Unnamed (northeast of Eldridge Glacier) (ARDF #MM178) Au, Cu

Unnamed (northeast of Eldridge Glacier)

Occurrence, Probably inactive

Commodities and mineralogy

Main commodities	Au; Cu
Ore minerals	chalcopyrite; malachite

Geographic location

Quadrangle map, 1:250,000-scale	MM
Quadrangle map, 1:63,360-scale	A-1
Latitude	63.0401
Longitude	-150.0027
Nearby scientific data	Find additional scientific data near this location
Location and accuracy	This occurrence is on the ridge between Eldridge Glacier and Partin Creek about two miles east of Eldridge Glacier. It is at an elevation of about 5200 feet, about on the boundary between the N1/2 of sections 2 and 3, T. 22 S., R. 13 W., Fairbanks Meridian. The locality is number 39 of Hawley and Clark (1974, pl. 1, table 16). The location is accurate.

Geologic setting

Geologic description This occurrence is in tuff in a dominantly calcareous argillite unit (Hawley and Clark, 1974). Small amounts of chalcopyrite are disseminated in the tuff, which locally is stained with malachite. Samples of the tuff contain about 1500 ppm of copper and 0.2 ppm gold. The occurrence is approximately on strike with and two miles southwest of the Partin Creek occurrence in the Healy A-6 quadrangle (Hawley and Clark, 1974, p. B46). The Partin Creek occurrence is in interlayered basalt and limestone of Late Triassic age. Exploration by private interests at Partin Creek since 1974 has discovered lenses of massive, auriferous pyrrhotite in the limestone adjacent to a monzodiorite stock of Late Cretaceous age.
Geologic map unit	(-150.004980408337, 63.0396145158302)
Mineral deposit model	Replacement deposit in tuff.
Age of mineralization	Probably Late Cretaceous, related to emplacement of monzodiorite of Late Cretaceous age, as at the nearby Partin Creek occurrence in the Healy A-6 quadrangle.
Alteration of deposit	Local oxidation of copper minerals.

Production and reserves

Workings or exploration	Surface exploration only.
Indication of production	None
Additional comments The occurrence is on state-selected land within one mile of the boundary of Denali National Park and Preserve. It is about 2 miles southwest of the Partin Creek occurrence in the Healy A-6 quadrangle, a complex skarn and vein deposit of gold, copper, and antimony (Hawley and Clark, 1974).

References

References Hawley, C. C., and Clark, A. L., 1974, Geology and mineral deposits of the upper Chulitna district, Alaska: U. S. Geological Survey Professional Paper 758-B, 47 p.
Reporters	C.C. Hawley
Last report date	12/18/2000