Volume 30, 2, 2011 |
|
A.I. Khanchuk, L.P. Plyusnina, Ye.M. Nikitenko, T.V. Kuzmina, N.N. Barinov. Noble metal distribution in black shales of the Degdekan gold ore deposit (Northeast Russia) 3 N.A. Goryachev, G.N. Gamyanin, V.Yu. Prokofyev, T.A. Velivetskaya, A.V. Ignatyev, N.V. Leskova. Silver-antimony mineralization of the Yana-Kolyma belt (Northeast Russia) 12 A.V. Koloskov. Petrological-and-geochemical features of Cretaceous and Cenozoic intrusive magmatism of Kamchatka, melt sources, and geodynamic conditions 27 T.K. Zlobin, L.N. Poplavskaya, A.Yu. Polets. Deep structure and seismotectonics of the southern part of the Sea of Okhotsk region (on the Southern Sakhalin–Southern Kurils profile) 46 A.N. Perestoronin, Ye.P. Razvozzhaeva. The system of Cenozoic depressions of Priamurye and Primorye: structure, tectonic position and geodynamic interpretation 58 S.V. Zyabrev. Oceanic deposits of the Amur terrane, their age and tectonic implications 75 A.I. Gresov. Geochemical classification of hydrocarbon gases of coal basins of Eastern Russia 85 V.A. Chudaeva, O.V. Chudaev. Specific features of chemical composition of the water and suspended matter of Primorye rivers (Far East Russia) 102 Reviews Yu.I. Bakulin. On the problem of sedimentary concentration of gold 120 Chronicles A.I. Obzhirov. Expedition of the Pacific Oceanology Institute, FEB RAS, to the Sea of Okhotsk on SRV “Akademik M.A. Lavrentyev” (Cruise No. 50) on June 5-28, 2010 123 Jubilees V.V. Kharakhinov (to the 70-th anniversary) 127 A.I. Khanchuk, L.P. Plyusnina, Ye.M. Nikitenko, T.V. Kuzmina, N.N. Barinov Noble metal distribution in black shales of the Degdekan gold ore deposit (Northeast Russia) The mineral and chemical composition of carbon-bearing rocks of the Late Permian Pionerskaya Formation,encompassing the Degdekan gold ore deposit, has been studied. Au, Ag, Pt and Pd bulk content of black shales and the light, sulfide and electromagnetic fractions were measured by the method of electrothermal atomization . The mineral composition and the phase analysis of the rocks were studied on the electron scanning microscope. Gold is present as fine xenomorphic grains of high essay standard of gold with a Fe admixture content of about 4 mass%, and also as aggregates of kustelite and electrum . Au and Pt content of black shales and ores widely ranges (ppm): Au, 0.01–13.12; and Pt, 0.001–1.34. Au maximal concentrations up to 1748 ppm were noted in the sulfide fraction. Attempts to establish Pt-bearing phases failed, whereas Pt content of about 0.61 mass.% was measured by the electron microscope in carbonaceous matrix. Pd concentration in the ores was stably low - < 0.007 ppm. The stable uniform distribution of Au in the study rocks is limted by the values 1.14 to 2.46 ppm. The chemical analysis of the soluble fraction of carbonaceous matter extracted from the black shales indicated the presence of Au 0.375, Ag 3.68, Pt 0.147, and Pd 0.052 ppm in its composition. It has been concluded that the carbon-bearing rocks of the Pionerskaya Formation plays a resource role in noble metals accumulation, whereas commercial concentrations of the latter are formed in the course of metamorphic-hydrothermal processes. Key words: black shales, gold, silver, platinum, palladium, Degdekan deposit, Magadan region, Northeast Russia. N.A. Goryachev, G.N. Gamyanin, V.Yu. Prokofyev, T.A. Velivetskaya, A.V. Ignatyev, N.V. Leskova Silver-antimony mineralization of the Yana-Kolyma belt (Northeast Russia) Mineral associations of the silver-antimony deposits of the Yana-Kolyma fold belt, Northeast Russia, have been studied. New data on the ore mineral composition, sulfur isotope composition in sulfides, oxygen and carbon isotope composition in carbonates from the ore veins are presented. Arsenopyrite from these deposits has a high concentration (1 to 16 mass. %) of antimony, which is related to the original antimony enrichment of the ore host rocks and the shallow depths of ore formation. According to the fluid inclusion study, Ag-Sb deposits were formed at Ò = 329–149° Ñ and Ð=0.30–1.04 kbar from low-salinity chloride-sulfate-bicarbonate solutions enriched in Sb and Ag. The antimony concentration and sulfur activity in the fluid essentially affect deposition of Ag-Sb minerals. Key words: silver-antimony mineralization, Sb-arsenopyrite, stable isotopes and fluid inclusions, Yana-Kolyma fold belt, Northeast Russia. A.V. Koloskov Petrological-and-geochemical features of Cretaceous and Cenozoic intrusive magmatism of Kamchatka, melt sources, and geodynamic conditions A comparative analysis was carried out aimed at identification of the geological position and composition of Cretaceous, Eocene and Miocene-Pliocene granitoids from the Sredinny Ridge, Kamchatka. New petrochemical, geochemical and isotope data are presented. The results of the study show that the higher alkaline granodiorites and granites of the Sredinny Ridge display an enriched isotope composition and are characterized by elevated concentrations of Rb, Th, U and LREE as compared with those in the eastern part of the region. The largest scale Cretaceous crust magmatism occurred during intense tectonic motions and metamorphism. The low-volume Eocene magmatism occurred as crust granitic melts within the Sredinny Ridge and as mantle-derived magmas evolved to granitic composition in southeastern Kamchatka and in the Ganalskiy Ridge. At that time the ancient crust was reanimated and the new continental crust formed in some places. The low-volume Miocene-Pliocene magmatism occurred within volcanic belts. It varied in composition, displayed both crust and mantle-derived magma genesis, and participated in the formation of the upper crust horizons on the existing crystalline basement. Key words: petrochemistry, geochemistry, isotopy, granitoids, magmatism, Kamchatka. T.K. Zlobin, L.N. Poplavskaya, A.Yu. Polets Deep structure and seismotectonics of the southern part of the Sea of Okhotsk region (on the Southern Sakhalin–Southern Kurils profile) A deep seismic