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Том 32, 6, 2013 |
| G.A. Gonevchuk, V.G. Gonevchuk.
Heterogeneity and polychroneity of the Chalba granitoid
massif (Komsomolsk ore region, Far East, Russia) in
the context of the present notions of the geological
structure of the region 3 A.S. Vakh, O.V. Avchenko, V.I. Kiselev, S.A. Sergeev, S.L. Presnyakov. U-Pb isotopic geochronologic study of zircons from granites and ore-bearing metasomatites of the Berezitovoe gold-polymetallic deposit (Upper Priamurye, Russia) 20 V.I. Gvozdev, N.A. Goryachev, A.S. Vakh, D.G. Fedoseev, B.I. Semenyak. Mineral composition and typomorphic features of minerals from gold-ore veins of the Kirovskoe deposit (Upper Priamurye) 40 V.G. Khomich, I.I. Fatyanov, N.G. Boriskina. Metallogenic analysis of type gold-bearing areas of the southern and eastern framing of the North-Asian craton (geotectonic position, geological structure, and features of formation) 52 S.V. Vysotskiy, A.V. Ignatiev, A.G. Khlestunova, T.A. Velivetskaya, A.S. Okrugin. Peculiarities of oxygen isotope features in precious opals 64 C.R. Cao, G.L. Kirillova, A.P. Sorokin, V.B. Kaplun, H.S. Cao, Y. Qu, Y.J. Zhang. Structural framework and evolution of the Sunwu-Jiayin Basin in NE China and its relation to the structures of the Zeya-Bureya Basin, the Far East of Russia 68 V.V. Krapiventseva. Catagenesis of Jurassic-Cretaceous coals and rocks of the Bureya Basin in respect to hydrocarbon generation (Far East) 79 Yu. V. Rybiakova, S. A. Gorbarenko, А.А. Bosin. Environmental and climaticchanges in the north Japan Sea and adjacent territory during the last 40 kyr, based on the record of spore-and-pollen analysis of bottom sediments 94 V.P. Shesterkin, V.S. Talovskaya, N.M. Shestrkina. Long-standing dynamics of iron content and flow in the water of the middle Amur River during the lowest winter water level 106 News from the expeditions Obzhirov A.I. The main results of comprehensive research as part of the International scientific expedition to the Sea of Okhotsk and the Sea of Japan, August 2012. 112 Index of paperspublished in 2013 г. 113 G.A. Gonevchuk, V.G. Gonevchuk Heterogeneity and polychroneity of the Chalba granitoid massif (Komsomolsk ore region, Far East, Russia) in the context of the present notions of the geological structure of the region The paper deals with the results of the latest geochemical and isotope-geochronological studies of the Chalba Massif, the largest granitoid intrusive of the Myao-Chan volcanic zone of the Khingan-Okhotsk magmatic area. In the limits of the zone the Komsomolsk tin district, the largest in Russia, is defined. This makes the granitoid association to be particularly examined as it displays a close genetic relation with tin mineralization throughout. The investigation and interpretation of the results should clarify a debatable question of the Chalba Massif heterogeneity and its assumed, buried under terrigenous and volcanogenic rocks extension at the best part of the ore district. Isotope geochronology (U/Pb from zircons and K-Ar from biotites and rarely rocks) reveals that two major granitic varieties of the massif - coarse-grained biotite and medium-granular pyroxene-bearing varieties are dated at 94-90 Ma. Their geochemical discrepancies and distribution of rare alkali and REE are not contrasting. All this, in the authors’ opinion, can reflect general peculiar features of magmatism of active continental margins. On the basis of the data obtained the combined occurrence of the Chalba rhyolite-granite and Silinka andesite-monzodiorite-granite complexes in the granitoid massif is justified. The latter is the main tin district. Key words: granitoids, heterogeneity, presence of tin, continental margin, Komsomolsk ore district, Far East. A.S. Vakh, O.V. Avchenko, V.I. Kiselev, S.A. Sergeev, S.L. Presnyakov U-Pb isotopic geochronologic study of zircons from granites and ore-bearing metasomatites of the Berezitovoe gold-polymetallic deposit (Upper Priamurye, Russia) Results of the U-Pb geochronologic studies of zircons from ore-bearing metasomatites of the Berezitovoe gold-polymetallic deposit of Upper Priamurye and the porphyry-like biotite-hornblende host granites of the Khaiktin-Orogzhan massif earlier thought to be Early Proterozoic magmatic formations of the Late Stanovoy Complex are examined. The studies were carried out by two methods: SHRIMP-II and LA-ICP-MS. It was revealed that Mass Spectrometer method coupled with laser