Synrift deposits of the Middle Riphean Mashak Formation, Southern Urals (a short lithochemical characterization)
DOI:
https://doi.org/10.21638/spbu07.2018.304Abstract
The article briefly describes the lithochemical features of sandstones and clayey rocks of Mashak Formation (Southern Urals), a second synrift volcano-sedimentary association in Riphean stratotype. It is shown that the sandstones of the Mashak Formation are characterised by wide variations in the bulk chemical composition (from greywacke to quartz arenite). The presence of the latter, as well as a relatively small proportion of arkoses and subarkoses,
distinguishes the second synrift association from the first one (the Ai Formation, Lower Riphean). There is no overlap in between the Mashak’s and Ai’s psammites on the diagram log(SiO2/Al2O3)–log(Na2O/K2O) of F. J. Pettijon and co-authors. It indicates significant differences in provenances and common features of accumulation of the Mashak and Ai formations. On the basis of bulk chemical composition, the clayey rocks of the Mashak Formation are related to smectite (with kaolinite and illite admixture) clays and their chlorite-smectiteillite varieties. The clayey rocks of the Ai Formation differ by lower values of total normative alkalinity (0.27 ± 0.06 vs. 0.42 ± 0.07). It is established that sandstones and clayey rocks of the Mashak Formation contain a significant proportion of the “first-cycle material”, i. e. they are composed mainly by products that have passed one sedimentation cycle. As opposite, there is a significant proportion of “second-cycle/lithogenic material” of the first synrift sandstones association (the Ai Formation). The high K2O/Na2O values, which are characterised for a half
studied samples of the Mashak Formation, indicate that they were influenced by processes of potassium metasomatism. The distribution of data points of terrigenous rock of the Mashak Formation on diagram F1—F2 (Roser and Korsch, 1988) displays that they are composed by products of erosion of acid, average or mafic igneous and/or metamorphic rocks. The individual data points of Mashak Formation terrigenous rocks, as well as sandstone composition
midpoint, are localised in the areas of riftogenic and collisional settings on the DF1—DF2 diagram (Verma and Armstrong-Altrin, 2013). It does not allow us to define their paleogeodynamic settings. In such a manner, the a critical role, traditionally, remains on general geological data and petrogeochemical characteristics of igneous rocks.
Keywords:
Southern Urals, Middle Riphean, Mashak Formation, sandstones, clay rocks, lithochemistry
Downloads
Download data is not yet available.
References
Литература
Гарань, М. И., 1969. Верхний докембрий (рифей): Стратиграфия, в: Геология СССР. Т. 12. Пермская, Свердловская, Челябинская и Курганская области. Ч. 1. Недра, Москва, 149–200.
Гареев, Э. З., 1989. Геохимия осадочных пород стратотипического разреза рифея. https://search.rsl.ru/ru/record/01000016736 (дата обращения: 14.03.2018).
Дымкин, А. М., Иванов, К. С., Иванов, С. Н., Краснобаев, А. А., Полтавец, Ю. А., Пумпянский, А. И., Пучков, В. Н., Русин, А. И., Самаркин, Г. И., Семенов, И. В., 1986. Формирование земной коры Урала. Наука, Москва.
Иванов, С. Н., 1980. О доордовикской истории Урала и предгеосинклинальном развитии земной коры вообще, в Доордовикская история Урала. Вып. 1. УНЦ АН СССР, Свердловск, 3–28.
Иванов, С. Н., 1981. О байкалидах Урала и Сибири. Геотектоника 5, 47–65.
Козлов, В. И., Сергеева, Н. Д., Генина, Л. А., 2007. К вопросу о строении и расчленении машакской свиты среднего рифея Южного Урала. Геологический сборник 6, 21–32. http://ig.ufaras.ru/publikatsii/geologicheskie-sborniki/geologicheskiy-sbornik-6-2007-g/ (дата обращения: 09.08.2018).
Ларионов, Н. Н., Бергазов, И. Р., Генина, Л. А., Грановская, Н. В., Захаров, А. А., Нигматуллина, А. М.,Цветкова, А. А., 2006. Государственная геологическая карта Российской федерации масштаба 1 : 200 000. Серия Южноуральская. Лист N-40-ХХII (Тукан). Объяснительная записка. Изд. ОАО «Башкиргеология», Уфа.
