Story Creek

Prospect, Inactive

Commodities and mineralogy

Main commodities Pb; Zn
Other commodities Ag; Au; Cu
Ore minerals anglesite; barite; cerussite; chalcopyrite; galena; hematite; hydrozincite; pyrite; sphalerite
Gangue minerals quartz

Geographic location

Quadrangle map, 1:250,000-scale HW
Quadrangle map, 1:63,360-scale B-4
Latitude 68.3829
Longitude -157.9374
Nearby scientific data Find additional scientific data near this location
Location and accuracy The Story Creek prospect is at the head of several, north-flowing tributaries to Story Creek. The most extensive mineralization is about 1.6 miles north of peak 1272 (in meters), about 0.5 mile southwest of the center of section 23, T. 12 S., R. 26 W.

Geologic setting

Geologic description

The Story Creek prospect was found in 1978 by the U.S. Bureau of Mines and was studied by them and the U.S. Geological Survey at various times through 1995 (Ellersieck and others, 1982; Kurtak and others, 1995). Anaconda Minerals, the Arctic Slope Regional Corporation, and Kennecott Exploration explored the deposit from 1980 to 1992. This work included geologic mapping in the area, extensive geochemical and geophysical surveys, and much sampling. The work included beneficiation tests of a bulk sample by the U.S. Bureau of Mines.
The mineralization is largely confined to the Lower Mississippian Isikut Formation, which is overlain by the Mississippian Kayak Shale and underlain by the the Struver Member of the Upper Devonian Kanayut Conglomerate (Ellersieck and others, 1982; Kurtak and others, 1995). The Isikut Formation is thrust over younger rocks and as a result is intensely deformed into an imbricate stack of overturned folds. Numerous minor thrust faults separate the folds. The mineralization occurs as a series of elongate bodies that generally parallel the axes of the folds in the area; the bodies trend about N55E. The bodies vary from 5 to more than 60 meters wide and are irregularly aligned for about 2,000 meters along strike. Most of the mineralization is seen in float and rubblecrop; there is only minor outcrop. The mineralized zones may once have been continuous but have been displaced by northwest-trending high-angle faults. The numerous mineralized bodies are scattered over a east-northeast-trending area about 1,000 meters wide by 2,000 meters long. The largest body is about 400 meters long and about 100 meters wide.
The mineralization occurs as quartz veinlets, banded massive-sulfide veins, and quartz-sulfide breccia. Sphalerite and galena are the dominant ore minerals (Ellersieck and others, 1982; Kurtak and others, 1995). Less abundant are chalcopyrite and pyrite; barite, hematite, cerussite, anglesite, and hydrozincite(?) are present. The mineralization is associated with widespread silicification. The sulfide veins consist mainly of massive sphalerite with lesser galena and quartz. The breccia mineralization generally consists of sphalerite and galena as interstitial cement to the broken host rock; some of the breccia consists of sphalerite clasts rimmed with galena. Open-space-filling textures and the low degree of alteration indicates that the mineralization is epigenetic. Some of the more notable samples include: 1) samples of banded, vein-type mineralization contained 30 percent lead, 696 grams of silver per tonne, 55.6 percent zinc, and 775 parts per billion (ppb) gold; 2) a series of continuous chip samples across 8.5 meters of rubblecrop averaged 14.2 percent zinc, 3.9 percent lead, 159 grams of silver per ton, and 111 ppb gold. Lead isotope analyses of galena give a late Mississippian model age for the lead of about 310-320 Ma.
In an unpublished report (cited in Kurtak and others, 1995), Kennecott Minerals estimated an indicated resource of 1.05 million tonnes with a grade of 8.1 percent zinc, 12.4 percent lead, and 1,028 grams of silver per ton; they estimated an addition inferred resource of 11 million tonnes. The U.S. Bureau of Mines estimated an inferred resource of 2.9 million tonnes with a grade of 14.2 percent zinc, 3.9 percent lead, and 159 grams of silver per tonne (Kurtak and other, 1995).
Geologic map unit (-157.940349523977, 68.3823635120513)
Mineral deposit model Epigenetic, sediment-hosted vein and brecciated Pb-Zn-Ag deposit.
Age of mineralization Mississippian or younger based on the age of the host rock and Mississippian based on lead-isotope analyses of galena.
Alteration of deposit Mineralization is accompanied by widespread silicification.

Production and reserves

Workings or exploration The Story Creek prospect was found in 1978 by the U.S. Bureau of Mines and was studied by them and the U.S. Geological Survey at various times through 1995. Anaconda Minerals, the Arctic Slope Regional Corporation, and Kennecott Exploration explored the deposit from 1980 to 1992. This work included geologic mapping in the area, extensive geochemical and geophysical surveys, and much sampling. The work included beneficiation tests of a bulk sample by the U.S. Bureau of Mines.
Indication of production None
Reserve estimates In an unpublished report (cited in Kurtak and others, 1995), Kennecott Minerals estimated an indicated resource of 1.05 million tonnes with a grade of 8.1 percent zinc, 12.4 percent lead, and 1,028 grams of silver per tonne; they estimated an additional inferred resource of 11 million tonnes. The U.S. Bureau of Mines estimated an inferred resource of 2.9 million tonnes with a grade of 14.2 percent zinc, 3.9 percent lead, and 159 grams of silver per ton (Kurtak and other, 1995).
Production notes None.

Additional comments

MAS number 0020200022.

References

MRDS Number A015688

References

Lueck, L., 1986, Petrologic and geochemical characteristics of the Red Dog and other base-metal sulfide and barite deposits in the De Long Mountains, western Brooks Range, Alaska: University of Alaska, Mineral Industry Research Laboratory Report 71, 105 p.
Reporters M.T. Powers, D.F. Huber, J.M. Schmidt, and J.H. Dover (U.S. Geological Survey); D.J. Grybeck (Contractor, U.S. Geological Survey)
Last report date 4/18/2010