Unnamed (near headwaters of Midnight Creek)

Occurrence, Inactive

Commodities and mineralogy

Main commodities Ag; Au; Pb
Other commodities Cu; Zn
Gangue minerals iron-oxides; quartz

Geographic location

Quadrangle map, 1:250,000-scale BN
Quadrangle map, 1:63,360-scale D-6
Latitude 65.8
Longitude -164.52
Nearby scientific data Find additional scientific data near this location
Location and accuracy This location is 1,500 feet east of the headwaters of Midnight Creek, a north tributary to Taylor Creek. It is a flat southeast-trending spur at 1,950 feet elevation that is 8,000 to 8,500 feet east of elevation 2,370 feet on the continental divide. The continental divide separates the headwaters of Hot Springs Creek and Midnight Creek.

Geologic setting

Geologic description

A linear altered zone in polydeformed metapelitic schist of possible Precambrian age (Till and others, 1986) trends about N 55 W across this spur. Sainsbury and others (1970) indicate that rusty graphitic schist and quartz vein fragments are present over a length of 2,000 feet. A sample of iron-stained fracture fillings contained 0.8 ppm Au, 700 ppm Ag, 10,000 ppm As, 1,500 ppm Cu, greater than 10,000 ppm Pb, 150 ppm Sb, and 5,000 ppm Zn. A composite grab sample of surface float collected along 300 feet of the altered zone contained 0.02 ppm gold, 3 ppm Ag, 300 ppm As, 150 ppm Cu, 1,500 ppm Pb, and 500 ppm Zn (Sainsbury and others, 1970, Table 2). The altered zone is probably developed along a high-angle fault. This occurrence, and other nearby occurrences in the headwaters of Humbolt and Ferndale Creeks to the north (BN049-BN052), are interpreted to be structurally above subsurface extensions of the Oonatut Granite Complex (Hudson, 1979). The Oonatut Granite outcrops 2.5 miles to the northwest of this occurrence. This large exposed granite complex is part of the western Seward Peninsula tin-granite suite (Hudson and Arth, 1983). Sainsbury and others (1970, p. H8) suggest that the polymetallic character of the mineralization in this altered zone is similar to what is found in the peripheral silver zone of tin deposit systems. However, only pan concentrate samples from this occurrence had anomalous tin values (to 200 ppm, Sainsbury and others, 1970, Table 2).
Geologic map unit (-164.522711605288, 65.7992826351545)
Mineral deposit model Polymetallic veins developed peripheral to tin deposits
Age of mineralization Probably Late Cretaceous; this occurrence may be associated with emplacement and crystallization of the Oonatut Granite Complex. K/Ar ages for the Oonatut Granite Complex are about 70 my (Hudson, 1979).
Alteration of deposit Quartz veining and iron-oxide fracture fillings and staining are common. There may have been some clay development. Unoxidized mineralization probably contains pyrite and base metal sulfides.

Production and reserves

Workings or exploration Shallow hand-dug prospect pits may be present.
Indication of production None

References