Tanner Prospect, Nome Mining District, Nome Census Area, Alaska, USAi

Regional Level Types
Tanner Prospect	Prospect
Nome Mining District	Mining District
Nome Census Area	Census Area
Alaska	State
USA	Country

The site has been selected by Bering Straits Native Corporation of Nome.
Location: The Tanner prospect is in the canyon of Steep Creek, a tributary to Goldbottom Creek; it is at an elevation of about 650 feet, 0.9 mile south of Mount Distin. It is about 4,500 feet north-northeast of the junction of the road up Goldbottom Creek and a jeep trail that leads to this prospect and the McDuffee prospect (NM092). The Tanner prospect is locality 18 of Hummel (1962 [MF 248]) and is included with locality 23 of Cobb (1972 [MF 463], 1978 [OFR 78-93]).
Geology: The Tanner prospect is in the sheared contact zone between massive marble and underlying mica schist. Schistosity strikes east-west and dips 20 to 40 degrees to the north. The marble is locally stained yellow-brown and may contain some secondary ankerite or dolomite. A pale-green mica, possibly chrome-bearing, occurs in the ankeritic (?) zone. Boudins of stibnite occur in schistose marble within a few feet of the overlying massive marble. The maximum thickness reported for the stibnite masses was 6 inches (Anderson, 1947, p. 4). Stibnite-bearing material was hand picked, and specimens as much as 5 inches across are stockpiled at the site. It is not known if any material was shipped. Native gold can be panned from the stibnite-bearing zone. The contact zone between schist and marble is exposed along Steep Creek. Immediately above the mineralized contact zone, a near-vertical, east-northeast-striking fault, downthrown to the north, contains crystalline calcite nearly 1-foot thick. Another fault with calcite veins is exposed in the Steep Creek canyon about 400 feet upstream from the Tanner prospect. The calcite veins are parallel to the gold-bearing quartz vein of the McDuffee prospect (NM092) about 500 feet downstream from the Tanner prospect. Kennecott Exploration Company drilled a reverse-circulation hole into the marble-schist contact zone near the Tanner prospect in 1995. The drill hole intersected a mineralized interval about 50 feet thick near the base of the marble. The 50-foot zone contained more than 0.05 ounce of gold per ton and a had a maximum 5-foot intercept of greater than 0.10 ounce of gold per ton. The marble at the Tanner prospect is probably in the younger part of the Nome Group, which has Proterozoic to early Paleozoic protoliths (Till and Dumoulin, 1994). The Nome Group underwent regional blueschist facies metamorphism in the Late Jurassic or Early Cretaceous (Sainsbury, Coleman, and Kachadoorian, 1970; Forbes and others, 1984; Thurston, 1985; Armstrong and others, 1986; Hannula and McWilliams, 1995). The blueschist facies rocks were recrystallized to greenschist facies or higher metamorphic grades in conjunction with regional extension, crustal melting, and magmatism in the mid-Cretaceous (Hudson and Arth, 1983; Miller and Hudson, 1991; Miller and others, 1992; Dumitru and others, 1995; Hannula and others, 1995; Hudson, 1994; Amato and others, 1994; Amato and Wright, 1997, 1998). Lode gold-antimony mineralization on Seward Peninsula is mostly related to the higher temperature metamorphism in the mid-Cretaceous (Apodoca, 1994; Ford, 1993 [thesis]; Ford and Snee, 1996; Goldfarb and others, 1997).
Workings: Prospecting prior to 1947 identified an essentially stratabound zone that contains native gold and stibnite in the basal schistose zone of a massive marble unit. Subsequently prospectors found and probably mined small quantities of native gold from this zone. In 1995, Kennecott Exploration Company drilled one reverse-circulation hole into the schist-marble contact zone to test it near crosscutting faults that contain calcite veins in marble. The contact zone was appreciably mineralized for about 50 feet, with a maximum 5-foot intercept of more than 0.10 ounce of gold per ton.
Age: Probably mid-Cretaceous or younger; appears to postdate regional metamorphism of mid-Cretaceous age.
Alteration: Development of ankerite (?) and pale-green mica .
Production: Stibnite was mined and stockpiled at the site. Small amounts of gold have been produced at the site from the schistose zone and from adjacent alluvium.

Commodities (Major) - Au, Sb
Development Status: Undetermined
Deposit Model: Massive stibnite lenses and disseminated gold-bearing mineralization in calcareo

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Link to USGS - Alaska:	NM091

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References