USGS Professional Paper 1697 - Alaska Resources Library

and comagmatic with volcanic rocks; both suites exhibit high
potassium contents. The Khingan-Okhotsk belt overlies the
Turan and Malokhingask terranes of the Bureya continentalmargin
arc superterrane and Badzhal and Ulban accretionarywedge
terranes (Nokleberg and others, 1994c, 1997c). The
belt defines the Khingan continental-margin arc in the Russian
Southeast (fig. 61) (Nokleberg and others, 2000).
The Khingan (southern) part of the Badzhal-Ezop-Khingan
metallogenic belt is also hosted in the Khingan-Okhotsk
volcanic-plutonic belt (isotopic age of 134 to 88 Ma). In the area
underying the Khingan part of the metallogenic belt, these igneous
rocks occur in a postaccretionary Cretaceous volcanic-tectonic
depression in the eastern part of Bureya continental-margin
arc superterrane. The volcanic-tectonic depression is filled with
mid- Cretaceous, intermediate-composition volcanic rocks and
overlying Late Cretaceous tuff and rhyolite lava. The volcanic
rocks range from 1.5 to 3.0 km thick. The volcanic rocks rest
on a basement Proterozoic metamorphic rocks of the Bureya
superterrane. The intrusive rocks of the Khingan-Okhotsk belt
in this area are dominantly granite and are comagmatic with the
volcanic rocks. The granitoid rocks of the Khingan-Okhotsk belt
are interpreted as subduction-related, calc-alkalic igneous rocks
that include both S- and I-type granites.
The Khingan continental-margin arc (ko) is herein interpreted
as forming from oblique subduction of the ancestral
Pacific oceanic plate. Fragments of this plate are interpreted
as occurring in tectonically interwoven fragments of the Amur
River (AM), Khabarovsk (KB; younger Early Cretaceous
part), and Kiselevka-Manoma accretionary-wedge terranes
(Natal’in, 1991, 1993; Nokleberg and others, 1994a; Sengör
and Natal’in, 1996a,b). This tectonic pairing is based on (1)
occurrence of accretionary-wedge terranes outboard (oceanward)
of and parallel to the various parts of the Khinghan
arc, (2) formation of mélange structures during the Early and
mid-Cretaceous (Natal’in, 1991; Nokleberg and others, 1994a;
Vrublevsky and others, 1988; Nechaev and others, 1996), and
(3) where not disrupted by extensive Cretaceous movement
along the Central Sihote-Aline strike-slip fault, dipping of
mélange structures and bounding faults toward and beneath
the igneous units of the arc (Natal’in, 1993). Formation of the
body
Ore
Hydrothermal
breccia
Level 414
Level 401
Level 340
Level 290
Level 230
Level 170
Level 110
Level 40
Late Early Cretaceous Metallogenic Belts (120 to 100 Ma; figs. 61, 62) 165
Rhyolite
(Late Cretaceous)
Granite porphyry
(Late Cretaceous)
Fault
Contact
0 100 m
Figure 75. Khingan Sn greisen
deposit, Badzhal-Ezop-Khingan
metallogenic belt, Russian
Southeast. Schematic threedimensional
figure. Levels and
contours in meters. Adapted
from Ore Deposits of the U.S.S.R.
(1978). See figure 61 and table 4
for location.