Metallogenesis and Tectonics of the Russian Far East, Alaska, and ...

Metallogenic Belts Formed in Tertiary
Collision of Outboard Terranes,
I Russian Southeast
I Central 8akhaRn Metdlogenlc Bdt of
I Au Quartz Vein and Talc Deposits (Belt CS)
I Sakhalin kland. Southeastern Part of
I Rusdan Far East
The Central Sakhalin metallogenic belt of Au quartz vein and talc deposits occurs in the Aniva subduction-zone teme in the central part of Sakhalin Island (fig. 102; tables 3,4) (Nokleberg and others, 1997b, 1998). The major deposit at
Langeriiskoe consists of Au-bearing quartz-sulfide veins in lenticular bodies of fractured and faulted Permian-Triassic spilik and
graywacke, Jurassic-Early Cretaceous slate, and Cenozoic volcanic rocks and chert (Khanchuk and others, 1988; Bekhtold and
I Semenov, 1990). The Au-bearing quartz-sulfide veins are interpreted as forming during metamorphism associated with middle or
I late Tertiary foldng and faulting. Also in the metal logenic belt are talc deposits, formed by hydrothermal alteration of ultramafic
I intrusive rocks which are also of economic interest.
I
The host Aniva terraw is composed of intensely deformed and metamorphosed sedimentary and volcanic rocks which
I locally display Late Cretaceous to Paleogene transitional glaucophane-greenschist facies metamorphism. The Aniva tenme is
interpreted as a subduction zone unit which was tectonically linked to the Cretaceous East Sikhote-Alin volcanic-plutonic belt
I
(Nokleberg and others, 1994c, 1997~). 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 temu~es
to the east.
Sredlnny Metallogenic Belt of
Au Quartz Vein and
Metamorphic REE Vein(?) Deposits
(Belt SR) Southorn Kamchatka Peninsula
I The Srediany metallogenic belt of Au quartz vein deposits and a single metamorphic REE vein(?) deposit OCCU~S in the
southern part of the Karnchatka Peninsula in the zoned metamorphic complexes of the Sredinny-Kamchatka terrae (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 cornrnun., 1986) occurs in quartz phyllite am.
which is interbedded with late Paleozoic metasandstone and metasiltstone. The major ore minerals are go14 arsenopyrite, and d?%
pyrite, with rare chalcopyrite and magnetite. The mineralized zones vary from 30 to 1 15 m long and 20 to 50 m thick and in
stockworks with gold, arsenopyrite, and pyrite. The deposit consists of a stockwork which 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 - 1:
average grade of the Tumannoe deposit is 0.4-2.2 g/t Au and 3 g/t Ag.
!,$
Anomalnoe Metamorphic REE Vein(?) Deposit . Zf
.c-. Y*m
The small metamorphic REE vein(?)deposit at Anomalnoe (D.A. Babushkin and others, written comun., 1986) consists
of an altered vein of K-feldspar and albite which 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 which contain Ta and Ni. Accessory minerals are
ilmenite-rutile and rare epidote. A K-Ar isotopic feldspar age for the veins is 170 Ma.
Origin of and Tectonic Controls for
Sredinny Metallogenic Belt
The Sredinny metallogenic belt is hosted by the by the Sredinnyi-Kamchatka metamorphic terrane which consists of
several metamorphic sequences (Nokleberg and others, 1994c, 1997~). The belt is herein interpreted as forrejng 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 hrla
for the REE vein(?)deposit at Anomalnoe is uncertain.