Unnamed (around mouth of Cahoon Creek)

Occurrence, Probably inactive

Commodities and mineralogy

Main commodities Au
Other commodities Ag
Ore minerals chalcopyrite; galena; gold; pyrite; sphalerite
Gangue minerals calcite; quartz

Geographic location

Quadrangle map, 1:250,000-scale SK
Quadrangle map, 1:63,360-scale B-4
Latitude 59.39
Longitude -136.24
Nearby scientific data Find additional scientific data near this location
Location and accuracy The location of this occurrence, in the center of section 1, T. 29 S., R. 54 E. of the Copper River Meridian, is somewhat arbitrary and applies to a broad northwest trending band of mineralization. It is taken from Eakin (1919) who describes a northwest trending band of quartz-sulfide veinlets in slate that is 1,200 feet thick and cuts across Cahoon Creek near its mouth. This band is contained within a larger zone of sporadic quartz-sulfide veins and stringers that Eakin describes as extending in a northwesterly direction from the Salmon (Tsirku) River, through Porcupine, Glacier, and Jarvis Creeks to the mountain mass north of the Jarvis Glacier.

Geologic setting

Geologic description

Eakin (1918 and 1919) describes a nearly 1,200-foot-wide band of abundant quartz-sulfide veining in slate that cuts across Cahoon Creek near its mouth. He further notes that this zone of abundant veining occurs within a northwest-trending larger area of sediment hosted, discontinuous lode mineralization that consist of quartz, iron sulfides, and calcite veins, veinlets, and lenses that extends from south of the Salmon (Tsirku) River across the basins of Porcupine, Glacier, and Jarvis Creeks and into the mountain mass north of the Jarvis Glacier. Eakin infers that this larger zone of veining is the source of the placer gold in the Klehini and Salmon (Tsirku) River basins.
Wright (1904 [B 225 and B 236]) noted that this zone of mineralization occurs in sedimentary rocks in the Porcupine area that are all more or less mineralized by veins of quartz and calcite. Iron sulfides that occur as films and conformable lenticular masses up to a few inches thick form an interrupted zone of mineralization in the southern portion of the sedimentary series. Quartz veins are not abundant and are often stringers parallel to the cleavage of the slate. The few crosscutting quartz veins carry galena, sphalerite, and minor chalcopyrite. Although these quartz-sulfide veins are quite narrow, they often persist for considerable distances. Light-brown-weathering calcite veins are more numerous than quartz veins, are often more than a foot thick; they may include pyrite cubes up to an inch across. Gold has been reported from veins of this nature up McKinley Creek ; see (SK046) and (SK047).
MacKevett and others (1974) observed that, 'Lode occurrences are localized mainly in or near the slate in the central part of the B-4 quadrangle, and the placers are mainly along streams that drain the slate terrane.'
Geologic map unit (-136.24185755968, 59.389670813014)
Mineral deposit model Auriferous quartz-sulfide veins in slate and in silica-carbonate-altered mafic dikes (Cox and Singer, 1986; model 22c).
Mineral deposit model number 22c
Age of mineralization Unknown, but probably Cretaceous or younger based on the age of intrusives in the area (MacKevett and others, 1974).
Alteration of deposit Some of the larger auriferous quartz-sulfide veins in the vicinity are associated with mafic dikes that have been altered to silica-carbonate rocks (see Golden Eagle (SK047)).

Production and reserves

Indication of production None

References

MRDS Number 10308248

References

Beatty, W.B., 1937, Geology of the placer deposits of Porcupine, Alaska: Seattle, University of Washington, B.Sci. thesis, 97 p.
Roppel, Patricia, 1975, Porcupine: Alaska Journal, v. 5, no. 1, pp. 2-10.
Reporters T.C. Crafford (T. Crafford & Associates, Anchorage)
Last report date 2/4/2001