Contents

Stratigraphy
Yu. B. Gladenkov, A. Yu. Gladenkov, L. V. Titova Lower Miocene of the Eastern Kamchatka region     3
I.V.Kemkin, V.S.Rudenko New data on cherts age of the Samarka accretionary prism (Southern Sikhote-Alin)    22
Petrology, Mineralogy and Geochemistry
V.S.Shkodzinsky, A.N.Zedgenizov Genesis of Precambrian complexes in the light of the latest data on global magmatic fractionation at the time of the earth accretion (as exemplified by the Aldan shield)    32
F.P.Lesnov, M.P.Gora, V.A.Bobrov, V.A.Kovalyova Distribution of rare-earth elements and genesis issues for the Beryozovsky mafic-ultramafic massif (the Island of Sakhalin)    42
T.N. Grigoryeva, G.A. Dubinina, T.N. Moroz, N.A. Pal’chik Mineral composition of manganese oxides synthesized with participation of microorganisms     59
Ore formation
V.P.Molchanov, V.G.Moiseenko, S.S.Zimin, A.V.Ignatyev, Lyang Chang Cheng Specific features of gold ore formation in ophiolites of the North Korean Peninsula     65
L.V.Eirish The perspectives of detecting Karlin-type deposits in Russia’s Far East     72
D.I.Kolesnikov, Ju.P.Shergina, M.I.Rosinov, N.G.Shatkov, G.S.Shkorbatova The age of silver and tin ore mineralization of the Kensky area (Russia’s North -East)      80
M.M. Zadornov, L.B. Khershberg, M.L. Shcolnik, I.N. Govorov, O.V. Chudaev, M.I. Yurinez, K.M. Kuznetsov, L.A. Bolotov The perspective of the exploration for cobalt-manganese crusts and phosphorites in the Western Pacific    87
Geophysics
V.Ya. Podgorny and Yu. F. Malyshev Layer-by-layer density modeling of the lithosphere on the geotraverse Dong Ujimqin - Donggou, East China    93
F.I.Manilov, Ye.G.Ivolga Retrospective constructions on the basis of paleogravimetric reconstructions (the Khanka massif, Primorye)     107
T.V.Merkulova, Yu.F.Manilov The structure of the south-western part of the Middle-Amur depression (from geoelectrical and gravimetric data)     116
Reviews and Discussions
N.P.Romanovsky, R.F.Cherkasov Earthly problems - cosmic problems (On A.N.Shilo's book " Four cosmoplanetary problems : from the Solar System to the Caspian Sea")     121
G.L.Kirillova , V.Yu.Zabrodin Fundamental work: systematics and classification of the sedimentary basins and their analogues    124
Yu.I.Bakulin Deposits of a Nevadian - type fine-dispersed gold - a type of primary sedimentary deposits regeneration    126
Obitnaries
А.D.Shcheglov (1926 - 1998)

Yu. B. Gladenkov, A. Yu. Gladenkov, L. V. Titova
Lower Miocene of the Eastern Kamchatka region
The analysis of fossil remains from the Gustovskaya and Ozyornovskaya suites of Eastern Kamchatka made it possible to define for the first time the Oligocene-Miocene boundary in this region. The Early Miocene assemblages of planktonic (diatoms) and benthic (molluscs) groups from different sections of the North Pacific are correlated.   

 I.V.Kemkin, V.S.Rudenko
New data on cherts age of the Samarka accretionary prism (Southern Sikhote-Alin)
New data on the age and structure of cherty enclosures, as well as on the age of chert-matrix transition deposits of the Samarka accretionary prism are given. There are 7 different-age radiolarian associations distinguished in the investigated section, and their brief characteristics are given. Five of them, covering the Middle Triassic-Middle Jurassic interval, correspond to a cherty part of the section, and two others of Middle Jurassic age occur in the terrigenous part. Photos of Triassic and Jurassic radiolarians are presented.

