Unnamed Occurrence (ARDF - MH060; on east side of West Fork Maclaren River), Valdez Creek Mining District, Matanuska-Susitna Borough, Alaska, USAi

Regional Level Types
Unnamed Occurrence (ARDF - MH060; on east side of West Fork Maclaren River)	- not defined -
Valdez Creek Mining District	Mining District
Matanuska-Susitna Borough	Borough
Alaska	State
USA	Country

Location: This occurrence is at an elevation of about 4,000 feet, about 1,300 feet south of the center of section 23, T. 19 S., R. 5 E., Fairbanks Meridian. The site corresponds to locality 16 in figure 4 of Cobb (1979 [OFR 79-238]). The location is probably accurate within one-quarter mile.
Geology: Rocks near the site are andesitic to basaltic volcanic rocks of the Nikolai Greenstone of Late Triassic age, a characteristic unit of the Wrangellia terrane (Nokleberg and others, 1981). Chalcocite or its oxidation product malachite occur in quartz-epidote veinlets and vesicles partly filled with quartz-epidote. The copper minerals also occur on fracture or joint surfaces of the host andesite and basalt. Copper is typically accompanied by some silver.
Workings: Natural exposures; copper minerals were found during geochemical investigations (Smith and others, 1973, 1975).
Age: Post-Late Triassic. It also postdates a folding event that occurred in pre-Late Jurassic time (Stout, 1976, p. 30-31). It probably occurred in the Cretaceous during regional metamorphism and granitic plutonism (Nokleberg and others, 1986) or in the early Tertiary at about the time of emplacement of dacite porphyry dikes (Stout, 1976, p. 23, 31).

Commodities (Major) - Cu; (Minor) - Ag (?)
Development Status: No
Deposit Model: Weak copper mineralization of cupriferous volcanic rocks. Basaltic Cu (Cox and

Other Databases

Link to USGS - Alaska:	MH060

Other Regions, Features and Areas containing this locality

References