Gulch Creek No. 3

Occurrence, Inactive

Commodities and mineralogy

Main commodities Ag; Au
Ore minerals arsenopyrite; gold
Gangue minerals quartz

Geographic location

Quadrangle map, 1:250,000-scale SR
Quadrangle map, 1:63,360-scale D-7
Latitude 60.7821
Longitude -149.2906
Nearby scientific data Find additional scientific data near this location
Location and accuracy This occurrence is located in the SW1/4 section 16, T. 8 N., R. 1 E., of the Seward Meridian, at elevations between 3,900 and 4,000 feet. It is situated on the divide between the south and middle headwater tributaries to Gulch Creek. This is location S-284 of Jansons and others (1984). The location is accurate to within a quarter of a mile.

Geologic setting

Geologic description

The Gulch Creek No. 3 occurrence consists of two quartz veins as much as 2 feet thick that occur along a well-developed shear zone that averages 4 feet wide. The shear zone strikes roughly northeast and dips vertically and is only one of numerous faults in the area. The larger vein, exposed along strike for about 100 feet, strikes N65W and dips vertically. The vein is offset in at least three places by northeast-trending faults that dip 65SE. The apparent motion of these faults is right lateral, and the displacement is about 5 feet (Hoekzema and Sherman, 1983). The shear zone and quartz veins are hosted by slate and metasiltstone of the Upper Cretaceous Valdez Group (Hoekzema and Sherman, 1983). The quartz is iron-stained and vuggy and contains arsenopyrite.
Four chip samples collected in 1981 by the U.S. Bureau of Mines contained less than 0.03 ppm gold and less than 1 ppm silver (Hoekzema and Sherman, 1983).
Geologic map unit (-149.292755530033, 60.7815384247008)
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 Late Cretaceous Valdez Group rocks.

Production and reserves

Workings or exploration No workings or improvements are present. The occurrence was discovered, mapped and sampled by the U.S. Bureau of Mines in 1981 (Hoekzema and Sherman, 1983). Five samples assayed traces of gold and a trace to 0.01 ounce of silver per ton (Jansons and others, 1984). The Bureau considered that the occurrence has a low potential for mineral development.
Indication of production None

Additional comments

More than 8,000 ounces of placer gold have been recovered from Gulch Creek downstream from this occurrence.

References

References

Reporters Jeff A. Huber (Anchorage)
Last report date 2/6/2000