Anarraaq

Prospect, Active

Commodities and mineralogy

Main commodities Ag; barite; Pb; Zn
Ore minerals barite; galena; pyrite; pyrrhotite; sphalerite
Gangue minerals quartz

Geographic location

Quadrangle map, 1:250,000-scale DL
Quadrangle map, 1:63,360-scale A-2
Latitude 68.155
Longitude -163.033
Nearby scientific data Find additional scientific data near this location
Location and accuracy The Anarraaq prospect is about 9.6 miles northwest of Deadlock Mountain on a small tributary to the Wulik River. It is near the center of section 21, T. 32 N., R. 19 W., of the Kateel River Meridian. The location is accurate.

Geologic setting

Geologic description

The Anarraaq prospect was found in 1999 by Teck Cominco by drilling a gravity anomaly (Kelley, Dumoulin, and Jennings, 2004). In plan view the deposit is about 300 by 400 meters in area and consists of a flat-lying lens of massive and banded sulfides up to about 100 meters thick, that is overlain stratigraphically by a thick, continuous layer of barite.
The Anarraag deposit is in shale, mudstone, and carbonate of the Mississippian Ikalukrok unit of the Kuna Formation, which is overlain by the Pennsylvanian to Permian Siksikpuk Formation (Kelley and Jennings, 2004, supplemental map; Kelley, Dumoulin, and Jennings, 2004). The Ikalukrok unit varies greatly in thickness from about 135 to 350 meters.
The sulfide zone at Anarraaq varies in thickness from a few meters to more than 100 meters. There are three types of mineralization: 1) low grade zones (less than 8 percent zinc) with sphalerite, galena, and up to 60 percent pyrite and marcasite; 2) banded sulfides with laminated sphalerite, galena, pyrite, marcasite, and quartz; and 3) massive sphalerite, galena, pyrite, and marcasite in breccias, contorted bands, and veins. The barite layer above the massive and banded sulfides is 65 to 140 meters thick under the entire drilled area and from the top down consists of modular barite, massive banded barite, and calcareous barite. Carbonate replacement by sulfides and barite played a critical role in localizing them.
The Anarraaq deposit is estimated to have a resource of as much as 1 billion tonnes of barite and 18 million tonnes of sulfide ore with a grade of 18 percent zinc, 5.4 percent lead, and 85 grams of silver per tonne (Kelley, Dumoulin, and Jennings, 2004).
Geologic map unit (, )
Mineral deposit model Sedimentary exhalative Zn-Pb (Cox and Singer, 1986; model 31a).
Mineral deposit model number 31a
Age of mineralization Mississippian based on the age of the host rock.
Alteration of deposit Carbonate replacement by sulfides and barite played a critical role in localizing them.

Production and reserves

Workings or exploration The Anarraaq prospect was found in 1999 by Teck Cominco by drilling a gravity anomaly (Kelley, Dumoulin, and Jennings, 2004). There are 14 holes in the ore body and numerous holes peripheral to it.
Indication of production None
Reserve estimates The Anarraaq deposit is estimated to have a resource of as much as 1 billion tonnes of barite and 18 million tonnes of sulfide ore with a grade of 18 percent zinc, 5.4 percent lead, and 85 grams of silver per tonne.

References

References

Kelley, K.D., Dumoulin, J.A., and Jennings, Scott, 2004, The Anarraaq Zn-Pb-Ag and Barite Deposit, Northern Alaska: Evidence for Replacement of Carbonate by Barite and Sulfides: Economic Geology, v. 99, p. 1577-1591.
Reporters D.J. Grybeck (Contractor, USGS)
Last report date 2/28/2011