USGS Professional Paper 1697 - Alaska Resources Library

pyrite, pyrite, galena, sphalerite, gold, electrum, freibergite,
tetrahedrite, Pb-Sb and Ag-sulfosalts, argentite, and stibnite.
The Au ore bodies extend to great depth into a large zone of
complicated mineralogy, geochemistry, and structure. The total
reserves are estimated at 32 tonnes Au averaging 29 g/t Au and
45 g/t Ag. The mine at the deposit has produced 17 tonnes Au
and 17 tonnes Ag from 1991 to 1997.
Eastern Asia-Arctic Metallogenic Belt:
Vostochno-Verkhoyansk Zone of Ag Polymetallic
Vein and Clastic Sediment-Hosted Hg Deposits
(Belt VV), West-Central Part of Russian Northeast
The Vostochno-Verkhoyansk metallogenic zone of Ag
polymetallic vein and clastic sediment-hosted Hg deposits (fig.
79; tables 3, 4) occurs in two fragments, each 250 km long
and 20 to 50 km wide, in the west-central part of the Russian
Northeast (Goryachev, 1998, 2003). The deposits are hosted
in Carboniferous and Permian clastic rocks of the North Asian
Craton Margin (Verkhoyansk fold belt, unit NSV; Nokleberg
and others, 1994c, 1997c). The Vostochno-Verkhoyansk
metallogenic belt is the loci of old mining that started in the
18th century. The belt contains newly discovered deposits,
which are currently being developed for mining. The significant
deposits in the belt are Ag polymetallic vein deposits at
Altaiskoe, Bezymyannoe, Kuolanda, Mangazeika, Prognoz,
and Verkhnee Menkeche and a Sn polymetallic vein deposit at
Imtachan (table 4) (Nokleberg and others 1997a,b, 1998). Ag
polymetallic vein deposits and occurrences, as at Altaiskoe,
Mangazeika, and Menkeche, occur in longitudinal and diagonal
faults that crosscut the hinges of major folds.
The age of mineralization for the Vostochno-Verkhoyansk
metallogenic belt is interpreted as Late Cretaceous to Paleogene
because the deposits formed prior to the development of
the clastic sediment-hosted Hg deposits of the Verkhoyansk-
Indigirka metallogenic belt in the same region (Indolev, 1979;
Goryachev, 1998). The Vostochno-Verkhoyansk metallogenic
zone is interpreted as forming in the rear (back-arc) part of the
Cretaceous and early Tertiary Okhotsk-Chukotka volcanic-plutonic
belt (fig. 79).
Mangazeika Ag Polymetallic Vein Deposit
The Mangazeika deposit (N.A. Tseidler, written commun.,
1985; Goryachev, 1998) consists of polymetallic veins
that occur in Early Permian argillite and sandstone that occur
in gently plunging tight folds. The veins fill fissures between
argillite and sandstone layers and are conformable to bedding.
The veins range from 50 to 1,300 m long and from 3 cm
to 1 m thick. The main ore minerals are galena and sphalerite;
minor minerals are pyrite, arsenopyrite, chalcopyrite,
owyheeite, freibergite, diaphorite, boulangerite, pyrargyrite,
miargyrite, cassiterite, stannite, native gold, native silver,
and argentite; gangue minerals are manganosiderite, quartz,
ankerite, sericite, chlorite, and tourmaline. This and similar
Early Late Cretaceous Metallogenic Belts (100 to 84 Ma; figs. 79, 80) 203
deposits do not contain significant amounts of sulfide minerals;
silver amalgam is locally present. Other deposits, as at
Menkeche and Bezymyannoe, are associated with Early and
Late Cretaceous basaltic dikes and associated Sn polymetallic
vein deposits. Wallrock alteration, including carbonization and
silicification, is not significant. Estimated reserves are 62,375
tonnes Pb, 2,900 tonnes Zn, and 324 tonnes Ag. Estimated
total resources are more than 1,000 tonnes Ag. Average grades
are 75 percent Pb; 0.3-5 percent An; 500 to 3,938 g/t Ag; and
0.1 to 0.5 g/t Au. Silver was mined from 1915 to 1922.
Eastern Asia-Arctic Metallogenic Belt: Adycha-
Taryn Zone of Au-Ag Epithermal Vein, Ag-Sb
Polymetallic Vein, and Clastic Sediment-Hosted
Sb-Au Deposits (Belt AT), Western Part of
Russian Northeast
The Adycha-Taryn metallogenic zone forms a linear array
of clastic sediment-hosted Sb-Au, Au-Ag epithermal vein, and
Ag-Sb polymetallic vein associated deposits (fig. 79; tables 3, 4)
that occur adjacent to the Adycha-Taryn fault in the western part
of the Russian Northeast (Goryachev, 1998). The Adycha-Taryn
Fault is a major collisional suture zone between the Kular-Nera
accretionary-wedge terrane of the Kolyma-Omolon terrane to
the northeast and the North Asian Craton Margin (Verkhoyansk
fold belt, unit NSV) to the southwest (Nokleberg and others,
1994c, 1997c). The metallogenic belt is about 750 km long and
5 to 10 km wide. Several groups of deposits occur in the metallogenic
belt (table 4) (Nokleberg and others 1997a,b, 1998)—
(1) small Au-Ag epithermal vein deposits, as at Ak-Altyn, (2)
small Ag-Sb polymetallic vein occurrences, and (3) high-grade
clastic-sediment-hosted Au-Sb deposits, as at Billyakh, Sarylakh,
Sentachan, and Uzlovoe. Many of the clastic-sedimenthosted
Au-Sb deposits, as at Sarylakh, are partly mined out.
The age and genesis of the Adycha-Taryn zone is more
complex than previously interpreted because some of the
deposits (1) are not evidently magmatism-related, (2) are relatively
younger than Au quartz vein and Sn-W vein deposits,
which occur in the same area, and (3) locally crosscut hornfels
near granite intrusions that exhibit K-Ar isotopic ages of 110
to 90 Ma. Three possible origins are suggested for the genesis
of the Au-Sb deposits in the Adycha-Taryn metallogenic
belt—(1) a deep and possible mantle origin may be indicated
by the local occurrence of native metals in the Au-Sb deposits
(Anisimova and others, 1983), (2) the clastic-sediment-hosted
Au-Sb deposits, which occur in and near the major Adycha-
Taryn fault, may have formed in an accretionary environment
and are related to metamorphism that occurred immediately
after collision and accretion of the Kolyma-Omolon superterrane
to the North Asian Craton Margin (Verkhoyansk fold belt,
unit NSV, fig. 79) along the Adycha-Taryn fault (Berger, 1978,
1993; Nokleberg and others, 2000), and (or) (3) the Au-Sb
epithermal deposits and the polymetallic vein deposits may
have formed in a postaccretional environment and are related
to younger, Cretaceous and Paleogene basaltic magmatism