section of the earth’s crust, passing through the Southern Sakhalin, south of the Sea of Okhotsk and the Southern Kurils was constructed, tectonic fault zones were distinguished, location of hypocenters, features of the stress state and types of seismic deformations in the earthquake foci were considered. Upthrow faults of the eastern side relative to the western side were established under the southern part of the Tatar Strait and Sakhalin Island, which during repeated upthrow fault movements along the fault during geologic time resulted in the rise and observable displacement of seismic boundaries for 5–8 km. The real rise of the Greater Kuril ridge was established based on the earthquake foci mechanisms. Seismotectonics and the real dynamics of the earth’s crust blocks were estimated based on the detailed joint analysis of location of structural boundaries on the seismic section. Key words: earth’s crust structure, seismotectonics, earthquakes, Sakhalin, Kurils, the Sea of Okhotsk. A.N. Perestoronin, Ye.P. Razvozzhaeva The system of Cenozoic depressions of Priamurye and Primorye: structure, tectonic position and geodynamic interpretation The synthesis and analysis of seismic data, local gravity field and geologic evidence show that the faults, which are the framework of the Priamurye and Primorye Cenozoic depression system, create various structural parageneses: en echelon series, extension duplexes, and conjugate knots. Being regularly arranged, they form a single branched-mesh regional disjunctive zone named the Ussuri-Okhotsk rifting zone (UORZ). Owing to its connection with the faults of the Tan-Lu system and grabens of the lower stage of depressions of marginal seas, UORZ is a part of the pericontinental zigzag lineament zone controlling the East Asian graben belt. It is a broad incipient right-lateral transtensional zone formed under conditions of pure shear deformation accompanied with additional tension. The compression axes were NE-oriented; while the extension ones, in the NW direction. This deformation caused passive and dispersed epiorogenic and epiplatform rifting. After the episode of the Late Miocene inversion of tectonic regime, rifting processes acquired the features of taphrogenesis. Tectonic movements occurred mainly along the extended deep faults. Extensive complex two-stage depressions formed. The role of active rifting increased considerably, which is indicated by the numerous plateaus of Neogene-Quaternary basalts. Rifting moved to a larger-scale level of development characterized by the more significant sizes of the formed depressions and the larger depth level of endogenous processes. This can be probably related to mantle magmatism, consolidation of the crust, changes of its structural anisotropy, and insignificant reconstruction of the tectonic stress field. Key words:Cenozoic, depressions, shears, parageneses, stresses, deformation, Priamurye, Primorye. S.V. Zyabrev Oceanic deposits of the Amur terrane, their age and tectonic implications In the Amur terrane, oceanic pelagic and hemipelagic chert and siliceous mudstone occur in a small amount and compose thin tectonic slices that are divided by thicker intervals of terrigenous continental margin deposits. Radiolarian biostratigraphic study reveals Middle and Late Jurassic ages of hemipelagic siliceous mudstone and Early Cretaceous ages of continental margin mudstone. This bears on the terrane’s stratigraphy and demonstrates younging of stratigraphic boundaries between different facies in the south-westerly direction. Multiple tectonic repetitions of oceanic and continental margin deposits are characteristic to accretionary complexes, and such interpretation of the tectonic nature of the Amur terrane matches to the composition and structure of its deposits. Key words: Radiolaria, Jurassic, Cretaceous, oceanic and continental margin deposits, Amur terrane. A. I. Gresov Gas-geochemical classification of hydrocarbon gases of coal basins of Eastern Russia This paper considers the problem of genetic classification of hydrocarbon gases of coal basins. The research made it possible to distinguish five cardinal genetic categories of hydrocarbon gases in the coal and coal-oil-and-gas-bearing basins. It is shown that the bulk of hydrocarbon gases in the coal basins is polygenetic. The distribution and genesis of hydrocarbon gases in the coal basins depend on geologic factors, such as tectonics and magmatic activity, stage of metamorphism of coal and organic matter-bearing rocks, hydrogeologic and creological conditions, migration of hydrocarbon gases from the oil-and-gas-bearing formations, and deep degassing of the Earth. Application of the molecular mass of hydrocarbon gases, the coefficient of transformation and isotopic analysis allow classification in the coal and coal-oil-and-gas-bearing basins of Eastern Russia of essentially different by origin hydrocarbon gases. Key words: coal gas-bearing basins, hydrocarbon gases, genesis, influence of geological factors, molecular mass, coefficient of transformation, ethane coefficients, genetic classification, East of Russia. V.A. Chudaeva, O.V. Chudaev Specific features of chemical composition of the water and suspended matter of Primorye rivers (Far East Russia) The authors’ data accumulated over many years on the chemical composition of the waters and suspended matter of Primorye rivers, first of all microelements, were summarized. A westward regional decrease in dissolved Si and an increase in Al, Rb, Sr, Ba and some other elements were ascertained. The important role of colloids in migration of dissolved Al, Fe, Mn, Cr was established. The relations of elements in this phase are more typical of suspensions than of solutions. In the rivers with appreciable pollution, concentrations of elements in solutions and suspended matter increase essentially depending on the specifics of contaminated discharge. Key words: chemical composition, microelements, river run-off, forms of migration, suspended matter, Primorye, Far East Russia. |