Unnamed (south of upper Caribou Creek)

Occurrence, Inactive

Commodities and mineralogy

Main commodities Ag; Zn
Other commodities As; Au; Cu; Pb; Sb
Ore minerals arsenopyrite; galena; limonite; pyrite; sphalerite; stibnite
Gangue minerals quartz

Geographic location

Quadrangle map, 1:250,000-scale MM
Quadrangle map, 1:63,360-scale C-2
Latitude 63.6014
Longitude -150.667
Nearby scientific data Find additional scientific data near this location
Location and accuracy This occurrence is at an elevation of about 3700 feet on the north flank of a ridge about 1.65 miles north of Spruce Peak. It is about 1100 feet northwest of the center of center of section 21, T. 15 S., R. 16 W., Fairbanks Meridian. The location is accurate. The occurrence is number 274 of Hawley and Associates (1978), and approximately at the same location as occurrence 92 of Thornsberry, McKee, and Salisbury (1984).

Geologic setting

Geologic description

The country rocks at the prospect are metafelsite, marble, and graphitic phyllite of the lower Paleozoic Spruce Creek sequence. The Spruce Creek rocks occur in a narrow, northeast-trending block downfaulted(?) into more widespread Birch Creek rocks (Hawley and Associates, 1978; Bundtzen, 1981; Thornsberry, McKee, and Salisbury (1984, v. 2).
The mineral deposits include vein and stratiform types. Thornsberry, McKee, and Salisbury (1984, v. 2, occurrence 92) described quartz veins up to a foot thick that cut hydrothermally altered metafelsite. The veins contain pyrite, galena, sphalerite, stibnite, and probably arsenopyrite. A sample of one vein assayed 0.12 ounce of gold per ton, 2.94 ounces of silver per ton, 3.95 percent arsenic, 2.15 percent lead, and 8.5 percent zinc (Thornsberry, McKee, and Salisbury, 1984, v. 2).
The stratiform occurrences consist of gossan in graphitic schist. One sample collected about 250 feet southwest of a vein contained 1.7 percent zinc, 3.4 ppm silver, and anomalous amounts of copper and lead (Hawley and Associates, 1978, sample 275).
Geologic map unit (-150.669285738351, 63.6009006391723)
Mineral deposit model Polymetallic veins (Cox and Singer, 1986; model 22c).
Mineral deposit model number 22c
Age of mineralization The veins are assumed to be Eocene (see record MM091). The stratiform ocurrence may be early Paleozoic, the protolith age of the Spruce Creek sequence.
Alteration of deposit 'Hydrothermal' alteration of metafelsite. Iron-oxide alteration.

Production and reserves

Workings or exploration The occurrence was discovered in about 1975 (Hawley and Associates, 1978). There are no workings.
Indication of production None

Additional comments

The occurrence is in Denali National Park and Preserve.

References