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Saint Petersburg, Russia

Panin A.V.,Moscow State University | Adamiec G.,Silesian University of Technology | Arslanov K.A.,Sankt Petersburg State University | Bronnikova M.A.,Russian Academy of Sciences | And 4 more authors.
Geochronometria | Year: 2014

A set of 121 radiocarbon and OSL dates has been compiled from the Upper Dnieper River and tributary valleys, Western European Russia. Each date was attributed according to geo-morphic/sedimentological events and classes of fluvial activity. Summed probability density func-tions for each class were used to establish phases of increasing and reducing fluvial activity. The old-est detected reduction of fluvial activity was probably due to glacial damming at LGM. Within the Holocene three palaeohydrological epochs of millennial-scale were found: (1) high activity at 12,000-8,000 cal BP marked by large river palaeochannels; (2) low activity at 8,000-3,000 cal BP marked by formation of zonal-type soils on -floodplains; short episodes of high floods occurred be-tween 6,500-4,400 cal BP; (3) contrasting hydrological oscillations since 3,000 cal BP with periods of high floods between 3,000-2,300 (2,000) and 900-100 cal BP separated by long interval of low floods 2,300 (2,000)-900 cal BP when floodplains were not inundated-zonal-type soils were de-veloping and permanent settlements existed on floodplains. In the last millennium, four centennial-scale intervals were found: high flooding intervals are mid-11-mid-15th century and mid-17-mid-20th century. Intervals of flood activity similar to the present-day were: mid-15-mid-17th century and since mid-19th century till present. In the context of palaeohydrological changes, discussed are selected pal-aeogeographic issues such as: position of the glacial boundary at LGM, role of changing amounts of river runoff in the Black Sea level changes, floodplain occupation by Early Medieval population.A set of 121 radiocarbon and OSL dates has been compiled from the Upper Dnieper River and tributary valleys, Western European Russia. Each date was attributed according to geo-morphic/sedimentological events and classes of fluvial activity. Summed probability density func-tions for each class were used to establish phases of increasing and reducing fluvial activity. The old-est detected reduction of fluvial activity was probably due to glacial damming at LGM. Within the Holocene three palaeohydrological epochs of millennial-scale were found: (1) high activity at 12,000-8,000 cal BP marked by large river palaeochannels; (2) low activity at 8,000-3,000 cal BP marked by formation of zonal-type soils on -floodplains; short episodes of high floods occurred be-tween 6,500-4,400 cal BP; (3) contrasting hydrological oscillations since 3,000 cal BP with periods of high floods between 3,000-2,300 (2,000) and 900-100 cal BP separated by long interval of low floods 2,300 (2,000)-900 cal BP when floodplains were not inundated-zonal-type soils were de-veloping and permanent settlements existed on floodplains. In the last millennium, four centennial-scale intervals were found: high flooding intervals are mid-11-mid-15th century and mid-17-mid-20th century. Intervals of flood activity similar to the present-day were: mid-15-mid-17th century and since mid-19th century till present. In the context of palaeohydrological changes, discussed are selected pal-aeogeographic issues such as: position of the glacial boundary at LGM, role of changing amounts of river runoff in the Black Sea level changes, floodplain occupation by Early Medieval population. © 2013 Silesian University of Technology. Source


Melchor-Aguilar D.,IPICyT | Kharitonov V.,Sankt Petersburg State University
International Journal of Robust and Nonlinear Control | Year: 2010

In this paper we consider a special class of integral delay systems arising in several stability problems of time-delay systems. For these integral systems we derive stability and robust stability conditions in terms of Lyapunov-Krasovskii functionals. More explicitly, after providing the stability conditions we compute quadratic functionals and apply them to derive exponential estimates for solutions, and robust stability conditions for perturbed integral delay systems. Copyright © 2008 John Wiley & Sons, Ltd. Source


Tikhomirov V.,Sankt Petersburg State University
Marine and Petroleum Geology | Year: 2015

To unravel the mystery of the relationship between evaporates, Ca-Cl brines and accumulations of oil and N2 in the basins of ancient cratons, their N2, CH4 and He concentration ratios, as well as the isotopic composition (δ15N, δ13C and 3He/4He) were compared within the Volga-Ural basin. The study allowed subsalt fluids from Volga-Ural Basin to divide into two genetic groups. The first one is found within the basin's platform area. It includes Ca-Cl brines, high-viscosity heavy oil, bitumen and N2, which has concentrations higher than that of CH4 and positive values of δ15N. The second one is tied to the edge of the platform, the Ural Foredeep and Peri-Caspian Depression. In this group, only the oil and gas reservoirs, which have more CH4 than N2, and possibly negative values of δ15N, were discovered. Interaction of gas components in compared fluids indicates great role of degassing in the formation of their composition. It is suggested that the fluids of the first group (N2CH4) is what remains, and the second group (N24) is what is disappears from the rocks during their metamorphism and degassing. •This study allows to divide the subsalt fluids for nitrogen and methane group.•The nitrogen group includes Ca-Cl brines, heavy oils, bitumens and N2 gases.•The methane group includes methane gases and possibly volatile crudes.•Gas exchange of the groups is accompanied by degassing and mass transfer between them.•It may be that the groups are products of metamorphism of different times and places. © 2015 Elsevier Ltd. Source


Foulger G.R.,Durham University | Panza G.F.,University of Trieste | Panza G.F.,China Earthquake Administration | Artemieva I.M.,Copenhagen University | And 9 more authors.
Terra Nova | Year: 2013

Geological and geodynamic models of the mantle often rely on joint interpretations of published seismic tomography images and petrological/geochemical data. This approach tends to neglect the fundamental limitations of, and uncertainties in, seismic tomography results. These limitations and uncertainties involve theory, correcting for the crust, the lack of rays throughout much of the mantle, the difficulty in obtaining the true strength of anomalies, choice of what background model to subtract to reveal anomalies, and what cross-sections to select for publication. The aim of this review is to provide a relatively non-technical summary of the most important of these problems, collected together in a single paper, and presented in a form accessible to non-seismologists. Appreciation of these issues is essential if final geodynamic models are to be robust, and required by the scientific observations. © 2013 John Wiley & Sons Ltd. Source


Kulish P.P.,Russian Academy of Sciences | Lyakhovsky V.D.,Sankt Petersburg State University | Postnova O.V.,Sankt Petersburg State University
Journal of Physics: Conference Series | Year: 2012

We study the decomposition problem for tensor powers of B 2-fundamental modules. To solve this problem singular weight technique and injection fan algorithms are applied. Properties of multiplicity coefficients are formulated in terms of multiplicity functions. These functions are constructed showing explicitly the dependence of multiplicity coefficients on the highest weight coordinates and the tensor power parameter. It is thus possible to study general properties of multiplicity coefficients for powers of the fundamental B 2-modules. Source

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