Geologiya I Geofizika, 2002, V 43, N 2, February.

TECTONICS AND GEOMORPHOLOGY 

THE OKHOTSK OCEANIC VOLCANIC PLATEAU 
N. A. Bogdanov and N. L. Dobretsov
93
 
     The plate of the Sea of Okhotsk is considered as an old oceanic 
volcanic plateau with tectonic boundaries. Its eastern and western 
boundaries are formed by right-lateral strike-slip faults; in the north, 
the plate is bounded by a Middle Cretaceous subduction zone, and the 
southern boundary is delineated by the ongoing subduction of the Pacific 
plate beneath Eurasia. On the plate margins (eastern Sakhalin, Taigonos 
Peninsula, Kuyul Ridge, and Omgon Peninsula in western Kamchatka), relict 
Middle Jurassic-Lower Cretaceous oceanic crust is exposed in accretionary 
prisms. The South Okhotsk basin is the largest fragment of the Kula 
oceanic plate.
     A volcanic uplift in the center of the Okhotsk plate is identified as 
the Okhotsk volcanic plateau. In terms of geophysics, the plateau is 
similar to other volcanic plateaus, such as Ontong-Jawa, Shatsky, Hess, 
etc. It is hypothesized that the Okhotsk volcanic plateau formed north of 
the mid-ocean ridge, within the Kula plate, in response to the late 
Jurassic-early Cretaceous activity of a hot mantle plume in the region of 
the triple junction of the Kula, Pacific, and Faralon plates. As a result 
of the northward motion of the Kula plate with the Okhotsk plateau, the 
latter blocked subduction beneath the Okhotsk-Chukchi volcanoplutonic belt 
in the late Turonian. Subduction zones blocked by oceanic volcanic 
structures are of broad occurrence near accretionary fold-nappe belts.
     Oceanic volcanic plateau, subduction, collision, accretionary prism, 
ophiolites, Sea of Okhotsk 

FORMATION OF THE LATE PALEOZOIC STRUCTURE OF THE TELETSKOE REGION:
KINEMATICS AND DYNAMICS (Gorny Altai-West Sayan junction) 
L. V. Smirnova, K. Theunissen, and M. M. Buslov
107
 
     The Late Paleozoic structure and evolution of the junction between 
Gorny Altai and West Sayan is considered on the basis of geochronology and 
structural analysis by morphological, stereogeometric, and microstructural 
methods. The distinguished evolution stages of the region (Early-Middle 
Devonian, Late Devonian-Early Carboniferous, and Permian) fit the general 
geodynamic setting of the Altai-Sayan folded area. The Early-Middle 
Devonian stage was marked by intrusion of the Altyntauss granitoids into 
greenschist rocks. During the Late Devonian-Early Carboniferous stage, the 
Teletskoe shear zone was initiated along the eastern margin of the 
Altyntauss pluton. The formation of the shear zone was accompanied by 
strike-slip and thrust faulting under NW-SE compression and corresponds to 
the stage of collision between Siberia and the Altai-Mongolian terrane. 
According to new data, the northern part of the shear zone may have been 
produced by thrusting that acted simultaneously with left-lateral 
strike-slip motions on the major fault. The amount of horizontal 
displacement is estimated at about 80 km. The Permian stage corresponds to 
the Kazakhstan-Siberia collision and was associated with the formation of 
the North Sayan strike-slip fault under WE compression, with the 
right-lateral slip of about 30 km. The North Sayan fault truncates and 
deforms the Late Devonian-Early Carboniferous structure.
     Structure, kinematics, strike-slip fault, Paleozoic basement 

RADON ANOMALIES AS EVIDENCE FOR ACTIVITY OF THE WEST SAYAN FAULT
IN NORTHERN LAKE TELETSKOE (Gorny Altai) 
B. Dehandshutter, V. A. Bobrov, R. Hus, N. E. Astakhov, N. V. Androsova, 
and Yu. P. Popov
120

     Lake Teletskoe, a major neotectonic unit of Gorny Altai, is a 
complexly structured graben formed during reactivation of Late Paleozoic 
fault zones. The formation of the graben in the northern part of the lake 
has been controlled by the West Sayan fault.
     The ongoing activity of the fault is evidenced by radon and mercury 
anomalies whose behavior was investigated by measurements along profiles 
perpendicular to active fault segments by various methods. Radon flux 
observed in activated charcoal showed anomalies over faults. Radon 
emanation in the soil-gas system was measured by scintillation and 
electric detectors that enable detection of anomalies in soil gas over 
fault zones. The concentration of radon measured in springs marked faults 
infiltrated with radon water. Enhanced concentrations of mercury measured 
in soil and water along the fault zone revealed an open fissure system 
channeling gas fluids. Therefore, the West Sayan fault zone is an active 
structure that provides vertical migration of radon and mercury.
     Radon, fault, neotectonics, vertical migration, gas geochemistry, 
Lake Teletskoe

PALEOHYDROLOGY OF LAKE BAIKAL IN RELATION TO NEOTECTONICS 
V. D. Mats, S. Fujii, K. Mashiko, L. Z. Granina, E. Yu. Osipov, I. M. 
Efimova, and A. V. Klimanskii
134

