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Все статьи: 1821
Geochronology of Precambrian formations of the north of the Urals
Статья научная
The paper summarizes results of work on the geochronological confirmation of the age of metamorphic structures occurring at the base of the Precambrian of the north of the Urals and the age of overlying Upper Precambrian basal sediments. It is shown that the occurrences of early stages of metamorphism of rocks of metamorphic (polymetamorphic) complexes date back to about 2.1 Ga. Their substrate is unambiguously related to the Lower Precambrian. We determined that Mesoproterozoic strata are absent Upper Precambrian sections of the north of the Urals, in contrast to more southern regions of the Urals. The basal strata in the Lyapin and Kharbey-Marunkeu anticlinoria, according to the data obtained, are dated to the Middle Neoproterozoic (cryogenian). The established fact of the absence of deposits of a huge age interval (Mesoproterozoic — at least 600 Ma) in the north of the Urals can be explained by a high standing of the territory of the northeast (in modern coordinates) of the Baltic craton, a fragment of which at that time was the Timan-Northern Ural lithospheric segment, and the location in the interiors of the Columbia (Nuna) supercontinent.
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Geological position and age of the Man’hobeyu suite (RF1?) in the Subpolar Urals
Статья научная
The geological position and age of the Man’hobeyu suite in the Subpolar Urals are considered, which in modern stratigraphic schemes refers to the Lower or Middle Riphean formations and is considered as the basal deposits of the Upper Precambrian of this region, which is stratotype for the Precambrian of the entire Timan-Northern Ural region. Based on the results of new isotope-geochronological studies, taking into account the available geological data (structural, petrological, mineralogical), the rationale for the idea, that the Man’hobeyu suite cannot be regarded as an independent stratigraphic subdivision is given. It is a rock association of predominantly low-temperature diaphthorites and cataclasites in high-temperature metamorphites, analogous to those of which the Lower Precambrian Nyartin complex consists. Isotopic-geochronological data make it possible to unambiguously classify the metamorphosed rocks, which is allocated as the Man’khobeyu suite, to the Lower Precambrian formations. At the same time, the most preferable assumption is the Early Proterozoic age of the protoliths of the metamorphic rocks of both the Man’khobeyu suite and the Nyartin complex.
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Granites of the Gerdiz massif (Polar Urals): new data
Статья научная
Petrographic, petrochemical and preliminary geochemical (ICP MS) and isotope geochemical (OZrn, Sm-Nd, (Lu-Hf)Zrn) data allow us to consider granitoids of the Gerdizsky massif as forming in an intraplate setting and represent A-type with crust-mantle characteristics. The new U-Pb (SIMS) geochronologic data show that the granitoids of the northern part of the Gerdizsky massif in the northern Urals are (496±7) Ma.
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Granitoids of the Nyarta block (Subpolar Urals): new data
Статья научная
The age (U-Pb, SIMS), features of the distribution of REE, Ti, Hf, Y in zircons of granitoids of the Nikolayshorsky massif (Subpolar Urals) were determined and isotope-geochemical data (O, Lu-Hf) were obtained. These data allowed establishing the age and characteristics of protolith. The data confirmed the formation of granites in the range of 640-520 Ma. Evidence of different age stages was found in one sample of zircons from the Nikolayshorsky massif. The determined temperature ranges for the formation of zircons indicated that their crystallization (620 Ma) had occurred at a temperature lower than zircons with ages 520 Ma. The isotopic composition of zircon oxygen indicated a crustal source, the hafnium isotopic composition indicated a crust-mantle one, the model ages of protoliths were 1.48-1.02 and 1.11 Ga for zircons of different ages. Granites with the petro-geochemical characteristics of S-granites were formed during granitogenesis processes appeared at different times - 620 and 520 Ma ago.
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Lateand post-magmatic alterations of alkaline picrites from Middle Timan
Статья научная
Different researchers find picrites and various lamprophyres and kimberlites within Chetlassky complex (Middle Timan) by petrochemical indicators. Such a diverse collection of magmatic rocks for a small magmatic complex seems unlikely. Coordinated research of geological, petrographic and petrochemical material leads to the conclusion that primary rock composition was alkali picritic. All deviations from this composition, used to distinguish other types of magmatic rocks in this complex, were generated by post magmatic processes even within one unit. Such processes were represented by autometasomatism, post magmatic hydrothermal alteration, fenitization, metasomatic carbonatite generation and hypergenesis.
