USGS Professional Paper 1697 - Alaska Resources Library

268 Metallogenesis and Tectonics of the Russian Far East, Alaska, and the Canadian Cordillera
average thickness of about 20 to 30 m. The deposit occurs
along the northern tectonic contact of the Tamvatney lherzolite
ophiolite body, which structurally overlays a clastic rocks of
Early Cretaceous (Aptian and Albian) and Oligocene-Miocene
age. The ultramafic rocks are intruded by Early Cretaceous
gabbronorite, Late Cretaceous plagiogranite, and Neogene
andesite and basalt. The age of the deposits is interpreted as
Early Pleistocene. The deposit is large with estimated reserves
of 30,000 tonnes Hg in ore that averages 0.81 percent Hg.
Porphyry Mo-Cu Deposits
Au-bearing, porphyry Mo-Cu occurrences, such as at
Kuibiveen, and numerous hydrothermal vein deposits, containing
Au, Ag, Cu, Mo, Pb, and Zn, also occur in the Central
Koryak metallogenic belt. These deposits formed at varying
temperatures, represent a variety of mineral deposit types. The
significant deposit is at Kuibiveen.
Kuibiveen Porphyry Mo Deposit
The porphyry Mo deposit at Kuibiveen consists of quartztourmaline
breccias, altered rocks, veins, and zones of linear
and stockwork quartz-sulfide veinlets that occur in a nearly
east-west-trending zone that is about 25 km long and about
4 km wide (Zakharov and V.P. Vasilenko, written commun.,
1977; I.S. Rozenblyum, written commun., 1991). The deposits
consists of disseminated molybdenite, arsenopyrite, chalcopyrite,
galena, and native gold that occur in zones from tens
of meters as much as hundreds of meters thick. The deposit
occurs in a Neogene complex of small intrusions and dikes of
intermediate and felsic composition. The deposit occurs along
a fault that thrusts Late Cretaceous siliceous sedimentary rocks
over Oligocene and Miocene sandstone and conglomerate. The
deposit is of small to medium size.
Origin of and Tectonic Controls for Central Koryak
Metallogenic Belt
The Kamchatka-Koryak volcanic belt, which hosts the
Central Koryak metallogenic belt, is of lesser Late Cretaceous
and mainly Paleocene, Eocene, and Miocene age., and
extends for 800 km parallel to, but mainly east of the northern
part of the Okhotsk-Chukotka volcanic-plutonic belt (fig.
102) (Nokleberg and others, 1994c, 1997c). The belt occurs
in discontinuous and isolated volcanic fields and consists of
gently dipping nonmarine volcanic rocks of various compositions,
and sandstone, gritstone, and conglomerate with flora.
The lower part of the volcanic belt consists of mafic volcanic
rocks, mainly Maastrichtian-Danian tholeiitic basalt, along
with abundant Paleocene to Eocene alkali basalt and associated
minor diorite, monzonite, gabbro, granodiorite, and granite
that yield K-Ar ages of 73 to 56 Ma. The upper part of the
volcanic belt consists of calc-alkaline dacite, rhyolite, andesite,
and basalt with late Eocene and early Miocene flora and
K-Ar ages and is associated with subvolcanic bodies and dikes
of rhyolite, granodiorite, and diorite. The Kamchatka-Koryak
volcanic belt is interpreted as a major, mainly early Tertiary
arc that formed along a continental margin-parallel transform
fault. (Khanchuk and Ivanov, 1999a,b).
Metallogenic Belts Formed in Tertiary Continental-Margin
Arcs, Kamchatka Peninsula, and
Southern Canadian Cordillera
Olyutor Metallogenic Belt of Igneous-Arc-
Related Deposits (Belt OT), Kamchatka Peninsula
The Olyutor metallogenic belt of igneous-arc-related
deposits (fig. 102; tables 3, 4) occurs in northern Kamchatka.
The metallogenic belt extends for more than 600 km along the
Bering Sea coast and is hosted in the East and Central Kamchatka
volcanic belts (Nokleberg and others, 1994c, 1997c).
The little studied Olyutor metallogenic belt contains a variety
of Au-Ag epithermal vein, Sn polymetallic vein, clastic
sediment-hosted Hg, and porphyry Mo-Cu deposits (table 4).
Several mineable Hg, Au, Mo, Cu, Pb and Zn deposits occur
in many, slightly eroded volcanic structures (Tarasenko and
Titov, 1969). Numerous, poorly explored, porphyry Cu-Mo,
Au-Ag epithermal vein, sulfur-sulfide, and Sn polymetallic
vein deposits occur along the southern flank of the belt, and a
zone of Hg-Sb and Hg-As deposits extends for more than 100
km along the Olyutor Bay coast. The deposits in the Olyutor
belt are hosted mainly in Tertiary sedimentary, volcanic, and
hypabyssal intrusive rocks. The Hg-Sb-As deposits also occur
in Neogene extrusive rocks, and in serpentinite melange zones.
The porphyry Mo-Cu deposits occur in Tertiary diorite and
granodiorite porphyry stocks and associated dikes that intrude
Late Cretaceous and early Paleogene tuffaceous and clastic
rocks. The porphyry Mo-Cu deposits extend more than 100
km in the northern part of the belt, with intrusions apparently
occurring along major faults. The significant deposits in the
Olyutor metallogenic belt are the Olyutor clastic sedimenthosted
Hg deposit, the Lalankytap porphyry Mo-Cu deposit,
and the Maletoivayam sulfur-sulfide deposit (Nokleberg and
others 1997a,b, 1998).
Olyutor Clastic Sediment-Hosted Hg Deposit
The Olyutor clastic sediment-hosted Hg deposit (Babkin,
1975; Vlasov, 1977) consists of veins and veinlets that occur
in steeply dipping fracture zones. The fracture zones radiate
from a large northeast-trending fault that cuts Paleogene and
Neogene volcaniclastic rocks that are deformed into small
linear folds. Individual ore bodies extend along strike from
tens of meters to 600 m. The veins have numerous apophyses
typically containing mineralized breccia, which often grades
into zones of veinlets. The most productive ore bodies occur
in tuff. The main ore minerals are cinnabar accompanied by
stibnite and sometimes realgar. The ore also contains quartz
cement and quartz-kaolinite breccia fragments. The main
gangue minerals are quartz and kaolinite and less commonly