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

tellurides, pyrargyrite, stephanite, and argentite. The Au:Ag ratio varies from 5: 1 to 1:100, and averages about 1:2 to 1:5. The
deposit contains estimated reserves of 3.8 tonnes Au and 70 tonnes Ag. The deposit averages 6.5 to 11.8 g/t Au and 65 to 174 g/t
Ag. Bonanza ores contain up to 30 kg/t Au.
Eastern Asia-Arctic Metallogenic Belt:
Koni-Yablon Zone of Porphyry Cu-Mo and
Cu-Mo Skarn Deposits (Belt EAKY)
Southern Part of Russian Northeast
The Koni-Yablon zone of porphyry Cu-Mo and Cu-Mo skarn deposits (fig. 79; tables 3,4) occurs in the southern part of
the Russian Northeast. The zone occ~~rs in the front of the Okhotsk-Chukotka volcanic-plutonic belt along the northwest margin of
the Sea of Okhotsk and in plutons which intrude the Koni-Murgal island-arc terrane. The significant deposits in the zone are (table
4) (Nokleberg and others 1997a, b, 1998): porphyry Mo deposits at Guan-Ti (Arkhirned), Khakandya, Molybdenitovy, Tikas, and
Travka; porphyry Cu-Mo deposits at Etandzha, Cora Krassnaya, Ikrimun, Osennee, Oksa, Usinskoe, Viking, porphyry Cu
deposits at Lora, Nakhtandjin, and Yapon; a granitoid-related Au deposit at Tsirkovy; Au-Ag epithermal vein deposits at
Berezovogor, Irgunei, Nyavlenga, Sergeev, and Serovskoe; a Cu skarn deposit at Maly Komui; a Mo greisen and vein deposit at
Lastochka; and a volcanic-hosted Hg deposit at Uralskoe. The porphyry Cu-Mo deposits occur in parts of the volcanic-plutonic
belt which are uplifted along major faults, as in the Okhoto-Kuhtui, Chelomdja-Yana, and Anadyr zones. Some of these zones
occur along a regional gravity gradient between the front and rear zones of the volcanic-plutonic belt.
In the northeastern part of the Koni-Yablon zone, the Primagadan area, the best known part of the Koni-Yablon zone,
extends along the coast of the Sea of Okhotsk for about 500 km and contains the Osenee, Usinskoe,, Nakhatandjin-Lori, Ikrimum,
and other deposits. These deposits occur in multiphase, large, Na-series Early Cretaceous gabbro, tonalite, granodiorite, and
plagiogranite plutons which display low initial Sr ratios (