Unnamed (mountain at head of Flume Creek)

Occurrence, Inactive

Commodities and mineralogy

Main commodities Zn
Other commodities Mo; Th; U
Ore minerals limonite; pyrite; sphalerite

Geographic location

Quadrangle map, 1:250,000-scale MM
Quadrangle map, 1:63,360-scale D-1
Latitude 63.917
Longitude -150.4418
Nearby scientific data Find additional scientific data near this location
Location and accuracy This occurrence is at an elevaton of about 2000 feet on an unnamed mountain at the northwest head of Flume Creek. It is 0.2 mile west-southwest of the center of section 35, T. 11 S., R. 15 W., Fairbanks Meridian. The occurrence is an unnamed locale of Cobb (1980 [OFR 80-363]), and 'gossan 1' (number 70), of Bundtzen, Smith, and Tosdal (1976). It also corresponds to number 31 of MacKevett and Hollway (1977), B70 of Hawley and Associates (1978), and 80a of Bundtzen (1981). A similar occurrence is in the E1/2 of section 35 near hill 2660 (Hawley and Associates, 1978).

Geologic setting

Geologic description

The western part of section 35 is underlain by mineralized metarhyolite tuff of the Devonian or Mississippian Totatlanika Formation (Bundtzen, Smith and Tosdal, 1976). To the east, an infaulted slice of Keevey Peak Formation separates the metarhyolite tuff from similar tuff exposed on hill 2616 (Hawley and Associates, 1978, fig. 4.1-A(3)).
The mineralized metarhyolite strikes NNE, and may dip NW at a shallow angle. The unit is pyritic and the outcrop is conspicuously ironstained. It also contains small amounts of sphalerite, which is exsolved in the pyrite (Bundtzen, Smith, and Tosdal, 1976). Samples assay up to 0.06 ounce of silver per ton, 1600 ppm zinc, 47 ppm molybdenum, and 35 ppm thorium (Bundtzen, 1981, occurrence 80a, table 10). Surface waters in contact with the sulfide-bearing metarhyolite are probably acidic enough to dissolve most of the near-surface zinc in the metarhyolite, but soils are locally anomalous in zinc. One soil sample contained about 425 ppm zinc, and soils collected on hill 2660 contained 275 to 330 ppm zinc (Hawley and Associates, 1978; fig. 4.1-A(3)).
The mineralization probably is Late Devonian and Mississippian, the age of the Totatlanika Formation host rock.
Geologic map unit (-150.444123813129, 63.9165059528773)
Mineral deposit model Volcanogenic deposit associated with acidic volcanic rocks.
Age of mineralization Probably related to Totatlanika Formation volcanism in Late Devonian and Mississippian time.
Alteration of deposit Conspicuous iron-oxide alteration.

Production and reserves

Workings or exploration The area has been reconnaissance mapped and sampled. There are no workings.
Indication of production None

Additional comments

The area is in Denali National Park and Preserve.

References