Wonder Gulch

Occurrence, Inactive

Commodities and mineralogy

Main commodities Au
Other commodities Hg; Pb
Ore minerals cerussite; cinnabar; gold; pyromorphite

Geographic location

Quadrangle map, 1:250,000-scale BN
Quadrangle map, 1:63,360-scale B-6
Latitude 65.315
Longitude -164.732
Nearby scientific data Find additional scientific data near this location
Location and accuracy Wonder Gulch is a tributary on the north side of Coffee Creek. The mouth of Wonder Gulch on Coffee Creek is at the Nome-Taylor road crossing at almost mile 75. This occurrence is on Wonder Gulch about 1,500 feet upstream form the mouth. The lower 1,500 feet of Wonder Gulch has been placer mined and this section of the drainage is included with the Coffee Creek mine (BN003). This is locality 5 of Cobb (1972; MF 417).

Geologic setting

Geologic description

The early descriptions of a residual gold placer on schist bedrock is believed to be at this location. This residual placer contains angular, spongy, and bright gold in 4 to 7 feet of angular schist and quartz and adjacent weathered schist bedrock (Collier and others, 1908). Small amounts of cinnabar, cerussite, and pyromorphite are present in placer concentrate from Wonder Gulch (Anderson, 1947). Sainsbury and others (1969) indicate that an attempt to mine an auriferous quartz ledge here was unsuccessful. Large iron-stained quartz boulders are present in the upper part of the placer on Wonder Gulch (Sainsbury and others, 1969). Bedrock here is part of a low grade Lower Paleozoic metasedimentary assemblage (Till and others, 1986).
Geologic map unit (-164.734661831276, 65.3142625010183)
Mineral deposit model Gold-bearing quartz veins and schist.
Age of mineralization Possibly mid-Cretaceous; this is the age of some lode gold deposits on southern Seward Peninsula. The southern Seward Peninsula lode gold deposits formed as a result of mid-Cretaceous metamorphism (Apodoca, 1994; Ford, 1993, Ford and Snee, 1996; Goldfarb and others, 1997) that accompanied regional extension (Miller and Hudson, 1991) and crustal melting (Hudson, 1994). This higher temperature metamorphism was superimposed on high pressure/low temperature metamorphic rocks of the region.

Production and reserves

Workings or exploration Open-cut mining of a residual placer has exposed weathered schist and angular surface debris of auriferous quartz and schist.
Indication of production None

Additional comments

Also see Coffee Creek (BN003).

References

MRDS Number A012741

References

Hudson, T.L., 1994, Crustal melting events in Alaska, in Plafker, G., and Berg, H. C., eds., The Geology of Alaska: Geological Society of America, DNAG, The Geology of North America, Vol. G-1, p. 657-670.
Reporters Travis L. Hudson (Applied Geology)
Last report date 3/15/1999