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

systems whicb converge locally along strike into podiform and platy veins. The ore minerals cement schistose, brecciated,
cabelastic, and graphite-altered Late Pennian tuffaceous sedimentary rocks. The deposit occurs along the Tenka strike-slip fault.
The ore deposit is deformed with synclines and anticlines which occur near the fault zone. The deposit is intruded locally by
abundant pre-ore and post-ore dikes of felsic to intermediate composition. The zone of mineralized vtinlets is approximately 300
rn wide; individual ore bodies occur in zones ranging from 50 to 300 m long and from 1 to 15 m thick. The gangue in the veinlets
are composed mainly of quartz (90-95%), albite, anorthoclase, carbonate, chlorite, and sericite; with lesser bolinite, barite,
apatite, and graphite. The ore mherals are dominated by fine-grained disseminated arsenopyrite infergrown witb pyrite in wall
rocks. Subor&nate and rare rnlllerds include galena, sphalerite, chalcopyrite, pyrrhotite, boumonite, boulangerite, tetrahedrite
tammtite, scheelite, rutile, ilmwite, and stibnite. Fine-grained and microscopic, low-grade Au is commonly associated with
arseoopyrite and galena in tbe veins and veinlets. A considerable proportion of the gold is intergrown in usempyrite in tbe wall
rock adjacent to the veins. The Natdka deposit is large with total reserves of 450 t Au. From 1945 to 1994, the Natalka mine ha9
produced 75 toon- Au and 22 tomes Ag. The annual production is 8 t Au and 4 t Ag. The lower grade ores average 4 glt. MOE
reeeat production data are wt available.
and Kholodnoe Au Quarh Vein Deposits
The Svetloe Au quartz veb deposit (fig. 70) (P.I. Skornyakov. written commun., 1953; Fedotov, IgiiOb, 1967,
Goryachev, 1998,2003) consi~ts of subparallel quartz veins 600-1 500 m long average 0.2-0.5 m thick. and 20-80 m apart. The
veins occur as conformable bodies or in acute fractures in the limbs of an asymmetric anticline and dip 70' to 85'. The om bodies
trend mainly northwest, but range from east-west to north-south. Hosting the Au quartz veins is Lpte Triassic and Early Jttmssic
sandstone and shale which are intruded by a transverse set of dikes of felsic and intermediate composition. The om minds are
maw arsenopyrite, pyrite, and galena containing gold (858 fine). Subordinate ore minerals are sphalerite, chalcopyrite, scblite,
pyrrhotite, and native gold. The deposit is small and has proven reserves 3.6 t Au with grade ranging from 1 .O to 100 glt Au. The
nearby Kholodnoe deposit, which occurs to the south, is made up of three sets of quartz veins and mineralized fracture zones
which &end northwest Some veins occur within the dikes. Gold occurs as very small inclusions or irregular messes.
Zhdannae Au Quartz Vehr Deposit
The Zhdannoe Au quartz vein deposit (Gavrikov and Zharova, 1963; Rozhkov and others, 1971; Yu. A. Vladima, written commun., 1987; V.A. Amuzinskyi, G.S. Anisimova, and Ya.Yu. Zhdanov, written commun., 1992) consists of a set of 13
interbedded veins which range from 0.1 to 3 m thick and to 500 m long. Some ore bodies occur in cross-cutting fissures. Ore
mmds are amampyrite, pyrite, galena, sphalerite, native gold (fineness 848), and very scarce boulangerite and chalcopyrite. Re
mineral content of 4114122 veh is 1 to 3%. Veins accompanied by minor wallrock alteration to bersite. The deposit is judged to be
exhausted and was small with an average grade of 22 to 95 glt Au. The deposit occurs in the hinge of a trrschyantieline at its
pericbalcl~ure and is basted Late Triassic (Carnian) silty shale and sandstone.
UZin Au Quarb Vein Deposit
Ttw Utin Aa quartz vein dcposit (1.R. Yakushev, written commun., 1950; P.I. Skomyakov, written CO~DLM~~., 1953;
Goryacbcv, 1995, 1998,2003) mcurs in a Late Jurassic suite of ore-bearing dikes which extend for about 35 km. The dikes cuts a
Middle Jurassic s&ntary sequence at an acute angle to beddlng. The host sedimentary rocks are isoclindly folded into weslnorthwest
trending structures Tbe main ore body extends 12 km and occurs in a steeply dipping dike, 0.4 to 1.3 m thick, which
c~iSh OEhydrOLhennaUy tllterad andesite porphyry. The dike is intensely crushed and dthed. Tb AU quartz veins forin
campIicrtted, often dingdy ms-cutting systems within the dike. Some quartz veins also cut the dikes obliquely, and extend
into Ihc surroundibg ndimenbery rocks. Arsenopyrite, pyrite, and pyrrhotite comprise up to several per cent of the veins. Also
occurring are mid, galena, sphnlerite, chalcopyrite, jamesonite, Bi-boulangerite, tetrahedrite, scbeelite, mmsite, and stiWte,
The gold di~tribution is quik irregular; individual ore shoots extend from 5 to 30 m in strike and are up Lo several hune of
me- in w a . The mall deposit was discovered in 1929 and produced 12 tonnes Au with grade ranging Erom 8.1 to 3,923 g/t
Au. The grade of ore shootr ranges from 5 to 3,923 g/t Au.
AlyaskRov~s 8R W Grehen Deposit
The Alyrtakitovoe Sn-W greisen deposit Shur, 1985; Yu. A. Vladimirtseva and V.M. Vldhnhev, written t%mr~un.,
1987) coasisls of veins and greisen which occur inside and adjacent to a stock of two-mica granite whicb intmk6 Late Triassic
sandstme and shale. The veins are greisen are variable in thickness and length and occur in fisam whicb strike north-northeast
and dip nprthwut at 75-85'. The veins have complex morphology with en-echelon lenses which alternate witb thin stringers. The
Main ore minds are wolffamito, cassiterite, and arsenopyrite. The gangue minerals are mainly quartz, muscovite, b-8,
and apatite. A complex combinnlion dsulfosalts of lead, silver, and bismuth occur in the veins. The wallrocLs exlibit qumlz-
mlistovite, mu!$coviie-apatik, and tourmaline greisen alteration. The deposit is small and has average: grades of 0.45 bo 1.33%
W03 and up 10 0.38% Sn.