Маслов, А. В., 1988. Литология верхнерифейских отложений Башкирского мегантиклинория. Наука, Москва.
Маслов, А. В., 1995. Типы источников сноса песчаных ассоциаций эталона рифея, в: Ежегодник-1994. ИГГ УрО РАН, Екатеринбург, 41–44.
Маслов, А. В., Гареев, Э. З., Котова, Л. Н., Подковыров, В. Н., 2018a. Литохимические особенности песчаников машакской свиты (средний рифей, Южный Урал), в: Проблемы минералогии, петрографии и металлогении. Материалы научных чтений памяти П. Н. Чирвинского 21, 153–161.
Маслов, А. В., Оловянишников, В. Г., Ишерская, М. В., 2002. Рифей восточной, северо-восточной и северной периферии Русской платформы и западной мегазоны Урала: литостратиграфия, условия формирования и типы осадочных последовательностей. Литосфера 2, 54–95. http://lithosphere.uran.ru/index.php/lith/article/view/1703 (дата обращения: 09.08.2018).
Парначев, В. П., 1988. Магматизм и осадконакопление в позднедокембрийской истории Южного Урала. https://search.rsl.ru/ru/record/01008564815 (дата обращения: 14.03.2018).
Парначев, В. П., Ротарь, А. Ф., Ротарь, З. М., 1986. Среднерифейская вулканогенно-осадочная ассоциация Башкирского антиклинория. Свердловск: УНЦ АН СССР, 103 с.
Петтиджон, Ф., Поттер, П., Сивер, Р., 1976. Пески и песчаники. Мир, Москва.
Пучков, В. Н., 2000. Палеогеодинамика Южного и Среднего Урала. ГИЛЕМ, Уфа.
Пучков, В. Н., 2010. Геология Урала и Приуралья (актуальные вопросы стратиграфии, тектоники, геодинамики и металлогении). ДизайнПолиграфСервис, Уфа.
Пучков, В. Н., 2013. Плюмы в истории Урала. Бюллетень МОИП. Отдел геологический 88(4), 64–73.
Пучков, В. Н., 2016. Взаимосвязь плитных и плюмовых процессов в глобальном и региональном масштабе, в: Плюмовые процессы на Урале. Металлогения древних и современных океанов-2016. От минералогенезиса к месторождениям. ИМин УрО РАН, Миасс, 17–21.
Романов, В. А., 1973. Типовые разрезы докембрия Южного Урала. Наука, Москва.
Ронов, А. Б., Мигдисов, А. А., Хане, К., 1995. Количественные закономерности эволюции состава алевропесчаных пород Русской плиты. Геохимия 3, 323–348.
Ротарь, А. Ф., 1974. Машакская свита (рифей) на Южном Урале. Советская геология 4, 116–123.
Ротарь, А. Ф., 1976. К вопросу о составе и стратиграфическом положении конгломератов машакской свиты на Южном Урале, в: Конгломераты и их роль в познании геологической истории Урала. УНЦ АН СССР, Свердловск, 14–20.
Семихатов, М. А., 2008. Хроностратиграфия и хронометрия: конкурирующие концепции общего расчленения докембрия. Бюллетень МОИП. Отдел геологический 83(5), 36–58.
Семихатов, М. А., Шуркин, К. А., Аксенов, Е. М., Беккер, Ю. Р., Бибикова, Е. В., Дук, В. Л., Есипчук, К. Е., Карсаков, Л. П., Киселев, В. В., Козлов, В. И., Лобач-Жученко С. Б., Негруца, В. З., Робонен, В. И., Сезько, А. И., Филатова, Л. И., Хоментовский, В. В., 1991. Новая стратиграфическая шкала докембрия СССР. Известия АН СССР. Серия геологическая 4, 3–13.
Смирнов, Ю. Д., 1964. История развития Уральской складчатой области в докембрии, в: Геология докембрия. Доклады советских геологов. МГК XXII сессия. Недра, Москва, 195–207.
Стратотип рифея. Стратиграфия. Геохронология, 1983. Келлер, Б. М., Чумаков, Н. М. (под ред.). Наука, Москва.
Юдович, Я. Э., Кетрис, М. П., 1988. Геохимия черных сланцев. Наука, Ленинград.
Юдович, Я. Э., Кетрис, М. П., 2000. Основы литохимии. Наука, Санкт-Петербург.
