USGS Professional Paper 1697 - Alaska Resources Library

the Badzhal-Ezop and Khingan parts and is hosted in granitoid
rocks of the Early and mid-Cretaceous Khingan-Okhotsk
volcanic-plutonic belt (fig. 61; Nokleberg and others, 1994c,
1997c). The significant deposits in the belt are the Festivalnoe,
Ippatinskoe, Loshadinayadgriva, and Solnechnoe Sn quartz
vein deposits, the Olgakanskoe and Pravourmiskoe Sn greisen
deposits, the Kapral porphyry Mo deposit, and the Ezop Sn
polymetallic vein deposit (table 4) (Nokleberg and others
1997a,b, 1998).
The Badzhal-Ezop part, which occurs in the northern part
of the metallogenic belt, consists of Sn greisen, Sn skarn, and
Sn quartz vein deposits. Sn minerals are predominant; Pb, Zn,
Ag, Bi, Cu, and W minerals are less prevalent. The distribution
of the Sn deposits is zoned. Quartz-cassiterite deposits (mainly
greisen with rare Sn skarn and Sn quartz vein deposits, as at
Verkhne-Ippatinskoe, Shirotnoe, Ezop, and Pravourmiiskoe)
occur along the contacts of large, crustal-origin granite and
leucogranite intrusions. These occur mainly in the western part
of the metallogenic belt adjacent to the craton. K-Ar isotopic
studies indicate the Sn deposits and associated Sn granites
formed between 75 to 100 Ma. The Badzhal-Ezop metal-
A
Map
0 750 1,500 m
Cross section
B
A
B
Late Early Cretaceous Metallogenic Belts (120 to 100 Ma; figs. 61, 62) 163
logenic belt contains Sn quartz vein deposits at Ezop, Festivalnoe,
Ippatinskoe, Loshadinayadgrive, and Solnechnoe. Sn
greisen and polymetallic vein deposits, as at Ezop, Olgakanskoe,
and Pravourmiiskoe generally occur in veins.
Disseminated manto replacement deposits, as at Shirotnoe,
also occur in the Badzhal-Ezop part of the belt. In this
and similar deposits, a major and relatively older assemblage
of ore minerals consists of quartz, cassiterite, topaz, fluorite,
muscovite, tourmaline, arsenopyrite, molybdenite, and
wolframite. A relatively younger and minor assemblage of ore
minerals consists of sphalerite, galena, chalcopyrite, bismuthite,
pyrrhotite, stannite, fluorite, and rare scheelite. This
younger assemblage is more dominant to the east, away from
source granitic intrusions, thereby illustrating a lateral zoning.
This zoned change of mineral composition of ore from east
to west is clearly observed in the Badzhal and Ezop mining
districts. In addition to Sn, the greisen deposits often contain
molybdenite and wolframite; locally each mineral is dominant.
The Khinghan part, which occurs in the southern part of
the metallogenic belt, contains Sn deposits are mainly associated
with potassic granitic intrusions with a K-Ar isotopic ages
Dacite (Late Cretaceous)
Rhyolite (Late Cretaceous)
Granite Dike (Late Cretaceous)
Granite-porphyry dike (Late
Cretaceous)
Alaskite (Late Cretaceous)
Greisen
Ore Body
Contact
Figure 74. Pravourmiskoe Sn
greisen deposit, Badzhal-Ezop-
Khingan metallogenic belt, Russian
Southeast. Adapted from
Semenyak and others (1988). See
figure 61 and table 4 for location.