Rock Glacier Occurrence, Yukon-Koyukuk Census Area, Alaska, USAi

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

Similar to Rat Fork-Headwall and Rat Fork-Base prospects (MG058; MG059) in McGrath B-2 quadrangle.
Location: The Rock Glacier occurrence is located in the headwall of an unnamed stream valley above an active rock glacier at an elevation of approximately 4,600 feet (1,402 m) in the SE1/4 sec. 8, T. 26 N., R. 26 W., of the Seward Meridian. The location is based on descriptions provided in Gilbert and others (1990). The reporter visited the site in 1984.
Geology: Pyrite-rich gossan zones were noted by Gilbert and others (1990) in a composite dike swarm, andesitic flows, and lappilli tuffs within the Windy Fork volcanic complex (Bundtzen, Harris, and Gilbert, 1997). Pyrite and pyrrhotite, which locally comprise up to 50 percent of the gossan-rich zones, are accompanied by carbonates, chlorite, epidote, and quartz. Individual gossan bodies are irregular in dimension, and reach maximum lengths of 40 meters Gangue mineralogy suggests formation by introduction of metasomatic fluids; i.e., skarns. Malachite staining was observed in some of the fractured hornfels in the gossan zones. No assay data is available for the Rock Glacier occurrence.
Workings: No assay data is available for the Rock Glacier occurrence.
Age: K-Ar age of 37.9 Ma published by Gilbert and others (1990).
Alteration: Propylitization.
Reserves: None.

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

Other Databases

Link to USGS - Alaska:	MG038

Other Regions, Features and Areas containing this locality

References