Bolnar, R., Kamber, B. S., Moorbath, S., Whitehouse, M. J., Collerson, K. D., 2005. Chemical characterization of earth’s most ancient clastic metasediments from the Isua Greenstone Belt, southern West Greenland. Geochimica et Cosmochimica Acta 69, 1555–1573. https://doi.org/10.1016/j.gca.2004.09.023
Condie, K. C., 1993. Chemical composition and evolution of the upper continental crust: contrasting results from surface samples and shales. Chemical Geology 104, 1–37. https://doi.org/10.1016/0009-2541(93)90140-E
Cox, R., Lowe, D. R., Cullers, R. L., 1995. The influence of sediment recycling and basement composition on evolution of mudrock chemistry in southwestern United States. Geochimica et Cosmochimica Acta 59, 2919–2940. https://doi.org/10.1016/0016-7037(95)00185-9
Herron, M. M., 1988. Geochemical Classification of Terrigenous Sands and Shales from Core or Log Data. Journal of Sedimentary Petrology 58, 820–829. https://doi.org/10.1306/212F8E77-2B24-11D7-8648000102C1865D
Ernst, R. E., Pease, V., Puchkov, V. N. Kozlov, V. I., Sergeeva, N. D., Hamilton, M., 2006. Geochemical Characterization of Precambrian magmatic suites of the southeastern margin of the East European Craton, Southern Urals, Russia. Geological Digest 5, 119–161.
Krasnobaev, A. A., Busharina, S. V., Kozlov, V. I., Puchkov, V. N., Sergeeva, N. D., Paderin, I. P., 2013. Zircon geochronology of the Mashak volcanic rocks and the problem of the age of the lower-middle Riphean boundary (Southern Urals). Stratigraphy and Geological Correlation 21(5), 465–481. https://doi.org/10.1134/S0869593813050055
Nesbitt, H. W., Young, G. M., 1982. Early Proterozoic Climates and Plate Motions Inferred from Major Element Chemistry of Lutites. Nature 299, 715–717.
Roser, B. P., Korsch, R. J., 1988. Provenance signatures of sandstone–mudstone suites determined using discriminant function analysis of major-element data. Chemical Geology 67, 119–139. https://doi.org/10.1016/0009-2541(88)90010-1
Semikhatov, M. A., Chumakov, N. M., Kuznetsov, A. B., 2015. Isotope age of boundaries between the general stratigraphic subdivisions of the Upper Proterozoic (Riphean and Vendian) in Russia: The evolution of opinions and the current estimate. Stratigraphy and Geological Correlation 23(6), 568–579. https://doi.org/10.1134/S0869593815060088
Taylor, S. R., McLennan, S. M., 1985. The continental crust: its composition and evolution. An examination of the geochemical record preserved in sedimentary rocks. Blackwell Scientific, Oxford.
Verma, S. P., Armstrong-Altrin, J. S., 2013. New multi-dimensional diagrams for tectonic discrimination of siliciclastic sediments and their application to Precambrian basins. Chemical Geology 355, 117–133. https://doi.org/10.1016/j.chemgeo.2013.07.014
References
Bolnar, R., Kamber, B. S., Moorbath, S., Whitehouse, M. J., Collerson, K. D., 2005. Chemical characterization of earth’s most ancient clastic metasediments from the Isua Greenstone Belt, southern West Greenland. Geochimica et Cosmochimica Acta 69, 1555–1573. https://doi.org/10.1016/j.gca.2004.09.023
Condie, K. C., 1993. Chemical composition and evolution of the upper continental crust: contrasting results from surface samples and shales. Chemical Geology 104, 1–37. https://doi.org/10.1016/0009-2541(93)90140-E
Cox, R., Lowe, D. R., Cullers, R. L., 1995. The influence of sediment recycling and basement composition on evolution of mudrock chemistry in southwestern United States. Geochimica et Cosmochimica Acta 59, 2919–2940. https://doi.org/10.1016/0016-7037(95)00185-9
