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

The Au quartz vein deposits are interpreted as synmetamorphic and formed relatively earlier than the nearly coeval Aupolymetallic
vein deposits (Goryachev, 1998, 2003). The Au quartz vein deposits are controlled by diagonal and longitudinal
faults and anticlinal domes (Amuzinsky, 1975) and occur both as sheeted ore bodies and sometimes as stockworks.
An example of an Au polymetallic vein deposit is at Chochimbal. An example of a Sn polymetallic vein deposits is at
Imtandzha. The polymetallic vein deposits occur in the southern half of the metallogenic belt and are closely associated with
Cretaceous granitoid rocks. The Au-Sn poly~netr~llic vein deposits are relatively older than associated granitoid rocks (lvensen and
others, 1975; Goryachev, 1998,2003).
Nikolaevskoe and Otkrytoe Au Quartz Vein Deposits
The Au quartz vein deposits at Nikolaevskoe and Otkrytoe (Abel and Slezko, 1988) consist of conformable and crosscutting
quartz veins with gold, galena, arsenopyrite, pyrite, tetrahedrite, sulfosalts, carbonates, and albite : which ar e hosted i n Early
Permian sandstone beds. The veins occur in anticlinal hinges, are up to 1 km long, and range from 0.2 to I 1 m thicl c, sometin ?es up
to 10 m thick. Sulfides comprise up to 5% of the veins. The Au quartz vein deposits are not economic, b ut the sou rce for thc
placer Au mines of the Verkhoyansk district.
Chochimbal Au Polymetallic Vein Deposit
The Au polymetallic vein deposit at Chochimbal (Goryachev, 1994,2003) consists of interbedded shallow-dipping,
steeply-dipping, cross-cutting carbonate-quartz-sulfide veins which are hosted in mid-Carboniferous clastic rocks. The ore bodies
vary from 0.1 to 2.8 m thick and from 400 to 500 m long. The major minerals are quartz, siderite, sulfides, pyrite, arsenopyrite,
Fe-sphalerite, and galena. Less common minerals are chalcopyrite, pyrrhotite, tetrahedrite, bournonite, native gold, and
boulangerite.
lmtandzha Sn polymetallic Vein Deposit
The lmtandzha Sn polymetallic vein deposit occurs in a zone of an intense fissures along the axis of an anticline which is
about 500 m wide and 2 km long. Coeval granodiorite porphyry dikes which both cut a and are cut by the polymetallic vein
deposits (Goryachev, 1998,2003). Early-stage polymetallic veins are mostly conformable whereas late stage, cross-cutting veins
are less common. The early-stage veins range from 0.01 to 0.85 m thick. The major minerals are galena, sphalerite, and siderite;
minor minerals are quartz, tetrahedrite, pyrite, arsenopyrite, and boulangerite. The late stage veins contain quartz, chlorite, pyrite,
arsenopyrite, galena, cassiterite, tourmaline, and stannite and range from 0.1 to 0.6 m thick.
Origin of and Tectonic Controls for
Verkhoyansk Metallogenic Belt
The Verkhoyansk metallogenic belt is hosted in rocks late Paleozoic to early Mesozoic clastic sedimentary rocks which
are weakly metamorphosed, lower greenschist facies with development of metamorphic chlorite and rare biotite. Permian and
Triassic diabase dikes are wide-spread along with isolated Cretaceous granitoid plutons and variable-composition dikes. The Au
quartz vein deposits of the Verkhoyansk metallogenic belt are interpreted as forming during regional deformation and
metamorphism associated with accretion of the Kolyma-Omolon superterrane to the Verkhoyansk fold belt of the North Asian
Craton Margin (Goryachev, 1998,2003). The slightly younger Au and Sn polymetallic vein deposits of the Verkhoyansk
metallogenic belt are interpreted forming during the Main part of the Early Cretaceous Verkhoyansk collisional granitic belt (vk)
(Nokleberg and others, 1994c, 1997~). The belt is interpreted as forming immediately after the Late Jurassic accretion of the
Kolyma-Omolon superterrane to the North Asian Craton Margin (Nokleberg and others, 1994c, 1997~).
Yana-Kolyma Metallogenic Belt of Au Quartz Vein,
Sn Vein and Greisen, W Vein, Granitoid-Related Au,
and ClasticSediment-Hosted Hg Deposits (Belt YA)
Central Part of Russian Northeast
The Yana-Kolyrna metallogenic belt of mainly Au quartz vein, lesser Sn vein, Sn greisen, granitoid related Au, W vein
deposits, and clastic-sediment-hosted Hg deposits (fig. 6 1; tables 3.4) occurs in the central part of the Russian Northeast
(Goryachev, 1998,2003). The Yana-Kolyma belt is hosted in the upper Paleozoic through middle Mesozoic rocks of the Kular-
Nera accretionary-wedge terrane of the Kolyma-Omolon superterrane (Nokleberg and others, 1994c, 1997~). Major, wide shear
zones, distinct folds, and numerous granitic intrusions characterize the host rocks of the metallogenic belt. These structures and
intrusions are interpreted as forming during collision of continental blocks in the Late Jurassic to Early Cretaceous. The collisional
zone contains a major belt of Early Cretaceous granitoid plutons which are mainly high alumina and S-type with lesser I-type
plutons (Shkodzinsky and others, 1992). The latter are associated with numerous andesite and granitic porphyry dike suites.
The numerous Au quartz vein lode and related placer Au deposits in the Yana-Kolyma metallogenic belt are sites of
extensive Russian Northeast Au production (Shilo, 1960; Firsov, 1957, 1985; Goryachev, 1998,2003). The total production has
been more than 2,570 tonnes of placer Au, and about 100 tonnes of lode Au. The most important lode Au deposits in the