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Life for the good of society (125th anniversary of the birth of Vera Aleksandrovna Varsanofeva)
Персоналии
We describe main stages of life of Vera Aleksandrovna Varsanofeva - glorious daughter of Russian people, who devoted all her life to serve Russia. We value her contribution to the knowledge and exploration of mineral resources of Russia resulting in raise and rapid development of national economy after the World War II. Vera Aleksandrovna left ever-lasting bright imprint on the science structures of Komi branch of Academy of Sciences and Institute of Geology, established with her participation. Vera Aleksandrovna’s activity is an example of whole-hearted service to the science for many generations of researchers.
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Статья научная
The paper describes lithological and geochemical features of the Lower Triassic sandstones from the far north of Timan-Pechora oil and gas-bearing province. These sandstones chemically coincide to typical graywackes. We discuss how sedimentation environments and diagenesis control the local heterogeneity of cementation, variability of void space and the potential oil content. Tectonic conditions are one of the provenance factors, the figurative points of the composition of sandstones on the diagrams fall into the field of the passive continental margin. The position of sandstone points on the diagrams and low values of the hydrolyzate module indicate the formation of deposits in an arid climate, which does not contradict to geological data.
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Middle-Late Paleozoic conodont ecogeochemistry: an overview
Статья научная
The ecogeochemistry is the application of geochemical features to study animal ecology. This approach is promising for using in reconstructions of ancient pelagic ecosystems. Among other Paleozoic fossils of pelagic animals, remains of conodonts are the most suitable for ecogeochemical investigations. The article reviews ecogeochemical applications of Middle to Late Paleozoic conodont elements. The following features are considered as the most informative: calcium isotopic composition and element ratios (e.g. Sr/Ca) of conodont apatite, and isotopic composition of carbon of conodont elements. These parameters allow us supposing ecological specialization of conodont species, and temporal and spatial dynamics of the ecogeochemistry of conodonts can be used to reconstruct transformations of ancient pelagic ecosystems.
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Статья научная
The article presents the results of a comprehensive mineralogical study of the ores of the Pravourmiysky deposit using optical microscopy and X-ray analysis, scanning electron microscopy. Mineralogical studies have identified and explained the causes of possible losses of tin with enrichment tails. Тhe data obtained were used in the development of the ore beneficiation scheme and were included in the technological regulations for the designing of the beneficiation plant.
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Mineralogy of blast furnace slags
Статья научная
National economy development requires an increase of metallurgical production accompanied by technogenic mineral matter characterized by heterogeneous phase composition and structure. The aim of this study is a comprehensive mineralogical investigation of blast furnace slags produced by OJSC «MMK» for prognoses of possibility and areas of their utilization. We implemented a complex of modern mineralogical-analytical methods. These blast furnace slags have porous structure of porphyry, intersertal and spherulite type. The main slag-forming minerals are akermanite, pseudowollastonite (79-94 %), secondary - fayalite, diopside, oldhamite, perovskite, jacobsite, bixbyite, ferrite (3 %). The amorphous component of slags does not exceed 18 %.
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Статья научная
We have presented the characteristics of seismic study, structural plan and parameters of local structures of Chernyshev Ridge. The newest fault dislocations (lineaments) were decrypted with the help of Lansat space images and digital model of the relief; the areas with different density of lineaments were determined, and the character of tectonic stress was observed. We showed that the newest tectonic processes affected the character of modern structural plan of the ridge, hydrocarbon migration and formation of oil and gas fields.