Garan’, M. I., 1969. Verkhnii dokembrii (rifei): Stratigrafiia [Upper Precambrian (Riphean): Stratigraphy], in Geologiia SSSR [Geology of USSR]. T. 12. Permskaia, Sverdlovskaia, Cheliabinskaia i Kurganskaia oblasti. Ch. 1 [V. 12. Perm, Sverdlovsk, Chelyabinsk and Kurgan districts. Part 1]. Nedra Publ., Moscow, 149–200. (In Russian)
Gareev, E. Z., 1989. Geokhimiia osadochnykh porod stratotipicheskogo razreza rifeia [Geochemistry of sedimentary rocks of the stratotypical Riphean cross-section]. https://search.rsl.ru/ru/record/ 01000016736 (accessed: 14.03.2018). (In Russian)
Dymkin, A. M., Ivanov, K. S., Ivanov, S. N., Krasnobayev, A. A., Poltavets, YU. A., Pumpyanskiy, A. I., Puchkov, V. N., Rusin, A. I., Samarkin, G. I., Semenov, I. V., 1986. Formirovanie zemnoi kory Urala [Formation of the Earth’s crust of the Urals]. Nauka, Moscow. (In Russian)
Herron, M. M., 1988. Geochemical Classification of Terrigenous Sands and Shales from Core or Log Data. Journal of Sedimentary Petrology 58, 820–829. https://doi.org/10.1306/212F8E77-2B24-11D7-8648000102C1865D
Ernst, R. E., Pease, V., Puchkov, V. N. Kozlov, V. I., Sergeeva, N. D., Hamilton, M., 2006. Geochemical Characterization of Precambrian magmatic suites of the southeastern margin of the East European Craton, Southern Urals, Russia. Geological Digest 5, 119–161.
Ivanov, S. N., 1980. O doordovikskoi istorii Urala i predgeosinklinal’nom razvitii zemnoi kory voobshche [About PreOrdovician history of the Urals and PreGeosynclinal development of the earth’s crust in general], in: Doordovikskaia istoriia Urala [PreOrdovician history of the Urals] 1. Ural Scientific Centre, USSR Academy of Sciences, Sverdlovsk, 3–28. (In Russian)
Ivanov, S. N., 1981. O baikalidakh Urala i Sibiri [About the Baikalides of the Urals and Siberia]. Geotektonika [Geotectonics] 5, 47–65. (In Russian)
Kozlov, V. I., Sergeeva, N. D., Genina, L. A., 2007. K voprosu o stroenii i raschlenenii mashakskoi svity srednego rifeia Iuzhnogo Urala [On the question of the structure and dismemberment of the Middle Riphean Mashak Formation, Southern Urals]. Geologicheskii sbornik [Geological digest] 6, 21–32. http://ig.ufaras.ru/publikatsii/geologicheskie-sborniki/geologicheskiy-sbornik-6-2007-g/ (accessed 09.08.2018). (In Russian)
Krasnobaev, A. A., Busharina, S. V., Kozlov, V. I., Puchkov, V. N., Sergeeva, N. D., Paderin, I. P., 2013. Zircon geochronology of the Mashak volcanic rocks and the problem of the age of the lower-middle Riphean boundary (Southern Urals). Stratigraphy and Geological Correlation 21(5), 465–481. https://doi.org/10.1134/S0869593813050055
Larionov, N. N., Bergazov, I. R., Genina, L. A., Granovskaya, N. V., Zakharov, A. A., Nigmatullina, A. M., Tsvetkova, A. A., 2006. Gosudarstvennaia geologicheskaia karta Rossiiskoi federatsii masshtaba 1 : 200 000. Seriia Iuzhnoural’skaia. List N-40-KhKhII (Tukan). Ob”iasnitel’naia zapiska [State Geological Map of the Russian Federation at a scale of 1 : 200 000. Series Yuzhnouralskaya. Sheet N-40-XXII (Tukan). Explanatory note]. Publ. Bashkirgeologiia Ltd, Ufa. (In Russian)
Maslov, A. V., 1988. Litologiia verkhnerifeiskikh otlozhenii Bashkirskogo megantiklinoriia [Lithology of Upper Riphean deposits of Bashkirian Meganticlinorium]. Nauka, Moscow. (In Russian)
Maslov, A. V., 1995. Tipy istochnikov snosa peschanykh assotsiatsii etalona rifeia [Provenance types for sandstone associations of the Riphean stratotype], in: Ezhegodnik-1994 [Yearbook-1994]. IGG UrB RAS, Ekaterinburg, 41–44. (In Russian)
