Unnamed Occurrence (ARDF - HE181), Valdez Creek Mining District, Matanuska-Susitna Borough, Alaska, USAi

Regional Level Types
Unnamed Occurrence (ARDF - HE181)	- 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 3,800 feet, one mile due east of the center of the airstrip at Susitna Lodge. The map site is in the SW1/4 of sec. 18, T. 21 S., R. 2 E., of the Fairbanks Meridian. The location is accurate to about 250 feet.
Geology: The area of this occurrence is underlain by the Middle or Upper Triassic Nikolai Greenstone, a thick sequence of subaerial and submarine basalt flows and minor interbedded volcaniclastic sedimentary rocks, aquagene and epiclastic tuff, breccia, argillite, and radiolarian chert (Nokleberg and others, 1992). The deposit is in a hydrothermally altered shear zone in greenstone and consists quartz, epidote, bornite, chalcocite, and an iron carbonate mineral. Weathering produces malachite- and azurite-coated float and encrustations. Glavinovich (1967) described the occurrence as follows: 'Bornite, minor chalcocite and malachite occur as small discontinuous stringers in a narrow fracture zone. The fracture zone trends northeast, is about two inches wide and three feet in length. At both ends the zone narrows to a single fracture that continues along strike but is unmineralized. Gangue minerals include quartz and epidote. The paragenesis as determined in hand specimen is epidote, quartz, sulfides. The country rock is moderately altered andesite and is well jointed. Malachite coatings on joint faces are common.'
Age: Triassic or younger.
Alteration: Propylitic alteration of greenstone.

Commodities (Major) - Cu
Development Status: None
Deposit Model: Hydrothermally altered shear zone

Other Databases

Link to USGS - Alaska:	HE181

Other Regions, Features and Areas containing this locality

References