On the accuracy of the bathymetry-generated gravitational field quantities for a depth-dependent seawater density distribution   总被引：1，自引：0，他引：1  

Robert Tenzer  Pavel Novák  Vladislav Gladkikh 《Studia Geophysica et Geodaetica》2011,55(4):609-626

In geophysical studies investigating the lithosphere structure, the gravitational field generated by the ocean density contrast (i.e., bathymetry-generated gravitational field) represents a significant amount of the signal to be modelled and subsequently removed from the Earth’s gravity field. The ocean density contrast is typically calculated as the difference between the mean density values of the Earth’s crust and seawater. The approximation of the actual seawater density distribution by its mean value yields relative errors up to about 2% in computed quantities of the gravitational field. To reduce these errors, a more realistic model of the seawater density distribution is utilized based on the analysis of existing oceanographic data of salinity, temperature, and pressure (depth). We study the accuracy of the bathymetry-generated gravitational field quantities formulated for a depth-dependent model of the seawater density distribution. This density distribution approximates the seawater density variations due to an increasing pressure with depth, whereas smaller lateral density variations caused by salinity, temperature, and other oceanographic factors are not taken into consideration. The error analysis reveals that the approximation of the seawater density by the depth-dependent density model reduces the maximum errors to less than 0.6%. The corresponding depth-averaged errors are below 0.1%. The depth-dependent seawater density model is further facilitated in expressions for computing the bathymetry-generated gravitational field quantities by means of the spherical bathymetric (ocean bottom depth) functions. The numerical realization reveals large differences in the results obtained with and without consideration of the depth-dependent seawater density distribution. The maxima of absolute differences reach 201 m²/s² and 16.5 mGal in computed values of the potential and attraction, respectively. The application of the depth-dependent seawater density model thus significantly improves the accuracy in the forward modelling of the bathymetric gravitational field quantities.  相似文献   

Rotation parameters of the Siberian domain and its eastern surrounding structures during different geological epochs     

V. Yu. Timofeev  A. Yu. Kazansky  D. G. Ardyukov  D. V. Metelkin  P. Yu. Gornov  N. V. Shestakov  A. V. Timofeev  G. Z. Gil’manova 《Russian Journal of Pacific Geology》2011,5(4):288-297

The motion of lithospheric blocks was analyzed in the junction zone between the Eurasian Plate and its surrounding structures. Its present-day stage was considered using GPS and seismologic data. Models of the movement of a rigid plate are considered for Eurasia. A model of Eurasia (northern part of Asia) was used to determine the rotation parameters of its southern periphery (Amur Plate) based on GPS data for the Far East (Sikhote Alin profile), and Transbaikal regions are shown as an example. A model of the Amur Plate was used to illustrate the behavior of the extension zone on its western boundary represented by the Lake Baikal depression during the Kultuk earthquake (M = 6.3, August, 27, 2008). Paleomagnetic data made it possible to determine the rotation pole of the Siberian Craton relative to its surrounding folded structures during the Mesozoic and to estimate its kinematic parameters. The permanent position of the rotation pole in the relative coordinate system since the terminal Paleozoic until the Recent indicates a constant rotation velocity of the Siberian domain within the Eurasian Plate structure.  相似文献   

Comparison of Synchrotron Radiation X-Ray Fluorescence with Conventional Techniques for the Analysis of Sedimentary Samples   总被引：3，自引：0，他引：3  

Michael A. Phedorin  Vladislav A. Bobrov  Evgeny P. Chebykin  Evgeny L. Goldberg  Michael S. Melgunov  Svetlana V. Filippova  Konstantin V. Zolotarev 《Geostandards and Geoanalytical Research》2000,24(2):205-216