Maslov, A. V., Gareev, E. Z., Kotova, L. N., Podkovyrov, V. N., 2018a. Litokhimicheskie osobennosti peschanikov mashakskoi svity (srednii rifei, Iuzhnyi Ural) [Lithochemical features of Mashak Formation sandstones, Southern Urals], in: Problemy mineralogii, petrografii i metallogenii. Materialy nauchnykh chtenii pamiati P. N. Chirvinskogo [Problems of mineralogy, petrography and metallogeny. Materials of scientific readings in memory of P. N. Chirvinsky] 21. Publishing house of the Perm State National Research University, Perm, 153–161. (In Russian)
Maslov, A. V., Olovyanishnikov, V. G., Isherskaya, M. V., 2002. Rifei vostochnoi, severo-vostochnoi i severnoi periferii Russkoi platformy i zapadnoi megazony Urala: litostratigrafiia, usloviia formirovaniia i tipy osadochnykh posledovatel’nostei [Riphean of the eastern, northeastern and northern periphery of the Russian platform and the western megazone of the Urals: lithostratigraphy, formation conditions and types of sedimentary sequences]. Litosfera [Lithosphere] 2, 54–95. http://lithosphere.uran.ru/index.php/lith/article/view/1703 (accessed: 09.08.2018). (In Russian)
Nesbitt, H. W., Young, G. M., 1982. Early Proterozoic Climates and Plate Motions Inferred from Major Element Chemistry of Lutites. Nature 299, 715–717.
Parnachev, V. P., 1988. Magmatizm i osadkonakoplenie v pozdnedokembriiskoi istorii Iuzhnogo Urala [Magmatism and sedimentation in the Late Precambrian history of the Southern Urals]. https://search.rsl.ru/ru/record/01008564815(accessed 14.03.2018). (In Russian)
Parnachev, V. P., Rotar’, A. F., Rotar’, Z. M., 1986. Srednerifeiskaia vulkanogenno-osadochnaia assotsiatsiia Bashkirskogo antiklinoriia [The Middle Riphean volcanic-sedimentary association of the Bashkir anticlinorium]. Urals Branch of USSR Academy of Sciences, Sverdlovsk. (In Russian)
Pettidzhon, F., Potter, P., Siver, R., 1976. Peski i peschaniki [Sands and sandstones]. Mir, Moscow. (In Russian)
Puchkov, V. N., 2000. Paleogeodinamika Iuzhnogo i Srednego Urala [Paleogeodynamics of the Southern and Middle Urals]. GILEM, Ufa, 146 p. (In Russian)
Puchkov, V. N., 2010. Geologiia Urala i Priural’ia (aktual’nye voprosy stratigrafii, tektoniki, geodinamiki i metallogenii) [Geology of the Urals and Cis-Urals (actual problems of stratigraphy, tectonics, geodynamics and metallogeny)]. DesignPoligraphService, Ufa. (In Russian)
Puchkov, V. N., 2013. Pliumy v istorii Urala [Plumas in the history of the Urals]. Biulleten’ MOIP. Otdel geologicheskii [Bulletin of the MSN. Geology] 4, 64–73. (In Russian)
Puchkov, V. N., 2016. Vzaimosviaz’ plitnykh i pliumovykh protsessov v global’nom i regional’nom masshtabe [Interconnection of plate and plume processes on a global and regional scale], in: Pliumovye protsessy na Urale. Metallogeniia drevnikh i sovremennykh okeanov-2016. Ot mineralogenezisa k mestorozhdeniiam [Plume processes in the Urals. Metallogeny of ancient and modern oceans-2016. From mineralogens to deposits]. IM, Urals Branch of RAS, Miass, 17–21. (In Russian)
Romanov, V. А., 1973. Tipovye razrezy dokembriia Iuzhnogo Urala [Typical sections of the Precambrian of the Southern Urals]. Nauka, Moscow. (In Russian)
Ronov, A. B., Migdisov, А. А., Khane, К., 1995. Kolichestvennye zakonomernosti evoliutsii sostava alevropeschanykh porod Russkoi plity [Quantitative patterns of the evolution of the composition of siltstones and sandstones of the Russian plate]. Geokhimiia [Geochemistry] 3, 323–348. (In Russian)
Roser, B. P., Korsch, R. J., 1988. Provenance signatures of sandstone–mudstone suites determined using discriminant function analysis of major-element data. Chemical Geology 67, 119–139. https://doi.org/10.1016/0009-2541(88)90010-1
