USGS Professional Paper 1697 - Alaska Resources Library

of fractured and faulted Permian-Triassic spilite and graywacke,
Jurassic-Early Cretaceous slate, and Cenozoic volcanic rocks
and chert (Khanchuk and others, 1988; Bekhtold and Semenov,
1990). The Au-bearing quartz-sulfide veins are interpreted as
forming during metamorphism associated with middle or late
Tertiary folding and faulting. Also in the metallogenic belt are
talc deposits, formed by hydrothermal alteration of ultramafic
intrusive rocks, which are also of economic interest.
The host Aniva terrane is composed of intensely deformed
and metamorphosed sedimentary and volcanic rocks that locally
display Late Cretaceous to Paleogene transitional glaucophanegreenschist
facies metamorphism. The Aniva terrane is interpreted
as a subduction-zone unit that was tectonically linked to the Cretaceous
East Sikhote-Alin volcanic-plutonic belt (Nokleberg and
others, 1994c, 1997c). The Central Sakhalin belt of Au quartz vein
and talc deposits hosted in the Aniva terrane are herein interpreted
as possibly forming in a collisional environment during the early
Tertiary(?) accretion of outboard terranes to the east.
Sredinny Metallogenic Belt of Au Quartz Vein
and Metamorphic REE Vein(?) Deposits (Belt SR),
Southern Kamchatka Peninsula
The Sredinny metallogenic belt of Au quartz vein deposits
and a single metamorphic REE vein(?) deposit occurs in the
southern part of the Kamchatka Peninsula in the zoned metamorphic
complexes of the Sredinny-Kamchatka terrane (fig.
102; tables 3, 4) (Nokleberg and others, 1997b, 1998). The Au
quartz vein deposits occur mainly in metasandstone and metasiltstone.
The major Au quartz vein deposit is at Tumannoe and
a single metamorphic REE vein(?) deposit is at Anomalnoe.
Tumannoe Au quartz vein deposit
The Tumannoe Au quartz vein deposit (D.A. Babushkin and
others, written commun., 1986) occurs in quartz phyllite that is
interbedded with late Paleozoic metasandstone and metasiltstone.
The major ore minerals are gold, arsenopyrite, and pyrite, with
rare chalcopyrite and magnetite. The mineralized zones vary from
30 to 115 m long and 20 to 50 m thick and occur in stockworks
with gold, arsenopyrite, and pyrite. The deposit consists of a
stockwork that is probably remobilized from black shale. This
and associated deposits are small, but are sources for placers on
the western coast of Kamchatka Peninsula. The average grade of
the Tumannoe deposit is 0.4 to 2.2 g/t Au and 3 g/t Ag.
Anomalnoe Metamorphic REE Vein(?) Deposit
The small metamorphic REE vein(?)deposit at Anomalnoe
(D.A. Babushkin and others, written commun., 1986) consists
of an altered vein of K-feldspar and albite that is hosted
in Proterozoic(?) schist. The vein is longer than 1 km and varies
from 1 to 12.5 m wide. The principal economic minerals
are columbite and tantalite that contain Ta and Ni. Accessory
minerals are ilmenite-rutile and rare epidote. A K-Ar isotopic
feldspar age for the veins is 170 Ma.
Early to Middle Tertiary Metallogenic Belts (52 to 23 Ma; figs. 102, 103) 265
Origin of and Tectonic Controls for Sredinny
Metallogenic Belt
The Sredinny metallogenic belt is hosted by the by the
Sredinnyi-Kamchatka metamorphic terrane that consists of
several metamorphic sequences (Nokleberg and others, 1994c,
1997c). The belt is herein interpreted as forming during accretion
of the outboard Olyutorka island arc and generation of
hydrothermal fluids. A K-Ar isotopic age of about 40 Ma for
the Tumannoe deposit is herein interpreted as a minimum time
for accretion of the Olyutorka arc. The K-Ar isotopic age of
170 Ma for the REE vein(?)deposit at Anomalnoe is uncertain.
Metallogenic Belts Formed in Tertiary Back-arc
Rifting and Continental-Margin Transform, and
Transcurrent Faulting, Russian Southeast
Kvinumsky Metallogenic Belt of Hornblende
Peridotite and Gabbroic Cu-Ni Deposits (Belt
KV), Southern Kamchatka Peninsula
The Kvinumsky metallogenic belt of hornblende peridotite
and gabbroic Cu-Ni deposits occurs in the southern Kamchatka
Peninsula and is associated with early Tertiary intrusive
rock (fig. 102; tables 3, 4) (Bundtzen and others, 2003a,b). The
major Cu-Ni deposits, at Shanuch, Kvinum, and Kuvalorog, are
associated with cortlandite-norite-diorite intrusions that intrude
the older metamorphic and granitoid rocks of the Sredinny-
Kamchatka metamorphic terrane (Nokleberg and others,
1997b, 1998, 2000). An incremental 40 Ar 39 Ar isotopic age for
the host intrusive rock ranges from 60 to 40 Ma (Bundtzen and
others, 2003a,b). The deposits generally consist of pentlandite,
Zn-bearing chrome spinel, pyrrhotite, chalcopyrite, and bornite
that occur in veinlets and as disseminations in hornblenditeperidotite-norite-diorite
intrusions. The deposits are small, and
the sulfides occur mainly as disseminations in gabbro (Shcheka
and Chubarov, 1984). Ni is less than 1.0 percent, and Cu is less
than 1.0 percent. The sulfide disseminations contain as much
as 1 g/t Au and as much as 6 g/t Pt. The region containing these
deposits is inaccessible and poorly explored. The Kvinumsky
metallogenic belt of hornblende peridotite and gabbroic Cu-Ni
deposits is herein interpreted as forming during back-arc intrusion
related to subduction beneath the Kamchatka Peninsula
part of Central Kamchatka continental-margin arc.
Central Koryak Metallogenic Belt of Igneous Arc
Deposits (Belt CKY), East-Central Part of Russian
Northeast
The Central Koryak metallogenic belt of igneous-arcrelated
deposits (fig. 102; tables 3, 4) occurs in the Koryak
Highlands in the east-central part of the Russian Northeast.
The belt extends from the Penzhina Inlet to the Anadyr Bay for