USGS Professional Paper 1697 - Alaska Resources Library

190 Metallogenesis and Tectonics of the Russian Far East, Alaska, and the Canadian Cordillera
deposits formed in the Late Cretaceous and early Tertiary (70-60
Ma) and are Sn silica-sulfide vein deposits, as at Arsenyevsky,
which are composed mainly of cassiterite and silicate minerals.
These deposits are often generally spatially related to the older
Sn polymetallic deposits and formed simultaneously with Zn-Pb
skarn deposits of the postaccretionary Taukha metallogenic belt to
the east. The Late Cretaceous and early Tertiary Sn silica-sulfide
vein deposits are interpreted as related to the formation of ultrapotassic
rhyolite volcanic porphyries; however, any direct relation to
intrusion rocks is quite obscure.
Tigrinoe Sn Greisen Deposit
The Tigrinoe Sn greisen deposit (fig. 91) (Rodionov and
Rodionova, 1980; Rodionov and others, 1984; Ruchkin and
Map
A B
0 100 m
Cross section
A
Victoria Zone
Polyarnaya Zone
Polymaya Zone
Victoria Zone B
Quaternary
deposits
Clastic rock
Andesite
dike
Diorite
porphyry
Mineralized
zone
Contact
Fault
Figure 90. Iskra deposit Sn polymetallic vein deposit, Luzhkinsky
metallogenic belt, Russian Southeast. Schematic geologic map
and cross section. Adapted from Gonevchuk and others (1998).
See figure 79 and table 4 for location.
others, 1986; Rodionov and others, 1987; Korostelev and
others, 1990; Gerasimov and others, 1990; Gonevchuk and
Gonevchuk, 1991; Gonevchuk and others, 1998) is a complex
Sn-W deposit consisting of (1) a stockwork of quartz-topazmicaceous
greisen along the contact of a massif of Li-F granite,
(2) a linear stockwork consisting of a thick network (5 to 70
veinlets per meter) of parallel north-south-trending quartztopaz
veins from 3 to 100 cm thick that are hosted in contactmetamorphosed
sedimentary rocks adjacent to the granite intrusion,
and (3) a sulfide breccia pipe consisting of rock fragments
of the stockwork and greisen cemented by quartz with lesser
carbonate, fluorite, and sulfides. Three stages of mineralization
are distinguished—(1) early quartz-molybdenite-bismuthinite,
(2) middle-stage REE greisen of wolframite-cassiterite with
high contents of Sc, Ni, and Ta, and (3) late hydrothermal
quartz-fluorite-carbonate-sulfide veins. In, Cd, Ag, and Se are
enriched in sulfides of the two last stages. A Rb-Sr age of the
lithium-fluorine granite is 86 ± 6 Ma with an initial Sr ratio of
0.7093. A Rb-Sr age of the greisen is 73 ± 18 Ma with an initial
Sr ratio of 0.7105. The average grade is 0.14 percent Sn and
0.045 percent W 2O 3. The deposit is of medium size.
Zimnee Sn Polymetallic Vein Deposit
The Zimnee Sn polymetallic vein deposit (P.G.
Korostelev and others, written commun., 1980; Nazarova,
1983; Gonevchuk and others, 1998) consists of mineralized
breccia,breccia- and fracture-filling veins, zones of closely
spaced veinlets, and pockets that occur in fracture zones. The
Sn polymetallic ore bodies have strike lengths as much as
1200 m, are extensive down dip, and vary in thickness from
several tenths of a meter to several tens of meters. The deposit
occurs near a granodiorite body and consists mainly of pyrrhotite,
pyrite, arsenopyrite, sphalerite, stannite, and cassiterite.
Ore far from the granodiorite and in the upper part of veins is
mostly galena with fine-grained cassiterite. Near the granodiorite,
the ore consists of breccia-bearing fragments of tin-sulfide
minerals that are cemented by a quartz-micaceous (greisen)
aggregate with arsenopyrite and cassiterite. The K-Ar age
of altered rocks associated with the Sn-polymetallic ores is 75
Ma. The age of greisen assemblage is approximately 50 Ma as
determined by a K-Ar age of 50 Ma for the granodiorite. The
deposit exhibits regional metamorphism and cataclasis, and is
small. Average grades are 0.1 to 3.0 percent Cu, 3.18 percent
Pb, 0.59 percent Sn, and 4.09 percent Zn.
Arsenyevskoe Sn Silica-Sulfide Vein Deposit
The Arsenyevskoe Sn silicate-sulfide vein deposit (fig. 92)
(Rub and others, 1974; Radkevich and others, 1980; Gonevchuk
and others, 1998), one of the larger Sn vein mines in the
Luzhkinsky belt, consists of a series of parallel, steeply dipping
quartz veins as much as 1,000 m along strike and 600 to 700 m
down dip. The deposit is closely associated with moderate to
steeply dipping rhyolite dikes with K-Ar isotopic ages of 60 Ma
(early Tertiary). The ore mineral assemblage is vertically zoned.
From the top downwards, the assemblages are quartz-cassiterite,