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

Origin of and Tectonic Controls for
Svyatoy-Nos Metallogenic Belt
The Svyatoy-Nos metallogenic belt is hosted in the younger (Neocomian) part of Late Jurassic and Early Cretaceous
Oloy-Svyatoy Nos volcanic belt (Nokleberg and others, 1994c, 1997~). This igneous belt occurs along the northeastern margin of
the Kolyma-Omolon superterrane and is part of the lndigirka-Oloy sedimentary-volcanic-plutonic assemblage. The belt contains
mainly andesite, rhyolite, and tuff with interlayered shallow-marine sandstone, conglomerate, and siltstone (Parfenov, 1995a, b).
The Oloy-Svyatoy Nos volcanic belt occurs adjacent to and southwest of the South Anyui terrane (fig. 48) and consists of mainly
shallow-marine, rarely nonmarine basalt, andesite, rhyolite, and tuff with interlayered sandstone, conglomerate, siltstone, and
shale. The volcanic belt also contains small bodies of granite, granodiorite, and monzogranite. The belt is interpreted as possibly
related to a short-lived period of Late Jurassic Early Cretaceous subduction of the part of the South Anyui oceanic terrane beneath
the northeastern margin of the Kolyma-Omolon superterrane, after accretion of the Kolyma-Omolon superterrane to the North
Asian Craton Margin (Nokleberg and others, 1994c, 1997c, 2000).
Kuyul Metallogenic Belt of Podiform Cr,
PGE and Associated Deposits (Belt KUY)
East-Central Part of Russian Northeast
The Kuyul metallogenic belt of podiform Cr and associated PGE deposits (fig. 48; tables 3,4) occurs in the southern part
of the major nappe and thrust belt of the Koryak Highlands in the east-central part of the Russian Northeast. The belt extends for
more than 900 krn from the Taigonoss Peninsula to the northern spurs of the Pekulney Range. The metallogenic belt is hosted in
the Kuyul ophiolite, part of the Gankuvayam and Elistratov units of the Kuyul subterrane (unit TLK) of the Talovskiy subduction
zone-oceanic terrane (Nokleberg and others, 1994c, 1997~). The Kuyul ophiolite contains about 20 poorly-prospected Cr deposits
in serpentinized peridotites which occur in about 50 mainly small, discontinuously-exposed ultramafic bodies. The significant
deposits in the belt are at Talov and Tikhorechen (table 4) (Nokleberg and others 1997a, b, 1998). These deposits consist of
chromite and accessory chromium spinel which occur with PGE minerals in dunite and associated ultramafic rocks. PGE minerals,
in association with gold, is hosted in serpentinite and rodingite adjacent to peridotite and dunite. Local Cu-Zn-Co-Ag sulfide
minerals occur in carbonate breccias (Gorelova, 1990).
Origin of and Tectonic Controls for
Kuyul Metallogenic Belt
The Kuyul subterrane of the Talovskiy terrane consists chiefly of tectonic sheets composed of (Nokleberg and others,
1994c, 1997~): (I) serpentinite melange with blocks of: (a) ultramafic rock, gabbro, plagiogranite, dike suites of oceanic and
subduction zone origin, and amphibolite; (b) island arc volcanic and sedimentary deposits composed mainly of andesite, dacite,
tuff; and glaucophane schist; and (c) forearc tuff and sedimentary rocks; (2) Kuyul ophiolite composed of harzburgite, gabbro,
troctolite, wehrlite, plagiogranite, sheeted dikes, and pillow lava of Bathonian and Tithonian age (Chekov, 1982; Markov and
others, 1982); (3) Kingiveem complex composed of oceanic volcanic, siliceous, and carbonate rocks of Permian, Middle and Late
Triassic, and Middle Jurassic age; and (4) the Kuyul subduction-zone melange composed of Late Jurassic and Early Cretaceous
turbidite deposits which contain Bzrchia and Middle Jurassic radiolarian chert.
The Kulul ophiolite assemblage which hosts the Kuyul metallogenic belt is interpreted as forming either: (1) during
spreading of a marginal-sea basin during the early stages of island arc formation; or (2) adjacent to a transform fault along the
margin of an ocean basin (Palandzhyan and Dmitrenko, 1990). The Talovskiy subduction-zone terrane is tectonically linked to the
mainly Late Jurassic and Early Cretaceous Koni-Murgal island-arc terrane (Nokleberg and others, 2000).
Metallogenic Belts Formed in Late Mesozoic
Koyukuk and Togiak Island Arc Systems in
Western and Southwestern Alaska
Eastern Seward Peninsula and
Marshall Metallogenic Belt of
Podiform Cr Deposits (Belt ESM)
Northwestern Alaska
The Eastern Seward Peninsula and Marshall metallogenic belt of podifom Cr deposits occurs in the eastern Seward
Peninsula and in the Marshall (Andreatsky River) area to the south in northwestern Alaska (fig. 49; tables 3.4) (Nokleberg and
others, 1997b, 1998). No significant lode deposits are known from the belt, but small, isolated occurrences of nickel sulfide
minerals are found in ultramafic rocks in the region. These occurrences are interpreted as the sources of PGE minerals which have
been recovered in placer mines in Sheep Creek and Dime Creek, and in the Ungalik River in the Koyuk district. The metallogenic
belt is hosted in a complexly-deformed, fault-bounded unit of ophiolite and related rocks which occur discontinuously in five
small areas (Foley and others, 1982). In the eastern Seward Peninsula area, the units consists of fault-bounded slivers of ultramafic