V.S.Shkodzinsky, A.N.Zedgenizov
Genesis of Precambrian complexes in the light of the latest data on global magmatic fractionation at the time of the earth accretion (as exemplified by the Aldan shield)
According to the model presented, the earth’s core formed prior to the mantle and had a higher initial temperature due to greater accretion rates of magnetic particles than of non-magnetic ones. This conditioned subsequent mantle heating by the core, appearance of convective flows in the mantle, and plate tectonic movements in the lithosphere. The processes of impact melting of the falling material and compression crystallization of the forming magmas at the time of mantle accretion were accompanied by the change of the residual melt from acid to picritic, and resulted in the stratified magmatic ocean. Grey-gneiss complexes were the product of crystallization and partial fractionation of the upper part of the acid melt’s layer; and granulite complexes, of its lower part, after partial buoying of the latter to the earth’s surface. K and Rb depletion of these complexes and Ca-, Mg-, Ni- and Co-enrichment are the consequence of diffusion interaction of the early acid melt of the magmatic ocean’s upper part with the mafic melt being formed during impact melting of the falling material. The pararocks of granulite complexes resulted from interaction of the cooling granulite migmas with a gas and steam envelope. The formation of greenstone belts reflects the appearance of the first massive convective flows in the mantle. The succession of magmatic processes in the gneiss complexes from K-Na granites to alkaline magmatites was conditioned by the deepening of the crystallization and fractionation front of the residual magmatic ocean which underlay these complexes. Orthogneiss granitization is the result of partial isolation and crystallization of the parent magmas’ residual melt.

F.P.Lesnov, M.P.Gora, V.A.Bobrov, V.A.Kovalyova
Distribution of rare-earth elements and genesis issues for the Beryozovsky mafic-ultramafic massif (the Island of Sakhalin)
The Beryozovsky polygenic mafic-ultramafic massif belongs to the Mesozoic ophiolitic association of the Island of Sakhalin. It consists of three main fragments: protrusions of alpinotype ultramafic rocks (harzburgites, lherzolites, dunites, serpentinites); a cross-cutting intrusive of mafic rocks (gabbro-norites, gabbro); and a transition zone (websterites, clinopyroxenites, wherlites, plagioclase-bearing ultramafites, olivine-bearing mafites). Chemical compositions of orthopyroxenes, clinopyroxenes and plagioclases from gabbronorites, websterites and lherzolites have been studied. Temperatures of chemical equilibrium for coexisting pyroxenes in the above rocks have been calculated. The average temperature did not exceed 1000 5o 0C which corresponds to the data on the final stage of the massif’s magmatic history. Using the neutron activation method and radiochemistry techniques, distribution of rare earth elements (REE) in gabbro-norites, websterites and lherzolites as well as in their minerals (orthopyroxenes, clinopyroxenes, plagioclases) has been studied. It appears that all the rocks in this ophiolitic massif are REE-depleted. Small positive anomalies of Eu are found in the gabbro-norites; however, some deficiency of this element is revealed in the websterites. Positive Eu anomalies in plagioclases from olivine-free gabbrides are higher than those from olivine-bearing gabbrides. On the basis of REE distribution among the co-existing orthopyroxenes and clinopyroxenes in experimental systems, and gabbro-norites from the massif under study, it is shown that the melts from which gabbro-norites were formed had been generated at a moderate degree of partial melting of mantle source.

T.N. Grigoryeva, G.A. Dubinina, T.N. Moroz, N.A. Pal’chik
Mineral composition of manganese oxides synthesized with participation of microorganisms
The investigation results of Mn-products of a biological synthesis by methods of X-ray diffraction, IR spectroscopy and thermal analysis are presented. The experiment was carried out with the binary culture Metalogenium. The source of manganese was rhodochrosite. The phase composition of bioproducts has been identified which involves birnessite, vernadite, mixed-layer asbolane-buserite and X-ray diffraction amorphous manganese oxides.

V.P.Molchanov, V.G.Moiseenko, S.S.Zimin, A.V.Ignatyev, Lyang Chang Cheng
Specific features of gold ore formation in ophiolites of the North Korean Peninsula
It has been established that the Kumbai gold deposit shows two stages of its formation that resulted in occurrences of gold-skarn and gold-quartz ores. The latter are of two mineral types: pyrite-molybdenite and gold-pyrite. It is shown that a granitic intrusion could be an abyssal homogeneous source of pyrite-molybdenite mineralization. Mineralogogeochemical and isotope-geochemical parameters of gold-pyrite mineralization of the central part have been compared with those of the western flank of the sublatitudinal vein series. Sulphides of the central part have been found to be enriched in S34 by 4.4‰ as compared with the western part. To explain these variations we have studied the isotope composition of carbonaceous matter of veins, skarns, and limestones. We have concluded that the participation of skarn-forming solutions in ore development is accompanied by redestribution of sulphur isotopes and supplying of gold, silver, cobalt, nickel, and magnesium from ultrabasites.

