|Quadrangle map, 1:250,000-scale||HE|
|Quadrangle map, 1:63,360-scale||A-1|
|Nearby scientific data||Find additional scientific data near this location|
|Location and accuracy||This site represents an area of placer gold mining that extends from near the mouth of Valdez Creek, upstream at least as far as White Creek and Lucky Gulch. The map site is on lower Valdez Creek, about a half-mile downstream from the historic mining town of Denali. The site is in the NW1/4 of sec. 24, T. 20 S., R 1 E., of the Fairbanks Meridian. This location is accurate to within a quarter mile.|
Valdez Creek drains an area underlain mostly by pelitic metasedimentary rocks of probable Jurassic age (Smith, 1981). The sedimentary sequence was regionally metamorphosed during the Cretaceous to pumpellyite-prehnite grade on the southeast, through greenschist grade, to amphibolite grade on the northwest. The metamorphic sequence appears to be telescoped, possibly by northward-dipping thrust faults. An east-trending strike-slip fault zone south of, and approximately parallel to, Valdez Creek appears to be important to the distribution of the origin of the placer gold. The fault zone has controlled the emplacement of many small intrusives of intermediate composition, and of quartz vein swarms, some of which are auriferous.
The genesis and distribution of the placer gold deposits are linked to the complex glacial history of the drainage. Near the lower end of Valdez Creek, at least three superimposed, gold-bearing paleochannels were cut into bedrock (Reger and Bundtzen, 1990). Each paleochannel is at a specific elevation and gradient, and the younger paleochannels cut the older paleochannels, thereby redistributing the gold. Gold concentrations are highest in the lowest portions of the paleochannels.
The paleochannels become less incised upstream and eventually are not found. The pay streaks merge into a large volume of lower grade auriferous gravel from the upper limit of mining by Valdez Creek Mining Company, apparently up into the White Creek drainage.The fineness of the gold runs about 852 with only minor variations. The gold itself showed several different varieties. Most of the gold is 'oatmeal' sized and shaped; other varieties include well-polished and rounded grains, rough, angular, and quartz-rich grains, and rough, angular, and oxide-coated grains.
|Geologic map unit||(-147.475259894432, 63.1745503922263)|
|Mineral deposit model||Placer Au-PGE (Cox and singer, 1986; model 39a)|
|Mineral deposit model number||39a|
|Age of mineralization||Paleochannel A is probably Sangamon in age, the Tammany channel is probably mid-Wisconsin in age, and Paleochannel B was probably deposited during the late Illinoian interstade (Reger and Bundtzen, 1990). The pay streaks and low-grade gravels in the White Creek drainage and Lucky Gulch are probably younger.|
|Workings or exploration||
Lower Valdez Creek was mined by hand methods after discovery in 1903. The Tammany Channel was mined by underground methods for a distance of about 3,500 feet from the confluence of the channel with Valdez Creek. The Dry Creek cut was mined by hand methods and hydraulicked. The lower portion of the Tammany Channel was hydraulicked. Channels A and B were mined by large-scale, open-pit methods for a distance of several miles upstream after have been thoroughly explored by reverse-circulation drilling during the period 1984 through 1994.
White Creek has been mined by small-scale methods below the west slope of Gold Hill and by open-pit methods just above its confluence with Valdez Creek. Lucky Gulch and its downstream extension has been mined by hand and by small-scale mechanical methods.Timberline Creek was mined for several years where the creek enters Valdez Creek valley.
|Indication of production||Yes; medium|
|Reserve estimates||Proven reserves are small because of a lack of detailed drilling. A very large quantity of gold remains but is not economic to mine at this time (1999). Detailed drilling in the most promising areas could reveal as much as 100,000 ounces of proven reserves.|
|Production notes||Recorded production for the Valdez Creek drainage and its tributaries is about 650,000 ounces.|
Mendenhall, W.C., 1905, Geology of the central Copper River region, Alaska: U.S. Geological Survey Professional Paper 41, 133 p., 4 sheets, scale 1:250,000.
Moffit, F.H., 1912, Headwater regions of Gulkana and Susitna Rivers, Alaska, with accounts of the Valdez Creek and Chistochina placer districts: U.S. Geological Survey Bulletin 498, 82 p.
Moffit, F.H., 1914, Preliminary report on the Broad Pass region: U.S. Geological Survey Bulletin 592-H, p. 301-305.
Reger, R.D., and Bundtzen, T.K., 1990, Multiple glaciation and gold-placer formation, Valdez Creek Valley, western Clearwater Mountains, Alaska: Alaska Division of Geological & Geophysical Surveys Professional Report 107, 34 p., 1 sheet, scale 1:63,360.
Ross, C.P., 1933, The Valdez Creek mining district, Alaska: U.S. Geological Survey Bulletin 849-H, p.425-468.
Smith, T.E., 1970, Gold resource potential of the Denali bench gravels, Valdez Creek mining district, Alaska, in Geological Survey research 1970: U.S. Geological Survey Professional Paper 700-D, p. D146-D152.
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.
Wiltse, M.A., 1988, Preliminary litho-geochemistry of Gold Hill and Lucky Hill, Valdez Creek mining district, Healy A-1 quadrangle, southcentral Alaska: Alaska Division of Geological and Geophysical Surveys Public-Data File 88-41, 9 p., 1 sheet, scale 1:12,000.
|Reporters||D.L. Stevens (Stevens Exploration Management Corporation)|
|Last report date||4/7/2000|