Volume 25, 4, 2006
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Volume 25, 4, 2006 |
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T.K. Zlobin, A.Ya. Iliev, L.M. Zlobina.
The nature and position of the surface of the sedimentary cover basement, Sea of
Okhotsk, from deep seismic sounding and CDP seismic reflection 3
V.M. Nikiforov, I.V. Dmitriev, S.S. Starzhinskiy. Deep
geoelectrical structure and seismicity of Primorye (Far East) 18
G.A. Stogniy, V.V. Stogniy. The structure of
crystalline basement of the northeastern Siberian platform based on results of
the geophysical field analysis 26
V.B. Kaplun. Geoelectrical structure of the Upper Amur
region from magnetotelluric sounding evidence 33
T.V. Volodkova. Anomalies of radioactive element ratios,
and the nature of ore mineralization in Priamurye 54
M.I. Kopylov, I.V. Pustovoitova. The potentialities for
integrated geophysical and petrophysical investigations in prospecting and
exploration of building materials within the Far East 69
A.A. Orekhov, G.A. Gonevchuk, V.G. Gonevchuk, V.A. Lebedev.
Rare metal granites of the Kavalerovo ore district (Primorye) 79
Ye.I. Medvedev, V.P. Molchanov V.G. Khomich.
Palladium-bearing gold, magnetite and shorlomite microspherules from placers of
the Blagodatnensky cluster (Primorye), and their possible sources 92
V.I. Roslikova. Present-day conceptions of subaquatic
pedogenesis 97
Reviews
V.P. Utkin. A new vision of the Earth's structure and geodynamics
104
Chronicles
A.G. Rodnikov. “InterMARGINS” International Project (Investigation of
continental margins) 107
Criticism and discussions
E.L. Shkolnik. Apropos of S.M. Rodionov and G.V. Roganov's paper "Mineral
phosphate raw material of the Far East, and the problems of its development"
110
S.V. Zyabrev. The realistic charater and reliability of tectonic
reconstructions 113
V.V. Golozoubov, A.I. Malinovsky, V.P. Simanenko. Tectonic
reconstructions of the Sikhote-Alin link of the East Asia margin: any possible
simple solutions? 115
Jubilees
Nikolai P. Romanovsky (75th birth anniversary) 120
T.K. Zlobin, A.Ya. Iliev, L.M. Zlobina
The nature and position of the surface of the sedimentary cover basement, Sea of
Okhotsk , from deep seismic sounding and CDP seismic reflection evidence
A comparison is made between deep seismic sounding data and CDP seismic
reflection evidence for distinguishing the basement of the Sea of Okhotsk
sedimentary cover. The velocity characteristics of the crystalline basement (Earth’s
crust surfaces of consolidated rocks) and the acoustic basement distinguished
from CDP seismic reflection evidence were considered. Based on the analysis,
three types of the basement and their spatial distribution within the sea of
Okhotsk were distinguished. Sections of the first type show that the surface of
crystalline rocks of the consolidated crust (B) and the acoustic basement (AB)
coincide. Sections of the second type exhibit coincidence of positions of the
crystalline basement and the acoustic basement; however, the boundary velocity
value along the AB is 5.5 km/sec. In the third type the acoustic basement AB
is above B, hence, their positions do not coincide. Distribution of the areas of
the above-mentioned basement types is considered. The possible geological nature
of the basement of these types within different parts of the bottom is discussed.
V.M.
Nikiforov, I.V. Dmitriev, S.S. Starzhinskiy
Deep geoelectrical structure and seismicity of Primorye (Far East)
The results of magnetotelluric soundings carried out in the Primorye territory
are discussed. The deep geoelectrical structure is shown to be formed both by
subhorizontal and steeply dipping interfaces. The latter are interpreted as
deep-seated faults. In the junction zones of en echelon faults duplexes can
develop, which due to filling-in of fractures with deep fluids acquire
anisotropic electrical conductivity. Crustal earthquake foci are spatially and,
probably, genetically related to such crustal rock complexes.
G.A. Stogniy, V.V. Stogniy
The structure of crystalline basement of the northeastern Siberian platform
based on results of the geophysical field analysis
The structure of the northeastern Siberian platform crystalline basement is
envisioned as the Olenek and Nakyn Archean cratons separated by the Late
Proterozoic Anabar-Lena mobile belt. A description is given of the inner
structure of the Anabar-Lena mobile belt which comprises two segments, Daldyn
and Khapchan separated by the Billyakh tectonic zone. It is shown that Mesozoic
kimberlite magmatism is localized in the Khapchan segment of the Anabar-Lena
mobile belt; and Paleozoic kimberlite magmatism, within the Olenek Archean
craton.
