Metallogenesis and Tectonics of the Russian Far East, Alaska, and ...

Beatson (Latouche) and Ellamar Besshi
Massive Sulfide Deposits
The Beatson (Latouche), and, Ellamar Besshi massive sulfide deposits (Johnson, 1915; Tysdal, 1978; Jansons and others,
1984; Crowe and others, 1992) consist of massive sulfide lenses and disseminations of mainly pyrite and pyrrhotite, and minor
chalcopyrite, cubanite, sphalerite. galena. Ag-bearing minerals. and gold. Gangue minerals are quartz, sericite, and ankerite. The
deposits occur in graywacke and argillite of the Paleocene and Eocene Orca Group. The deposits range up to 120 m thick and 300
long along strike. The Latouche and Beatson deposits produced more than 84 million kg Cu from 4.5 million tonnes of ore. The
average ore grade was about 1.7% Cu, and 9.3 g/t Ag. The Ellamar deposit produced 7.2 million kg Cu, 1,596 kg Au, and 5,960
kg Ag from 273,760 tonnes of ore. The deposit at Beatson (Latouche) was developed and produced mainly from about 1903 to
1934, and the Ellamar deposit was mined from 1897 to 1934.
Midas Besshi Massive Sulfide Deposit
The Midas deposit consists of disseminated to massive chalcopyrite, pyrite, pyrrhotite, sphalerite, and minor galena in a
folded, lens-shaped body (Moffrt and Fellows, 1950; Rose, 1965; Jansons and others, 1984; Crowe and others, 1992). The sulfides
occur in highly deformed phyllite and metagraywacke of the Late Cretaceous Valdez Group in the southern Chugach accretionary
wedge-turbidite terrane. Mafic metavolcanic rocks crop out in the footwall within a few hundred meters of the ore body. On the
basis of whole rock REE analyses, the mafic volcanic rocks in the southern Chugach terrane are interpreted by Lull and Plafier
(1990) as forming in a short-lived island-arc environment.
Copper Bullion (Rua Cove) Cyprus
Massive Sulfide Deposit
The Copper Bullion (Rua Cove) Cyprus massive sulfide deposit (fig. 1 16) (Koski and others, 1985; Crowe and others,
1992) is a lens-shaped massive body of pyrrhotite with minor chalcopyrite and sphalerite which is hosted in sheared pillow basalt
of the lower Tertiary Orca Group of the Prince William terrane. The lens is about 200 m long and is locally interlayered with
pillow basalt and hyaloclastite that occur stratigraphically above sheeted dikes. The sulfides include pyrite, phrrhotite,
chalcopyrite, sphalerite, cubanite, galena, and marcasite. The gangue assemblage consists of abundant quartz and chlorite, which
occur as fine disseminations with massive sulfides, and in pervasive and massive zones in the stockwork zone where fine-grained
talc also occurs. The deposit contains a well-preserved feeder zone that underlies the massive sulfide lens is dominanted by
pyrrhotite and chalcopyrite. The deposit contains reserves of 990,000 tonnes grading 1.25% Cu, and