USGS Professional Paper 1697 - Alaska Resources Library

sists of cinnabar and metacinnabarite that are relatively younger
than the Sb-Au vein deposits, which consist of stibnite and
berthierite. The Zagadka deposit occurs in Late Permian sandstone
and siltstone that is gently folded and cut by steeply dipping
faults. The deposit is located along a linear zone about 2.4
km long within one of the faults. The thickness and morphology
of the ore bodies is influenced by shear zones and associated
feathered veins and stringers. The ore bodies, mainly cinnabar,
range from 0.4 to 3 m thick. Subordinate minerals are galena,
sphalerite, stibnite, Pb-sulfosalts, and cassiterite. Gangue minerals
are quartz, dickite, and carbonate minerals. The wall rocks
exhibit dickite, quartz and carbonate alteration. Average grades
are 0.22 to 6.2 percent Hg, 0.8 to 20 percent Pb, 2 to 10 percent
Zn, 4 to 10 percent Sb, and as much as 30 g/t Ag. Estimated
resources are 1,718 tonnes mercury and 1,000 tonnes antimony.
Map
0 2 km
Cross section
Late Cretaceous and Early Tertiary Metallogenic Belts (84 to 52 Ma) (figs. 102, 103) 221
Kuchus
0
100
Kyuchyus Sb-Au-Hg Vein Deposit
The Kyuchyus Sb-Au-Hg vein deposit (fig. 105) (Ivensen
and others, 1975; Indolev and others, 1980; Konyshev and
others, 1993) occurs in steeply dipping mineralized reverse
shear zones as much as 1 m thick and in veins as much as 0.5
m thick. The shear zones and veins contain quartz-stibnite,
cinnabar-stibnite-quartz, realgar-quartz and quartz, with various
amounts of ankerite, calcite, kaolinite, dickite, arsenopyrite,
pyrite, orpiment, berthierite, sphalerite, galena,bournonite,
pyrrhotite, tetrahedrite, native mercury (as much as 15 percent),
and gold. The veins and shear zones crosscut a Middle
Triassic (Anisian and Ladinian) sequence of sandstone and
siltstone flysch. Alteration types include argillaceous, silicic,
carbonate, and hydromica aureoles that occur near the deposit.
200 m
Sn
Au
Pb
Triassic sedimentary rock
Fault
Alluvial deposits (Quaternary)
Granitic intrusions
(Early Cretaceous)
Late Triassic rocks
Early and Middle Triassic rock
Jurassic rocks
Permian terrigeneous rock
Fault
Contact
Fold axis
Ore zone
Ore body
Drill hole
Occurrences
Figure 105. Kyuchyuss Sb-Au-Hg vein deposit, Verkhoyansk-Indigirka (Dulgalak) zone, eastern Asia-Arctic
metallogenic belt, Russian Northeast. Schematic regional geologic map of Kyuchyus area and cross
section of deposit. Elevation at and below sea level.Adapted from Ivensen and others (1975) and Konyshev
and others (1993). See figure 102 and table 4 for location.