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61.
62.
We derive expressions for computing the gravitational field (potential and its radial derivative) generated by an arbitrary
homogeneous or laterally varying density contrast layer with a variable depth and thickness based on methods for a spherical
harmonic analysis and synthesis of gravity field. The newly derived expressions are utilised in the gravimetric forward modelling
of major known density structures within the Earth’s crust (excluding the ocean density contrast) beneath the geoid surface.
The gravitational field quantities due to the sediments and crust components density contrasts, shown in numerical examples,
are computed using the 2 × 2 arc-deg discrete data from the global crustal model CRUST2.0. These density contrasts are defined
relative to the adopted value of the reference crustal density of 2670 kgm−3. All computations are realised globally on a 1 × 1 arc-deg geographical grid at the Earth’s surface. The maxima of the gravitational
signal due to the sediments density contrast are mainly along continental shelf regions with the largest sedimentary deposits.
The corresponding maxima due to the consolidated crust components density contrast are over areas of the largest continental
crustal thickness with variable geological structure. 相似文献
63.
The structurally adequate model of the geomagnetosphere consists of the following modules: A. Bow shock as a source of power for magnetospheric processes. B. The generation of magnetospheric convection. C. The plasma pressure distribution in the magnetosphere and electron-proton precipitations into the ionosphere. D. The magnetosphere-ionosphere coupling. Field-aligned currents. Essentially, each module presented in an analytical form is a model of a particular process described in physical terms. It has an input and output to couple with other modules. When combined, the modules comprise a single large physically adequate model describing a phenomenon in such a way that we understand its essence and contribution of each physical process into the overall picture. 相似文献
64.
Methane fluxes in the southeastern Baltic Sea 总被引:2,自引:2,他引:0
Marina Ulyanova Vadim Sivkov Timur Kanapatskij Pavel Sigalevich Nikolay Pimenov 《Geo-Marine Letters》2012,32(5-6):535-544
New data from surveys of gas-bearing mud areas in the Gdansk Deep (southeastern Baltic Sea) were collected during four research cruises in 2009–2011. These revealed the presence of seven large pockmarks apart from the three already known, and enabled significant improvement of the existing digital map of gassy mud distribution. Based on geochemical sediment analyses, calculated diffusive methane fluxes from the upper (0–5?cm) seabed layer into near-bottom waters were highest—3.3?mmol/(m2?day)—in pockmark mud, contrasting strongly with the minimum value of 0.004?mmol/(m2?day) observed in typical, background mud. However, fluxes of less than 0.1?mmol/(m2?day) were observed in all sediment types, including pockmarks. In a newer attempt to roughly estimate budgets at a more regional scale, diffusive methane venting amounts to 280?×?106?mmol/day for southeastern Baltic Sea muddy sediments. Elongated pockforms in the southern Gotland Deep, known since the end of the 1980s as pockmarks, had methane concentrations that were similar to those of gassy mud from the Gdansk Basin, and there was no geo-acoustic evidence of considerably increased gas levels. 相似文献
65.
Kappa and regional attenuation for Vrancea (Romania) earthquakes 总被引:1,自引:0,他引:1
66.
Deep magnetotelluric (MT) sounding data were collected and processed in the western part of the East European Craton (EEC). The MT sounding results correspond well with impedances obtained by magnetovariation (MV) sounding on the new geophysical observatory situated not far from the western border of Russia. Inversion based on combined data of both induction soundings let us evaluate geoelectrical structure of the Earth’s crust and upper and mid-mantle at depths up to 2000 km, taking into account the harmonics of 11-year variations. Results obtained by different authors and methods are compared with similar investigations on the EEC such as international projects CEMES in Central Europe and BEAR in Fennoscandia. 相似文献
67.
Bilohuščin Vladimír Uher Pavel Koděra Peter Milovská Stanislava Mikuš Tomáš Bačík Peter 《Mineralogy and Petrology》2017,111(4):643-658
Mineralogy and Petrology - Borate minerals of the ludwigite group (LGM) and szaibélyite in association with hydroxylclinohumite, clinochlore, a serpentine mineral, magnesian magnetite, spinel,... 相似文献
68.
69.
The newly obtained geological data indicate the presence of a major metalliferous province within the buried Yakut basement
uplift in the Siberian platform. The province shows a similarity to the eastern part of the Witwatersrand rift in the South
African Republic. Sources for diamonds are established. Modern trains of gold-platinum minerals are delineated, reflecting
mineralization of fossil conglomerates and layered ultrabasites from the middle and lower structural stages.
Published in Russian Doklady Akademii Nauk, 2009, Vol. 425, No. 5, pp. 649–650.
Presented by Academician N.P. Yushkin May 16, 2008
The article was translated by the authors. 相似文献
70.
Abstract Agricultural watersheds in the Czech Republic are one of the primary sources of non-point-source phosphorus (P) loads in receiving waters. Since such non-point sources are generally located in headwater catchments, streamflow and P concentration data are sparse. We show how very short daily streamflow and P concentration records can be combined with nearby longer existing daily streamflow records to result in reliable estimates of daily and annual P concentrations and loads. Maintenance of variance streamflow record extension methods (MOVE) can be employed to extend short streamflow records. Constituent load regressions are used to predict daily P constituent loads from streamflow and other time varying characteristics. Annual P loads are then estimated for individual watersheds. Resulting annual P load estimates ranged from 0.21 to 95.4 kg year-1 with a mean value of 11.77 kg year-1. Similarly annual P yield estimates ranged from 0.01 to 0.3 kg ha-1 year-1 with an average yield of 0.07 kg ha-1 year-1. We document how short records of daily streamflow and P concentrations can be combined with a national network of daily streamflow records in the Czech Republic to arrive at meaningful and reliable estimates of annual P loads for small agricultural watersheds. Citation Beránková, T., Vogel, R. M., Fiala, D. & Rosendorf, P. (2010) Estimation of phosphorus loads with sparse data for agricultural watersheds in the Czech Republic. Hydrol. Sci. J. 55(8), 1417–1426. 相似文献