Unnamed (on a tributary to upper Pirate Creek)

Occurrence, Inactive

Commodities and mineralogy

Main commodities Fe
Other commodities Cu; Zn
Ore minerals chalcopyrite; copper carbonate; iron oxide; magnetite; sphalerite

Geographic location

Quadrangle map, 1:250,000-scale MM
Quadrangle map, 1:63,360-scale B-1
Latitude 63.3308
Longitude -150.4805
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 setting

Geologic description

This 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.

Production and reserves

Workings or exploration The deposit was discovered by W. J. Shannon in about 1930.
Indication of production None

Additional comments

The occurrence is in Denali National Park and Preserve.

References

MRDS Number A011286

References

Reporters C.C. Hawley
Last report date 10/23/2000