USGS Professional Paper 1697 - Alaska Resources Library

(Nokleberg and others, 1994c, 1997c). Southeast Missouri
Pb-Zn-fluorite deposits, as at Urultun, are most prevalent,
and occur in Late Ordovician through Middle Devonian strata
(Shpikerman, 1987, 1988). The significant deposits are the
Urultun Southeast Missouri Pb-Zn deposit, the Uochat carbonate-hosted
Hg deposit, the Batko basaltic Cu deposit, the Lyglykhtakh
volcanogenic Mn deposit, and the Prizovoe bedded
barite deposit (table 4) (Nokleberg and others 1997a,b, 1998).
Urultun Southeast Missouri Pb-Zn Deposit
The Urultun Southeast Missouri Pb-Zn deposit (fig. 27)
(Shpikerman, 1987, 1998) consists of disseminated veinlets
and brecciated ore that occur in Early Devonian dolomite
overlain by Middle Devonian (Givetian) marl. The ore bodies
are composed of dolomite, calcite, fluorite, galena, sphalerite,
and anthraxolite. Barite, pyrite, and cinnabar are present
locally. The deposit is interpreted as forming in two stages—
(1) an early sphalerite-fluorite stage that resulted in disseminated
metasomatic ore, and (2) a galena-fluorite-calcite stage
0 0.5 km
60
o
50
o
Middle and Late Devonian Metallogenic Belts (387 to 360 Ma; figures 16, 17) 61
80
o
70
o
that resulted in brecciated and veinlet ores. The ore-bearing
dolomite sequence is as much as 240 m thick and occurs along
a synclinal limb of a fold that generally trends northwesterly.
Two to five conformable ore horizons, varying in thickness
from 1 to 10 m, occur in the dolomite sequence. The ore bodies
are sporadic within a given horizon. The deposit occurs
over an area of about 20 by 4 km. This and other deposits
and host rocks are stratigraphically overlapped by deep-sea
argillaceous and carbonaceous sedimentary rocks. The deposit
contains an estimated resource of 23 million tonnes with an
average grade of about 2.85 percent Pb, 6.74 percent Zn, and
10 percent fluorite.
Carbonate-Hosted Hg Deposits
The carbonate-hosted Hg deposits of the Urultun and
Sudar Rivers metallogenic belt are interpreted as forming in
the same event as the Southeast Missouri Pb-Zn deposits. The
significant deposit at Uochat (Babkin, 1975) consists of disseminated,
cinnabar-bearing veinlets that occur in brecciated
60
o
Unconsolidated Quaternary
sediment
Diabasic sill (Late Paleozoic)
Siltstone, argillaceous and
cherty shale (Late Devonian
and Early Carboniferous)
Limestone (Late Devonian)
Dolomite, dolomitic marl, &
dolomite breccia (Middle
Devonian)
Limestone (Early Devonian)
Diagenetic dolomite (Early
Devonian)
Dolomitic marl (Late Silurian and
Early Devonian)
Thrust fault
Fault, displacement unknown
Contact
High grade fluorite-lead-zinc ore
Strike and dip of bedding
Figure 27. Urultun Southeast Missouri Pb-Zn deposit, Urultun and Sudar Rivers metallogenic belt, Russian Northeast. Generalized geologic
map of the Bitum-Sdvig area of stratabound F-Pb-Zn deposit. Adapted from Shpikerman (1987). See figure 16 and table 4 for location.