Glacier Creek Mines, Kantishna Mining District, Denali Borough, Alaska, USAi

Regional Level Types
Glacier Creek Mines	Group of Mines
Kantishna Mining District	Mining District
Denali Borough	Borough
Alaska	State
USA	Country

Glacier Creek was probably the second or third most productive creek draining the Kantishna Hills. Its production is second to that of upper Caribou Creek (MM042), and about the same or perhaps slightly less than that of Eureka Creek (MM122). The creek is in Denali National Park and Preserve.
Location: Glacier Creek (Cobb, 1980 [OFR 80-363]) rises against Glacier Peak. It flows westerly for about two miles, then gradually turns northwesterly. The creek is auriferous for at least six miles; the location marks placer tailings in the SW 1/4 of section 19, T. 15 S., R. 17 W., Fairbanks Meridian. The location is accurate. Glacier Creek is fed by Yellow Creek (MM079) and Twentytwo Gulch (MM066). It is location 53 of Cobb (1972 [MF 366]).
Geology: Glacier Creek above Fifteen Gulch is incised in weathered and altered schist bedrock of the Birch Creek Schist (Bundtzen, 1981; Hawley and Associates, 1978). The schist is cut by occasional quartz veins. Headwater tributaries to Glacier Creek, especially Yellow Creek and Twentytwo Gulch, head into strata of the Spruce Creek sequence. Although many of the lode deposits of the Kantishna Hills are in Spruce Creek bedrock, several lodes in upper Glacier Creek are in Birch Creek Schist (see MM066, MM069, MM074, and MM082). Below Fifteen Gulch, Glacier Creek flows on weathered schist for about a mile, then on moderately-indurated, clay-rich, Tertiary or lower Quaternary gravel false bedrock. The lower reaches of the creek have extensive fluvioglacial bench terraces, occasionally containing remnant masses of Pleistocene or Holocene alluvial gravel (Prindle, 1907; Capps, 1919; Levell, 1984, v. 2). Locally, as near the point where the creek leaves the Kantishna Hills, ancient bedrock channels diverge to the northwest and are covered by more-recent bench gravels (Capps, 1919, p. 91). In the narrower upstream parts of the creek, alluvial gravels are locally buried by landslide or talus from steep walls or side canyons. Prindle (1907, 1911) reported that the best ground in Glacier Creek was near where the creek leaves the Kantishn Hills and its gradient flattens. At that point, the gravels are 2 to 5 feet thick on schist bedrock. In 1983, mining from that point for about a mile downstream was of weakly oxidized gravels 4-6 feet thick on oxidized, clay-rich,Tertiary gravel false bedrock; the pay zone was about 200 to 300 feet wide (Levell, 1984, v. 1 and 2). The creek above that point and below the hills was worked by dragline in about 1940. The main accessory minerals in the lower placer gravels are garnet and magnetite; the gold is mainly fine-grained and about 750-760 fine. The ground contained about 0.023 ounce (about 0.017 fine ounce) of placer gold per cubic yard. In 1983, a placer mine operated on schist bedrock in a section of the creek between Twentytwo and Eighteen Gulches. The gold was coarser and rougher than that in the downstream section, mostly of 0.05 to 0.25 ounce size. Galena was abundant in the concentrates, along with smaller amounts of pyrite and stibnite. The computed grade of mined material was 0.038 ounce of gold per cubic yard. The commercial placers on Glacier Creek are mainly Holocene. The buried bedrock channel deposits are probably Pleistocene.
Workings: Auriferous gravels were discovered in Glacier Creek in 1905 and mining commenced immediately (Prindle, 1907; Wells, 1933). When the district was visited by Capps in 1916, there were at least four claims, starting from claim No. 20, about 1 1/2 miles above the point where the creek leaves the hills, to claim no. 12 on the valley flat (Capps, 1919, p. 89-92). In 1921, there were two operations on upstream claims (Davis, 1923, p. 116). According to annual reports summarized by Cobb (1980 [OFR 80-363]), the creek was mined or prospected on a relatively small scale between 1922 and 1938. A medium-size dragline plant operated at the head of the lower section between about 1939 and 1942 (Bundtzen, Smith, and Tosdal, 1976, p. 16). The creek was mined in the 1970s and early 1980s. There were six operations on the creek in 1983 (Levell, 1984, v. 2), and it was active in 1984. There has been little if any mining since 1985.
Age: Pleistocene to Holocene.
Production: The amount of gold recovered is uncertain. Based on the mining reported in 1984 by Levell (1984, v. 2), the minimum production probably was more than 5000 ounces. A total of 10,000 ounces is not unreasonable.
Reserves: Levell (1984, v. 2) calculated gold resources in Glacier Creek, based on measured volumes of gravel and on grades established by testing or computed from the amount of gold recovered by mining operations in 1983. Levell also classified the resources on the basis of then-claimed and unclaimed ground. The resources in claimed ground are divided into blocks. Block G-2 is the farthest downstream; it is about 13,000 feet long and starts about 1500 feet below Fifteen Gulch. It contains about 2,340,000 cubic yards of alluvial and bench material with estimated grades that range from 0.0012 to 0.019 ounce of gold per cubic yard. Block G-3 is 1800 feet long and is centered on Fifteen Pup; a total resource of 258,000 cubic yards is estimated to contain between 0.012 and 0.017 ounce of gold per cubic yard. Block G-4 is about 3500 feet long and extends from Fifteen to Eighteen Gulch. Based on a mine active in 1983, it contains about 70,000 cubic yards of pay gravel at a grade of 0.038 ounce of gold per cubic yard. G-5, the uppermost claimed block, is about 5000 feet long and extends from Eighteen to Twentytwo Gulch; it has a measured resource of 45,000 cubic yards at an extrapolated grade of 0.038 ounce of gold per cubic yard. The total high-resource potential ground in blocks G-2 to G-5 is about 2,713,000 cubic yards that contains 25,618 to 46,510 ounces of gold, using the lowest and highest values of each block. Block G-6 is on unclaimed ground between Twentytwo Gulch and Yellow Creek, a distance of about a mile. Based on testing, this ground could have a resource of about 240,000 cubic yards containing 2640 to 4800 ounces of gold.

Commodities (Major) - Au; (Minor) - Ag, Pb, Sb
Development Status: Yes; small
Deposit Model: Au-PGE placer deposit (Cox and Singer, 1986; model 39a). Complex deposit: shal

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Link to USGS - Alaska:	MM048

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References