Geologiya I Geofizika, 2002, V 43, N 9.

STRATIGRAPHY AND PALEONTOLOGY 

A NEW REFERENCE SECTION FOR THE UPPER JURASSIC AND CALLOVIAN IN 
NORTHERN WEST SIBERIA
A. L. Beizel', Yu. N. Zanin, A. G. Zamirailova, V. I. Il'ina, N. K. Lebedeva,
L. K. Levchuk, M. A. Levchuk, S. V. Meledina, B. L. Nikitenko, B. N. Shurygin, 
and P. A. Yan 
811
 
The section of Zapadno-Purpeiskaya BH-710, drilled in the central part of the 
plate, is one of the reference sections of the Upper Jurassic in northern West 
Siberia. This section is represented by a succession of formations most typical 
of this range in West Siberia: Vasyugan, Georgievka, and Bazhenov. The rock 
lithology was examined in detail. The section was paleontologically
 characterized using a complete range of fossils: ammonites, bivalves, 
microfauna, dinocysts, spore, and pollen. On this basis the section was 
subdivided biostratigraphically. Logging data have been analyzed. Some new 
stratigraphic results have been obtained. The middle part of the Callovian 
(uppermost Lower Callovian, Middle Callovian and, partly, Upper Callovian) in 
the studied section is severely reduced to absent. The ammonites Indosphinctes 
(Elatmites) mokschaensis (Sas.) have been found in West Siberia for the first 
time. This species is widespread in the Middle (and partly Upper) Callovian of 
the Russian Platform. The Middle-Upper Volgian part of the Bazhenov Formation is 
much reduced in thickness. It has been established that the largest (upper) part 
(about two thirds) of the Bazhenov Formation in this section is of Berriasian 
age. The interval between the ammonite-based uppermost beds of the Lower 
Berriasian and the lowermost beds of the Lower Valanginian is about 12 m. About 
a half of them is occupied by the upper part of the Bazhenov Formation 
overlapped by the Sortym Formation.
Upper Jurassic and Callovian deposits, stratigraphy, lithology, ammonites, 
bivalves, microfauna, spore and pollen, dinocysts 


NEW DATA ON BIOSTRATIGRAPHY OF THE LOWER AND MIDDLE CAMBRIAN SERIES
IN THE NORTHEASTERN SIBERIAN PLATFORM (section of the Khorbosuonka River, Olenek 
uplift) 
I. V. Korovnikov 
826

Several sections of Lower and Middle Cambrian series have been studied on the 
Khorbosuonka River. Our analysis of stratigraphic distribution of trilobites and 
brachiopods permitted amendments in biostratigraphic zonal subdivision of Lower 
and Middle Cambrian deposits. Intervals corresponding to all regional zones of 
the Atdabanian Stage have been established in the section for the first time. 
Because of poor paleontological description, no local biostratigraphic 
subdivisions corresponding to the Profallotaspis jakutensis and Fallotaspis 
Zones have been recognized in the intervals of Section 1. We have established 
local biostratigraphic zones, Pagetiellus anabarus and Judomia mattaiensis-
Uktaspis granulata, counterparts of the regional zones Pagetiellus anabarus-
Nevadella and Judomia-Uktaspis (Prouktaspis), respectively. The preceding zonal
 subdivision has been confirmed for the Botomian and Toyonian Stages. We only 
propose to use the name Protolenus-Nelegeria lata instead of Protolenus borealis 
for the first local biostratigraphic zone. A local biostratigraphic zone, 
Triplagnostus gibbus, corresponding to the regional Triplanognostus gibbus Zone, 
has been recognized in the Amgaian Stage, at the bottom of the Kuonamka 
Formation. Beds with Anomocarioides limbataeformis have been established in the
Mayaian Stage, in the upper half of the Yunkyulyabit-Yuryakh Formation. Of the 
paleontological collection of trilobites and brachiopods, several forms have 
been identified as new taxons.
  Lower Cambrian, Middle Cambrian, complexes of trilobites, brachiopods, 
biostratigraphy, northeastern Siberian Platform 

PETROLOGY, GEOCHEMISTRY, AND MINERALOGY 

ESTIMATION OF HF CONTENTS IN MAGMATOGENE FLUIDS OF PORPHYRY
 Cu-Mo ORE-MAGMATIC SYSTEMS (Siberia, Mongolia) 
V. I. Sotnikov, A. N. Berzina, A. P. Berzina, V. O. Gimon, and V. Yu. Kiseleva
837