L.V.Eirish
The perspectives of detecting Karlin-type deposits in Russia’s Far East
Brief characteristics of the Karlin, Gold Quarry, and other deposits are given. The most prominent metallogenic features of their localization are emphasized: confinement of the regional structure to the areas of Mesozoic-Cenozoic tectono-magmatic activation registered by the global and regional gravity minima; traverse of the fold structure by the transversal deformation zone; ore-forming carbonate and carbonic environment; localization of ore mineralization in dome-like structures and anticlines beneath the geological units of impermeable siltstone-pelitic rocks; fine-impregnated ore type and microscopic size of gold shows; and optimal erosional section of ore-bearing structures. In view of the above specific features, areas with Karlin-type (or close to it) gold mineralization potential were distinguished: in the South Verkhoyansky synclinorium and in the Sette-Dobansky pericratonic trough, in the superimposed troughs of the Aldan shield, in the Devonian terrigenous-carnonate unit in the west of the Mongol-Okhotsk area.

D.I.Kolesnikov, Ju.P.Shergina, M.I.Rosinov, N.G.Shatkov, G.S.Shkorbatova
The age of silver and tin ore mineralization of the Kensky area (Russia’s North -East)
An investigation of the connection of rhyolite dikes with ore bodies has been conducted. The results of this investigation and isotopic-geochronologic Rb-Sr study of ore-bearing rhyodacites of the Nayachansky suite (90.8±2.3 m.y.), rhyolites of a dike complex (80.9 ±1.1 m.y.) and metasomatites concomitant with silver -polymetallic and tin ores of the Kensky area deposits are reported. The two stages of productive mineralization are substantiated: silver-polymetallic- 88 ±2.1 m.y.; and tin,75.7±3.6 m.y.

M.M. Zadornov, L.B. Khershberg, M.L. Shcolnik, I.N. Govorov, O.V. Chudaev, M.I. Yurinez, K.M. Kuznetsov, L.A. Bolotov
The perspective of the exploration for cobalt-manganese crusts and phosphorites in the Western Pacific
On the two guyots MA-15 and MЖ-35 (Magellan seamounts, Pacific ocean) are shown that the active formation of the manganese crusts and phosphorites occurred at a depth of 1250-3200 m with average thickness-6-7cm. The total Co-Ni-Mn resources of these guyots were determined. These data were compared with other Co-Mn deposits in the Pacific ocean and on the continent. Preliminary data indicate a high profit margin (22-26%) for exploration Co-Ni-Pt manganese crusts on the Magellan seamounts.

V.Ya. Podgorny and Yu. F. Malyshev
Layer-by-layer density modelang of the lithosphere on the geotraverse Dong Ujimqin - Donggou, East China
Based on elaborated method of determining layer-by-layer density distribution the quantitative evaluation of the gravitational contribution to the measured gravity field of the crust and lithosphere boundaries along the geotraverse Dong Ujimqin—Donggou, East China, is given. The connection is revealed between the structural elements of the Sino-Korean Platform, paleozoic fold systems and their junction and the deep structure, geodynamics, and density characteristics of the crust and upper mantle. This confirms the reducing of the ancient crust, remainder of relicts of the paleoocean at depth and horizontal displacements of the layers.The new additional information is obtained on the most important geophysical boundary in the east of Asia - the “Pogranichnaya” (Dahinggan-Taihang-Wulin) gravitational step separating the continental margin from its internal areas. It is shown first that the gravitational effect of the step is caused by density distribution within the lithospheric layer as a whole with the significant role of the crustal thickness. Change of the sign of the density step at the lower crustal layer and the asthenosphere is noted.

F.I.Manilov, Ye.G.Ivolga
Retrospective constructions on the basis of paleogravimetric reconstructions
(the Khanka massif, Primirye)
The article suggests a variant of the methods of constructing age structural profiles. The method involves paleogravity reconstructions by means of complex analysis of geophysical, petrophysical (paleomagnetic data included) and model research results. Approbation results of the suggested method (two levels of detailed approach) are presented as exemplified by the south-eastern part of the Khanka massif are presented. Some new data were obtained on the following: datum definition of paleomagnetic poles, structural plan evolution of the territory beginning from the Early Cambrian to the Cenozoic, and additionally, structure and time regularities of distribution of fluorite, tin and uranium mineralization.

T.V.Merkulova, Yu.F.Manilov
The structure of the south-western part of the Middle-Amur depression (from geoelectrical and gravimetric data)
As a result of joint interpretation of VES-data and gravimetric data, new information was obtained on the structure of a number of grabens in the Middle-Amur depression included in the Tan Lu fault system. The paper deals with some questions devoted to the methods of interpretation. The peculiarities of the geoelectrical section of the Byrofeldsky graben are determined. The thickness of the sedimentary cover of the grabens is defined more precisely thus providing additional evidence for evaluation of oil and gas potential.