Unnamed (in headwaters of Niukluk River)

Prospect, Inactive

Commodities and mineralogy

Main commodities Ag; Cu; Pb; Zn
Ore minerals chalcopyrite; galena; sphalerite
Gangue minerals actinolite; biotite; calcite; chlorite; epidote; garnet; mica; quartz

Geographic location

Quadrangle map, 1:250,000-scale BN
Quadrangle map, 1:63,360-scale A-4
Latitude 65.19
Longitude -163.84
Nearby scientific data Find additional scientific data near this location
Location and accuracy This prospect is on the ridge between two unnamed northeast headwater tributaries of Niukluk River. It is on the east-souteast slopes at an elevation of 2,995 feet. It is approximately location 82 of Gamble (1988).

Geologic setting

Geologic description

This prospect is a sulfide-bearing skarn prospect (Hudson and Wyman, 1983). It is developed in impure carbonate layers in high grade metasedimentary rocks that are variably replaced by epidote and garnet. Alteration of the skarn includes development of mica, actinolite, and chlorite. Lenses and pods of galena and sphalerite also replace metacarbonate layers, but chalcopyrite seems to favor replacement of metaclastic, metavolcanic (?), or amphibolite layers. Grab samples of skarn contained from up to 1.4 % Cu, 13.5 % Pb, 9.5 % Zn, and 5.1 ounces/ton Ag. Gold was below the detection level (5 ppb) in these samples (Hudson and Wyman, 1983). A sample from a sulfide-bearing limonitic quartz vein from the top of the ridge east of elevation 2,995 feet contained 6.22 % Cu, 7.75 % Pb, 2.38 % Zn, 4.98 ounces/ton Ag, and only 10 ppb Au. In general, skarn mineralization appears to carry more lead, zinc and silver values than copper. This base metal prospect, and several other occurrences in this part of the Bendeleben A-4 quadrangle, are in high grade metasedimentary rocks that are structurally above or peripheral to the crosscutting Pargon pluton. The Pargon pluton is mostly granodiorite and assumed to be Cretaceous in age (Till and others, 1986). It was emplaced at shallower depths than the more deep-seated Bendeleben pluton to the east. The metamorphic rocks peripheral to the Pargon pluton are also intruded by small, felsic dikes and plugs including quartz porphyry and muscovite granite. A sample of altered quartz porphyry contained 475 ppm Cu and 520 ppm Pb (Hudson and Wyman, 1983).
Geologic map unit (-163.842642007813, 65.1892756430363)
Mineral deposit model Zn-Pb skarn (Cox and Singer, 1986; model 18c).
Mineral deposit model number 18c
Age of mineralization Cretaceous; this occurrence is probably related to emplacement of the Pargon pluton which is assumed to be Cretaceous in age.
Alteration of deposit The epidote-garnet skarn appears to have an overprinting hydrous alteration of mica, actinolite, and chlorite. Limonitic staining is present.

Production and reserves

Workings or exploration Mining claims have existed on this prospect (Hudson and others, 1977). Work has consisted of surface observations and shallow, hand-dug prospecting pits.
Indication of production None


MRDS Number A012771


Reporters Travis L. Hudson (Applied Geology)
Last report date 3/15/1999