Volume 20, 3, 2001
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Volume 20, 3, 2001 |
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Geodynamics, Sedimentology and Stratigraphy
Melnikov, L.I. Poplavskaya , T.V.Nagornykh A system of stresses in Sakhalin earthquake sources and its relation with tectonics 3 O.V. Dudarev, A.I. Botsul, V.V. Anikiev, G.M. Kolesov, D.Yu. Sapozhnikov. Modern sedimentation in the Northwestern Anadyr Bay Cryolithozone (the Bering Sea) 12
A.N. Philippov, G.I. Buriy, V.S. Rudenko. Stratigraphic sequence of volcanogenic-sedimentary deposits from the Samarka terrane (Central Sikhote-Alin): a record of paleooceanic sedimentation 26
V.K. Popov, A.V. Grebennikov. New data on the age of effusives from the Bogopolsky suite in Primorye 47
Mineralogy and Geochemistry
S.S. Zimin, V.P. Molchanov, V.I. Sapin. Biotite-cordierite-andalusite hornfels from ultrabasites of the Chkhonzhin-Kaishantunsky ophiolitic zones 55
P.Ya. Tishchenko, A.N. Derkachev, G.Yu. Pavlova, Ye. Zyuss, K. Walman, G. Borman, Ye. Grainert. Formation of carbonate concretion in places of methane show on the seafloor 58
Yu.D. Markov, A.V. Mozherovsky, A.N. Derkachev, N.N. Barinov. Minerals of the green clay formations in the sediments of the Korean Strait 68
Minerageny
I.Ya. Nekrasov, G.G. Likhoidov, L.P. Plusnina, T.V. Kuzmina. Peculiarities of geology, geochemistry and genesis of Ulakhan-Sissky, Kular and Kharaulakh gold major zones, Verkhoyansk orogenic area 79
A.A. Kokovkin. On some peculiarities of exogenic Cenozoic metallogeny of Central Asian and Pacific mobile belts joint areas 87
A.P. Van-Van-Ye. Erodibility of endogenic deposits in tectono-magmatic activization zones of the Far East 97
Reviews
V.G. Khomich, V.P. Utkin, A.N. Mitrokhin, N.G. Borikina. Gold-bearing ore-forming systems of Southeastern China 105
Chronicles
Yu.Ya. Vashchilov. Problems of geophysics at the 31 International Geological Congress in Brazil 113
Anniversaries
N.P. Romanovsky (to the 70-th birth anniversary) 117
O.A. Melnikov, L.I. Poplavskaya , T.V.Nagornykh
A System of stresses in Sakhalin earthquake sources and its relation with tectonics
A great number of data on mechanisms of crustal earthquake sources of Sakhalin Isl. was obtained for the first time and analyzed from the geological and tectonical points of view. It was ascertained that a system of stresses in the insular Earth's crust is characterized by distinctly expressed sub-meridional alternation of compression and extension zones. The authors think that such a regularity is explained by the interaction between two main types of structures composing the insular megaanticlinal structure - modified-revived relict and young newly formed anticlinoria and synclinoria. Compression zones are attributed to the sections of direct opposition of young and ancient anticlinoria. These sections are separated with extension zones. Variations of the field of elastic stresses of the Earth crust of Sakhalin are also interpreted from the position of the Earth's rotational model earlier offered by O.A Melnikov.
O.V. Dudarev, A.I. Botsul, V.V. Anikiev, G.M. Kolesov, D.Yu. Sapozhnikov
Modern sedimentation in the Northwestern Anadyr Bay Cryolithozone (the Bering Sea)
At the present time, the largest part of the bottom surface within the northwestern part of the Anadyr Bay is defined as the asedimentogenic zone, wherein both relict and recent near-coastal sediments occur. The plume of the Anadyr River is formed beyond reach of the wave process influence on the bottom. Outside the area with the river water runoff action, within the bay basin, the terrigenous profile of the recent sediment accumulation is balanced by the biogenic silica sedimentation. The bottom sediment depletion in the most of the chemical elements is connected with the sedimentary material mobilization under conditions of the continental cryolithozone. The cryogenic process influence is traced in the temperatural field character for the near-bottom waters and in the distribution features for the bottom sediments and individual elements like Na and Br.
A. N. Philippov, G. I. Buriy, V. S. Rudenko
Stratigraphic sequence of volcanogenic-sedimentary deposits from the Samarka terrane (Central Sikhote-Alin): a record of paleooceanic sedimentation
Both sedimentological study and data on microfauna (radiolarians and conodonts) allowed reconstruction the stratigraphic sequence of sedimentary deposits on two areas of the Samarka terrane - a fragment of the Middle-Late Jurassic subduction-accretionary wedge of the Central Sikhote-Alin. In the western part of the terrane (Matai River right bank), it consists of the Upper Paleozoic chert, limestone and basalt, the Lower Triassic carbonaceous chert and siliceous mudstone, the Middle-Upper Triassic chert, the Lower-Middle Jurassic siliceous mudstone, the Middle-Upper Jurassic siltstone, and Upper Jurassic(?) basalt and mixtite. In the eastern part of the terrane (Katen River right bank in the middle course), a Triassic-Middle Jurassic chert unit with phtanite in the basement, the Middle-Upper Jurassic siliceous mudstone and siltstone, the Upper Jurassic siltstone, and the Upper Jurassic-Lower Cretaceous sandstone units occur. These sequences represent the original sections of the sedimentary cover on different areas of the ancient oceanic plate and reflect the sedimentary history during its movement from spreading ridge to convergent zone. Sedimentary environments of lithostratigraphic elements accumulation have been determined and it was established that in the near-continental area they differed significantly when different areas of the oceanic crust had been accreted. At the initial stages of accretionary wedge formation in the middle of Middle Jurassic (Matai River right bank section), the slides were the main sedimentary processes and simultaneously underwater basaltic volcanism occurred. Besides pyroclastics of a marginal-continental arc have been found in the sediments. Later, at the beginning of Late Jurassic (Katen River middle course) mainly turbidites were accumulated, the clastics of which are represented in main by granitoids. Volcanic events occurred neither in the sedimentary basin nor on the continent. These distinctions are, perhaps, the consequence of different subduction-accretionary processes during long-term (about 20 Ma) development of the Samarka terrane accretionary wedge.
