Willow Creek; Big Willow Creek; Little Willow Creek; Wilson Creek; Hansen; Jennings; Rice; Rocky Gulch; Slate Gulch; Snow Gulch Mine, Yentna Mining District, Matanuska-Susitna Borough, Alaska, USAi

Regional Level Types
Willow Creek; Big Willow Creek; Little Willow Creek; Wilson Creek; Hansen; Jennings; Rice; Rocky Gulch; Slate Gulch; Snow Gulch Mine	Mine
Yentna Mining District	Mining District
Matanuska-Susitna Borough	Borough
Alaska	State
USA	Country

Similar deposits occur on Thunder Creek (TL032, 058) and Dollar Creek (TL031), both tributaries to Cache Creek. See also Peters Creek (TL045). The structural grain of the area is defined by major northeast-trending, steeply dipping faults (Hawley and Clark, 1968).
Location: C.C. Hawley and Associates, Inc. (1978, Fig. 4.2-B(3)) show this locality about one-and- one-half miles upstream north of the confluence of Little Writer Creek with Willow Creek, a tributary to Cottonwood Creek in the northeast quarter of Section 30, T. 29 N., R. 8 W., of the Seward Meridian.
Geology: Willow Creek drains across the contact between Mesozoic slate and graywacke (KJs) and Tertiary strata of the Sterling (?) (Tcp) and Tyonek (?) (Tts) Formations of the Kenai Group (Reed and Nelson, 1980). The placer gold deposits within Willow Creek are mostly hosted in Pleistocene stream gravels. C.C. Hawley and Associates, Inc. (1978) describe a Tertiary (?) white quartz conglomerate at the head of the main placer pay streak near the contact of the Tertiary strata on the Mesozoic strata. The conglomerate is a limonite- cemented, angular quartz grit consisting of sand- to pebble-size fragments. Hydrothermally altered intrusive rocks with associated quartz veins are found within a fault zone in the Willow Creek drainage and could represent a source for some of the placer gold (Capps, 1925; C.C. Hawley and Associates, Inc., 1978). Mertie (1919) reports 20% tin in concentrates, equivalent to 25% cassiterite from Willow Creek. Gold, ilmenite, magnetite, platinum, pyrite, garnet, quartz, and zircon are also reported in the concentrates. He believed that the gold and cassiterite were derived from mineralized bedrock within the drainage. The gold is fine with an average fineness of 870, as reported by Clark and Hawley (1968). The white quartz conglomerate placers (e.g. Willow Creek, Thunder Creek, TL032, 058, Dollar Creek, TL031) represent the oldest placers in the Cache Creek area. Capps (1925) describes the white quartz conglomerate as the basal unit of the Tertiary Kenai Formation. However Clark and Hawley (1968) suggest that the white quartz conglomerate is older and that the Kenai Group was deposited on it. They believe the auriferous conglomerate is near its original source in part because the characteristics of the gold show a common source that has not moved far or has not been reworked. Further, they indicate that the conglomerate is a product of shearing and weathering in situ of argillic altered, auriferous Tertiary quartz porphyry intrusive rocks and associated quartz veins that were emplaced along northeast, high angle normal faults. The lineaments in Dutch and Cache Creeks represent two of these faults. Tributaries to Willow Creek which have been mined include: Ruby Creek (TL041), Gopher Creek (TL074), Falls Gulch, Rocky Gulch, Slate Gulch, and Snow Gulch. Also see Peters Creek (TL045).
Workings: Garrett (1998) reports current placer mining by mechanical cut-and-fill techniques and feed hopper, trommel and sluice processing. Exploration has been conducted by test drilling and pits. According to Garrett (1998) Willow Creek and its tributatries were mined as early as 1906. He describes the mining history of the area as follows: In 1911 pick and shovel and hydraulic methods were used. Gold pieces weighing one-half ounce were common. In the mid-30's about 2000 ounces of gold were produced from Little Willow Creek. Owners Frank and Helena Jenkins conducted hydraulic and hand-mining operations until 1939, when they and two other persons were murdered on the property. Exploration and mining was sporadic until 1979, when 4920 ounces of gold were recovered from a bench on the north side of Willow Creek. Mining has continued in this area until the present.
Age: Tertiary and Pleistocene (Clark and Hawley,1968).
Alteration: Argillic alteration along fault zones (Clark and Hawley, 1968).

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

Other Databases

Link to USGS - Alaska:	TL042

Other Regions, Features and Areas containing this locality

References