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

Archean granulite facies metamorphic rock, and Paleozoic greenschist to amphibolite facies metamorphic rock. The Lantrasky-
Dzhugdzhur anorthosite complex is elongated along the Stanvoy suture zone, is 170 km long, varies from 5 to 34 km wide, and
covers and areas of approximately 2,700 km2. The complex is composed of approximately 70 percent anorthosite, and 30 percent
gabbro, norite, and ultramafic rock. The complex contains a classic layered series of anorthosite plutons, incli~ding those in
Finland, Canada, and South America (Papunen, 1986; Ryan and others, 1995). The five gabbroic Cu-Ni-Co-PGE prospects, that
have been identified since 1990, are at Avlandzhinsky, Kontaktovy, Nyandomi, Ozerny, and Odorin. These prospects occur near
the contact between anorthosite and gabbro layers, and REE-bearing alkali granitic rock. The two largest prospects at the
Kontaktovy and Nyandomi are 300 to 600 m wide and range up to several km long. Surface samples of massive sulfides contain
up to 3.4% Cu, 0.74% Ni, 0.17% Co, 5.43 g/t Pt, 2.8 g/t Pd, and 0.85 g/t Rh (Pollack, 1997; Panskikh, 1978). These prospects are
geological and geochemical analogs to the Cu-Ni-Co-PGE deposits in the layered Svecokarelian complexes of Finland and
Western Russia, and Cu-Ni-PGE deposits in the Nain plutonic suite at Voisey Bay, Canada (Papunen, 1986; Pollack, 1997). The
deposits in the Lantasky-Dzhugdzhur belt have been explored by Vostok Gold Corporation.
Another similar group of anorthosite Apatite-Ti-Fe deposits are the Bogidenskoe, Gayumskoe, Maimakanskoe, and
Dzhaninskoe deposits. These deposits occur to the south of the above-described deposits generally consist of apatite, ilrnenite, and
titanium magnetite which are hosted in melanocratic olivine gabbro, gabbrosyenite, gabbro-pyroxenite, and pyroxenite. These
mafic and ultramafic rock often forms stock-like bodies in the Geransky anorthosite massif (Lennikov and others, 1987) that has a
Pb-Pb isotopic age of 2.2 to 1.8 Ga. The deposits occur on the southern, southwestern, and western margins of the Geransky
anorthosite massif. The four largest deposits are spaced about 15 to 30 km between each other, and together contain an estimated
350 million tonnes PzO5 (Panskikh and Gavrilov. 1984). Together, the deposits in the belt contain approximately one billion
tonnes of PzO5, an amount which is comparable with deposits in the Kola province in northwestern Russia near Sweden.
Origin of and Tectonic Controls for
Lantarsky-Dzhugdzhur Metallogenk Belt
The Lantasky-Dzhugdzhur metallogenic belt is interpreted as forming during Mesoproterozoic rifting along the edge of
the North Asian Craton. During rifting, coeval, large anorthosite plutons intruded the Stanovoy suture and adjacent area for a
distance of more than 1,000 krn, and adjacent region to the south.
Ulkan Metallogenic Belt of
Felsic Plutonic REE Deposits (Belt UL)
Northwestern Part of Russian Southeast
The Ulkan metallogenic belt of felsic plutonic REE deposits occurs in the northwestern part of the Russian Southeast (fig.
2; tables 3,4) (Nokleberg and others, 1997b, 1998). The belt occurs mainly in the Paleoproterozoic Ulkan volcano-tectonic basin
that has isotopic ages of 1.9 to 1.5 Ga, and which overlies folded Archean basement rocks of the North Asian Craton (unit NSC)
The REE, Be, U-Mo, Nb-Ta and related deposits are interpreted as forming in two periods.
Ornolon Metallogenic Belt of Ironstone
(Superior Fe) Deposits (Belt OM)
Central Part of Russian Northeast
The Omolon metallogenic belt of ironstone (Superior Fe) deposits (fig. 2; tables 3.4) occurs in the central part of the
Russian Northeast. The belt is hosted in Archean metamorphic rocks of the Omolon cratonal terrane of the Kolyma-Omolon
superterrane (Nokleberg and others, 1994~. 1997c; Shpikerman, 1998). More than ten local ironstone deposits are known in the
belt (table 4) (Nokleberg and others, 1997a, b, 1998). The significant deposit is at Verkhny-Ornolon.
Verkhny-Omolon Ironstone Deposit
The significant Verkhny-Omolon ironstone deposit (fig. 6) consists of sheet-like and podiform bodies of banded iron
formation which occur in Archean migmatite, amphibole and biotite-amphibole plagiogneiss, amphibolite, and rnafic schist
(Gelman, Titov, and Fadeev, 1974; Fadeev, 1975; Zhulanova, 1990; Milov, 199 1). The banded iron ore consists of medium- to
coarse-grained masses or layers of magnetite and quartz which is intergrown with apatite and actinolite. The deposit extends for
3.5