|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||The location corner of the Highway claim (Cobb, 1980 [OFR 80-363]) was reported by Reed (1933, p. 284) to be on the northwest ridge of Bald Mountain at an elevation of 4600 feet. He also reported other mineralization in the same area 'near the northwest base of Bald Mountain and above the east side of the Thorofare River.' For this record, the approximately located site represents mineral deposits on the northwest side of Bald Mountain. The Highway claim is number 41 of Cobb (1972 [MF 366]).|
The northwest flank of Bald Mountain is underlain by Paleozoic, calcareous sedimentary rocks cut by numerous sills of mid-Tertiary porphyritic granodiorite. The mountain is about 1/2 mile north of the main east-west Contact fault of the Mt. Eielson district. The main granodiorite intrusion forms a small, wedge-shaped mass north of the fault (Reed, 1933, plate 22).The Highway claim was prospected by two small pits that exposed a sphalerite-bearing deposit. Reed (1933, p. 284) stated that the northwest base of Bald Mountain, including the area of the Highway claim, is appreciably mineralized. The mineralization is Oligocene, roughly contemporaneous with the Eocene or Oligocene emplacement age of the granodiorite (Reed and Lanphere, 1974; Decker and Gilbert, 1978; Cole, 1998).
|Geologic map unit||(-150.245256039155, 63.3847097647539)|
|Mineral deposit model||Replacement deposit or zinc-bearing skarn (Cox and Singer, 1986; models 19a, 18c).|
|Mineral deposit model number||18c, 19a|
|Age of mineralization||The mineralization is Oligocene, roughly contemporaneous with the Eocene or Oligocene emplacement age of the granodiorite (Reed and Lanphere, 1974; Decker and Gilbert, 1978; Cole, 1998).|
|Workings or exploration||The area was prospected by Ben Cleary around 1931. Cleary excavated small pits that disclosed sphalerite. There apparently has been no further exploration of the deposit.|
|Indication of production||None|
Additional commentsThe site is in Denali National Park and Preserve.
|MRDS Number||A011222; A011257|
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.
Decker, J. E., and Gilbert, W. G., 1978, The Mt. Galen volcanics-A new middle Tertiary volcanic formation in central Alaska Range: Alaska Division of Geological and Geophysical Surveys Geological Report 59, 11 p.
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||12/15/2000|