Boundary

Prospect, Active

Commodities and mineralogy

Main commodities Ag; Au; Ba; Cu; Pb; Zn
Other commodities As; Co
Ore minerals barite; chalcopyrite; pyrite; pyrrhotite
Gangue minerals barite; calcite; quartz

Geographic location

Quadrangle map, 1:250,000-scale SK
Quadrangle map, 1:63,360-scale B-4
Latitude 59.3506
Longitude -136.4723
Nearby scientific data Find additional scientific data near this location
Location and accuracy The Boundary prospect is along and just to the east of the Alaska-Canada border, about 1.8 miles south of Mt. Henry Clay at 5,700 to 6,000 feet elevation. It is about 0.4 mile south-southeast of the center of section 15, T. 29 S., R. 53 E. The location is accurate.

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, and ground geochemical and geophysical surveys. The Boundary prospect, the southwestern-most prospect in the area has almost certainly 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.
Still and others (1991) describe this prospect as: 'Narrow bands of iron-stained metasedimentary rocks and altered metabasalt that crop out through glacial ice. Float and bedrock samples of sedimentary and volcanic rocks contained up to 0.034 parts per million (ppm) gold, 1.214 ppm silver, 280 ppm zinc, 1,390 ppm copper, 390 ppm cobalt, 400 ppm arsenic, and 200 ppm nickel. A barite-rich band in white phyllite contained 47 percent barium. Rubicon Minerals (1998) in an unpublished Executive Summary, cites work by Kennecott Alaska Exploration that describes the Boundary prospect as: '...quartz-sericite-pyrite schist and felsite with chalcopyrite.' Rubicon also cites Kennecott samples that contained up to 6.5 percent copper, 16 ppm lead, 3,610 ppm zinc, 12 ppm silver, and 1.980 ppm gold. More recently, Constantine found barite-sulfide boulders that contained up to 2.28 percent copper, 19.7 percent zinc, and 0.61 parts per million gold.
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 (-136.474171533269, 59.3502519083142)
Mineral deposit model Besshi- or Kuroko-type massive sulfide? (Cox and Singer, 1986; models 28a? or 24b?).
Mineral deposit model number 28a? or 24b?
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 Quartz-sericite-pyrite alteration associated with baritic massive-sulfide mineralization.

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 Boundary prospect, the southwestern-most prospect in the area has almost certainly 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

References

Constantine Metal Resources Ltd., 2008, Palmer property info: http://www.constantinemetals.com/projects/palmer/palmer/ (as of April 8, 2008).
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