|Quadrangle map, 1:250,000-scale||TL|
|Quadrangle map, 1:63,360-scale||C-4|
|Nearby scientific data||Find additional scientific data near this location|
|Location and accuracy||Reed and others (1978, locality 24 and 25) locate this occurrence in the southwest quarter of Section 25, T. 31 N., R. 14 W., of the Seward Meridian on a nunatak within the Dall Glacier in Denali National Park and Preserve.|
Geologic descriptionReed and others (1978) describe this coincident mineral occurrence of a quartz-molybdenite vein cutting Paleozoic and (or) Mesozoic (Reed and Nelson, 1980) or Late Cretaceous/early Tertiary (?) (Foley and others, 1997) chromite-bearing dunite. The quartz-molybdenite vein is 20 to 50 centimeters thick, with as much as 20 volume percent molybdenite as foliated tabular crystals up to 5 centimeters in diameter. It is probably genetically related to the middle Tertiary (38 m.y.) granodiorite of Mt. Foraker (Reed and Nelson, 1980) and may indicate porphyry molybdenum/copper potential (Reed and others, 1978). The dunite is part of the Dall trend described in TL002, 003, TL009 - 012, and TL055.
|Geologic map unit||(-151.828243681434, 62.7444546229496)|
|Mineral deposit model||Podiform chromite (Cox and Singer, 1986; model 8a); vein is possibly related to Porphyry Cu-Mo (Cox and Singer, 1986; model 21a) or Porphyry Mo, Low-F (Cox and Singer, 1986; model 21b).|
|Mineral deposit model number||8a and 21a or 21b|
|Age of mineralization||Mesozoic and (or) Paleozoic (Reed and Nelson, 1980) or Late Cretaceous/early Tertiary (?) (Foley and others, 1997) chromite-bearing dunite. Tertiary; vein hosted quartz-molybdenite presumed to be related to the middle Tertiary (38 m.y.) granodiorite (Reed and others, 1978).|
|Workings or exploration||Reconnaissance mapping, stream silt and rock sampling are all that have been done here. Chromium content of 0.7 to 1% from typical dunite is given in Reed and others (1978). The average of 3 microprobe analyses of one sample was 58.4% Cr2O3, 21.1% FeO, 8.9% MgO, and 9.7% Al2O3.|
|Indication of production||None|
Additional commentsThis prospect is located within Denali National Park and Preserve.
Foley, J.Y., Light, T.D., Nelson, S.W., and Harris, R.A., 1997, Mineral occurrences associated with mafic-ultramafic and related alkaline complexes in Alaska, in Goldfarb, R.J., and Miller, L.D., eds., Mineral Deposits of Alaska: Economic Geology Monograph 9, p. 396-449.
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.
Reed, B.L., and Nelson, S.W., 1980, Geologic map of the Talkeetna quadrangle: U.S. Geological Survey Miscellaneous Investigations Map I-1174, 1 sheet, scale 1:250,000.
|Reporters||Madelyn A. Millholland (Millholland & Associates)|
|Last report date||8/10/1998|