Dexter Creek

Site Name

Primary: Dexter Creek

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Commodity

Primary: Silver
Primary: Gold
Secondary: Tin

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Location

State: Alaska
District: Nome

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Land Status

Not available

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Holdings

Not available

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Workings

Not available

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Ownership

Not available

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Production

Not available

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Deposit

Record Type: Site
Operation Category: Past Producer
Operation Type: Unknown
Years of Production:
Organization:
Significant:

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Physiography

Not available

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Mineral Deposit Model

Model Name: Placer Au-PGE

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Orebody

Not available

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Structure

Not available

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Alterations

Not available

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Rocks

Not available

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Analytical Data

Not available

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Materials

Ore: Cassiterite
Ore: Gold

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Comments

Comment (Geology): Geologic Description = Placer gold mining was underway on Dexter Creek by 1899. About 14,500 ounces of gold were produced in 1900 (Schrader and Brooks, 1900; Brooks and others, 1901). Most of Dexter Creek has been worked from its mouth to its headwater tributaries (Collier and others, 1908). Bench deposits at elevations 75 feet above the creek were worked at a few locations on the north side of the creek valley. One such is 1 mile above the mouth and 100 yards above the mouth of Grouse Gulch. Near the mouth of Dexter Creek, pay was on a blue clay false bedrock 5 feet below the surface. Upstream, 3 to 10 feet of stream gravels are on schist and marble bedrock, and pay continued downward into decomposed or fractured bedrock. Solution-enlarged fractures in marble were locally very rich and extended as much as 30 feet below the base of the gravels; karst features in bedrock probably contributed to water loss that commonly hindered mining operations on Dexter Creek (Moffit, 1913). The bench gravels were as much as 30 feet thick. The bench deposit 100 yards above the mouth of Grouse Gulch contained 5 feet of yellow clay over 15 feet of poorly sorted schist, marble, granite, and sandy clay gravels. The low elevations of the creek, from less than 50 feet to 250 feet, and proximity to the lower Nome River valley and coastal plain suggest that Quaternary sea-level fluctuations could have influenced development of some of the lower Dexter Creek placers, although most of the gold ultimately came from high-bench placer deposits. The upper south tributary to Dexter Creek is Wet Gulch, which taps the high-bench gravel between North Newton Peak and Anvil Mountain (NM248). Other headward tributaries include Grouse Gulch and Deer Gulch, which tap the Dexter high-bench (NM246), and Grass Gulch (NM266), which taps the Summit high-bench (NM247). Bedrock in Dexter Creek is marble and schist, probably of early Paleozoic protolith age (Hummel, 1962 [MF 247]; Till and Dumoulin, 1994). Bundtzen and others (1994) classified bedrock on the uplands above Dexter Creek as porphyroclastic micaceous graphitic schist. The completion of the Miocene Ditch to Dexter in 1903 allowed parts of the creek to be worked hydraulically, although drift mines were in operation as late as the winter of 1912-13 (Chapin, 1914). A dredge was installed in about 1918 and operated at least until 1926 (Cathcart, 1920; Smith, 1932). Cassiterite was reported from one locality (Cobb, 1973 [B 1374]). Gold on Dexter Creek ranged in size from dust to large nuggets; gold was approximately 900 fine (Purington, 1905).

Comment (Geology): Age = Quaternary.

Comment (Exploration): Status = Inactive

Comment (Deposit): Model Name = Alluvial placer Au (Cox and Singer, 1986; model 39a).

Comment (Reference): Primary Reference = Collier and others, 1908

Comment (Workings): Workings / Exploration = Dexter Creek has been extensively placer mined from its mouth to its headwater tributaries. All types of surface placer mining operations have taken place, from hand operations to dredging. Dredging was the principal mining operation from 1918 to 1926 (Cobb, 1978 [OFR 78-93]).

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References

Reference (Deposit): Bundtzen, T.K., Reger, R.D., Laird, G.M., Pinney, D.S., Clautice, K.H., Liss, S.A., and Cruse, G.R., 1994, Progress report on the geology and mineral resources of the Nome mining district: Alaska Division of Geological and Geophysical Surveys, Public Data-File 94-39, 21 p., 2 sheets, scale 1:63,360.

Reference (Deposit): Chapin, Theodore, 1914, Placer mining on Seward Peninsula: U.S. Geological Survey Bulletin 592-L, p. 385-395.

Reference (Deposit): Till, A.B., and Dumoulin, J.A, 1994, Geology of Seward Peninsula and St. Lawrence Island, in Plafker, G., and Berg, H.C., eds., The Geology of Alaska: Geological Society of America, The Geology of North America, DNAG, v. G-1, p. 141-152.

Reference (Deposit): Hummel, C.L., 1962, Preliminary geologic map of the Nome C-1 quadrangle, Seward Peninsula, Alaska: U.S. Geological Survey Miscellaneous Field Studies Map MF-247, 1 sheet, scale 1:63,360.

Reference (Deposit): Cobb, E.H., 1972, Metallic mineral resources map of the Nome quadrangle, Alaska: U.S. Geological Survey Miscellaneous Field Studies Map MF-463, 2 sheets, scale 1:250,000.

Reference (Deposit): Cobb, E.H., 1973, Placer deposits of Alaska: U.S. Geological Survey Bulletin 1374, 213 p.

Reference (Deposit): Cobb, E.H., 1978, Summary of references to mineral occurrences (other than mineral fuels and construction materials) in the Nome quadrangle, Alaska: U.S. Geological Survey Open-File report 78-93, 213 p.

Reference (Deposit): Smith, P.S., 1932, Mineral industry of Alaska in 1929, in Smith, P.S., and others Mineral resources of Alaska, report on progress of investigations in 1929: U.S. Geological Survey Bulletin 824-A, p. 1-81.

Reference (Deposit): Schrader, F.C., and Brooks, A.H., 1900, Preliminary report on the Cape Nome gold region, Alaska: U.S. Geological Survey Special Publication, 56 p.

Reference (Deposit): Brooks, A.H., Richardson, G. B., and Collier, A. J., 1901, Reconnaissance in the Cape Nome and Norton Bay regions, Alaska, in 1900: U.S. Geological Survey Special Publication, p. 1-180.

Reference (Deposit): Purington, C.W., 1905, Methods and costs of gravel and placer mining in Alaska: U.S. Geological Survey Bulletin 263, 273 p.

Reference (Deposit): Collier, A. J., Hess, F.L., Smith, P.S., and Brooks, A.H., 1908, The gold placers of parts of Seward Peninsula, Alaska, including the Nome, Council, Kougarok, Port Clarence, and Goodhope precincts: U.S. Geological Survey Bulletin 328, 343 p.

Reference (Deposit): Moffit, F.H., 1913, Geology of the Nome and Grand Central quadrangles, Alaska: U.S. Geological Survey Bulletin 533, 140 p.

Reference (Deposit): Cathcart, S.H., 1920, Mining in northwestern Alaska: U.S. Geological Survey Bulletin 712, p. 185-198.

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