|Quadrangle map, 1:250,000-scale||MH|
|Quadrangle map, 1:63,360-scale||A-3|
|Nearby scientific data||Find additional scientific data near this location|
|Location and accuracy||This occurrence is at an elevation 6,400 feet on a sharp ridge east of Gakona Glacier. It is about 5.3 miles north-northeast of the center of Devils Lake in the terminus of Gakona Glacier and near the northeast corner of section 32, T. 19 S., R. 14 E.|
Rose (1967) identified gabbro, pyroxenite, peridotite, and dunite here. Nokleberg and others (1992 [MF]; 1992 [Open-File]) included them in their 'ultramafic and associated rocks' unit that occur as klippen above thrust faults. The ultramafic rocks are thrust over volcanic and sedimentary rocks of the Pennsylvanian and Permian, Slana Spur Formation. Nokleberg and others suggest that an Early Cretaceous (123-126 Ma) age from the ultramafic unit probably represents regional metamorphism. However, Bittenbender and others (2007) suggest that Early Cretaceous ages on biotite and hornblende in similar rocks indicates primary crystallization.Bittenbender and others (2007) identified several mineralized occurrences along the ridge in this vicinity. The rocks at the mineralized occurrences are mainly gabbro, pyroxenite and and peridotite that commonly contains patches of fresh biotite with minor tremolite and calcite (Bittenbender and others, 2007). The rocks are cut by thin, locally altered, pegmatitic gabbro dikes. The dikes contain 2-3 percent, chalcopyrite, bornite, and pyrrhotite, with minor digenite, covellite, and pyrite. Magnetite is a common accessory mineral and locally comprises up to 10 percent of the rock. At one location, 5-6 square feet in area, Bittenbender and others (2007) collected 5 iron-stained samples. The best contained 29 parts per billion (ppb) gold, 3.9 parts per million (ppm) silver, 363 ppb platinum, 72 ppb palladium, and 7,570 ppm copper. A 5.3-foot sample contained 17 ppb gold, 1.1 ppm silver, 258 ppb platinum, 68 ppb palladium, and 3.320 ppm copper. Other iron-stained occurrences in the area may be up to 100 feet long and 50 feet wide (Rose, 1967).
|Geologic map unit||(-145.101423529898, 63.230397296281)|
|Mineral deposit model||Disseminated copper-PGE minerals in thin gabbro dikes that cut mafic and ultramafic rocks.|
|Age of mineralization||Unclear, possibly Early Cretaceous but may be older.|
|Alteration of deposit||Rocks are generally fresh but thin mineralized gabbro dikes are locally altered.|
|Workings or exploration||Only limited surface sampling by state and federal agencies.|
|Indication of production||None|
Bittenbender, P.E., Bean, K.W., Kurtak, J.M., and Deininger, James Jr., 2007, Mineral assessment of the Delta River Mining District area, east-central, Alaska: U.S. Bureau of Land Management, Alaska Technical Report 57, 675 p.
Nokleberg, W. J., Aleinikoff, J. N., Dutro, J. T., Lanphere, M. A., Silberling, N. J., Silva, S. R., Smith, T. E., and Turner, D. L., 1992, Map, tables, and summary of fossil and isotopic age data, Mount Hayes Quadrangle, eastern Alaska range, Alaska: U.S. Geological Survey Miscellaneous Field Studies Map MF-1996-D, 43 p., 1 sheet, scale 1:250,000.
Nokleberg, W.J., Aleinikoff, J. N., Lange, I. M.; Silva, S. R., Miyaoka, R. T., Schwab, C. E., Zehner, R. E., Bond, G. C., Richter, D. H., Smith, T. E., and Stout, J. H., 1992, Preliminary geologic map of the Mount Hayes quadrangle, eastern Alaska Range, Alaska: U.S. Geological Survey Open-File Report 92-594, 39 p. 1 sheet, scale 1:250,000.
Nokleberg, W.J., Lange, I.M., Roback, R.C., Yeend, Warren, and Silva, S.R., 1991, Map showing locations of metalliferous lode and placer mineral occurrences, mineral deposits, prospects, and mines, Mount Hayes quadrangle, eastern Alaska Range, Alaska: U.S. Geological Survey Miscellaneous Field Studies Map MF-1996-C, 42 p., 1 sheet, scale 1:250,000.
|Reporters||W.T. Ellis (Alaska Earth Sciences), C.C. Hawley (Hawley Resource Group), and W.J. Nokleberg (USGS); D.J. Grybeck (Contractor, USGS)|
|Last report date||5/13/2012|