|Quadrangle map, 1:250,000-scale||MM|
|Quadrangle map, 1:63,360-scale||B-1|
|Nearby scientific data||Find additional scientific data near this location|
|Location and accuracy||This occurrence is on the west side of a north-flowing tributary of Pirate Creek about a mile west of Muldrow Glacier. It is probably within a few hundred feet of the north end of the section line between sections 29 and 30, T. 18 S., R. 15 W., Fairbanks Meridian. The occurrence is included in the description of the Twin Hills lode (MM168) by Cobb (1972, location 35 [MF 366]; 1980 [OFR 80-363]), and in the description of location 44 by MacKevett and Holloway (1977).|
Geologic descriptionThis occurrence is immediately east of the Twin Hills lode (MM168), in the contact zone of the McGonagall granitic pluton mapped by Reed (1961, plate 1). The deposit consists of replacement veins and disseminations of magnetite in a zone estimated to be 20 to 30 feet wide (Moffit, 1933, p. 324). A small amount of chalcopyrite occurs with the magnetite, and the rocks locally are iron-stained and coated with copper carbonate(?). Sphalerite occurs in a fracture zone about 100 yards north of the magnetite deposit. The deposit probably is middle Tertiary, the approximate age of the emplacement of the Eocene or Oligocene McGonagall pluton (Reed and Lanphere, 1974). The occurrence is one of several in a belt of mineral deposits along the north flank of the McGonagall pluton.
|Geologic map unit||(-150.482747833891, 63.3303007241777)|
|Mineral deposit model||Disseminated and vein-form, polymetallic lodes and contact deposits (Cox and Singer, 1986; model 22c).|
|Mineral deposit model number||22c|
|Age of mineralization||The deposit probably is middle Tertiary, the approximate age of the emplacement of the Eocene or Oligocene McGonagall pluton (Reed and Lanphere, 1974; Cole, 1998).|
|Alteration of deposit||Oxidation of iron and copper minerals.|
|Workings or exploration||The deposit was discovered by W. J. Shannon in about 1930.|
|Indication of production||None|
Additional commentsThe occurrence is in Denali National Park and Preserve.
Cobb, E. H., 1972, Metallic mineral resources map of the Mount McKinley quadrangle, Alaska: U. S. Geological Survey Miscellaneous Field Studies Map MF-366, 1 sheet, scale 1:250,000.
Cobb, E.H., 1980, Summary of references to mineral occurrences (other than mineral fuels and construction materials) in the Mount McKinley quadrangle, Alaska: U. S. Geological Survey Open-File Report 80-363, 150 p.
Cole, R. B., 1998, Early Tertiary post-subduction volcanism and deformation along the north side of the McKinley fault, Alaska [abs]: Geological Society of America. Abstracts with program, v. 30, p. 177.
Cox, D.P., and Singer, D.A., eds., 1986, Mineral deposit models: U.S. Geological Survey Bulletin 1693, 379 p.
MacKevett, E.M., Jr., and Holloway, C.D., 1977, Map showing metalliferous and selected non-metalliferous mineral deposits in the eastern part of southern Alaska: U.S. Geological Survey Open-File Report 77-169-A, 99 p., 1 sheet, scale 1:1,000,000.
Moffit, F.H., 1933, The Kantishna district, in Smith, P.S. and others, Mineral resources of Alaska: report on investigations in 1930, U. S. Geological Survey Bulletin 836, p. 301-338.
Reed, B. L., and Lanphere, M. A., 1974, Offset plutons and history of movement along the McKinley segment of the Denali fault system, Alaska: Geological Society of America Bulletin, v. 85, p. 1883-1892.
|Last report date||10/23/2000|