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

magmatism-related deposits occurs in the Oloy metallogenic belt. Au-Ag epithermal veins generally occur peripheral to granitic
intrusions which host porphyry Cu-Mo deposits whereas Au quartz-carbonate-sulfide polymetallic vein deposits occur in
intermediate sites between the Au-Ag epithermal vein and porphyry Mo deposits.
Peschanka Porphyry Cu-Mo Deposit
The Peschanka porphyry Cu-Mo deposit (fig. 53) (Gorodinsky and others, 1978; Volchkov and others, 1982; Kaminskiy
and Baranov, written commun., 1982; Migachev and others, 1984; V.V. Gulevich and others, written cornrnun., 1993) occurs in
the eastem portion of the Late Jurassic to Early Cretaceous Egdegkych multiphase pluton which is composed of monzodiorite and
quartz monzodiorite which are intruded by planar bodies of quartz monzonite and granodiorite porphyry. The deposits consists of
sulfide veinlets and disseminations, with pervasive Cu and Mo minerals which occur throughout the entire elongated quartz
monzonite and granodiorite porphyry body and which extend into the wall rock. The main ore minerals are pyrite, chalcopyrite,
bomite, tetrahedrite-tennantite, and molybdenite. Minor or rare minerals are magnetite, hematite, sphalerite, galena, chalcocite,
native gold Au-tellurides, enargite, arsenopyrite, pyrrhotite, and marcasite. The gangue minerals are quartz, carbonate, and
anhydrite. Four mineral associations occur: (1) molybdenite which is associated with the quartz-sericite subzone of phyllic
alteration; (2) pyrite and chalcopyrite which are associated with quartz-sericite-chlorite alteration; (3) chalcopyrite, bornite, and
tetrahedrite which are associated with quartz-sericite and biotite alteration; and (4) polysulfide minerals which occur with aU
alteration types. Mineralization was preceded by wide-spread pyritization in the peripheral propylitic zone. The deposit contains
an estimated resource of 940 million tonnes with an average grade 0.5 1% Cu, 0.019% Mo, 0.42 g/t Au, and 1.4 glt Ag.
Surficial rock (Quaternary)
Andesite and dacite
% . (Late Cretaceous)
Continental sedimentary rocks:
sandstone & siltstone with
interlayered gritstone,
con lomerate, and coal (Early
~reieceous)
Marine sedimentary rocks:
siltstone, mudstone,
sandstone, conglomerate,
tuff, and lava (Late
Jurassic)
Late Jurassic-Early Cretaceous
Subvolcanic and Intrusive rock
Trachydacite, trachyrhyolite,
trachyandesite
Quartz syenite, granosyenite-
porphyry,.quartz monzonlte.
monozon~te-porphyry
Gabbro, monzodiorite.
gabbro-monzonlte
/ Contact CU-MO ore
/ Fault AUA~ ore
Figure 53. Peschanka porphyry Cu deposit, Oloy metallogenic belt, Russian Northeast. Schematic geologic map. Adapted from
Migachev and others (1984) using materials of V.V. Gulevich and E.F. Dylevsky.
Vesennee Au-Ag Epithermal Vein Deposit
The Vesennee Au-Ag epithermal vein deposit (Gorodinsky and others, 1974; Shilo and others, 1975; Shapovalov, 1976;
Sidorov, 1978; V.V. Gulevich and others, written cornrnun., 1993) consists of carbonate-quartz veins, altered veinlets, and
mineralized breccias which occur in structurally complex forms. The veins are controlled by northeast- and approximately east-
west-trending fractures which cut northwest-trending zones of associated granitoid rocks. Individual ore bodies range from 150 to
500 m long. The ore minerals are sphalerite, galena, pyrite, chalcopyrite, tetrahedrite, temantite, bournonite, and electn~m, with
minor Ag-sulfides and sulfosalts, stannite, and matildite. The main gangue minerals are quartz, calcite, and rhodochrosite with