Unnamed (northwest of upper Otter Creek)

Occurrence, Inactive

Commodities and mineralogy

Main commodities Ag; Pb
Other commodities As; Bi; Cd; Cu; Sb; Sn; Zn
Ore minerals iron oxide
Gangue minerals quartz

Geographic location

Quadrangle map, 1:250,000-scale ID
Quadrangle map, 1:63,360-scale B-4
Latitude 62.4974
Longitude -157.86111
Nearby scientific data Find additional scientific data near this location
Location and accuracy This occurrence is in a saddle of a northeast-trending ridge about 4 miles northeast of Discovery camp on Otter Creek and 0.2 mile northeast of hill 1807. The occurrence is at an elevation of about 1,700 feet near the southwest corner of section 20, T. 28 N., R. 46 W., of the Seward Meridian. The location is accurate.

Geologic setting

Geologic description

This occurrence is a zone of quartz stringers in heavily iron-oxide-stained sandstone of the Upper Cretaceous, Kuskokwim Group. The quartz stringers are next to a quartz-feldspar porphyry dike (Bundtzen and others, 1992). The dike trends northeast along the ridge. Grab samples contained up to 200 parts per million (ppm) silver, 2.00 percent lead, more than 2,000 ppm antimony, 2,000 ppm zinc, 200 ppm copper, 50 ppm tin, 1,600 ppm arsenic, 100 ppm cadmium, and 18 ppm bismuth (McGimsey and others, 1988; Bundtzen and others, 1992). The primary sulfides are entirely oxidized, but the original primary minerals probably included galena or a lead sulfosalt and sphalerite.
Geologic map unit (-157.863508594501, 62.496716656165)
Mineral deposit model Sn-polymetallic deposit or Polymetallic vein (Cox and Singer, 1986; model 20b or 22c).
Mineral deposit model number 20b or 22c
Age of mineralization Undated; a nearby intrusion is 70.5 Ma (Bundtzen and others, 1992).
Alteration of deposit Intense iron-oxide staining.

Production and reserves

Workings or exploration Surface samples were collected by the U.S. Geological Survey and Alaska Division of Geological and Geophysical Surveys in 1986 (McGimsey and others, 1988; Bundtzen and others, 1992).
Indication of production None

References