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

Secondary minerals are barite, gypsum, marcasite, pyrite (up to 15%), and molybdenite. The age of mineralization is Pliocene and
Quaternary. The deposit is large. Average grades are up to 20-80% S and up to 0.5% MoS2. The deposit contains about 5 million
tonnes sulfur.
Prasolovskoe Au-Ag Epithermal Vein Deposit
The Prasolovskoe Au-Ag epithermal vein deposit (Danchenko, 1991) consists of ore veins which are mostly steeply-
dipping, and range from 2-3 m thick, with a few up to 10 m thick. The veins consist mainly of banded metacolloidal gold,
telluride, and quartz veins which contain up to 1-3% ore minerals. The deposit exhibits a vertical succession of assemblages. From
bottom to top the assemblages are: gold-cassiterite-quartz; polysulfide-quartz; gold-telluride-quartz; and gold-adularia (carbonate)-
quartz. The dominant ore minerals are pyrite, chalcopyrite, bornite, chalcocite, covellite, and sphalerite. Arsenopyrite,
molybdenite, cassiterite, galena, argentite, native silver, gold, hessite, naumannite, and goldfieldite are also abundant. Limonite,
covellite, malachite, and azurite occur in an oxidized zone. The ore bodies are explored to a depth of over 200 m. An area 1.5 by
0.5 km is propylitically altered and impregnated with pyrite as well as numerous quartz veinlets with epidote, sericite, adularia,
chlorite, calcite, and rare barite. Earlier veinlet and disseminated ore is related to Miocene intrusions. The later Au-Ag ore is
related to the Pliocene volcano-plutonic complex. The deposit is associated with Pliocene plagiogranite and quartz diorite which
intrude early and middle Miocene pyroclastic green tuff deposits. The deposit is of medium size and was mined before the 1990's.
Koshkina Cu-Pb-Zn Polymetallic Vein Deposit
The small Koshkina Cu-Pb-Zn polymetallic vein deposit (Petrachenko, 1978) consists of ore bodies up to 200 m long
which occur hydrothermally altered rock types outside a granodiorite and diorite intrusion. The ore bodies consist of areas of
closely-spaced sericitized and hydromicatized veins and veinlets with variable composition. Mineral assemblages in veins and
veinlets are quartz-tourmaline, quartz-chlorite-sericite, chlorite-carbonate with zeolites, and quartz-chlorite-epidote. The ore
minerals are chalcopyrite, cleiophane, galena, stibnite, realgar, orpiment, arsenopyrite, pyrite, marcasite, hematite, and magnetite.
Polymetallic and antimony-arsenic ores are spatially separated and various alterations. The mineralogy and metal content of the
deposit vary widely. The deposit occurs on the northern part of Shumshu Island and covers an area of approximately 5 krn2. The
deposit is hosted in heavily altered early-middle Miocene volcanic rocks which are intruded by numerous extrusive and intrusive
rocks, all part of a volcano-plutonic complex. Host rocks are propylitized up to epidote-chlorite facies, and are locally silicified.
Propylitized granodiorite and diorite crops out in the middle part of the mineralized area. Alteration was the result of sulfate and
halogene-acid hydrothermal solutions. The age of mineralization is late Miocene(?).
Valentinovskoe Kuroko Cu-Pb-Zn Deposit
The Valentinovskoe kuroko Cu-Pb-Zn deposit (Neverov, 1964) consists of two steeply-dipping, thin, lens-like deposits,
up to 150 m long. Two ore types exist. (1) The first and most common type consists of massive, fine-grained sphalerite, galena,
chalcopyrite, chalcocite, tetrahedrite, melnikovite, barite, gypsum, quartz, chalcedony, chlorite, sericite, and calcite. This ore
contains approximately 1% Cu, 1.5-1.7% Pb, and 10-13% Zn. And (2) the second and less common ore type consists of pyrite,
sphalerite, and chalcopyrite with galena and other sulfides. This ore contains up to 4% Cu, 10- 16% Zn, and 1-1.7% Pb. The
deposit occurs in early Miocene rhyolite, dacite, andesite, and andesitic tuff with chert interbeds. The host rocks are propylitized
or sericitized and are part of a submarine tuff complex. The deposit is small with average grades of 1% Cu, 151.7% Pb, and 10-
13% Zn in fine-grained ore, and locally up to 4% Cu, 10-16% Zn, and 1-1.7% Pb.
Origin of and Tectonic Controls for
Kuril Metallogenic Belt
The Kuril volcanic arc which hosts the Kuril metallogenic belt consists chiefly of tuff, breccia, andesite, basalt, and local
hypabyssal and plutonic rocks including gabbro, diorite, and diabase (Nokleberg and others, 1994~). The arc occurs as large
Quaternary active volcanoes which are tectonically linked to middle Tertiary through Holocene subduction of the western margin
of the Pacific oceanic plate (Nokleberg and others, 1994c, 1997~).
Summary of Metallogenic and
Tectonic History
The preceding analysis of the metallogenesis and tectonics of the Russian Far East, Alaska, and the Canadian Cordillera
reveals a series of metallogenic belts which formed during a complicated geologic history. The metallogenic belts are hosted in
older rock units of tectonostratigraphic terranes, along suture zones between accreted terranes, or in overlap assemblages of
continental margin igneous arcs. Metallogenic belts formed before accretion (pre-accretion) are interpreted as forming in the early
history of terranes and are inherently linked to the older geology and tectonic history of the host rocks. Accretionary metallogenic
belts are interpreted as forming during collision of terranes with continental margins, resulting in varying amounts of regional