Nunatak

Prospect, Active

Alternative names

Saksaia Glacier

Commodities and mineralogy

Main commodities Ag; Au; Ba; Cu; Pb; Zn
Ore minerals barite; chalcopyrite; galena; gold; pyrite; sphalerite; sulfosalts
Gangue minerals quartz; sericite

Geographic location

Quadrangle map, 1:250,000-scale SK
Quadrangle map, 1:63,360-scale B-4
Latitude 59.3699
Longitude -136.4125
Nearby scientific data Find additional scientific data near this location
Location and accuracy The Nunatak prospect extends for 1,500 feet between 3,800 and 4,500 feet elevation on a nunatak about 1.5 miles above the terminus of the Saksaia Glacier. It is near the center of section 12, T. 29 S., R. 53 E.

Geologic setting

Geologic description

Mineralization in this area was discovered in 1969 by Merrill Palmer and associates and has been explored by a succession of companies including Alyu Mining in 1976 and 1977; Anaconda Minerals in 1979 and 1980; Southeastern Minerals from 1980 to 1983; Bear Creek Mining from 1983 to 1985; Newmont Exploration from 1987 to 1989; Granges Exploration Ltd. in 1989; Cominco Alaska from 1990 to 1993; Kennecott Minerals from 1993 to 1997, Rubicon Minerals from 1998 to 2000; and Toquima Minerals Corp. in 2004. It was also mapped and sampled by the U.S. Geological Survey (MacKevett 1974) and the U.S. Bureau of Mines (Still, 1984), and the Alaska Division of Geological and Geophysical Surveys (Still and others, 1991). In 2006, Constantine Metal Resources acquired the property under a long-term lease and they have been actively explored it to the present (early 2011). Their work has included detailed geologic mapping and sampling, ground geochemical and geophysical surveys. The Nunatak prospect has been mapped, sampled, and covered by geochemical and geophysical surveys by several of the companies that have worked in the area. It is now part of the large block of claims held by Constantine. It has not been drilled.
The rocks in the region are part of the Upper Triassic Hyd Group that hosts similar volcanic massive sulfide deposits the length of southeastern Alaska (Newberry and others, 1997). The rocks are predominantly massive and pillow basalts and fragmental basalt and andesite(?), intercalated with siltston, tuff, and rare rhyolite flows and dikes. They have been subject to greenschist-facies metamorphism; folding and faulting locally repeats the stratigraphy in places, and the rocks are highly altered.
The prospect is in intensely quartz-sericite-pyrite-altered and iron-stained schist and altered volcanic rocks more than 100 feet thick exposed for 1,500 feet across the face of a nunatak (MacKevett and others, 1974; Still, 1984; Greig and Giroux, 2010). Barite lenses and beds up to 6 meters thick occur in the altered rocks. The mineral assemblage and field relationships are similar to those at the Glacier Creek prospect (SK066) (MacKevett and others, 1974). Samples of the baritic rock contain up to 2.58 parts per million (ppm) gold, 335.3 ppm silver, 2.38 percent zinc, 1,820 ppm copper, 2.0 percent lead, 48 percent barite, and 1,000 ppm arsenic. A 200-pound sample collected by Merrill Palmer was divided into 13 parts and analyzed by Newmont Gold Company. The samples averaged 11.84 ounces of silver per ton and 0.092 ounce of gold per ton. This prospect lies along a northwesterly mineral trend that extends through the Cap prospect (SK060) to the Mount Henry Clay prospect (SK068). Rubicon Minerals believed that these prospects occur at the same mineralized stratigraphic horizon and attributes their distribution to a northwest-trending, gently plunging antiform that brings the massive-sulfide horizon close to the surface (Rubicon Minerals, 1998).
There have been several published studies of the mineral deposits in the area by government and academe (MacKevett and others, 1974; Still, 1984, Still and others, 1991; Newberry and others, 1997; Greig and Giroux, 2010) and unpublished studies by industry. The consensus from early on was that the they are Late Triassic, stratiform volcanogenic massive-sulfide deposits.
Geologic map unit (-136.414367288022, 59.3695595529559)
Mineral deposit model Besshi- or Kuroko-type volcanogenic massive sulfide deposit (Cox and Singer, 1986; models 24b or 28a).
Mineral deposit model number 24b or 28a
Age of mineralization Late Triassic by analogy with other similar deposits of that age along the length of southeastern Alaska and into Canada.
Alteration of deposit Intense quartz-sericite-pyrite alteration adjacent to baritic massive-sulfide layers.

Production and reserves

Workings or exploration Mineralization in this area was discovered in 1969 by Merrill Palmer and associates and has been explored by a succession of companies including Alyu Mining in 1976 and 1977; Anaconda Minerals in 1979 and 1980; Southeastern Minerals from 1980 to 1983; Bear Creek Mining from 1983 to 1985; Newmont Exploration from 1987 to 1989; Granges Exploration Ltd. in 1989; Cominco Alaska from 1990 to 1993; Kennecott Minerals from 1993 to 1997, Rubicon Minerals from 1998 to 2000; and Toquima Minerals Corp. in 2004. It was also mapped and sampled by the U.S. Geological Survey (MacKevett 1974) and the U.S. Bureau of Mines (Still, 1984), and the Alaska Division of Geological and Geophysical Surveys (Still and others, 1991). In 2006, Constantine Metal Resources acquired the property under a long-term lease and they have been actively explored it to the present (early 2011). Their work has included detailed geologic mapping and sampling, and ground geochemical and geophysical surveys. The Nunatak prospect has undoubtedly been mapped, sampled, and covered by geochemical and geophysical surveys by several of the companies that have worked in the area. It is now part of the large block of claims held by Constantine. It has not been drilled.
Indication of production None
Reserve estimates None.
Production notes None.

References

MRDS Number A013089

References

Greig, C.J., and Giroux, G.H., 2010, Palmer VMS project, southeast Alaska; Mineral resource estimation and exploration update: Technical l report for Constantine Metal Resources Ltd. 82 p. (posted on www.sedar.com, Mar. 8, 2010).
Newberry, R.J., Crafford, T.C., Newkirk, S.R., Young, L.E., Nelson, S.W., and Duke, N.A., 1997, Volcanogenic massive sulfide deposits of Alaska, in Goldfarb, R.J. and Miller, L. D., eds., Mineral deposits of Alaska: Economic Geology Monograph 9, p. 120-150.
Rubicon Minerals, 1998, Palmer VMS Project, southeast Alaska, Executive Summary: Unpublished report by Rubicon Minerals Corporation, Vancouver, British Columbia, 25 p.
Reporters T.C. Crafford (T. Crafford & Associates, Anchorage); D.J. Grybeck (Contractor, USGS)
Last report date 2/28/2011