Unnamed (on the Yentna Glacier)

Occurrence, Inactive

Commodities and mineralogy

Main commodities Cu; Mo
Ore minerals chalcopyrite; molybdenite; pyrite

Geographic location

Quadrangle map, 1:250,000-scale TL
Quadrangle map, 1:63,360-scale C-4
Latitude 62.707
Longitude -151.716
Nearby scientific data Find additional scientific data near this location
Location and accuracy Reed and others (1978, locality 28) show the location of mineralized cobbles in moraine along the west limit of the Yentna Glacier in the northeast quarter of Section 9, T. 30 N., R. 13 W., of the Seward Meridian within Denali National Park and Preserve. This site is located approximately two and a half miles south-southwest of TL056.

Geologic setting

Geologic description

Granodiorite cobbles with fractures containing molybdenite, pyrite and minor chalcopyrite found at this site on the Yentna Glacier moraine are probably derived from the middle Tertiary (38 m.y.) Foraker pluton (Reed and others, 1978; Reed and Nelson, 1980). Minor malachite staining in Paleozoic sedimentary rocks is noted near the pluton contact. Further information that supports the Foraker pluton as the source of the float is anomalous copper (300 to 700 ppm) in a stream sediment and glacial debris sample taken from a site on the Yentna Glacier which drains the Foraker pluton (Curtin, Karlson, O'Leary, Day, and McDougal, 1978).
Use of a porphyry for this occurrence is not to suggest that a cobble with mineralized fractures is in itself a porphyry deposit. Instead, its possible affiliation with the Mt. Foraker pluton suggests that these veins could be a distal feature related to a concealed porphyry system. Not enough data exists to quantify this determination (Reed and others, 1978).
This site is located approximately two and a half miles south-southwest of TL056 on the Yentna Glacier moraine.
Geologic map unit (-151.718252867481, 62.7064577845776)
Mineral deposit model 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 21a or 21b
Age of mineralization Middle Tertiary; mineralization is interpreted to be related to the 38 m.y. Foraker pluton (Reed and Nelson, 1980).

Production and reserves

Workings or exploration Reconnaissance mapping and rock sampling are all that have been done here (Reed and Nelson, 1980). Minor malachite staining in Paleozoic sedimentary rocks is noted near the pluton contact. Further information that supports the Foraker pluton as the source of the float is anomalous copper (300 to 700 ppm) in a stream sediment and glacial debris sample taken from a site on the Yentna Glacier which drains the Foraker pluton (Curtin, Karlson, O'Leary, Day, and McDougal, 1978).
Indication of production None

Additional comments

This site is within Denali National Park and Preserve.

References