Rotar’, A. F., 1974. Mashakskaia svita (rifei) na Iuzhnom Urale [Mashak Formation (Riphean) in the Southern Urals]. Sovetskaia geologiia [Soviet geology] 4, 116–123. (In Russian)
Rotar’, A. F., 1976. K voprosu o sostave i stratigraficheskom polozhenii konglomeratov mashakskoi svity na Iuzhnom Urale [On the composition and stratigraphic position of conglomerates of the Mashak Formation in the Southern Urals], in: Konglomeraty i ikh rol’ v poznanii geologicheskoi istorii Urala [Conglomerates and their role in the knowledge of the geological history of the Urals]. USC of the USSR Academy of Sciences, Sverdlovsk, 14–20. (In Russian)
Semikhatov, M. A., 2008. Khronostratigrafiia i khronometriia: konkuriruiushchie kontseptsii obshchego raschleneniia dokembriia [Chronostratigraphy and chronometry: competing concepts of the general dismemberment of the Precambrian]. Biulleten’ MOIP. Otdel geologicheskii [Bulletin of the MSN. Geology] 83(5), 36–58. (In Russian)
Semikhatov, M. A., Chumakov, N. M., Kuznetsov, A. B., 2015. Isotope age of boundaries between the general stratigraphic subdivisions of the Upper Proterozoic (Riphean and Vendian) in Russia: The evolution of opinions and the current estimate. Stratigraphy and Geological Correlation 23(6), 568–579. https://doi.org/10.1134/S0869593815060088
Semikhatov, M. A., Shurkin, K. A., Aksenov, E. M., Becker, Yu. R., Bibikova, E. V., Duk, V. L., Esipchuk, K. E., Karsakov, L. P., Kiselev, V. V., Kozlov, V. I., Lobach-Zhuchenko, S. B., Negrutsa, V. Z., Robonen, V. I., Sez’ko, A. I., Filatova, L. I., Khomentovsky, V. V., 1991. Novaia stratigraficheskaia shkala dokembriia SSSR [The new stratigraphic scale of the Precambrian of the USSR]. Izvestiia AN SSSR. Seriia geologicheskaia [Proceedings of the USSR Academy of Sciences. Geological series] 4, 3–13. (In Russian)
Smirnov, Yu. D., 1964. Istoriia razvitiia Ural’skoi skladchatoi oblasti v dokembrii [History of development of the Ural fold region in the Precambrian]. Geologiia dokembriia. Doklady sovetskikh geologov. MGK XXII sessiia [Reports of Soviet geologists. IGC XXII session]. Nedra, Moscow, 195–207. (In Russian)
Stratotip rifeia. Stratigrafiia. Geokhronologiia [Stratotype of Riphean. Stratigraphy. Geochronology], 1983. Keller, B. M., Chumakov, N. M. (Eds.). Nauka, Moscow. (In Russian)
Taylor, S. R., McLennan, S. M., 1985. The continental crust: its composition and evolution. An examination of the geochemical record preserved in sedimentary rocks. Blackwell Scientific, Oxford.
Verma, S. P., Armstrong-Altrin, J. S., 2013. New multi-dimensional diagrams for tectonic discrimination of siliciclastic sediments and their application to Precambrian basins. Chemical Geology 355, 117–133. https://doi.org/10.1016/j.chemgeo.2013.07.014
Yudovich, Ya. E., Ketris, M. P., 1988. Geokhimiia chernykh slantsev [Geochemistry of black shales]. Nauka, Leningrad. (In Russian)
Yudovich, Ya. E., Ketris, M. P., 2000. Osnovy litokhimii [Basics of lithochemistry]. Nauka, St-Petersburg. (In Russian)
Downloads
Published
2018-11-15
How to Cite
Maslov, A. V. (2018) “Synrift deposits of the Middle Riphean Mashak Formation, Southern Urals (a short lithochemical characterization)”, Vestnik of Saint Petersburg University. Earth Sciences, 63(3), pp. 303–325. doi: 10.21638/spbu07.2018.304.
Issue
Section
Articles
License
Articles of "Vestnik of Saint Petersburg University. Earth Sciences" are open access distributed under the terms of the License Agreement with Saint Petersburg State University, which permits to the authors unrestricted distribution and self-archiving free of charge.