A comparison is made of elemental analyses of sediment samples (lake bottom sediments and sediments from the petroliferous Bazhenovka Formation) by five competitive methods (synchrotron radiation X-ray fluorescence (SR-XRF), INAA, ICP-MS, AAS and traditional XRF). The object of this study was to identify the most suitable analytical techniques for applications in sedimentary geochemistry. Advantages and shortcomings of the five techniques were considered with respect to applications related to studies of palaeo-climate changes recorded in sedimentary cores from Lake Baikal and the geochemical stratigraphy of the Bazhenovka Formation, which is rich in organic material. We have concluded that SR-XRF was the best technique for producing extensive analytical data series, from the point of view of its speed, ease of application, cost, non-destructive nature and sensitivity, which allowed for the simultaneous determination of more than twenty elements of geochemical interest in small samples of sediments. An additional benefit of the method was demonstrated when used for the independent certification of geological reference materials. International reference samples BIL-1 and SDO-1 were certified by means of this method without use of reference materials. Analyses were based on the physics of the theory of energy transport.  相似文献   

Multi-Wavelength Synchrotron Radiation XRF Determination of U and Th in Sedimentary Cores from Lake Baikal   总被引：1，自引：0，他引：1  

Michael A. Phedorin  Evgeny L. Goldberg  Vladislav A. Bobrov  Oleg M. Khlystov  Michael A. Grachev 《Geostandards and Geoanalytical Research》2000,24(2):217-226

A new technique for the determination of uranium and thorium in lacustrine sediments is based on non-destructive synchrotron radiation X-ray fluorescence analysis (SR-XRF) of sediment samples using monochromatic beams of different energies as excitation sources, with the recording and subsequent iterative processing of the X-ray fluorescence spectra. The technique has a multielement capability and enables fast, simultaneous analysis of a few tens of elements. The proposed SR-XRF technique was tested against INAA and ICP-MS methods and showed a number of advantages with a generally good correlation of results by the three methods. Uranium and Th profiles have been measured at a time resolution of 2 kyr in a drill core (BDP-96) from Lake Baikal bottom sediments deposited between 780 and 40 kyr B P. During this time span, peaks in the U and U/Th concentration marked warm climates. Oscillations of U and U/Th in Baikal bottom sediments during the Brunhes chron reflect climate-induced global change in the volume of polar ice, controlled by long-term cyclicity of the Earths orbital parameters. The response of these warm periods is similar to that observed earlier in shorter cores that span the two last interglacials (220-0 kyr BP).  相似文献   

GPS measurements (2003–2006) in the Sikhote Alin network,the Far East     

V. Yu. Timofeev  P. Yu. Gornov  D. G. Ardyukov  Yu. F. Malyshev  E. V. Boiko 《Russian Journal of Pacific Geology》2008,2(4):314-324

This paper considers results of geodynamic studies using the GPS method in the territory of the Far East. GPS measurements using TRIMBLE-4700 geophones were launched along the Sikhote Alin profile in 2003. The technology of the GPS measurements and the problems of selecting the measurement sites and network configuration with reference to the region’s structure are discussed. The results of GPS measurements in 2003–2006 were used to study the fault system of the Far East continental margin. Different models of the Eurasia rotation (from the known NNR-NUVEL-1A to the recent ones) were analyzed. The solid-body rotation of Eurasia was predicted in the framework of the AR-IR-2006 model with a pole located at 51.045°N latitude, 255.842° longitude and rotating at a rate of 0.2423°/Ma. The parameters of the Amur plate rotation were preliminarily estimated (57.6° ± 0.5°N, 117.1 ± 0.5°E, and 0.083° ± 0.004°/m.y) using results on the Sikhote Alin and Transbaikalian network.  相似文献   

Soil cover geochemistry of mining landscapes in the South-East of Transbaikalia (City of Zakamensk)     

