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

(fig. 84; table 4) (Nokleberg and others 1997a, b, 1998; Valuy and Rostovsky, 1998). An isolated porphyry Cu deposit occurs at
Plastun, and an isolated Au-Ag epithermal vein deposit occurs at Soyuz (Valuy and Rostovsky, 1998).
The B skarn deposits of the Taukha metallogenic belt are interpreted as fonning early in the history of the East Sikhote-
Alin igneous belt, from about 90 to 70 Ma when part of the Taukha terrane was overlapped by ignimbrite sequences. Pb-Zn skam
deposits occur in the central part of the Taukha metallogenic belt, mainly in the Dalnegorsk district has produced about forty
percent of Russia's zinc and lead. The Pb-Zn skarn deposits are interpreted as forming after the B skarn deposits during a later
stage of post-accretion volcanism, with K-Ar ages of 70-60 Ma, and composed mainly of rhyolite and dacite. The skarn deposits
generally occur in large limestone blocks enclosed in Early Cretaceous olistostromes. The skams occur along the contacts between
limestone and clastic rocks and chert, and between limestone and overlying post-accretion volcanic rocks which overlie the Early
Cretaceous olistostrome.
r j
. '4:rF
C r
Surficial deposits (Cenozoic)
Granite porphyry (Late Cretaceous)
Granodiorite (Late Cretaceous)
Sedimentary rocks (Late Jurassic)
Undifferentiated sedimentary rocks
(Middle Jurassic)
Undifferentiated metamorphic rocks
(Permian)
Undifferentiated granitoid rocks
(Late Paleozo~c)
Gold-bearing shear and disseminated
zones
/1 Diamond drill hole
-
Fault
Contact
Figure 82. Askold Au granitoid-related Au deposit, Sergeevka metallogenic belt, Russian Southeast. Schematic geologic map and
cross section. Adapted from Goryachev (1995a).