Nugget Creek; Nugget Bench High Channel Mine, Yentna Mining District, Matanuska-Susitna Borough, Alaska, USAi

Regional Level Types
Nugget Creek; Nugget Bench High Channel Mine	Mine
Yentna Mining District	Mining District
Matanuska-Susitna Borough	Borough
Alaska	State
USA	Country

Both Quaternary glaciofluvial deposits and Tertiary conglomeratic units have been mined on Nugget Creek. Glaciofluvial deposits similar to Nugget Creek can be found on Windy Creek (TL027) and Bird Creek (TL040). Older Tertiary conglomeratic units probably represent southwest flowing drainages similar to those in Thunder (TL032, 058), Falls (TL030), Dollar (TL031) and Willow (TL042) Creeks. Gold was reconcentrated from these older Tertiary channels into the modern Cache Creek drainage (C.C. Hawley and Associates, Inc., 1978). Also see Cache Creek (TL029).
Location: C.C. Hawley and Associates, Inc. (1978, Fig. 4.2-B(3)) show placer ground from the confluence of Nugget Creek with Cache Creek to about 1.5 miles upstream through Sections 9, 15, and 16 in T. 29 N., R. 9 W., of the Seward Meridian. The Nugget Bench High Channel Deposit is shown on Fig. 4.2-B(3) about one mile upstream from the confluence. Coordinates given in this record are for the Nugget Bench High Channel.
Geology: Both Quaternary glaciofluvial deposits and Tertiary conglomeratic (white quartz-breccia, Clark and Hawley, 1968) units have been mined on Nugget Creek. The area is underlain by the Sterling Formation (Tps), the upper member of the Tertiary Kenai Group, and Mesozoic argillite (KJs) (Reed and Nelson, 1980). Quaternary auriferous stream gravels from 6 to 8 feet deep and bench gravels 1 to 6 feet deep above the Sterling Formation have been mined (Clark and Hawley, 1968, p. 11). The Nugget Bench High Channel cuts down through the Tertiary formations into the underlying Mesozoic argillite (KJs) exposing the Tertiary conglomerate/white quartz breccia deposits. The channel slopes away from present drainage direction and bedrock drains have been cut to Nugget Creek where it has been mined for 1000 feet along a northeast-southwest trend across Nugget Creek (C.C. Hawley and Associates, Inc.,1978). The channel can be projected magnetically for 400 feet beyond the mined section (C.C. Hawley and Associates, Inc., 1978). The gold fineness ranges from 860 to 864 and averages 861 (Clark and Hawley, 1968). C.C. Hawley and Associates, Inc. (1978) report that as much as 30,000 ounces of placer gold may have been produced from the Nugget Bench deposits. In late 1907 grades were about $3 per bedrock foot. Hawley and Clark (1973, p. A6) note that the highest grade lode deposits in Yentna district are located at the Nugget Creek, the Colby (TL037), Bird (TL040) prospects. Glaciofluvial deposits similar to Nugget Creek can be found on Windy Creek (TL027) and Bird Creek (TL040). Older Tertiary conglomeratic (white quartz breccia, Clark and Hawley, 1968) units probably represent southwest flowing drainages similar to those in Thunder (TL032, 058), Falls (TL030), Dollar (TL031) and Willow (TL042) Creeks. Gold was reconcentrated from these older Tertiary channels into the modern Cache Creek drainage (C.C. Hawley and Associates, Inc., 1978). Also see Cache Creek (TL029).
Workings: Nugget Bench High Channel has been mined by conventional placer methods for 1000 feet along a northeast-southwest trend across Nugget Creek.
Age: Pleistocene and Tertiary (Clark and Hawley,1968).
Alteration: Argillic alteration is locally associated with the white quartz conglomerate (Clark and Hawley, 1968).
Production: C.C. Hawley and Associates, Inc. (1978) report that as much as 30,000 ounces of gold may have been produced from these deposits. In late 1907 grades were about $3 per bedrock foot.

Commodities (Major) - Au; (Minor) - Sn, W
Development Status: Yes
Deposit Model: Placer Au-PGE (Cox and Singer, 1986; model 39a).

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Link to USGS - Alaska:	TL035

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References