|Quadrangle map, 1:250,000-scale||NB|
|Quadrangle map, 1:63,360-scale||A-2|
|Nearby scientific data||Find additional scientific data near this location|
|Location and accuracy||This prospect is on lower Bonanza Creek about 2,000 feet upstream of its mouth. The site is in the SE1/4 of section 35, T. 4 N., R. 19 E. of the Copper River Meridian. This is locality 42 of Richter and others (1975) and the site is included in National Park Service locality WRST-62 (unpublished data). Cobb and Richter (1980) included this prospect under the name 'Erie'. It is located to within a few hundred feet.|
Geologic descriptionAt this prospect, Cretaceous volcanic and volcaniclastic rocks contain disseminated pyrite; the rocks are locally cut by pyrite-bearing dikes (Moffit, 1943; Richter and Jones, 1973). Small pyrite and quartz veins in volcanic rock and in a dike that strikes N 20 W and dips 75 N contain free gold and galena with up to 22 ounces silver per ton (Capps, 1916). A grab sample of massive, green fragmental volcanic rock contained 1,500 parts per million (ppm) copper and 500 ppm lead (Richter and Matson, 1970 [OFR 70-275]). Short adits have been driven to explore this prospect. This mineralized zone is on the southeast flank of Gold Hill, where intrusive rocks of the Chisana pluton intrude volcanic rocks of the Cretaceous, Chisana Formation.
|Geologic map unit||(-141.869530057819, 62.0805377314687)|
|Mineral deposit model||Polymetallic veins? (Cox and Singer,1986; model 22c)|
|Mineral deposit model number||22c?|
|Age of mineralization||Mid-Cretaceous? The deposit may be related to emplacement of the Chisana pluton which has a K/Ar age of 110 +/- 3.0 Ma (Richter, Lanphere, and Matson, 1975).|
|Alteration of deposit||Disseminated pyrite and quartz-sulfide veining. Oxidation has produced iron-staining.|
|Workings or exploration||This altered and mineralized zone has been explored by surface prospecting and short adits.|
|Indication of production||Undetermined|
Additional commentsThe prospect is in the Wrangell-St. Elias National Preserve.
Capps, S.R., 1916, The Chisana-White River district, Alaska: U.S. Geological Survey Bulletin 630, 130 p.
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.
Moffit, F.H., and Wayland, R.G., 1943, Geology of the Nutzotin Mountains, Alaska, with a section on The igneous rocks: U.S. Geological Survey Bulletin 933-B, p. 103-199.
Richter, D.H., and Jones, D.L., 1973, Reconnaissance geologic map of the Nabesna A-2 quadrangle, Alaska: U.S. Geological Survey Miscellaneous Investigations Series Map I-749, 1 sheet, scale 1:63,360.
Richter, D.H., and Matson, N.A., Jr., 1970, Geochemical data from the Nabesna A-2 quadrangle, Alaska: U.S. Geological Survey Open-File Report 70-275, 12 p., 1 sheet, scale 1:63,360.
Richter, D.H., Lanphere, M.A., and Matson, N.A., Jr., 1975, Granite plutonism and metamorphism, eeastern Alaska Range, Alaska: Geological Society of American Bulletin, v. 86, p. 819-820.
|Reporters||Travis L. Hudson (Applied Geology)|
|Last report date||11/24/2002|