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

Orlgln of and Tectonic Controls for
Vatyrt Medallogenic Be&
i The volcanogenic Mn and Fe deposits of the Vatyn metallogenic belt are interpreted as forming in a deep marginal-sea or
oceanic bash environment during submarine basalt eruption as part of the Olyutorka subterrane of the Olyutorka-Kamchatka
! island-arc lerrane (fig. 79) which is described in the above section on the Koryak Highlands metallogenic belt. After deposition,
the Mn and Fe &posits were metamorphosed and locally redeposited as cross-cutting veins (Kolyasnikov and Kulish, 1988).
I Eastern Asia-Arctic Metallogenic Belt Formed in
Late Mesozoic Part of Okhotsk-Chukotka
I ContinentaCMargin Arc, Russian Northeast
General belting of Metallogenic Zones in
I Eastern Asia-Arctic Metallogedc Belt
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The major Eastern Asia-Arctic metallogenic belt of igneous-arc-related lode deposits occurs far several thousand
kilom&ers abng the eastern margin of the Russian Northeast (fig. 79, tables 3,4). The mineral deposits of he belt occur in, and or
are adjacent to the Cretaceous and early Tertiary Okhotsk-Chukotka volcanic-plutonic belt (Gelman, 1986; Nokleberg and others,
1 Wc, 1997~). The major deposit types in the belt are porphyry Cu-Mo, Au-Ag epithermal vein, disseminated Au-sulfide,
granitoid-related Au, Sn-Ag polyrnetallic vein, porphyry, and skam, Hg, Sb, and associated deposits. The Eastern Asia-Arctic
metallogenic beIt includes the rear, frontal and perivolcanic zones of the Okhotsk-Chukotka volcanic-plutonic belt.
The major Eastern Asia-Arctic metallogenic belt is subdivided into smaller metallogenic zones which each exhibit a
distinctive suite of feisic-magmatism-related lode deposits (fig. 79; table 4). In alphabetical order, the zones are: Anyui-Beringov.
Chawn-Seward, Chukotka, Dogdo-Erikit, Koni Yablon, Okhotsk, Omusukchan, Verkhne-Kolyma, and the VerkhneYukonsky.
These distinctive suites of lode deposits in each zone are defined or subdivided on the basis of: (1) the kxrane(s) which locally
underlies the zone; (2) the occurrence of longitudinal and orthogonal faults which trend north-south or northwest; and (3) regional
magmatic zonation of the Okhotsk-Chukotka volcanic-plutonic belt (fig. 79). In some cases, the longitudinal and orthogonal faults
extend several hundreds of kilometers to the northwest away from the northeast-trending mass of the Okhotsk-Chukotka volcanic-
plutonic belt;
I Origin of and Tectonic Contrda for
Eastern Asia-Arctic Metaltogenlc Belt
The Easlern Asia-Arctic metallogenic belt is hosted in or near the Okhotsk-Chukotka volcanic-plutonic bdl which
caastitules a major Eariy Cretaceous, Late Cretaceous, and locally Paleocene age assemblage which overlaps previously-accreted
ternanas. The igneous belt extends for 3,000 km along western margin of Sea of Okhotsk, and across the Bering Straits into the
Seward Peninsuk (figs. 79, 80). and consists mainly of gently dipping basalt, andesite-basalt, andesite, dacite, rhyolite, and tuff
(Nokleberg and others, 1994c, 1997~). Rare beds of nonmarine clastic rocks, with conglomerate, grit, and sandstone occur at the
base. The belt also contains local widespread silicic volcanic rock (mainly ignimbrites) and associated tonalite, quartz-diorite, and
spar granite. To the northwest, into tbe continent, Late Cretaceous plutonic rocks grade into subalkalic and alkdic granile. The
Paleocene part of the igneous belt locally consists mainly of plateau theoleiitic basalt.
The Okhotsk-Chukoika belt overlies the southeastern margin of the North Asian Craton and the Kolyma-holon
superternme, as well as the Chukotka, Kony-Murgal, Okhotsk, Seward, South-Anyui, and Zolotogorskiy terranes of the Russian
Northeast (fig. 79). The Okhotsk-Chukotka belt is interpreted as a Pacific-facing, continental-margin arc which f o d the Albh through Campsnian and locally Paleocene boundary of northeastern Asia. The frontal part of the Okhotsk-Chukotka volcanicplutoaic
belt is dominated by basalt, and the rear zone is dominated by andesite and rhyolite. Coeval granitic through gabbroic
intrusions also occur in the rear zone (Bely, 1977, 1978; Filatova, 1988). The Okhotsk-Chukotka belt is equivalent to the East
Sikhote-Alin volcanic-plutonic belt (unit es) in the Russian Southeast (fig. 79). Together, these two igneous bells constitute a
major continental-margin arc of Cretaceous and early Tertiary age which were tectonically linked subduction zone assemblages.
To the north, the Okhotsk-Chukotka igneous belt was tectonically linked to the Ekonay oceanic crust, and the West Kamchatka
turbidite basin and Yanranay accretionary-wedge terranes; to the south, the East Sikhote-Alin igneous belt was tectonically linked
to the Aniva, Hikada, and Nabildy accretionary wedge and subduction-zone terranes (Nokleberg and others, 2000).