Gopher; Gopher Gulch; Gopher Creek; Gopher Cr. Mine, Yentna Mining District, Matanuska-Susitna Borough, Alaska, USAi

Regional Level Types
Gopher; Gopher Gulch; Gopher Creek; Gopher Cr. 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. Also see 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 in the northeast quarter of Section 25, T. 29 N., R. 9 W., of the Seward Meridian at the head of Gopher Gulch about two miles north of the confluence of Little Writer with Willow Creek. Also shown as locality 28 by Clark and Cobb (1972).
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 and the headwater drainages, Gopher and Ruby Gulches, are hosted in Pleistocene stream gravels. At the head of Gopher Gulch, highly argillaceous white quartz congomerate contained about 1500 ounces of angular gold in a 320 by 660 foot cut (C.C. Hawley and Associates, Inc., 1978). Gold is concentrated mainly on bedrock (Cobb and Reed, 1980). Mertie (1919) describes intricately intergrown gold and lead in one specimen from this locality. Mining was conducted on Gopher Gulch as early as 1917 (Garrett, 1998). 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), Willow Creek (TL042); Falls Gulch, Rocky Gulch, Slate Gulch, and Snow Gulch. See also Peters Creek (TL045).
Workings: Hand-mining and (?) hydraulic operations were conducted since 1917 (Garrett, 1998).
Age: Tertiary and Pleistocene (Clark and Hawley,1968).
Alteration: C.C. Hawley and Associates, Inc. (1978) describe argillic alteration of the Tertiary quartz porphyry intrusive rocks.
Production: At the head of Gopher Gulch, highly argillaceous white quartz conglomerate contained about 1500 ounces of angular gold in a 320 by 660 foot cut (C.C. Hawley and Associates, Inc., 1978).

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

Other Databases

Link to USGS - Alaska:	TL074

Other Regions, Features and Areas containing this locality

References