Dennison Fork Prospect, Southeast Fairbanks Census Area, Alaska, USAi

Regional Level Types
Dennison Fork Prospect	Prospect
Southeast Fairbanks Census Area	Census Area
Alaska	State
USA	Country

Location: Dennison Fork is a tributary of the South Fork of the Fortymile River; its mouth is about 1.6 miles south-southeast of Chicken. Prospecting and drilling took place near the confluence of Dennison Fork with Mosquito Fork and South Fork. The coordinates are an arbitrarily point near the mouth of Dennison Fork,in section 8, T. 26 N., R. 18 E., of the Copper River Meridian. This site is locality 84 of Burleigh and Lear (1994), locality 21 of Eberlein and others (1977), and locality 53 of Cobb (1972 [MF-393]).
Geology: The rocks in the lower part of the Dennison Fork valley consist predominantly of the Triassic granodiorite of the Taylor Mountain batholith (Foster, 1976). A rubidium/strontium date on biotite from granodiorite of the batholith gives an age of approximately 190 Ma (Wasserberg and others, 1963). The granodiorite has been intruded by minor Tertiary gabbro. Quaternary alluvium, colluvium, and terrace deposits are extensive in the Dennison Fork drainage. Considerable prospecting and drilling has been carried out near the mouth of Dennison Fork, but there is no record of actual placer mining. A ditch was dug in 1911 to work the bench gravels (Porter, 1912); despite completion of the ditch, no mining occurred (Ellsworth and Davenport, 1913). Gold near the mouth of Dennison Fork is very fine grained. In 1918, there was extensive prospecting of high benches near the mouth of Dennison Fork,and plans were made to build a 21-mile-long ditch (Martin, 1920). Additional systematic prospecting of a large body of gravel occurred in 1920 (Brooks, 1922). A sample from the foot of the bluff at the junction of Dennison and Mosquito Forks contained trace scheelite (White and others, 1963).
Workings: Considerable prospecting and drilling has been carried out near the mouth of Dennison Fork, but there is no record of actual placer mining. A ditch was dug in 1911 to work the bench gravels (Porter, 1912); despite completion of the ditch, no mining occurred (Ellsworth and Davenport, 1913). Gold near the mouth of Dennison Fork is very fine grained. In 1918, there was extensive prospecting of high benches near the mouth of Dennison Fork,and plans were made to build a 21-mile-long ditch (Martin, 1920). Additional systematic prospecting of a large body of gravel occurred in 1920 (Brooks, 1922). A sample from the foot of the bluff at the junction of Dennison and Mosquito Forks contained trace scheelite (White and others, 1963).
Age: Quaternary.

Commodities (Major) - Au; (Minor) - W
Development Status: None
Deposit Model: Placer Au (Cox and Singer, 1986; model 39a).

Other Databases

Link to USGS - Alaska:	EA136

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References