I. V. Timofeev  N. S. Kasimov  N. E. Kosheleva 《Geography and Natural Resources》2016,37(3):200-211

Presented is a detailed characterization of the present state and pollution of soil cover in the influence area of the Dzhidinskii tungsten-molybdenum plant which takes into consideration the spatial geological inhomogeneity and the functional purpose of urban territories. As part of the investigation, we determined the content levels of heavy metals and metalloids in background soils, and the elements which are the main pollutants of urban soils in the zones of different functional purposes, ascertained the degree of technogenic geochemical transformation of soil cover in the city of Zakamensk, and identified the leading soiland landscape-geochemical factors for accumulation of heavy metals and metalloids in the urban topsoil (0?10 cm) horizons. An assessment was also made of the ecological hazard of soil pollution by a set of heavy metals and metalloids in the main functional zones of the city. A soil-geochemical survey was carried out, and the ICP-MS method was used to determine the total content levels of 14 heavy metals and metalloids of hazard classes I?III as well as Be, Sn, Cs and Bi. The elements were determined, which are the main pollutants of the soils in Zakamensk: W, Bi, Cd, Pb and Mo. The study revealed a need to take into account the metallogenic specific character and geological inhomogeneity of the area by using the local coefficients of concentration (EF _l ) and dispersal (DF _l ) which must be calculated not with respect to the average regional background but from the individual (for each parent material) background value in order to more accurately determine the degree of technogenic geochemical transformation of soils, and the ecological hazard of pollution. It is suggested that the ecological hazard should be assessed on the basis of the Integrated Pollution Index (IPI) which is calculated with respect to the world’s average concentrations of heavy metals and metalloids in soils and takes into account hazard classes of elements.  相似文献   

Experimental study of the angular method for the determination of the sea surface temperature from space in the 8–12 μm window     

N. A. Timofeev 《Physical Oceanography》1989,1(2):129-139

The structure of the field of outgoing into space radiation for the 8–12 m spectral interval is studied using the data of satellite observations of the oceans. The regularity found is employed to substantiate the angular method for the sea surface temperature (SST) reconstruction. The band of the angles of view is determined in which the error of the SST reconstructon does not exceed 0.3°C with the assigned error of the satellite measurements of radiation temperatures of 0.05°C.UDK 551.507.362.2Translated by Mikhail M. Trufanov.  相似文献   

Tidal ice drift in the White Sea: Results of a numerical experiment     

B. A. Kagan  A. A. Timofeev 《Oceanology》2006,46(6):796-802

The tidal ice drift is considered as an element of the tidal dynamics in a sea covered with ice. The appropriate problem is solved with the use of a combination of a simple viscoelastic continuum model of the tidal ice drift with the QUODDY-4 three-dimensional finite-element hydro-thermodynamical model. The combined model is used for simultaneous calculations of the tidal regime and the tidal ice drift in the White Sea. The calculated distributions of the characteristics of the semidiurnal (M₂ wave) tidal ice drift such as the ice drift velocity and the tidal variations of the ice concentration and the pressure of the ice compression are discussed. The distributions are used for detecting the zones of the quasi-steady tidal compression and extension of ice and regions of ridging of ice floes. Particular attention is paid to the residual tidal ice drift, a phenomenon that has remained almost unnoticed so far.  相似文献   

A new approach to analysis of landslide slope stability     

E. V. Kalinin  L. L. Panas’yan  E. M. Timofeev 《Moscow University Geology Bulletin》2008,63(1):19-27

This paper is based on data from engineering-geological research on the landslide slopes of the Moscow River valley from the site of a proposed bridge crossing reconstruction. A method for delineating the slippage surface is suggested, which allows a more reliable evaluation of landslide stability and pressure for planning and decision-making purposes during the reconstruction of the bridge crossing, and an appropriate mitigation strategy.  相似文献   

A Comparison Between Machine Learning and Functional Geostatistics Approaches for Data-Driven Analyses of Sediment Transport in a Pre-Alpine Stream     

Didkovskyi  Oleksandr  Ivanov  Vladislav  Radice  Alessio  Papini  Monica  Longoni  Laura  Menafoglio  Alessandra 《Mathematical Geosciences》2022,54(3):467-506

Mathematical Geosciences - The problem of providing data-driven models for sediment transport in a pre-Alpine stream in Italy is addressed. This study is based on a large set of measurements...  相似文献