Timberline (ARDF #HE203) Ag, Au, Cu

Timberline

Prospects, Inactive

Commodities and mineralogy

Main commodities	Ag; Au; Cu
Ore minerals	arsenopyrite; chalcopyrite; gold; pyrite; pyrrhotite
Gangue minerals	calcite; quartz

Geographic location

Quadrangle map, 1:250,000-scale	HE
Quadrangle map, 1:63,360-scale	A-1
Latitude	63.188
Longitude	-147.401
Nearby scientific data	Find additional scientific data near this location
Location and accuracy	The site represents several prospects at an elevation of about 3,950 feet on the west slope of the ridge between Timberline Creek and Valdez Creek. The map site is in the N1/2 of sec. 17, T. 20 S., R. 2 E., of the Fairbanks Meridian. The location is accurate to within 1,000 feet. These prospects are shown as Sites 6 through 10 on Plate I of Smith, 1981.

Geologic setting

Geologic description The country rock in the area of this site is spotted phyllite, cut by CHLORITIZED DIORITE of probable Cretaceous age. The deposit consists of five veins in shear zones in altered diorite. The largest vein, the Big Caribou, has been traced for 1,000 feet; it is up to 8 feet wide, and contains kidneys and lenses of quartz, arsenopyrite, pyrite, pyrrhotite, and chalcopyrite. Other veins include the Big Water Hole, Freda G., Valdez Creek 6, and Little Caribou. Veins comprise quartz bands up to 2 feet wide. Some of the sulfides also are disseminated in the diorite. The veins appear to be localized in a conjugate fracture system associated with east-trending fault zones. Samples of the veins contain up to 0.33 ounce of gold per ton (Smith, 1981).
Geologic map unit	(-147.403259510866, 63.1875514973935)
Mineral deposit model	Polymetallic veins (Cox and Singer, 1986, model 22c)
Mineral deposit model number	22c
Age of mineralization	Probably Cretaceous or younger.
Alteration of deposit	The quartz veins are associated with chloritization of the adjacent diorite.

Production and reserves

Workings or exploration	Surface exploration consists of trenches and pits along the traces of the veins. A short adit was driven which encountered the down-dip extension of the Big Caribou and Little Caribou vein systems. Samples of the veins contain up to 0.33 ounce of gold per ton (Smith, 1981).
Indication of production	Yes; small
Production notes	A small mill was installed in about 1934; it consisted of a jaw crusher, ball mill, classifier, and amalgamating plates. Production was very small.
Additional comments This was one of the very few lode gold producers in the Valdez Creek drainage.

References

MRDS Number	A011335
References Kaufman, M.A., 1964, Two new occurrences of ore minerals in the Denali area: Alaska Division of Mines and Minerals Prospect Evaluation 67-4, 5 p. Ross, C.P., 1933, The Valdez Creek mining district, Alaska: U.S. Geological Survey Bulletin 849-H, p.425-468. Smith, P.S., 1936, Mineral industry of Alaska in 1933: U.S. Geological Survey Bulletin 864-A, p. 1-94. Smith, P.S., 1936, Mineral industry of Alaska in 1934: U.S. Geological Survey Bulletin 868-A, p. 1-91. Smith, P.S., 1937, Mineral industry of Alaska in 1935: U.S. Geological Survey Bulletin 880-A, p. 1-95. Smith, T.E., 1971, Geology, economic geochemistry, and placer gold resources of the western Clearwater Mountains, east-central Alaska: Reno, University of Nevada, Ph.D. dissertation, 440 p. Smith, T.E., 1981, Geology of the Clearwater Mountains, southcentral Alaska: Alaska Division of Geological and Geophysical Surveys Geologic Report 60, 72 p., 3 sheets, scale 1:63,360. Tuck, Ralph, 1938, The Valdez Creek mining district, Alaska, in 1936: U.S. Geological Survey Bulletin 897-B, p. 109-131.
Reporters	D.L. Stevens (Stevens Exploration Management Corporation)
Last report date	4/7/2000