From results of microprobe analysis and experimental data on biotite systems of 
ore-bearing porphyry complexes (stocks, dikes) and the host granitoids 
(massifs), we have calculated concentrations of HF in magmatogene fluids 
coexisting with biotite. Porphyry complexes of Cu-Mo deposits of Siberia and 
Mongolia are characterized by low concentrations of HF (MHF): from 0.0153 to 
0.0024 mole/dm3 at T = 800-700 °C. The MHF of the deposits decreases in the
 sequence: Sora-Vykhodnoe-Zhireken, Aksug-Erdenetuin-Obo-Shakhtama. This 
sequence (except for the Shakhtama deposit) is to a certain extent correlated 
with the silica content of ore-bearing porphyries, intensity of potassic 
metasomatism, and Cu/Mo in ores. We have found no correlation of MHF with 
(87Sr/86Sr)0 of porphyries, abundance of mineralization, and contents of ore-
forming components. The ore-bearing porphyries and more ancient host granitoids 
(except for the large Erdenetuin-Obo deposit and Vykhodnoe ore occurrence) 
differ slightly in MHF. Therefore, the elevated activity of HF in porphyry Cu-Mo 
ore-magmatic systems is related not only to the concentration of F in magmas but 
also to the evolution of porphyry melts in more open settings. The great spread 
in (87Sr/86Sr)0 values of ore-bearing porphyry complexes at different deposits
(from 0.70393 to 0.70774) suggests mantle-crustal sources of fluorine.
Porphyry Cu-Mo deposits, magmatogene fluids, concentration of HF, sources of 
fluorine, Siberia, Mongolia


ELVANS OF CORNWALL (England) AND SOUTHERN SIBERIA AS SUBVOLCANIC
COUNTERPARTS OF SUBALKALIC RARE METAL GRANITES 
V. S. Antipin, C. Halls, M. A. Mitichkin, P. Scott, and A. N. Kuznetsov
847

Elvans are known from several rare metal provinces, where they are spatially and 
genetically closely related to subalkalic rare-metal granites. Elvan magmatism 
manifests itself at the final stage of the evolution of lower-crustal granitoid 
magma chambers. Elvans are produced by differentiation of a subalkalic granitoid 
magma. Occurrence of elvans in zones of deep-seated faults and dike belts, where 
basite and monzonitoid magmatism is expressed, as well as isotope-geochemical 
data suggest that the elvan formation was much affected by a subcrustal fluid
 enriched in specific rare elements.
Elvans and rare-metal granites, geochemistry, magmatism, petrology, basalts and
 monzonitoids, dike belt, subvolcanic rock, isotope-geochemical study 


ULTRAMAFIC ROCKS OF RAKOVAYA BAY (Eastern Kamchatka): COMPOSITION 
 AND GEODYNAMIC CLASSIFICATION 
A. B. Osipenko and G. I. Anosov
858

We present results of detailed mineralogical and geochemical investigations of 
peridotites from allochthonous plate in Rakovaya Bay (the north of Avachinskaya 
Bay, Eastern Kamchatka). In geologic position and composition the studied rocks 
are much similar to ultramafic rocks of other massifs of the East Kamchatkan 
ophiolite belt and <%-2>are referred to as restite peridotites of the so-called 
suprasubductional type transformed by multistage metamorphism. It is suggested
 that peridotites of Rakovaya Bay along with ultramafic rocks of the Ganal'sky 
Ridge and ultrabasic xenoliths of the Avachinsky Volcano form a linear NW-
oriented zone, which spatially coincides with the Avacha-Kolpakova zone of 
structural deformations and is the southern margin of the area of occurrence of 
ophiolite-type ultramafic rocks in Eastern Kamchatka.
Ultramafic rocks, ophiolites, mineralogy, geochemistry, paleogeodynamics, 
Eastern Kamchatka


GEOPHYSICS

LABORATORY SEISMIC MODELING OF A MEDIUM CONTAINING FLUID-SATURATED
 SANDSTONE 
A. M. Verkhovskii
873

The paper addresses modeling of sandstone as a mixture of sand grains with 
predetermined size distribution, modal diameter, and sorting coefficient of 
grains and content of fine-grained (viscous) component. Sandstone is considered 
a granular medium whose properties are analyzed in terms of controlling 
processes and modeling suitability. The behavior of grain contacts is the
 most difficult point of modeling.The suggested 2D (sheet) model simulates a 
medium containing a layer of fluid-saturated sandstone. The model includes 
acoustic and filtration properties of grain contacts with flat surfaces. Vacuum 
fluid saturation may account for various types of natural settings, namely, oil
 plus bound water (oil reservoir), gas plus bound water (gas reservoir), and 
water alone (water reservoir).
Physical modeling, fluid-saturated sandstone


CRACKED SOLID GEOMETRY AND PARAMETRIC RESONANCE 
B. P. Sibiryakov
882

Resonance phenomena are often observed in seismology and seismic exploration: 
vibration applied to oil wells, earthquakes caused by periodic oscillations of 
hydropower stations, crust movements associated with Moon rotation, or motions 
of the Earth's surface felt in regions of active petroleum production. These 
phenomena have a surprisingly poor theoretical background in geophysics, though 
parametric resonance is well known in physics. The reason may be that wave
 phenomena in rocks are simulated in geophysics in the context of continuum 
media that lack internal geometry and, hence, characteristic sizes of structures 
related to the specific surface area. However, resonance phenomena fraught with 
natural and technical risk can be theoretically investigated in terms of a model 
containing specific surface area of cracks with a length-inverse dimension.
Pore geometry, specific surface area, instability, resonance

PERSONALIA

 To the 70th birthday of Al'girdas-Zenonas Stanislovo Dagis 
888