Unnamed (upper East Fork of Clearwater Creek) (ARDF #MM155) Zn

Unnamed (upper East Fork of Clearwater Creek)

Occurrence, Inactive

Commodities and mineralogy

Main commodities	Zn
Other commodities	Ag; Au; Cu; Pb
Ore minerals	chalcopyrite; galena; pyrite; pyrrhotite; sphalerite

Geographic location

Quadrangle map, 1:250,000-scale	MM
Quadrangle map, 1:63,360-scale	B-2
Latitude	63.3114
Longitude	-150.524
Nearby scientific data	Find additional scientific data near this location
Location and accuracy	This occurrence is on the east side of a prominent ridge in the upper part of the East Fork of Clearwater Creek. The ridge lies between two north-flowing tributaries to the East Fork. Its position is known only from a location by Reed (1961) on a 1:250,000-scale map. The occurrence is probably a few hundred feet east of the center of section 36, T. 18 S., R. 16 W., Fairbanks Meridian, between 4000 and 4500 feet elevation. The location is probably correct within one-half mile. A nearby deposit is described in record MM154.

Geologic setting

Geologic description This mineral occurrence is in the Eocene or Oligocene McGonagall pluton (Reed and Lanphere, 1974; Cole, 1998). Reed (1961, explanation on plate 1) described the occurrence only as a mixed sulfide deposit consisting mainly of pyrrhotite and sphalerite, accompanied by lesser amounts of galena, pyrite, and chalcopyrite. The deposit is inferred to be Oligocene, roughly contemporaneous with the Eocene or Oligocene emplacement age of the McGonagall pluton.
Geologic map unit	(-150.526246636052, 63.3108991977588)
Mineral deposit model	Pluton-hosted, polymetallic lode (Cox and Singer, 1986; model 22c).
Mineral deposit model number	22c
Age of mineralization	The deposit is inferred to be Oligocene, roughly contemporaneous with the Eocene or Oligocene emplacement age of the McGonagall pluton (Reed and Lanphere, 1974; Cole, 1998).

Production and reserves

Workings or exploration	The occurrence is known only from a map location. No claims are known to have been filed on it.
Indication of production	None
Additional comments The occurrence is within Denali National Park and Preserve.

References

References 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. 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. Reed, J. C., Jr., 1961, Geology of the Mt. McKinley quadrangle, Alaska: U. S. Geological Survey Bulletin 1108-A, p. A1-A36.
Reporters	C.C. Hawley
Last report date	12/13/2000