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Na-доминантный в M2-позиции аналог эвдиалита: кристаллическая структура и индикаторное значение
Статья научная
Минералы группы эвдиалита из ультраагпаитовых ассоциаций часто характеризуются высокими содержаниями (вплоть до доминирования) натрия в позиции M 2, которая в эвдиалите заселена железом. Обсуждаются особенности блочного изоморфизма с замещением IVFe2+ на IVNa и VNa в М 2-микрообласти. Методами электронно-зондового микроанализа, рентгеноструктурного анализа и ИК-спектроскопии исследован потенциально новый минерал, М2Na-доминантный аналог эвдиалита из щелочного массива Илимаусак (Гренландия). Его кристаллическая структура уточнена до итогового фактора расходимости R = 5.6 % в анизотропном приближении атомных смещений с использованием 1095 независимых рефлексов с F > 3s( F ). Параметры элементарной тригональной ячейки: a = 14.208(1), c = 30.438(1) Å, V = 5321(1) Å3, пр. гр. R -3 m . Идеализированная формула минерала ( Z = 3): (Na,H3O)15Ca6Zr3[Na2Fe][Si26O72](OH)2Cl∙2H2O.
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Статья научная
We have studied conditions influencing the results of the isotopic composition analysis of oxygen and carbon of carbonate skeletons of fossil ammonites, taking into account that they had been open for post-sedimentation processes. The object of study was shells of Ringsteadia, Eurasenia, Perisphinctes, Dichotomoceras, Cardioceras ammonites from outcrops on the right bank of the Unzhi River, near the city of Makaryev of Kostroma Region. The most probable reason for the difference in d13Сcarb and d18Ocarb values of ammonite shells from coeval belemnites, except for mineral affinity (calcite, aragonite), was the presence of «pure» authigenic calcite shells. The indicator of the isotopic composition of carbonates was determined not only by the nature and origin of source substances, but also by the fractionation of the isotopes in various processes during their formation. We supposed that the multistage sulfate reduction could have changed isotopic characteristics of the carbonate of the shells.
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Off-line-пиролиз керогена доманиковых отложений Тимано-Печорского осадочного бассейна
Статья научная
Изучен состав алифатической и ароматической фракций продуктов пиролиза керогена из доманиковых пород Тимано-Печорского бассейна, характеризующихся различным уровнем термической зрелости органического вещества. Выявлены закономерности в изменении состава пиролизата с ростом катагенеза ОВ, которые заключаются в снижении концентраций н -алканов и н -алкенов-1, н -алкилнафталинов и н -алкилбензолов. К середине главной фазы нефтеобразования практически полностью исчезают из матрицы керогена сернистые структуры. В наиболее зрелых образцах доманикового керогена содержание алифатических углеводородов сопоставимо с их содержанием в незрелом керогене верхнеюрских сланцев Восточно-Европейской платформы, что свидетельствует о хорошем остаточном углеводородном потенциале органического вещества катагенетически преобразованных доманиковых отложений.
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Oil and gas potential of Domanik horizon of the Timan-Pechora oil and gas province
Статья научная
Domanik horizon is located in the north-eastern part of the East European platform in the Timan-Pechora province. Domanik has different facies. There are shallow-water offshore, reefs and deep-sea-shelf sediments. Depression rocks attract the attention of researchers, because they contain shale with high C org. (5-24%) in carbonate-siliceous sediments. Mainly there is fractured reservoir type, which contain oil and gas deposits. One of important tasks is to do the oil and gas reservoir prediction of different facies in Domanik of Late Devonian age within the Timan-Pechora province without disrupting maternal strata of the depression facies.
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Статья научная
The results of studies of organic matter and technological features of coal from a number of deposits of the Pechora coal basin are presented. Based on data on the composition of biomarker hydrocarbons, data on the thermal maturity of organic matter (OM) of coal are confirmed, assumptions are made about the influence of aquatic and terrigenous vegetation on the formation of the initial OM, and differences between its composition for brown coals concentrated in the southern part of the Pechora coal basin are shown, and coal of the northern areas of the basin. The work demonstrates the possibility of obtaining an ash-free concentrate - the so-called hypercoal by extraction of the initial coal with N-methylpyrrolidone at the boiling point of the solvent in high yields and the similarity of the structure of the obtained product with the structure of the organic mass of the initial coal.
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Organic matter and types of sections depression middlefrasnian sediments Timan-Pechora province
Статья научная
Various sections of depression deposits middlefrasnian age were studied. Depresionnye deposits have a significant spread in the Timan-Pechora province. Features of conditions of accumulation of these deposits different impact on the component composition of organic matter and it is generational capacity. Analysis of the composition of the rocks, in conjunction with the study micro components of organic matter and its hydrocarbon potential will reveal the distribution of rich source rocks of complex.
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