V. V. Holodnov, G. B. Fershtater
Institute of Geology and Geochemistry, Ural Branch of RAS E. S. Shagalov, G. Yu. Shardakova
Institute of Geology and Geochemistry, Ural Branch of RAS
Ural State Mining University
Annotation The analysis of the evolution of composition and mineral occurences of the Low and Middle Riphean magma-tic rocks from the riftogenic structures of the Bashkirian anticlinorium involving of some neighboring structures from the western slope of the Southern Urals was produced. In time the evolution is following: from rocks having the geochemical features as OIB (trachybasalts of the Sibirka deposit) and rocks as E-MORB (volcanic rocks of the Mashak formation, basic and acid rocks of the Kusa-Kopan’ complex, dyke swarms etc.) to rocks with N-MORB pecularities (Nazyam metabasites). This evolution agrees with the change of isotopic and geochemical parameters. Initial ratios of Nd isotopes of magmatic rocks and their ore-metasomatic haloes vary from the negative values noting to the formations from mature continental crust (gabbro and Ti-Mt-Ilm ores of Kusa-Kopan’ complex deposits) to positive values (eNd +4…+5 and more of Nazyam amphibolites), it reflects the increase of the depletion degree of the Riphean-Vendian lithospheric mantle and the evolution of magmatic and fluid sources in time. Described regularity for the age interval 1750–1200 Ma as well as data on Nd and Sr isotopes for magmatic rocks of continental crust formation of Uralian epioceanic orogen indicate the possible disclosure of the oceanic basin to the east of the East European platform during the Middle Riphean.
S. G. Kovalev, E .A. Timofeeva
Institute of Geology Ufa Science Centre of RAS
Annotation The article gives a detailed mineralogical, petrographic and petrogeochemical characteristics of eclogites of the Beloretsk metamorphic complex (BMK). It was found that the most likely the eclogite protoliths were Early-Middle Riphean basites of the Bashkir meganticlinorium. The calculations show that the maximum thermobaric parameters of eclogites formation in BMK reached: P – ~13 kbar, T – ~650°C. At the same time, widespread in rocks with symplectic structures who formed at P = 4.4–5.5 kbar, T = 480–500°C indicate a relatively rapid exhumation of the complex on the surface. It is concluded that the formation of para- and ortho- rocks of the Beloretsk metamorphic complex with a certain degree of conditionality can be divided into two main stages.
The first stage is due to local(?) rifting, manifested at ~730–710 million years ago. The second stage – the basic –
happened during orogeny in fold area of Timanides under stress load (or stress + lithostatic pressure), which makes BMK as typical representative of metamorphic complexes collision type.
A. M. Sazonov
Siberian Federal University
Research Tomsk State University K. A. Zablotsky
Krasnoyarskgeologiya U. Linnemann
Museum for Mineralogy and Geology, Dresden, D-01109, Germany E. A. Zvyagina, N. A. Nekrasova
Siberian Federal University
Research Tomsk State University E. A. Naumov
Institute of Geology and Mineralogy Siberian Branch of RAS S. A. Sil'yanov
Siberian Federal University
Research Tomsk State University
Annotation The paper provides justification of Paleo Archaean age (3221 ± 15 Ma) of the granulite plutonic metamorphism that formed the Kan metamorphic complex of the Archaean crust in the Angara-Kan block of the Siberian craton. The age was defined on the basis of zircon and was calculated as per 207Pb/206Pb. Zircon was extracted from cordierite-sillimanite gneiss of the Atamanovo series. Gneiss contains zircons of the Meso-Archaean, Lower Paleo Proterozoic and Lower Proterozoic gneiss characterizing successive tectono-magmatic events reflected in paleometamorphite.
I. L. Nedosekova, D. A. Zamyatin
Institute of Geology and Gtochemistry Urals Branch of RAS O. V. Udoratina
Institute of Geology Komi Science Centre Urals Branch of RAS
Annotation The ore specialization of carbonatite complexes of Urals-Timan region has been established: niobium and rare earth-niobium – for the Urals’ carbonatite complexes, the rare-earth – for carbonatites of Timan. The carbonatites of Il'menī-Vishnevogorsky miaskite-carbonatite complex (Urals) are a type of industrial niobium deposits (pyrochlore type of ores). The carbonatites of Baiksky ultrabasic complex (The Urals) are rare earth-niobium type deposits (monazite-aeschynite-columbite-pyrochlore type of ores). The carbonatites of Chetlassky complex (Middle Timan) are cerium type deposits of bastnesite carbonatites (with monazite-bastnesite type of ores). The picrite-lamprophire series of Chetlassky complex have diamond prospects. The ore specialization of the Urals and Timan carbonatite complexes are determined by their formational affiliation.
