Unnamed Occurrence (ARDF - MH091; west of lower Eureka Glacier), Valdez Creek Mining District, Southeast Fairbanks Census Area, Alaska, USAi

Regional Level Types
Unnamed Occurrence (ARDF - MH091; west of lower Eureka Glacier)	- not defined -
Valdez Creek Mining District	Mining District
Southeast Fairbanks Census Area	Census Area
Alaska	State
USA	Country

Location: This occurrence is at an elevation of about 5,000 feet in a south-flowing tributary of the East Fork Maclaren River about 2 miles west of the toe of Eureka Glacier. The occurrence is at the southeast corner of section 32 T. 18 S. R. 7 E. Fairbanks Meridian, and corresponds to locality A8 of Kurtak and others (1992).
Geology: This occurrence is approximately on a major east-west fault that separates granitic rocks of Jurassic or Cretaceous age (on the north) from Paleozoic metasedimentary rocks or Nikolai Greenstone of Late Triassic age (Nokleberg and others, 1991). A steep northwest cross fault was mapped at about this locality by Rose (1966 [ADMM GR 20, figure 3). Rose also mapped lenticular masses of dunite and gabbro farther north, within dioritic rocks of the granitic complex. The U.S. Bureau of Mines traversed along the gulch that exposes the occurrence between about 4,500 and 5,500 feet elevation and found inclusions or dikes of serpentinized dunite in a granitic host that they called quartz monzonite (Kurtak and others, 1992, locality A 8). The serpentinized dunite contained 0.21 to 0.24 percent nickel and 0.13 to 0.15 percent chromium. The mineral host(s) of the nickel and chromium is unknown. Silicified quartz monzonite in a fault zone contained 12 parts per billion palladium and 5 parts per million platinum. Platinum and palladium were also detected in creek gravel and dunite float (Kurtak and others, 1992, table A8).
Workings: U.S. Bureau of Mines geologists traversed the deep gulch that crosses the intrusive rock-metasedimentary rock contact (Kurtak and others, 1992). Their samples of serpentinized dunite contained as much as 0.24 percent nickel and 0.15 percent chromium; an altered quartz monzonite contained 12 parts per billion palladium. The occurrence is on active MAN Resources claims (W.T. Ellis, written communication, 2001).
Age: Mesozoic (?), possibly the age of the ultramafic host rocks.
Alteration: Silicification of quartz monzonite; serpentinization of dunite (Kurtak and others, 1992).

Commodities (Major) - Cr, Ni; (Minor) - Pd, Pt
Development Status: None
Deposit Model: Ultramafic related.

Other Databases

Link to USGS - Alaska:	MH091

Other Regions, Features and Areas containing this locality

References