ablation system enable precise U-Pb age dating of the rocks and the results obtained are comparable with the data obtained with the help of SHRIMP-II. Established weighted average isotopic ages of zircons are 344–355 Ma from porphyry-like granites of the Khaiktin-Orogzhan massif and 323–366 Ma from ore-bearing metasomatites of the Berezitovoe gold-polymetallic deposit. The data definitely indicate that the former were formed from granitoids of the Khaiktin-Orogzhan massif which are assumed to relate to an independent Late Paleozoic magmatic complex. Close-in-age Paleozoic magmatic complexes are widespread within the Selenga-Stanovoy superterrane in the Eastern and Western Transbaikalia. Key words: isotopic geochronology, U-Pb method, zircon, granite, gold-polymetallic deposit, North Asian craton, Upper Priamurye. V.I. Gvozdev, N.A. Goryachev, A.S. Vakh, D.G. Fedoseev, B.I. Semenyak Mineral composition and typomorphic features of minerals from gold-ore veins of the Kirovskoe deposit (Upper Priamurye) A collection of quartz veinlets with ore mineralization has been sampled from the dumps of the old pit of the S.M. Kirov mine and new exploring traverse trenches of the Kirovskoe deposit. Mineral associations productive for gold mineralization have been distinguished, the composition of main ore minerals has been studied, and their typomorphic features have been described. Problems of genesis of the associations and deposit are discussed. Key words: gold deposits, mineral associations, mineralogy, genesis, Upper Priamurye. V.G. Khomich, I.I. Fatyanov, N.G. Boriskina Metallogenic analysis of type gold-bearing areas of the southern and eastern framing of the North-Asian craton (geotectonic position, geological structure, and features of formation) Large ore-placer localities of the southern and eastern framing of the North Asian craton (Bodaibinsky, Verkhneselemdzhinsky, Yuzhnoverkhoyansky, and Ten’kinsky) are characterized by some common features such as restriction to the areas of the earth’s crust lowered thickness and gradient zones of the gravity field traced by deep-seated faults; fold-thrust structure of the terrigenous black shale beds; phyllite, greenschist, and sometimes epidote-amphibolite metamorphism of ore-enclosing rocks; complicated and prolonged history of Au concentration process manifested by successive-stepwise change of several ore-preparing stages by an ore-generating one. The latter is conjugate in space and time with manifestations of orogenic (volcano-plutonic) magmatism producing the mineralization оf gold-quartz, gold-sulfide-quartz, gold-black shale, gold-rare metal, and gold-silver formations. Special features of their spatial relationships (coincidence-superposition or lateral zonality) correlate with the scales of precious metal concentration, economic importance of some deposits, and metallogenic potential of the regions. The established features of similarity in the formation and structure of the districts are suggested to be taken into consideration when choosing new promising areas and forecast evaluation of potentially gold-bearing territories in the limits of the North Asian and other cratons. Key words: gold-bearing ore-placer districts, metallogenic potential, black shale formation, East of Russia. S.V.
Vysotskiy, A.V. Ignatiev, A.G.
Khlestunova, T.A. Velivetskaya, A.S. Okrugin
Peculiarities of oxygen isotope features in precious opals The results of comparative investigation of 18O in precious opals of Primorye (the Raduzhnoye deposit), Australia, Ethiopia, and in modern opals from thermal springs of Mendeleev volcano on Kunashir Island (the Kuril Islands) are presented. It has been determined that oxygen isotope ratio in opals could serve as a criterion for assessment of the opals formation temperature. Low-temperature sedimentary opals are characterized by relatively heavy isotopic composition of oxygen, no matter sedimentary or volcanogenic rocks they were formed in. A-type opals from Australia and Slovakia are a good example. As for hydrothermal opals, they have light oxygen isotopic composition, which value is governed by the solution temperature at sedimentation. The higher solution temperature, the lighter isotopic composition of oxygen in precipitated opals and the closer it is to the oxygen isotopic composition of the hydrothermal solution. Key words: opal, oxygen isotopes, hydrogen isotopes, stable isotopes. C.R.
Cao, G.L. Kirillova, A.P. Sorokin, V.B. Kaplun, H.S.
