Graben Occurrence, Valdez Creek Mining District, Matanuska-Susitna Borough, Alaska, USAi

Regional Level Types
Graben Occurrence	Occurrence
Valdez Creek Mining District	Mining District
Matanuska-Susitna Borough	Borough
Alaska	State
USA	Country

Location: The Graben occurrence is on the north bank of the Susitna River, about 0.2 mile east of the mouth of Watana Creek. The location is accurate.
Geology: This occurrence is in basalt of the Triassic, Nikolai Greenstone. Fractures in the amygdaloidal basalt are marked by orange-red to orange-brown coatings, locally accompanied by yellow-green coatings and white and yellow efflorescence (J. Schmidt, written commun., 2001). Rock samples collected by the U.S. Geological Survey contain up to 2,120 parts per million copper, 110 parts per million nickel, 226 parts per million cobalt, 0.2 part per million gold, and 1.05 percent titanium; one sample contains 1.56 parts per million mercury (J. Schmidt, written commun., 2001). (The 0.2-part-per- million gold value is an ICP analysis done by XRAL Laboratories; a fire assay shows less than 0.005 ppm gold. The cause of the discrepancy is not known.)
Workings: Only surface sampling by U.S. Geological Survey (J. Schmidt, written commun., 2001).
Age: Occurs in Triassic basalt.
Alteration: Iron-oxide(?) and undetermined secondary minerals.

Commodities (Major) - Co, Cu, Ni; (Minor) - Au, Hg, Ti
Development Status: None
Deposit Model: Basaltic copper? (Cox and Singer, 1986; model 23?)

Other Databases

Link to USGS - Alaska:	TK025

Other Regions, Features and Areas containing this locality

References