USGS Professional Paper 1697 - Alaska Resources Library

148 Metallogenesis and Tectonics of the Russian Far East, Alaska, and the Canadian Cordillera
Yana-Polousnen Metallogenic Belt of Granitoid-
Related Au, Sn Quartz Vein, W Vein, Sn Greisen,
Co-, Au-, and Sn-Skarn, Sn-Silicate Sulfide Vein
and Related Deposits (Belt YP), Central Part of
Russian Northeast
The Yana-Polousnen metallogenic belt of granitoidrelated
Au, Sn quartz vein, W vein, Sn greisen, Co-, Au-, and
Sn-skarn, Sn-silicate sulfide vein and related deposits (fig.
61; tables 3, 4) occurs in an enormous, discontinuous wide
zone, about 1,000 km and as much as 200 km wide in the
northwestern part of the Russian Northeast (Shpikerman and
Goryachev, 1995, 1996, 2003). The belt trends from the lower
part of the Alazeya River in the southwest to the headwaters of
the Yana River in the northeast. The belt is locally extensively
overlain by unconsolidated Cenozoic sedimentary deposits.
The granitoid-related deposits occur in or near granitoid rocks
that intrude (1) the North Asian Craton Margin (Verkhoyansk
fold belt, unit NSV), (2) carbonate, clastic, and igneous
rocks of the Omulevka, Munilkan, and Kular-Nera terranes
of the Kolyma-Omolon superterrane, and (3) the overlapping
Polousnen flysch of the Indigirka-Oloy sedimentary-volcanic
assemblage (unit io; Nokleberg and others, 1994c, 1997c).
Several types of lode deposits occur in the Yana-Polousnen
metallogenic belt (table 4) (Nokleberg and others 1997a,b,
1998): (1) Medium to major Sn and W quartz vein, and Sn
greisen mines and deposits, some of that are now mostly
exhausted, occur at Argin, Kester, Balyktaah, Ploskoe, Odinokoe,
Polyarnoe, and Takalkan. These deposits generally occur
in the apical portions of granitoid plutons and are associated
with placer Sn and W placer deposits. (2) Co, Au, and Sn
skarn deposits, as at Kandidatskoe and Arbatskoe, and granitoid
related Au quartz vein deposits, as at Chistoye and Tuguchak-2,
generally occur along the contacts of granitoid plutons.
(3) Sn-silicate-sulfide and Sn polymetallic vein deposits,
usually associated with Ag, occur at Alys-Khaya, Anomalinoe,
Bugdogar, Burgachan, Ege-Khaya, Khoton-Khaya, Ilin-Tas,
Sigilyakh, and Ulakhan-Egelyakh. These deposits generally
occur adjacent to intrusions along contacts, often adjacent to
mafic and intermediate dikes, and are associated with the late
stage mineralization and associated granitic magmatism. (4)
Sb, Pb, and Zn polymetallic vein deposits, as at Altinskoe,
Aragochan, Dalnee, Dokhsun, and Verkhne-Naanchan, are
associated with granitoid plutons. Isotopic studies indicate the
deposits and associated granitoid rocks formed from about 130
to 110 Ma (Nenashev, 1979; Goryachev, 1998, 2003; Parfenov,
1995; Parfenov and others, 1999).
Polyarnoe Sn Greisen and Vein Deposit
The Polyarnoe Sn greisen and vein deposit (Nekrasov,
1962; O.G. Epov and G.S. Sonin, written commun., 1964;
Flerov, 1974) consists of quartz and quartz-topaz veins that
dip gently to moderately (5-40°) near and within a stock of
apogranite at the top of the major Cretaceous Omchikandin
leucogranite batholith. The veins range from 0.1 to 3.5 m
thick, are as much as 300 m long, and extend as much as 260
m down dip. The main minerals are quartz, topaz, fluorite,
muscovite, zinnwaldite, wolframite, cassiterite, arsenopyrite,
molybdenite, tourmaline, sphalerite, galena, pyrite, chalcopyrite,
stibnite, bismuth, bismuthine, and bismuth sulfosalts. No
size or grade data are available. The deposit is associated with
quartz-topaz greisen.
Kandidatskoe Au Skarn Deposit
The Kandidatskoe Au skarn deposit (Nekrasov, 1962;
Bakharev and others, 1988) consists of zones of garnet-pyroxene,
pyroxene-wollastonite, pyroxene, and epidote-pyroxene
skarn, which are as much as 100 to 150 m long and as much as
50 m thick. The skarn zones occur in a block of Devonian carbonate
and Permian clastic rocks located between granodiorite
of the Early Cretaceous Ulakhan-Tass pluton and monzonite of
the mid-Cretaceous Kandidatsky stock. The main (No. 1) ore
body occurs as a steeply-plunging, funnel-shaped pipe of massive
and disseminated ore with an outcrop area of 150 m long
and as much as 20 m wide. The main minerals are arsenopyrite,
löllingite, pyrrhotite, molybdenite, glaucodot, cobaltite,
gold, bismuth, bismuthine, maldonite, hedleyite, and A and
B joseite. The gold is fine-grained (98 percent less than 0.08
mm) and has a fineness of 650 to 1,000. At the adit level (50
m), the thickness of the ore body is half of that at the surface.
The deposit contains as much as 55 g/t Au, 3 percent Co, 20
percent As, 0.5 percent Bi, 3 percent Zn, 0.5 percent Ni, 0.1
percent Te.
Chistoe Granitoid-Related Au Deposit
The Chistoe granitoid-related Au deposit (Bakharev and
others, 1988) consists of a set of quartz veins that range from
10 to 50 m long and from 0.1 to 0.5 m thick. The veins occur
in two steep-lying, northeast-striking shear zones that are as
much as 500 m long and are hosted in contact metamorphosed
Late Jurassic sandstone and in Early Cretaceous granodiorite
stocks. The main minerals are muscovite, quartz, tourmaline,
arsenopyrite, cobaltite, calcite, wolframite, native bismuth,
native gold (fineness 500 to 1000), bismuthine, joseite (A,
B, M, L types), and maldonite. The veins are associated with
greisen zones that are as much as 1 to 2 m wide. The deposit
contains as much as 20 g/t Au, 0.9 percent W, 0.5 percent Bi,
and 1 percent As.
Ilin-Tas Sn Silicate-Sulfide Vein Deposit
The Ilin-Tas Sn silicate-sulfide vein deposit (Shur and
Flerov, 1979; T.N. Spomior and others, written commun.,
1985) consists of complex veins and less common shear
zones and stringers that occur in contact metamorphosed
Late Triassic sandstone and siltstone adjacent to the Bezymyanny
granitoid pluton. Granodiorite of the early magmatic
phase has an Rb-Sr isotopic age of 170 Ma with an initial Sr
isotopic age of 0.7035, and fine-grained granite of the second