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

Figure 52. Kunarev Pb-ZRGu-Ag skarn deposit, Yasachnaya River metallogenic belt, Russian Northeast. Schematic g eow nap
and crass section. Adapted Irom Shpikerman (1998).
The nearby Shokoe Ag occurrence occurs farthest from the central part of the volcanic shrtcture at the northwestem end
a€ the ore field. The deposit occurs in the lower volcanic sequence and consists of quartz-carbnak-~~ck stockwork and veins
dich are hosted in Early and Wddle Devonian limestone. The stockwork and veins form conformable and ctossiag are bdl6s
with rt complex morphology. The ore minerals are galena, Pb sulfostibnites, sphalerite, Ag sulfosalls, freibergite, acanthite,
betechtinite, bournonite, native silver, and stibn~te (N.E.Savva, written commun., 1989). The average grade of high-mde ore is
1,100 El/t A$, 1.3% Pb, 0.6% 24, aad 0.4% Sb.
The Kmarev Pb-ZnCu-Ag &am depos~t is hosted in an eroded, oval-shaped, late Mesozoic volcanic structure. At the
base of the volcanic sequence are faulted Paleozoic clastic and carbonate rocks. The main part of the voicdc equc;n~e GO~SS~SB of
gently-lying, Late Jurassic volcanic and sedimentary rocks. The lower part the volcanic sequence conkins d c ~ ~
conglomerates, up to 150 m thick, overlain by argillite which is about 350 m thick. The upper part consisis OF a mixed t d
member, with a thickness of about 80 m. In the central part of the volcanic sequence is downdropped caldera with a diameter ctf
about 4-5 km whichextends into he folded Paleozoic basement. The caldera 1s filled with the upper volcartic sequence. Intrusive
rocks iaciude subvolcanic stocks camposed of andesite, dacite, diorite, and granite-porphyries, Explosive breccias aho occur. A