Lone Occurrence, Yukon-Koyukuk Census Area, Alaska, USAi

Regional Level Types
Lone Occurrence	Occurrence
Yukon-Koyukuk Census Area	Census Area
Alaska	State
USA	Country

See Nixon Fork and Whirlwind skarn deposits (MD040, MD064, MD062) in Medfra quadrangle.
Location: The Lone occurrence is located about 0.5 miles south of VABM Lone at an elevation of 2,500 feet (762 m) in the SE1/4 sec. 18, T. 28 N., R. 29 W., of the Seward Meridian. The reporter visited the site in 1982 and 1992.
Geology: A leucocratic, biotite granite radiometrically dated at 71.0 Ma (Solie and others, 1991) intrudes Lower Ordovician deepwater carbonate of the Nixon Fork Subterrane (Decker and others, 1994). The intrusion created a 760 meter wide thermal aureole, which locally has formed hornfels and small, discontinuous pods of skarn. The skarns at the Lone occurrence consist of magnetite, epidote, undetermined amphibole, and weakly disseminated pyrite and chalcopyrite. The magnetite bearing skarns crop out over a 10 meter by 12 meter area (Bundtzen, Harris, and Gilbert, 1997). Selected analyses (2) of the skarn zones at the Lone occurrence contain up to 0.50 percent copper, 35.00 percent iron, and 4.7 grams/tonne silver.
Workings: Selected analyses from surface samples at the Lone occurrence contain up to 0.50 percent copper, 35.00 percent iron, and 4.7 g/tonne silver.
Age: Inferred to be related to the 71.0 Ma granite intrusion (Solie and others, 1991).
Alteration: Epidote.
Reserves: None.

Commodities (Major) - Cu, Fe; (Minor) - Ag
Development Status: No
Deposit Model: Copper-iron skarns (Cox and Singer, 1986; model 18b).

Other Databases

Link to USGS - Alaska:	MG012

Other Regions, Features and Areas containing this locality

References