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Unnamed (on ridge between Chistochina Glacier and the glacier near the head of West Fork Chistochina River)

Occurrence, Inactive

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Commodities and mineralogy

Main commodities Fe
Ore minerals hematite; magnetite
Gangue minerals quartz

Geographic location

Quadrangle map, 1:250,000-scale MH
Quadrangle map, 1:63,360-scale A-2
Latitude 63.1733
Longitude -144.9534
Nearby scientific data Find additional scientific data near this location
Location and accuracy The occurrence is about 2.5 miles north of the confluence of the Chistochina River and the West Fork Chistochina Rivers at an elevation of about 5,600 feet. It is in the NW1/4 section 19, T. 20 S., R. 15 E., Fairbanks Meridian. It corresponds to locality 11 on figure 2 of Rose (1967) and locality 3 on figure 6 of Cobb (1979 [OFR 79-238]). The location is probably accurate to within 0.1 mile.

Geologic setting

Geologic description

The rocks at the site consist of andesite to dacite agglomerate, flows, and tuff of the Chisna Formation of Pennsylvanian to Permian (?) age (Rose, 1967). The volcanic rocks probably correlate with Tetelna Volcanics of Pennsylvanian age or Slana Spur Formation of Pennsylvanian to Permian age (Richter and Dutro, 1975).
Specular hematite and hematite with quartz and some magnetite occur in float and in a banded-hematite outcrop exposed for about 15 feet. The float occurrences are scattered along a north-trending zone about 300 feet long. The deposit appears to be a replacement of the volcanic rocks (Rose, 1967). It is on the west flank of the same Mesozoic quartz monzonite dike as occurrences MH279 and MH281.
Geologic map unit (-144.955623071216, 63.1728993297315)
Mineral deposit model Fe skarn? (Cox and Singer, 1986; model 18d?).
Mineral deposit model number 18d?
Age of mineralization Possibly related to Pennsylvanian to Permian volcanic rocks or the Mesozoic quartz monzonite.
Alteration of deposit Replacement of intermediate volcanic rocks by quartz, hematite, and magnetite.

Production and reserves

Workings or exploration Geologic mapping.
Indication of production None

References

References

Cobb, E.H., 1979, Summary of references to mineral occurrences (other than mineral fuels and construction materials) in the Mount Hayes quadrangle, Alaska: U.S. Geological Survey Open-File Report 79-238, 140 p.
Richter, D.H., and Dutro, J.T., Jr., 1975, Revision of the type Mankomen Formation (Pennsylvanian and Permian), Eagle Creek area, eastern Alaska Range, Alaska: U.S. Geological Survey Bulletin 1395-B, p. B1-B25.
Rose, A.W., 1967, Geology of the upper Chistochina River area, Mount Hayes quadrangle, Alaska: Alaska Division of Mines and Minerals Geologic Report 28, 41 p., 2 maps, scale 1:40,000.
Reporters W.T. Ellis (Alaska Earth Sciences), C.C. Hawley (Hawley Resource Group), and W.J. Nokleberg (USGS)
Last report date 6/29/2003