Unnamed (headwaters of Safari Creek)

Occurrence, Undetermined

Commodities and mineralogy

Main commodities Ag; Cu; Pb; Zn
Ore minerals chalcopyrite; galena; sphalerite

Geographic location

Quadrangle map, 1:250,000-scale HW
Quadrangle map, 1:63,360-scale B-3
Latitude 68.3498
Longitude -157.7223
Nearby scientific data Find additional scientific data near this location
Location and accuracy This occurrence is on an unnamed tributary in the headwaters of Safari Creek. It is about 0.9 mile east-northeast of peak 950 and about 0.5 mile northeast of the center of section 16. T. 34 N., R. 5 W.

Geologic setting

Geologic description

This occurrence is at the eastern margin of the Safari Creek Window where Upper Devonian Noatak Sandstone is thrust over Early Mississippian Kayak Shale (Kurtak and others, 1995). The Noatak Sandstone here consists of thick bedded, light gray to white sandstone with numerous quartz veinlets.
A 3-meter-wide zone with massive pods and lenses of galena, sphalerite, and minor chalcopyrite can be traced for 350 meters in float and rubble of silicified Noatak Sandstone. A 1.1-meter-thick chip sample across this zone assayed 25.2 percent lead, 8.5 percent zinc, 178 grams of silver per ton, and 925 parts per million copper. Several faults are present and there is evidence of post-mineralization movement. There is also stringer and disseminated mineralization adjacent to the massive mineralization. A 7.80-meter-wide chip sample averaged 11 percent lead, 7 percent zinc, and 274 grams of silver per ton. A VLF geophysical survey line across the mineralization showed no response.
Lead-isotope values on galena are: Pb 206/204 = 18.281; Pb 207/204 = 15.608; and Pb 208/204 = 38.152. Kurtak and others (1995) suggest that these values could be explained mixing upper crustal lead with lead such as found in Devonian volcanogenic-massive-sulfide deposits in the Ambler District on the south side of the Brooks Range. They also suggest that the mineralization is the result of hydrothermal fluids which flowed along the thrust fault during the Cretaceous, Brooks Range orogeny.
Geologic map unit (-157.725243254972, 68.3492698766051)
Mineral deposit model Epigenetic, galena-sphalerite pods and lenses in Upper Devonian sandstone.
Age of mineralization Younger than the Devonian host rock and probably Cretaceous.
Alteration of deposit The Noatak Sandstone host rock is silicified.

Production and reserves

Workings or exploration Only sampling and examination by government agencies.
Indication of production None
Reserve estimates None.
Production notes None.

Additional comments

MAS number 0020200021.

References

References

Ellersieck, I.F., Tailleur, I.L., and Mull, C.G., 1990, Reconnaissance geologic map of the Story Creek area, National Petroleum Reserve, Alaska: U.S. Geological Survey Open-File Report 90-533, 13 p.
Reporters D.J. Grybeck (Contractor, U.S. Geological Survey)
Last report date 4/18/2010