Key words: ore-formational types of carbonatites, types of niobium and rare earths deposits, pyrochlore carbonatites, bastnesite carbonatites, the Urals, Timan
Š. R.I. Zainullin
Institute of Geology Ufa Science Centre of RAS
Bashkir State University
Annotation Results of the study of volcaniclastic sandstones of the Uskul’ and Il’tibanovo strata of the Lower Devonian are presented. Sandstones are of feldspathic greywacke and greywacke lithoclastic types after classification
V.N. Shvanov. They are composed primarily of fragments of basic and intermediate composition volcanic rocks, crystals of plagioclase and pyroxene. Greywacke of Il’tibanovo section are distinguished by the presence of fragments metamorphic, carbonate rocks. These rocks are different from sandstones of the sections Uskul and Talyshman by the composition and distribution of small elements. Island arc is a source of material for the sandstones. The clastic material was transported by turbidite flows.
Key words: sandstone, greywacke, petrographic and geochemical composition, the Lower Devonian, West-Magnitogorsk zone, island arc
O. V. Kravchenko, S. N. Rychagov
Institute of Volcanology and Seismology FED RAS
Annotation On the basis of well drilling and prospect-hole digging and detailed level-by-level approbation the lithological structure of hydrothermal clays of Nizhne-Koshelevo geothermal anomaly, one of the largest on Kamchatka, is investigated. The hydrothermal clays forms a uniform geological body, which have layered structure, thickness from 1.5 up to 3.0 m and extent ?500 m. On active thermal ground (unloadings of hydrotherms) the vertical displacement of clays layers take place, apparently, owing to formation of large cavities inside clays – as a result of intensive gas and solution circulation. Also the landslips processes in deep V-shaped valley of Gremuchii stream are wide display. The mineralogical-geochemical criteria of allocation of three horizons of hydrothermal clays are received: 1) zones of sulphuric leaching – in the field of superficial unloading of thermal waters; 2) intensively sulfidization “blue clays” – in the middle part of sections; 3) siliceous and metalliferous deposits – in the basis of clays horizons. Other clays layers are diagnosed less precisely. The hydrothermal clays of Nizhne-Koshelevo geothermal anomaly differ, as a whole, the high contents of pyrite and other sulfides, which concentrate noble, rare, and other metals. The model of transformation of rocks to hydrothermal clays, as reflection of influence of deep metalliferous fluids on hypergenesis zone of modern hydrothermal systems is offered.
E. M. Golubeva
Institute of Tectonics and Geophysics FEB RAS L. M. Kondrat'yeva
Institute of Water and Ecological problems FEB RAS V. S. Komarova, A. V. Abragevitch
Institute of Tectonics and Geophysics FEB RAS
Annotation In the paper we report experimental study of biomineralization processes occurring on biogeochemical barriers involving community of bacteria from natural groundwater . After 2-years experiment, the formation of a crystalline iron-containing mineral occurred in the contact zone of zeolite-sand with the introduction of biomass of iron bacteria. The experimental samples were examined using scanning electron microscopy and X-ray diffractometry. Analysis of the magnetic properties of biomineral shown presence of various structures of the iron hydroxides, including goethite and lepidocrocite. It is established that the formation of the structure of biominerals depends on the nature of the development of bacterial biofilms in the pore space and the intensity of accumulation of different elements in their polymer matrix.
Yu. M. Nesterenko, M. Yu. Nesterenko
Geoecologic department Orenburg Science Centre UB of RAS
Annotation Water pressure system of Southern Pre-Uralian groundwater and man-made changes to it in the areas of hydrocarbon production are considered. The hydrogeological zoning is given and the aquifers complexes based on geological structure of the region are represented. The hydrodynamic connection of aquifers through halogen-sulfate deposits Iren' horizon of Kungurian stage, separating the upper and lower floors of underground water is proved. In the development of and gas fields decreased reservoir pressure and change levels of reservoir water. According to model of reservoir pressure dynamics with time after the cessation of hydrocarbon production, at the Orenburg gas condensate field the influx of water from the surrounding aquifer the recovery pressure to 50% from 7 to 15 MPa occured after about 500 years, and to 97%, to 20 MPa after 1500 years.
O. G. Stolova
Central Scientific Research Institute of Geology of Industrial Minerals O. V. Pavlova
Institute of problems of ecology and subsurface use, Academy of Sciences of Tatarstan Republic
Annotation In the paper the need for comprehensive study of karstified territories (including caves) in lithogenic aspect to identify among them objects of geological heritage of Russia and their entry in the online Help and search system www//geomem/ru is substantiated. The sizes, numbers and areal distribution of caves under karstified territories of Russian Federation and their representation in the mentioned system among the nine types of Unique Geological Objects (UGO) are shown. It is concluded that there is a significant number of highly informative lithogenic-type natural objects which unfortunately very little use in the status of UGO of Russia. For that reason they are not being used as tourist attractions or educational exhibits, and are not protected by environmental legislation.