USGS Professional Paper 1697 - Alaska Resources Library

ock, including coarse clastic rock, carbonate, volcaniclastic
rock, and black shale. Based on Devonian graptolites, the age
of the upper complex ranges from Devonian to Triassic. The
upper complex is interpreted as having been deposited along
the middle Paleozoic passive continental margin in the Verkhoyansk
fold belt (North Asian Craton Margin). The basaltic
Cu and sediment-hosted Cu deposits of the Rassokha metallogenic
belt are interpreted as forming during Ordovician rifting
of an island arc (Shpikerman, 1998).
Metallogenic Belts Formed During Early
Paleozoic Rifting of Continental Margins or in
Continental-Margin Arc Terranes
Dzhardzhan River Metallogenic Belt of
Southeast Missouri Pb-Zn, Sediment-Hosted
Cu and Sandstone-Hosted U deposits (Belt DZ),
Northern Part of Eastern Siberia
The Dzhardzhan River metallogenic belt of Southeast
Missouri Pb-Zn, sediment-hosted Cu, and sediment-hosted U
deposits (fig. 2; tables 3, 4) occurs in two areas in the northern
part of eastern Siberia in the northeastern North Asian
Craton Margin (Verkhoyansk fold belt, unit NSV; Nokleberg
and others, 1994c; Shpikerman, 1998). The two parts of the
belt trend for more than 400 km from the Dzardzhan River
in the south to the Laptev Sea in the north. The Dzhardzhan
River metallogenic belt contains sparse stratabound deposits in
Vendian, Early Cambrian, Late Devonian, and Early Carboniferous
sedimentary rocks. The major Southeast Missouri Pb-Zn
deposits are at Manganiler and Aga-Kukan, and the major
sediment-hosted U deposit is at Kyongdyoi (table 4) (Nokleberg
and others 1997a,b, 1998).
Manganiler Southeast Missouri Pb-Zn and Deposit
The Manganiler Southeast Missouri Pb-Zn and similar
deposits generally consist of layers of concordant, lenticular
galena-sphalerite ore bodies that occur in Early Cambrian
dolomite (Shpikerman, 1998). The ore bodies vary from 0.4
to 3.6 m thick and are as much as 135 m long. Disseminated
sulfides are locally replaced by massive, predominantly
sphalerite in the lower portion of the deposit. The sulfides
are banded locally. The major ore minerals are sphalerite and
lesser galena. Subordinate ore minerals are pyrite, marcasite,
and smithsonite. The occurrences also exist to the south, as at
the Aga-Kukan deposit, is a Southeast Missouri Pb-Zn occurrence,
and is hosted in Early Carboniferous limestone. Nearby
Late Devonian sandstone and shale contain sediment-hosted
Cu occurrences.
Kyongdyoi Sandstone-Hosted U Deposit
The Kyongdyoi sandstone-hosted U deposit consists of
uraninite crust, which occurs in Late Proterozoic (Vendian)
Cambrian through Silurian Metallogenic Belts (570 to 408 Ma) 31
and Early Cambrian sandstone and limestone (unit NSV, Verkhoyansk
fold belt; Yu.M. Arsky and others, written commun.,
1963). Uranium occurs in disseminated sulfides, such as pyrite
and sphalerite, and in bitumen (kerite) inclusions. The deposit
occurs in various stratigraphic levels of anticlinal domes and
in lens-shaped bodies that range from 0.3 to 2.3 m thick and
from 100 to 400 m long. The uranium-bearing zone is as much
as 50 km long.
Origin of and Tectonic Controls for Dzhardzhan River
Metallogenic Belt
The southeast Missouri Pb-Zn deposits of the Dzhardzhan
River metallogenic belt occur along two stratigraphic
horizons—in the lower part of a Cambrian sedimentary rock
sequence and in the Early Carboniferous Aga-Kukan suite.
The Lower Cambrian sedimentary rocks, about 110 m thick,
consist of bituminous and clay limestone and sandstone, conglomerate,
basalt flows, tuff (Natapov and Shuligina, 1991).
The Early Carboniferous Aga-Kukan suite is about 150 m
thick and consists of limestone and sandstone (Melnikov and
Izrailev, 1975). The sediment-hosted Cu deposits are hosted
in the Late Devonian and Early Carboniferous Artygan suite,
which is about 800 m thick and is stratigraphically beneath
the Aga-Kukan suite. The suite is composed of red limestone,
siltstone, and sandstone (Melnikov and Izrailev, 1975). The
sandstone-hosted U deposits are hosted in Vendian sandstone,
which contains local bitumen (kerite).
The Southeast Missouri Pb-Zn and sediment-hosted U
deposits in the Dzhardzhan River metallogenic belt are herein
interpreted as forming during prolonged action of subsurface
water in carbonate and sandstone along the passive margin of
the North Asian Craton Margin (Verkhoyansk fold belt, unit
NSV; Shpikerman, 1998). The sediment-hosted Cu deposits
are interpreted as forming during migration of Cu from the
craton to a shallow sea during both Riphean and Late Devonian
rifting of the North Asian Craton Margin. This unit is
chiefly a thick wedge of continental margin deposits, which
are as much as 20 km thick (Nokleberg and others, 1994c,
1997c). The sedimentary rocks of the Verkhoyansk fold belt
are apparently tectonically detached from crystalline basement
of craton. The fold belt is separated from the Siberian platform
by the Late Cretaceous, west-verging Lena thrust belt (fig. 2).
Anvil Metallogenic Belt of Zn-Pb-Ag SEDEX
Deposits, Yukon Territory, Canada (Belt AN)
The Anvil metallogenic belt of Zn-Pb-Ag sedimentary
exhalative (SEDEX) deposits (fig. 3; tables 3, 4) occurs in the
Anvil district in the western Selwyn Basin, Yukon Territory, Canada.
The deposits are hosted in the passive continental margin
rocks of the North American Craton, which represent the transition
from shelf to off-shelf facies. The SEDEX deposits occur
in calcareous and noncalcareous phyllites, which are correlated
(Jennings and Jilson, 1986) with Early Cambrian to Silurian
strata in the Howards Pass region (Gordey and Anderson, 1993)