V.B. Kaplun
Geoelectrical structure of the Upper Amur region from magnetotelluric sounding
evidence
125 magnetotelluric soundings carried out in the south of the Aldan-Stanovoy
Shield and its folded framing have been analyzed, the less distorted amplitude
curves have been chosen, and the reference curve has been determined for the
study area. The above soundings were divided into five profiles including three
submeridional profiles stretching across the strike of the main structures, and
two sublatitudinal profiles stretching along this strike. As a result of
interpretation the geoelectrical sections of the lithosphere have been
constructed down to 130-150 km depths where the high-resistivity crust is
distinguished with the underlying low-resistivity mantle and the main tectonic
structures separated by deep faults. The geoelectrical sections show the
non-uniform structure of the area particularly within the structures of the
Central-Asian and Pacific Tectonic Belts. The Gonzhinsky bulge within the
Central-Asian Tectonic Belt and the Unakhin greenstone belt in the Stanovoy
granite-greenstone area are noted for the most non-uniformity. A change in the
resistivity has been revealed along the main structure-controlling faults (Dzheltulak,
South and North Tukuringra) from west to east, which is related to the change in
the geodynamic environment in this direction.
T.V. Volodkova
Anomalies of radioactive element ratios, and the nature of ore mineralization in
Priamurye
The paper shows the principal possibility of using the ratio of the natural
radioactive elements (NRE) of magmatic complexes to define the nature of their
mantle or crustal sources. The NRE values of magmatic complexes related to “hot
spots” obtained using aerogammaspectrometry are analyzed. The paper also
generalizes and analyzes the NRE ratio distribution characteristic of certain
types of mantle reservoirs and the Earth’s shells.
It is assumed that the magmatic complexes specialized for gold are formed due to
the influence of mantle metasomatism processes or the enriched mantle reservoirs.
M.I. Kopylov, I.V. Pustovoitova
The potentialities for integrated geophysical and petrophysical investigations
in prospecting and exploration of building materials within the Far East
The conduction of leading integrated
geophysical and petrophysical investigations makes it possible to use different
correlation dependencies between physical-and-mechanical properties of rocks and
geophysical parameters aimed at distinguishing the most promising areas for
prospecting of building materials (stone, sand, and clay), which essentially
facilitates the process of the study of a deposit and reduces the volume of
high-priced mining and laboratory procedures.
A.A. Orekhov, G.A. Gonevchuk, V.G.
Gonevchuk, V.A. Lebedev
Rare metal granites of the Kavalerovo ore district (Primorye)
The principal geochemical features of granites (65±2 Ma) and accompanying
greisens (63±2 Ma) that occur in the zone of the Central Sikhote-Alin fault in
the southwestern part of the Kavalerovo ore district (Primorye) are described.
The examined granites and greisens have been compared with analogous
associations of the Dubrovskoe tin deposit located in the central part of the
district (at a distance of 50 km from the Central Sikhote-Alin fault). The
characterized granites are similar by many features, and being non-typical
lithium-fluorine varieties, they bear the features of rare metal leucogranites.
Their formation is attributed to processes of crystallization differentiation of
granitoid magma followed by activation of the residual melt chambers. The age of
leucogranites (65-58 Ma) indicates that the activation could be caused by the
change of the geodynamic regime of the Late Cretaceous subduction margin to the
regime of a transform type margin that is fixed for this period in models of
geological evolution of the region. Geochemically, the geodynamic type of the
investigated granites has been determined as complex – intra-plate or
collisional. The main reason for this fact is presumed to be genesis and
evolution of magmatic melts in the deep fault zone at the boundary of
compositionally different lithosphere blocks – Samarka and Zhuravlevka terranes.
Ye.I. Medvedev, V.P. Molchanov V.G. Khomich
Palladium-bearing gold, magnetite and shorlomite microspherules from placers of
the Blagodatnensky cluster (Primorye), and their possible sources
The paper presents data on typomorphism and composition of native gold and its
areal distribution in gold formations and products of their exogenous
destruction. In association with Pd-gold microspherules of shorlomite are
recognized which is present solely in ultrabasic rocks. The presence of these
microspherules is considered as evidence of platinoid gold mineralization
involvement in placer formation. Platinoid gold mineralization formed due to
hydrothermal reworking of hypothetical basic and/or ultrabasic rocks concealed
at depth.
V.I. Roslikova
Present-day conceptions of subaquatic pedogenesis
Present-day conceptions of the development of pedogenesis processes of
subaquatic landscapes are analyzed by specialists in different disciplines. A
new view of the methods approach to their investigation is offered.