Twin Creek; Big Boulder Creek; Little Boulder Creek; John Creek; Notobac Creek Mine, Yentna Mining District, Matanuska-Susitna Borough, Alaska, USAi

Regional Level Types
Twin Creek; Big Boulder Creek; Little Boulder Creek; John Creek; Notobac Creek Mine	Mine
Yentna Mining District	Mining District
Matanuska-Susitna Borough	Borough
Alaska	State
USA	Country

Some data for Twin and Mills (TL059) Creeks are combined in the literature. Cobb and Reed (1980) indicate that Notobac Creek is probably another name for Twin Creeks or for a tributary to Twin Creek and that John(s) Creek is a small, steep-sided gulch tributary to Twin Creek that is cut in the Tertiary Kenai Group sediments. Capps (1913) reports that Johns Creek saw small production for a few years during the first quarter of the 20th century.
Location: The location given is the center of a placered area which extends for about 3000 feet upstream and about one mile downstream in Sections 16, and 21, T. 26 N., R. 12 W., of the Seward Meridian. John, Big Boulder, and Little Boulder Creeks are headwater tributaries to Twin Creek. Clark and Cobb (1972) show this property as locality 17 on MF-369. It is also shown by Reed and others (1978) as locality 68 and by MacKevett and Holloway (1977) as locality 13.
Geology: The Twin Creek area is a major contributor to the gold production in the Yentna district. A productive placer area covers approximately 36 square miles, including streams draining Fairview Mountain, with the main area of interest generally northeast and southeast of the summit of Fairview Mountain. No lode occurrences have been found in the placer deposits near Fairview Mountain/Collinsville (Hawley and Clark, 1978). C.C. Hawley and Associates, Inc. (1978) describe this placer occurrence as Pleistocene auriferous gravels with the main gold-bearing section lying on a brown to orange-brown clay bed about 15 feet deep, consisting of about 5 feet of quartz-bearing gravel. The gravel is underlain by the continentally derived Tertiary sedimentary rocks of the Kenai Group (Reed and Nelson, 1980). Twin Creek has been mined nearly the entire distance from the confluence with Mills Creek up into headwater tributaries; probable reserves are largely covered by old tailings. Platinum minerals have been reported from the area (0.78 oz/ton), although the exact location was not specified. Hawley, C.C.and Associates, Inc. (1978) show possible reserve of 752,000 cubic yards on Figure 4.2-B(4). Some data for Twin and Mills (TL059) Creeks are combined in the literature. Cobb and Reed (1980) indicate that Notobac Creek is probably another name for Twin Creek or for a tributary to Twin Creek and that John Creek is a small, steep-sided gulch tributary to Twin Creek that is cut in the Tertiary Kenai Group sediments. Capps (1913) reports that Johns Creek saw small production for a few years during the first quarter of the 20th century. Also see Pass Creek (TL024).
Workings: Mined in a drag line washing plant and sluice box (C.C.Hawley and Associates, Inc., 1978).
Age: Pleistocene and possibly Tertiary.
Production: One sample of about 10 lb/yard (probably cubic yards) of black sand contained 0.78 oz/ton platinum metals (C.C. Hawley and Associates, Inc., 1978). Capps (1913) reports that Johns Creek saw small production for a few years during the first quarter of the 20th century.
Reserves: C.C.Hawley and Associates, Inc. (1978) show possible reserve of 752,000 cubic yards on Figure 4.2-B(4); probable reserves are largely covered by old tailings.

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

Other Databases

Link to USGS - Alaska:	TL026

Other Regions, Features and Areas containing this locality

References