V.K. Popov, A.V. Grebennikov
New data on the age of effusives from the Bogopolsky suite in Primorye
The paper presents the first data on Rb-Sr absolute age of the effusive rocks from the Bogopolsky suite. The stratified tuffs and hyaloignimbrites of the Yakutinskaya volcanic structure are accepted as a reference section of the Bogopolsky suite. The absolute age of the effusive rocks of the upper part of the suite is 59.68 ± 1.59 -52.92 ± 1.00 Ma. The obtained data have allowed us to make more precise a position of the Bogopolsky suite and other Cretaceous-Paleogene strata in the stratigraphic scale. On the basis of the materials considered, the scheme of stratification of Cretaceous-Paleogene formations in the stratotypical area is proposed. The age of strata substantiated by the geochronological data is in good accordance with Cretaceous and Paleogene global geologic events.
S.S. Zimin, V.P. Molchanov, V.I. Sapin
Biotite-cordierite-andalusite hornfels from ultrabasites of the Chkhonzhin-Kaishantunsky ophiolitic zones
The paper describes biotite-cordierite-andalusite hornfels originated at the contact of thin sill of ultrabasites with clayey shales and siltstones of the Upper Paleozoic (P1), which occur on the northern flank of the Chkhonzhin-Kaishatunsky ophiolitic zone (Korean People's Democratic Republic). Chemical compositions of the altered rocks, cordierite, and andalusite were determined and the temperature of their formation was estimated.
P.Ya. Tishchenko, A.N. Derkachev, G,Yu. Pavlova, Ye. Zyuss, K. Walman, G. Borman, Ye. Grainert
Formation of carbonate concretion in places of methane show on the seafloor
On the northeastern slope of Sakhalin Island there have been found carbonate concretions in places of the methane show. The mechanism of formation of chemogenic carbonate concretion is offered. Sulfate reduction and methanogenesis, which create a high alkaline reserve of pore water are thought to be a necessary preparatory stage. The removal of dissolved carbonic acid from pore water by means of methane bubbles is an obligatory condition for concretion formation.
Yu.D. Markov, A.V. Mozherovsky, A.N. Derkachev, N.N. Barinov
Minerals of the green clay formations in the sediments of the Korean Strait
Distribution and mineral composition of the green clay formations have been studied for the first time along the profile line in a wide part of the Korean Strait. It has been established that mineral composition of the sedimentary rock fragments, lumps, moulds of test cavities of foraminifera, and pseudomorphism from fauna, has appeared homogeneous and is represented by dioctaheidral smectite (tetrasiliceous nontronite), and at a lesser degree by mixed-layered smectite-illite. It appears that moulds of the test cavities of foraminifera in the South China and East China seas have the same mineral composition. It is concluded that tetrasiliceous nontronite on the shelf and continental slope of marginal seas in the northwestern Pacific might have a common mechanism of sedimento-diagenetic formation.
I.Ya. Nekrasov, G.G. Likhoidov, L.P. Plusnina, T.V. Kuzmina
Peculiarities of geology, geochemistry and genesis of Ulakhan-Sissky, Kular and Kharaulakh gold major zones, Verkhoyansk orogenic area
Gold mineralization within carbon-bearing complexes of the northwestern part of the Verkhoyansk orogenic area are considered. To evaluate a temperature effect on redistribution of Au and C within enclosing rocks, chemical sorption of Au on organic matter (OM) was experimentally studied at 20-500 °C, 1 kb. It was ascertained that sorption capacity of OM increases with growing temperature and more stable Au-C complexation may be an effective mechanism of Au accumulation in the black shales. Syngenetic-epigenetic character of the gold deposits in the C-bearing rocks was proposed with assignment of those to sedimentary-fluid-metamorphogenetic type.
A.A. Kokovkin
On some peculiarities of Cenozoic exogenic metallogeny of Central Asian and Pacific mobile belts joint areas
Peculiarities of the development of deflation and crust-forming processes are analyzed. The model of lateral zonation of these processes is suggested. Within the framework of this model, the basic regularities of Cenozoic exogenic ore-genesis are considered taking hydrogeneous and placer-forming ore-forming systems as an example.
A.P. Van-Van-Ye
Erodibility of endogenic deposits in tectono-magmatic activization zones of the Far East
The paper deals with main techniques of erosional shear depth determination of ore fields and ore deposits. Definition of erodibility degree of some ore-bearing structures and geoblocks is exemplified. In this connection problems of discovering concealed ore deposits, including those in the Far Eastern region are discussed.