|Quadrangle map, 1:250,000-scale||MG|
|Quadrangle map, 1:63,360-scale||B-3|
|Nearby scientific data||Find additional scientific data near this location|
|Location and accuracy||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.|
Geologic descriptionPyrite-rich gossan zones were noted by Gilbert and others (1990) in a composite dike swarm, andesitic flows, and lapilli 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.
|Geologic map unit||(-154.130222546653, 62.3533806459992)|
|Mineral deposit model||Copper skarn? (Cox and Singer, 1986; model 18b?).|
|Mineral deposit model number||18b?|
|Age of mineralization||K-Ar age of 37.9 Ma published by Gilbert and others (1990).|
|Alteration of deposit||Propylitization.|
|Workings or exploration||No assay data is available for the Rock Glacier occurrence.|
|Indication of production||None|
Additional commentsSimilar to Rat Fork-Headwall and Rat Fork-Base prospects (MG058; MG059) in McGrath B-2 quadrangle.
Bundtzen, T.K., Harris, E.E., and Gilbert, W.G., 1997, Geologic Map of the eastern McGrath quadrangle, Alaska: Alaska Division of Geological and Geophysical Surveys Report of Investigations 97-14, 34 p., 1 sheet, scale 1:125,000.
|Reporters||T.K. Bundtzen (Pacific Rim Geological Consulting)|
|Last report date||12/4/1998|