USGS Professional Paper 1697 - Alaska Resources Library

Berezovka River Metallogenic Belt of Kuroko
Massive Sulfide Deposits (Belt BE) Central Part
of Russian Northeast
The Berezovka River metallogenic belt of kuroko massive
sulfide and sulfide vein deposits occurs in the Berezovka
River basin in the west-central part of the Russian Northeast
(fig. 16; tables 3, 4) (Nokleberg and others, 1997b, 1998).
The belt is hosted in the Late Devonian through Late Permian
turbidite deposits that are part of the Beryozovka turbidite
basin terrane of the Kolyma-Omolon superterrane (Nokleberg
and others, 1994c, 1997c). The northwest-trending belt is
120 km long and as much as 100 km wide. The belt occurs
in four areas separated by units of postaccretionary volcanic
rocks. In addition to kuroko massive sulfide deposits, the belt
also contains numerous stratiform vein and veinlet-disseminated
Au- and Ag-bearing Ba-Pb-Zn deposits. The significant
deposit at Berezovskoe and other similar deposits are hosted
in the Tynytyndzhin formation of Late Devonian (Frasnian and
Famennian) age.
Berezovskoe Kuroko Massive Sulfide Occurrence
The Berezovskoe deposit consists of tuffaceous sandstone
and siltstone, and rhyolite and basalt flows (Gorodinsky and
others, 1974; N.A. Bobrov, written commun., 1976; Shpikerman,
1998). The Berezovskoe deposit consists of quartzsulfide
veins and stratiform barite-sulfide bodies, which are
conformable to bedding in the host rocks. The major sulfide
minerals are galena and sphalerite. Some of the vein deposits
are interpreted as forming during late Mesozoic magmatism
that remobilized and redeposited the volcanic-rock-hosted
massive sulfide deposits (Davydov and others, 1988). Because
of a bimodal assemblage of basalt and rhyolite has recently
been recognized in the Devonian rocks of the Berezovka terrane
(Dylevsky, 1992), potential exists for the discovery of
new stratiform massive sulfide deposits.
Origin of and Tectonic Controls for Berezovka River
Metallogenic Belt
The Beryozovka turbidite basin terrane occurs in a series
of tectonic sheets that are thrust southward over the northern
margin of the Omolon terrane (Nokleberg and others, 1994c,
1997c). The Beryozovka terrane consists of (1) a basal section
of deep- and shallow-marine basalt, rhyolite, siliceous siltstone,
chert, sandstone, and conglomerate that formed in a rift setting
and that contains Late Devonian conodonts and radiolarians and
Early Carboniferous forminiferas, conodonts, and macrofossils,
and (2) Middle and Late Carboniferous to Early Jurassic chert,
siltstone, mudstone, and shale with pelitomorphic limestone
layers and argillaceous-calcareous concretions. The Late Devonian
Kuroko massive-sulfide deposits and associated bimodal
volcanic rocks are herein interpreted as forming during rifting,
which was the earliest interpreted event for the Beryozovka terrane
(Nokleberg and others, 1994c, 1997c).
Middle and Late Devonian Metallogenic Belts (387 to 360 Ma; figures 16, 17) 63
Metallogenic Belts Formed During Middle Paleozoic
Rifting of North American Craton Margin or
in Low-Temperature Brines Along Craton Margin
Mystic Metallogenic Belt of SEDEX Bedded
Barite and Southeast Missouri Pb-Zn Deposits
(Belt MY) West-Central Alaska
The Mystic metallogenic belt of SEDEX massive bedded
barite and Southeast Missouri Pb-Zn deposits occurs in West-
Central Alaska (fig. 17; tables 3, 4) (Nokleberg and others,
1997b, 1998). The belt is hosted in the Mystic and Nixon
passive continental-margin terranes (Nokleberg and others,
1994c, 1997c). The significant deposits are at Gagaryah and
Reef Ridge. The belt also contains younger a younger Besshi
massive sulfide(?) deposit at Shellebarger Pass. In addition,
very high Cu background values (350 to 450 ppm Cu) occur
in Late Triassic basalt, and several small syngenetic Cyprustype
chalcopyrite deposits occur within interstices of pillow
structures and in aquagene tuff of the Mystic terrane in the
McGrath quadrangle (T.K. Bundtzen, written commun., 1992).
Bedded Barite and Southeast Missouri Pb-Zn Deposit
A sedimentary-exhalative (SEDEX) bedded barite deposit
is hosted Gagaryah at in Late Devonian (Frasnian) shales and
clastic rock host barite mineralization in the Lime Hills D-4
Quadrangle (Bundtzen and Gilbert, 1991). The deposit consists
of nodular, laminated, composite, and massive, light gray barite
in Frasnian (early Late Devonian) shale, limestone, and minor
chert of Mystic Terrane. The deposit extends along strike for 640
m, has an average thickness of 20 m, and an estimated down-dip
extension of 300 m. The deposit contains slightly elevated levels
of Av, V, Sr (in celestite), but no lead or zinc. Sulfide isotopic
analyses of +20 and +24 determined from nodular and massive
barite, respectively. The deposit contains 2.3 million tonnes grading
51 percent barite. The barite is interpreted as deposited syngenetically
into host shale basin with barite rapidly precipitating
from low temperature hydrothermal fluids distal from exhalative
vents. Barite nodules and spheroids are also commonly encountered
in either Devonian or Mississippian strata at other localities
in the Mystic terrane to the northeast.
A Southeast Missouri Pb-Zn deposit at Reef Ridge consists
of stringers of brown sphalerite and minor galena in hydrothermal
breccia in carbonate rocks of the Silurian and Devonian
Whirlwind Creek Formation in the Nixon Fork terrane (Harold
Noyes, written commun., 1984). The deposit extends along
strike for 2,000 m and is as much as 15 m thick. The sulfides
pinch and swell along strike. The deposit is the best known
of ten similar nearby occurrences, and contains bout 181,000
tonnes of 15 percent combined Zn and Pb.
Shellebarger Pass Besshi Massive Sulfide(?) Deposit
The younger Shellebarger Pass Besshi massive sulfide(?)
deposit (Reed and Eberlein, 1972; Bundtzen and Gilbert,