Unnamed (upper East Fork of Glen Creek)

Prospect, Inactive

Commodities and mineralogy

Main commodities Ag; Au
Other commodities As; Pb
Ore minerals arsenopyrite; galena; pyrite
Gangue minerals quartz

Geographic location

Quadrangle map, 1:250,000-scale MM
Quadrangle map, 1:63,360-scale C-2
Latitude 63.569
Longitude -150.7332
Nearby scientific data Find additional scientific data near this location
Location and accuracy This prospect is on the west side of the upper East Fork of Glen Creek at an elevation of about 3200 feet. It is about in the center of the N1/2 SW1/4 section 31, T. 15 S., R. 16 W., Fairbanks Meridian. The location is probably accurate within 500 feet. The prospect is occurrence 80 of Thornsberry, McKee, and Salisbury (1984).

Geologic setting

Geologic description

The country rock in the area of this prospect is metafelsite of the Spruce Creek sequence. The metafelsite is cut by a dike or small plug of Tertiary dacite that has been sheared and brecciated. The shear zone strikes NE and is almost vertical (Thornsberry, McKee, and Salisbury, 1984, v. 2, occurrence 80). The deposit consists of mineralized brecciated dacite. The breccia is cemented by quartz containing as much as 35 percent pyrite, small amounts of arsenopyrite, and possibly some galena. The sulfides also replace the dacite. The deposit is nearly vertical. Selected samples contain as much as 4.2 ppm gold, 5.1 ppm silver, 0.031 percent lead, and 0.84 percent arsenic. The deposit has been explored by a short adit.
Geologic map unit (-150.735483188622, 63.5684985897074)
Mineral deposit model Pyritic shear zone.
Age of mineralization The mineralization postdates the Eocene emplacement of the dacite. The deposit is assumed to be Eocene (see record MM091).
Alteration of deposit Silicification; replacement of hostrock by sulfides.

Production and reserves

Workings or exploration An adit was driven probably before 1920.
Indication of production None

Additional comments

The prospect is in Denali National Park and Preserve.

References