Cao, Y. Qu, Y.J. Zhang
Structural framework and evolution of the Sunwu-Jiayin Basin in NE China and its relation to the structures of the Zeya-Bureya Basin, the Far East of Russia The Sunwu-Jiayin Basin is located on the Amur River right side and comprises four depressions and three separating them NE-trending uplifts. The bounding first-order faults (mostly normal faults) with a steep to vertical dip were formed in the conditions of extension and control the development of the structural units of the basin. The sedimentary cover of the depressions developed in five stages: depression extension, early inversion, thermal subsidence, late inversion, and formation of depressions. The basement of the basin composed of granitoids and metamorphosed Late Paleozoic and Precambrian shales is exposed in the limits of the uplifts and plunged into depressions to a depth ranging from 0.5 to 2.4 km. As a whole, its depth is deepened from south to north to the Amur River, and then raised to a higher level. From the formation conditions and the structure of the sedimentary cover the basin under consideration belongs to the southern margin of the Zeya-Bureya Basin. Key words: structure, evolution, Sunwu-Jiayin Basin, Zeya-Bureya Basin, NE China, Far East. V.V. Krapiventseva Catagenesis of Jurassic-Cretaceous coals and rocks of the Bureya Basin in respect to hydrocarbon generation (Far East) The catagenesis of the Jurassic-Cretaceous deposits and coals has been comprehensively examined from a complex of features including reflectance (Ro and Ra), qualitative properties, and from their petrochemical characteristics (density and saturation porosity) for the host rocks. The catagenesis of the Jurassic-Cretaceous deposits was studied from structural zones in which coal-bearing deposits occur at different depths ranging from ~ 10 to 300 m, to 700m, and from 5 to 3460 m in the Western, Central, and Kyndal zones, accordingly. The following certain regularities in the change of coal catagenesis have been established: from mark and group 3B to 1G, 2G, GFL – from gradation PC3 to MC1-MC2 and from MC2 to MC3-MC4 with the change of mark composition of coals from long-flame coal to gas and gas-fat-lean coal. In the intrusive bodies distribution areas breaking through the coal-bearing deposits the coal seams are metamorphosed to the marks of lean baking and lean coals. The data obtained have made an assessment of hydrocarbon generation in the Jurassic-Lower Cretaceous deposits of the basin. Key words: catagenesis, reflectance, mark of coals, formation, coal seam, Bureya Basin, Far East. Yu. V. Rybiakova, S. A. Gorbarenko, А.А. Bosin Environmental and climaticchanges in the north Japan Sea and adjacent territory during the last 40 kyr, based on the record of spore-and-pollen analysis of bottom sediments Based on the results of integrated study of bottom sediments of the north Japan Sea, we present reconstruction of vegetation changes on adjacent land during the last 40 kyr caused by global climatic changes. When constructing an age model for marine sediments, previously obtained radiocarbon datings, planktonic foraminifera oxygen isotope records and their correlation with similar indicators from other dated cores from the Japan Sea, and palynological evidence were used. On the basis of pollen study of marine bottom sediments 6 pollen zones with definite pollen assemblages have been established. In addition, the paleoclimatic coefficient Kp, and temperature index T were calculated. The age model and reconstructed vegetation and climatic changes made it possible to compare a series of the revealed dark layers enriched in organic carbon in the core of bottom sediments which is typical for the Japan Sea with the type of regional and global climatic changes which occurred during the sedimentation. Key words: paleoclimate, vegetation, pollen zones, the Japan Sea. V.P. Shesterkin, V.S. Talovskaya, N.M. Shestrkina Long-standing dynamics of iron content and flow in the water of the middle Amur River during the lowest winter water level The dynamics of different-formed iron content and flow in the water of the middle Amur River during the lowest winter water level in the period of 1949-2012 is studied. It has been established that economical activity affects the iron content and overall flow. The concentration of the dissolved iron dominates in the water of the left side of the middle Amur and suspended iron is predominant in the right-bank part. A decrease in the content of the overall iron in the Amur River water was marked in 2011-2012 as compared with 1949-1975 by the factor 1.3 and increase in its flow 2.1 times. The foreground role of the regulated Zeya and Bureya rivers on the dynamics of the content and flow of the dissolved iron is shown. It has been established that the content of the overall iron in the subglacial water of the Amur River does not exceed 3 MPCm and that of the dissolved iron – 4MPCmd that makes it impossible to speak about considerable contamination of the Amur River water. Key words: water-storage basin, winter lowest water level, content, flow, overall iron, dissolved and suspended iron, middle Amur River. |