Unnamed (claims on lower Granite Creek, Mt. Eielson district) (ARDF #MM159) Pb, Zn

Unnamed (claims on lower Granite Creek, Mt. Eielson district)

Prospects, Inactive

Commodities and mineralogy

Main commodities	Pb; Zn
Other commodities	Ag; Cu
Ore minerals	chalcopyrite; galena; pyrite; sphalerite
Gangue minerals	epidote; quartz

Geographic location

Quadrangle map, 1:250,000-scale	MM
Quadrangle map, 1:63,360-scale	B-1
Latitude	63.3997
Longitude	-150.3028
Nearby scientific data	Find additional scientific data near this location
Location and accuracy	The MacKenzie and Mary claims abut each other in lower Granite Creek north of Mt. Eielson. The location is the approximate center of the end line between the claims. This location is at an elevation of about 4000 feet in the SW1/4NE1/4 sec. 31, T. 17 S., R. 14 W., Fairbanks Meridian. The location is accurate to about 500 feet.

Geologic setting

Geologic description The McKenzie and Mary claims are in lower Granite Creek and are mainly covered by talus and alluvial fan deposits. South of the McKenzie claim, pyrite and chalcopyrite are disseminated in altered sedimentary rock cut by Eocene or Oligocene, fine-grained granodiorite and porphyritic granodiorite (Reed,1933, p. 283; Decker and Gilbert, 1978; Reed and Lanphere, 1974, and Cole, 1998). On the east part of the Mary claim, sulfide-bearing rock is exposed in two pits. At one pit, mineralized strata strike about N. 75 E. and dip about 75 N. Epidotized sedimentary rock exposed in an eight-foot-high face contains sphalerite, galena, and chalcopyrite; a chip sample assayed 0.3 ounce of silver per ton, 0.2 percent copper, and 2.31 percent zinc. At the other pit, the rocks are appreciably copper stained (Reed, 1933, p. 283). The mineralization is probably Oligocene, roughly contemporaneous with the emplacement age of the granodiorite.
Geologic map unit	(-150.305054839478, 63.3992077637003)
Mineral deposit model	Polymetallic replacement deposits; Pb-Zn skarn (Cox and Singer, 1986; models 19a; 18c).
Mineral deposit model number	19a; 18c
Age of mineralization	The mineralization is probably Oligocene, roughly contemporaneous with the Eocene or Oligocene emplacement age of the granodiorite (Reed and Lanphere, 1974; Decker and Gilbert, 1978; Cole, 1998).
Alteration of deposit	Introduction of epidote and silica into metasedimentary rocks. Local oxidation of copper minerals.

Production and reserves

Workings or exploration	The McKenzie and Mary claims were owned by prospector Hugh Matheson at the time of Reed's study in 1931 (Reed, 1933). The claims lapsed and were later restaked as the Lead No. 1 and Lead No. 2 (Muir, Thomas, and Sanford, 1947). The claims were prospected with shallow pits.
Indication of production	None
Additional comments The claims are in 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. 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. Muir, N. M., Thomas, B. I., and Sanford, R. S., 1947, Investigation of the Mount Eielson zinc-lead deposits, Mount McKinley National Park, Alaska: U. S. Bureau of Mines Report of Investigations 4121, 13 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., 1933, The Mount Eielson district, Alaska: U. S. Geological Survey Bulletin 849-D, p. 231-287.
Reporters	C.C. Hawley
Last report date	12/15/2000