|Quadrangle map, 1:250,000-scale||NB|
|Quadrangle map, 1:63,360-scale||A-4|
|Nearby scientific data||Find additional scientific data near this location|
|Location and accuracy||This prospect is on the lower-west flank of the ridge along the east side of Nabesna Glacier. It is at an elevation of about 3,500 feet, 600 feet east of the glacier, and 4,500 feet northwest of peak 5901. The site is in the SW1/4 of section 22, T. 4 N., R. 14 E. of the Copper River Meridian. This is locality 12 of Richter (1973) and locality 27 of Richter and others (1975). Cobb and Richter (1980) included this prospect under the name 'Nabesna Glacier'. It is located to within a few hundred feet.|
Geologic descriptionAn area 100 feet wide and 300 feet long is strongly hydrothermally altered and cut by abundant quartz-pyrite veins and veinlets (Richter and Matson, 1970 [OFR 70-276]; Richter and others, 1975). Alteration includes silicification, and oxidation has produced abundant iron-oxide staining and some copper staining. The veins contain some galena, sphalerite, and chalcopyrite. A random chip sample across 300 feet of copper-stained and silicified rock contained 300 parts per million (ppm) copper and a channel sample across a 2-foot-wide quartz-pyrite vein contained 0.02 ppm gold, 30 ppm silver, 15,000 ppm copper, 15,000 ppm lead, and more than 10,000 ppm zinc (Richter and Matson, 1970 [OFR 70-276]). The host rock is a buff to gray-green massive volcanic rock, locally brecciated and mineralized, that has quartz eyes up to 0.5 inch in diameter in a fine-grained matrix of quartz, feldspar, and white mica. The deposits occur in upper Paleozoic metavolcanic porphyry and metabasalt flows of the Tetelna Volcanics. Cretaceous and Tertiary granitic plutons and dikes, locally associated with base metal mineralization, intrude these host rocks in many parts of the Nabesna A-4 quadrangle (Richter, 1973).
|Geologic map unit||(-142.838625060322, 62.1135036533552)|
|Mineral deposit model||Polymetallic veins (Cox and Singer, 1986; model 22c)|
|Mineral deposit model number||22c|
|Age of mineralization||Cretaceous or Tertiary? The upper Paleozoic host rocks are locally cut by Cretaceous and Tertiary intrusive rocks associated with base metal mineralization elsewhere in the Nabesna A-4 quadrangle (Richter, 1973).|
|Alteration of deposit||Alteration includes silicification, and oxidation has produced abundant iron-oxide staining and some copper staining.|
|Workings or exploration||Some surface prospecting has probably occurred at the site.|
|Indication of production||None|
Additional commentsThe prospect is in the Wrangell-St. Elias National Preserve.
Cobb, E.H., and Richter, D.H., 1980, Summaries of data on and list of references to metallic and selected nonmetallic mineral deposits in the Nabesna quadrangle, Alaska: U.S. Geological Survey Open-File Report 80-927, 117 p.
Richter, D.H., and Matson, N.A., Jr., 1970, Geochemical data from the Nabesna A-4 quadrangle, Alaska: U.S. Geological Survey Open-File Report 70-276, 14 p., 1 sheet, scale 1:63,360.
|Reporters||Travis L. Hudson (Applied Geology)|
|Last report date||11/24/2002|