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

Origin of and Tectonic Controls for
Central Koryak Metallogenic Belt
The Karnchatka-Koryak volcanic belt, which hosts the Central Koryak metallogenic belt, is composed of lesser Late
Cretaceous and mainly of Paleocene, Eocene, and Miocene age. The belt extends for 800 km parallel to, but mainly east of the
northern part of the Okhotsk-Chukotka volcanic-plutonic belt (fig. 102) (Nokleberg and others, 1994c, 1997~). The belt occurs in
discontinuous and isolated volcanic fields and consists of gently dipping nonmarine volcanic rocks of various compositions, md
sandstone, gritstone, and conglomerate with flora. The lower part of the volcanic belt consists of mafic volcanic rocks, mainly
Maastrichtian-Danian tholeiitic basalt, along with abundant Paleocene to Eocene alkali basalt, and associated minor diorite,
monzonite, gabbro, granodiorite, and granite which yield K-Ar ages of 56-73 Ma. The upper part of the vokanic belt consists of
calc-alkaline dacite, rhyolite, andesite, and basalt with late Eocene and early Miocene flora and K-Ar ages, and is associated with
subvolcanic bodies and dikes of rhyolite, granodiorite, and diorite. The Karnchatka-Koryak volcanic belt is interpreted as a major,
mainly early Tertiary arc which formed along a continental margin-parallel t~ansform fault. (Khanchuk and Ivanov, 1999a, b).
Metallogenic Belts Formed in Tertiary
Continmntal-Margin Arcs, Kamchatka Peninsula,
and Southern Canadian Cordillera
Olyutor Metallogenic Belt of
Igneous-Arc-Rebted Deposits (Belt OT)
Kamchatka Peninsula
The Olyutor metallogenic belt of igneous-arc-related deposits (fig. 102; tables 3,4) occurs in noahem Kamchatka. The
metallogenic belt extends for more than 600 km along the Bering Sea coast and is hosted in the East and Central Karnchatka
volcanic belts (Nokleberg and others, 1994c, 1997~). The little studied Olyutor metallogenic belt contains a variety of Au-Ag
epilbermal vein, Sn polymetallic vein, clastic sediment-hosted Hg, and porphyry Mo-Cu deposits (table 4). Several mineable Hg,
Au, Mo, Cu, Pb and Zn deposits occur in many, slightly-eroded volcanic structures (Taraserdro and Tttov, 1969). Numerous,
poorly explored, porphyry Cu-Mo, Au-Ag epithermal vein, sulfur-sulfide, and Sn polymetailic vein deposits occur along the
southern flank of the belt, and a zone of Hg-Sb and Hg-As deposits extends for more than 100 krn along the Olyutor Bay coast
The deposits in the Olyutor belt are hosted mainly in Tertiary sedimentary, volcanic, and hypabyssal intrusive rocks. The Hg-Sb
As deposits also occur in Neogene extrusive rocks, and in serpentinite melange zones. The porphyry Mo-Cu deposits occur in
Tertiary diorite and granodiorite porphyry stocks and associated dikes which intrude Late Cretaceous and early Paleogene
tuffaceous and clastic rocks. The porphyry Mo-Cu deposits extend more than 100 krn in the northern part of the belt, with
intrusions apparently occurring along major faults. The significant deposits in the Olyutor metallogenic belt are the Olyutor clastic
sediment-hosted Hg deposit, the Lalankytap porphyry Mo-Cu deposit, and the Maletoivayam sulfur-sulfide deposit (Nokleberg
and others 1997a, b, 1998)..
Olyutor Clastic Sediment-Hosted Hg Deposit
The Olyutor clastic sediment-hosted Hg deposit (Babkin, 1975; Vlasov, 1977) consists of veins a ~~d veinlets which occur
in steeply-dipping fracture zones. The fracture zones radiate from a large northeast-trending fault which cuts Paleogene atld
Neogene volcaniclastic rocks which are deformed into small linear folds. Individual ore bodies extend along strike fiom tm of
meters to 600 m. The veins have numerous apophyses typically containing mineralized breccia which often grade into zones of
veinlets. The most productive ore bodies occur in tuff. The main ore minerals are cinnabar accompanied by stibnite and sometimes
realgar. The ore also contains quartz cement and quartz-kaolinite breccia fragments. The main gangue minerals are quartz and
kaolinite, and less commonly dolomite. Wall rock alteration includes weak silicification, kaolinization, and carbonathation, The
deposit is large and contains an estimated 700 tonnes Hg averaging 1.4% Hg, and up to 0.4% Sb and 4 gh Au.
Lalankytap Porphyry Mo-Cu Deposit
The Lalankytap porphyry Mo-Cu deposit (Brazhnik and Kolyasnikov, 1989; Brazhnik and Morozov, 1989) consists of an
oval stockwork about 1.2 by 0.6 km in area which contains randomly oriented quartz veinlets with irregularly disselninated pyrite,
molybdenite, and chalcopyrite; and minor pyrrhotite, sphalerite, galena, magnetite, martite, rutile, anatase, and sphene. The ore
minerals occur both in the veinlets and in disseminations. Cu- and Mo-minerals are related to a zone of quartz-biotite-sencite
pyrite alteration which occurs in a Paleogene quartz diorite and monzodiorite pluton and in adjacent, intruded Late Cretaceous
flysch. The pluton is bounded by a nearly east-west zone of pyritized altered rocks more than 1 1 krn long and from 1 to 4 km
wide. The deposit is of small to medium size. Small amounts of gold occur in goethite-cemented, Quaternary alluvial
conglomerate near the deposit.