    New data prove that the rise of the Baikal level in the past (to 
120-150 m) may have really occurred and was caused by tectonic uplift of 
the western side of the Baikal basin. As the lake level rose, medium and 
high terraces were forming and sands deposited in the Selenga delta and 
elsewhere; the discharge through the Lena along the paleo-Manzurka valley 
(2.0-0.5 Ma ago) was blocked, and a new outlet appeared through the 
Il'cha-Irkut valley into the Yenisei system (0.5-0.6 Ma ago). That outlet 
was broken about 60 ka ago by the collapse of the Listvyanka block, which 
at the same time produced the present-day discharge channel through the 
Angara. Calculations show that the lake level may hardly have dropped for 
a geologically long time, but short episodes of low stand were possible. 
The terraces on the lake sides result from the joint effect of tectonic 
and hydrological factors. Analysis of the past evolution of the river 
network in the Western Baikal region allowed prediction of its possible 
changes in the future.
     Water level fluctuations, terraces, evolution of drainage network, 
Lake Baikal 

PALEONTOLOGY 

A MESOZOIC OCEAN IN ARCTIC: PALEONTOLOGICAL EVIDENCE 
V. A. Zakharov, B. N. Shurygin, N. I. Kurushin, S. V. Meledina, and B. L. 
Nikitenko
147
     The fauna of Mesozoic epicontinental seas that existed on the 
territory of the present-day Arctic margin of Eurasia, North America, and 
islands in the Arctic Ocean is dominated by stenohaline mollusks 
(ammonoids, coleoids, bivalves, gastropods, brachiopods, foraminifers, 
ostracods, radiolarians, etc.). The marine biota consists of cosmopolitan 
taxa of the boreal Pacific and boreal Atlantic origin, Tethyan immigrants, 
and endemics, including hundreds of endemic species, tens of endemic 
genera, and six endemic families. Numerous lines of invertebrates in the 
Arctic basin evolved sustainably for tens of millions of years. The high 
taxonomic diversity of the specific marine biota and the ways of its 
panboreal migration could have been maintained by an oceanic basin that 
existed on the territory of the present-day Arctic throughout the 
Mesozoic, as a great volume of oceanic water was necessary to provide 
stable salinity and temperature in the surrounding epicontinental basins 
through 180 Ma.
     Long and sustainable development of the specific Mesozoic marine 
biota was provided by the South Anyui ocean in Triassic and Jurassic time 
and by the Amerasian ocean in the Cretaceous. This evidence substantiates 
the hypothesis of the presence of oceans in the Arctic territory through 
the Mesozoic which was suggested proceeding from geodynamic 
reconstructions.
     Mesozoic, paleoocean, paleontology, geodynamics, paleobiogeography, 
Arctic 

PETROLOGY, GEOCHEMISTRY, AND MINERALOGY 

THE MECHANISM OF TRACE-ELEMENT INTAKE DURING CRYSTAL GROWTH 
V. L. Tauson, I. Yu. Parkhomenko, V. I. Men'shikov, and K. V. 
Nepomnyashchikh
174
     The mode of occurrence of cadmium in stoichiometric pyrrhotite 
synthesized hydrothermally at 450° C and 1 kbar was studied by combined 
atomic absorption spectroscopy and thermal analysis. The results, along 
with the available data on relatively highly fugitive elements (Cd, Pb) in 
solid phases, show that sorption may play a key role in the intake of 
incompatible elements during crystal growth under the PT-conditions of 
endogenic mineral formation. Incompatible elements in a growing crystal 
form an adsorbed surface compound or a complex if their concentration is 
relatively low or a surface nonautonomous phase if their concentration 
approaches the saturation limit. Of this concentration, only a small 
portion may be in the structural form, and special techniques are thus 
required to separate it if the occurrence limit of the elements is 
estimated by routine methods.
     Incompatible elements, trace elements, mode of occurrence, sorption, 
endocrypty, cadmium, pyrrhotite

GEOLOGY OF OIL AND GAS 

AN OLD OIL AND GAS ACCUMULATION ZONE IN THE SOUTHERN SIBERIAN PLATFORM
(Katanga uplift) 
A. V. Khomenko, E. N. Kuznetsova, and A. O. Gordeeva
180

     The paper presents evidence that a large synsedimentary uplift 
existed in the southern Siberian Platform in the Early Paleozoic, which 
has been a zone of oil and gas accumulation since the late Early Cambrian. 
A number of carbonate reservoirs within the uplift yielded flows of 
petroliferous fluids and possibly contain the greatest portion of the oil 
and gas resources of the region.
     Cambrian, synsedimentary structure, hydrocarbons, Siberian Platform

GEOPHYSICS 

RECALCULATION OF STANDING WAVES IN DETAILED SEISMOLOGICAL 
ENGINEERING STUDIES 
A. F. Emanov, V. S. Seleznev, A. A. Bakh, S. A. Gritsenko, I. A. Danilov,
A. P. Kuz'menko, V. S. Saburov, and G. I. Tat'kov
184

     A new approach is suggested that enables detailed seismological 
engineering investigation of buildings, bridges, dams, etc. by the method 
of standing waves using small-channel instruments. Recalculation of 
standing waves from one point to another, which is possible to a 
predetermined accuracy, allows simultaneous recording of standing waves on 
networks of points of any density from microseismic records obtained at 
these points at different times.
     Specific features of observation systems and standing waves 
recalculation algorithms are considered for various types of structures.
     Experimental data show that the new method has high potentialities 
for detection and detailed investigation of standing waves in engineering 
structures. Investigation of the geometry of standing waves and spatial 
distribution of phases provides information on the physical state of the 
structures.
     The new method is highly effective and cheap.
     Engineering seismology, standing waves, Wiener filter