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

Eastern Asia-Arctic Metallogenic Belt:
Dogdo-Erikit Metallogenic Zone of
Au-Ag Epithermal Vein, Sn-polymetallic vein
(Southern Bolivian type?), and Volcanic-Hosted
Hg (Plamennoe type) Deposits (Belt DE)
West-Central Part of Russian Northeast
The Dogdo-Erikit metallogenic zone of Au-Ag and Ag-Sb epithermal vein, and volcanic-hosted Hg deposits (fig. 79;
tables 3,4) extends for about 1,000 km and up to 50 to 70 krn wide in a narrow band from the northwest to he southeast in the
west-central part of the Russian Northeast (Goryachev, 1998,2003). This belt is hosted in the volcanic rocks of the Uyandin-
Yasachen volcanic belt and the clastic deposits of the lnyali-Debin flysch basin (both parts of the Indigirka-Oloy sedimentary-
volcanic assemblage), and the underlying carbonate rocks of the passive continental margin Omulevka terrane of tbe Kolyma-
Omolon superterrane.
The Dogdo-Erikit zone contains significant Au-Ag epithermal vein deposits, as at Kysylga, Tikhon, and Shuokoe, Sn-
polymetallic vein (Southern Bolivian type?) deposits at Solkuchan, and a volcanic-hosted Hg deposit Dogdo (table 4) (Nokleberg
and others 1997a, b, 1998). The Au-Ag epithermal vein deposits are closely related to Late Cretaceous hypabyssal rhyolite bodies
with K-Ar isotopic ages of 90 to 56 Ma. The hypabyssal rhyolite5 crosscut contact metamorphic aureoles ofolder Cretaceous
granitoid plutons (Gamyanin and Goryachev, 1988). The Dogdo volcanic-hosted Hg deposit and similar deposits are hosted in
Early Cretaceous(?) felsic volcanic rocks which are associated with rhyolite and andesite hypabyssal bodies with K-Ar ages of
125 to 63 Ma (Ganeev, 1974). The volcanic-hosted Hg deposits are small, uneconomic, and occur in the northwest part of the
metallogenic belt which overlies the Selennyakh metallogenic belt of pre-accretionary Hg deposits (fig. 79). The Dogdo-Erikit
metallogenic zone is interpreted as forming in a transverse (orthogonal) limb of the Cretaceous Okhotsk-Chukotka volcanic-
plutonic belt (Goryachev, 1998,2003).
Kysylga Au-Ag Epithermal Vein Deposit
The Kysylga Au-Ag epithermal vein deposit (Shoshin and Vishnevsky, 1984; Yu.A. Vladimirtseva, written comun.,
1985; Nekrasov and others, 1987; Gamyanin and Goryachev, 1988) consists of veins in a zone which varies from 0.60-1.25 m
thick and up to 400 rn long. The veins are composed of quartz, calcite, and ore minerals (1-5%) including arsenopyrite, pyrite, Ag-
tetrahedrite, pyrrhotite, sphalerite, galena, chalcopyrite, boulangerite, Ag-jamesonite, and a low gold fineness (638). The veins
strike from roughly east-west to northeast and dip steeply to south. The veins exhibit breccia or, less commonly, comb and
massive structures, and often grade into stringer lodes. The deposit occurs in feathered fissures of a northwest-striking major fault
and is hosted in Late Triassic sandstone and siltstone which exhibits linear folding and intense contact metamorphic alteration
adjacent to a granitic intrusive. Waltracks display sericite, chlorite, and feldspar alteration. Average grades are 3.0-84.5 g/t Au, 1-
37 g/t Ag; 0.01-0.1 As; 0.01-0.04% Sb; 0.002% Sn, and 0.03% Pb.
Solkuchan Sn-Ag Polymetallic Vein
(Southern Bolivian type?) Deposit
The Solkuchan Sn-polyrnetallic vein (Southern Bolivian type) deposit (S.M. Khaustova and Yu.A. Vladimirtseva, written
cornmun., 1987; Nekrasov and others, 1987; Shkodzinsky and others, 1992) consists of three steeply-dipping quartz-carbonate-
sulfide veins which occur in an Early Cretaceous subvolcanic dacite stock. The veins are up to 3.4 m thick and up to 900 m long.
The ore minerals are pyrite, pyn-hotite, arsenopyrite, sphalerite, galena, Ag-tetrahedrite (3 1-39% Ag), boulangerite, pyrargyrite,
canfieldite, electnun (fmeness 685), cassiterite, covellite, scordte, cerussite, smithsonite, melnikovite, and Fe-hydroxides.
Anomalous Cu, Sb, Ge, and Id are present. The deposit is of medium size. Average grades are 200 g/t Ag, from 0.04 to 2.16% Sn,
0.03 to 2.7 1% Pb, and 0.02 to 5.85% Zn.
Dogdo Volcanic-Hosted Hg (Plamennoe type) Deposit
The Dogdo volcanic-hosted Hg (Plamennoe type) deposit (Klimov, 1979; Yu.A. Vladimirtseva, written commun., 1987)
consists of four lenticular and podiform ore bodies which occw in strongly silicified Late Jurassic andesite-dacite tuff. The ore
bodies are 20 to 100 m long and 2 to 8 m wide. The ore minerals are quartz, calcite, barite with disseminations and stringers of
cinnabar, pyrite, arsenopyrite, sphalerite, galena, and chalcopyrite. The ore district is characterized by a close correlation between
Hg content and barite. Mineralization is controlled by a northwestern thrust fault, secondary quartzite occurrences, and occurrence
of ore bodies along feathering fractures of the thrust fault. The deposit is of minor-to-medium size. Average grades are 0.35 to
0.90% Hg.