphosed, silty to sandy graywacke, pebble conglomerate, and minor slate of the Valdez Group of Late Cretaceous age (Nelson and others, 1985). Several barren-appearing stockwork-type quartz veins also occur in the area.
Twelve samples collected in 1981 by the U.S. Bureau of Mines assayed from a trace to 0.18 ounce of gold per ton and from a trace to 22.5 ounces of silver per ton. Other metal values, including arsenic, copper, lead, zinc, and antimony, ranged from none detected to 4,600 ppm (Hoekzema and Sherman, 1983).
Geologic map unit (-149.30775468287, 60.7627375141274)
Mineral deposit model Low-sulfide Au-quartz veins (Cox and Singer, 1986; model 36a)
Mineral deposit model number 36a
Age of mineralization Cretaceous or younger; the veins cut rocks of the Valdez Group of Late Cretaceous age.
Alteration of deposit Local iron staining.

Production and reserves

Workings or exploration The U.S. Bureau of Mines discovered the occurrence in 1981. They collected 12 samples that assayed from a trace to 0.18 ounce of gold per ton and from a trace to 22.5 ounces of silver per ton (Jansons and others, 1984). Other metals values tested for included arsenic, copper, lead, zinc, and antimony. Antimony values ranged from a trace to 0.23 percent (Jansons and others, 1984).
Indication of production None
Reserve estimates The U.S. Bureau of Mines estimated reserves of 200 tons of ore containing 0.1 ounce of gold per ton and 20 ounces of silver per ton (Jansons and others, 1984).

Additional comments

The U.S. Bureau of Mines reported that other quartz veins occur in the area, but because of time limitations and precipitous terrane, they did not sample them (Hoekzema and Sherman, 1983). The Bureau recommended additional exploration.

References

References

Reporters Jeff A. Huber (Anchorage)
Last report date 2/4/2000