Three-dimensional inversion of the single-profile magnetotelluric data     

P. V. Ivanov  P. Yu. Pushkarev 《Izvestiya Physics of the Solid Earth》2012,48(11-12):871-876

It is preferable to use the three-dimensional (3D) magnetotelluric inversion, which provides volumetric geoelectric models, to handle the array input data. However, the soundings are frequently conducted on the single profiles or on the profiles that are considerably spaced apart from each other. We explore the possibilities of the 3D inversion of such data by the example of a three-layer model containing three local inhomogeneities. We previously showed that the simple processing of the data and their 1D or 2D inversion enable reconstructing the background cross section and locating all the three inhomogeneities. In the present paper, we use this information for constructing several versions of the starting model and carrying out the smoothing 3D inversion of the data. The experiments show that if the background cross section is incorporated into the starting model, the final model provided by the inversion closely reproduces the real distribution of all geoelectric parameters. At the same time, if the starting model that hosts the inhomogeneities has the form of a homogeneous half-space, the inversion is not able to reconstruct an adequate final model.  相似文献   

Geochemistry of organic matter in bottom sediments of the Ashadze hydrothermal field   总被引：3，自引：0，他引：3  

I. P. Morgunova  V. N. Ivanov  I. V. Litvinenko  V. I. Petrova  T. V. Stepanova  G. A. Cherkashev 《Oceanology》2012,52(3):345-353

Comparative studies of the composition and distribution of the dispersed organic matter (DOM) were performed for the bottom sediments from active areas of the Ashadze hydrothermal field (the Mid-Atlantic Ridge, 13° N) and for background sediments from the area treated (sampled during the cruises of R/V Professor Logachev in 2003 and 2007). The content of hydrocarbons (HCs) in the hydrothermal samples is about 20 times as high as the background values. The HCs composition includes both low-transformed (isoprenoids, hopenes, ββ-hopanes, and ααα27R-steranes) and geologically mature chemofossils (C₁₆-C₃₅ n-alkanes, geohopanes, moretanes, and polyaromatic hydrocarbons). The polyaromatic hydrocarbons (PAHs) are mainly represented by phenanthrene and its alkyl homologues, i.e., by possible products of the diagenetic transformation of biogenic precursors. The results obtained point to the mixed genesis of the hydrothermal DOM, which is caused first by the diversity of the biota composition in the considered region, as well as by the specificity of the processes of the DOM’s maturing under the extreme environmental conditions.  相似文献   

The Porcupine Bank Canyon coral mounds: oceanographic and topographic steering of deep-water carbonate mound development and associated phosphatic deposition   总被引：1，自引：1，他引：0  

A. Mazzini  A. Akhmetzhanov  X. Monteys  M. Ivanov 《Geo-Marine Letters》2012,32(3):205-225

The head of a canyon system extending along the western Porcupine Bank (west of Ireland) and which accommodates a large field of giant carbonate mounds was investigated during two cruises (INSS 2000 and TTR-13). Multibeam and sidescan sonar data (600?C1,150?m water depth) suggest that the pre-existing seabed topography acts as a significant factor controlling mound distribution and shape. The mounds are concentrated along the edges of the canyon or are associated with a complex fault system traced around the canyon head, comprising escarpments up to 60?m high and several km long. The sampling for geochemical and petrographic analysis of numerous types of authigenic deposits was guided by sidescan sonar and video recordings. Calcite-cemented biogenic rubble was observed at the top and on the flanks of the carbonate mounds, being associated with both living and dead corals (Lophelia pertusa, Madrepora oculata and occasional Desmophyllum cristagalli). This can plausibly be explained by dissolution of coral debris facilitated by strong currents along the mound tops and flanks. In turn, the dissolved carbon is recycled and precipitated as interstitial micrite. Calcite, dolomite and phosphatic hardgrounds were identified in samples from the escarpment framing the eastern part of the survey area. The laterally extensive phosphatic hardgrounds represent a novel discovery in the region, supplying hard substrata for the establishment of new coral colonies. Based on existing knowledge of regional oceanographic conditions, complemented with new CTD measurements, it is suggested that water column stratification, enhanced bottom currents, and upwelling facilitate the deposition of organic matter, followed by phosphatisation leading to the formation of phosphate-glauconite deposits. The occurrence of strong bottom currents was confirmed by means of video observations combined with acoustic and sampling data, providing circumstantial evidence of fine- to medium-grained sand. Evidently, slope breaks such as escarpments and deep-water canyon headwalls are important structural elements in the development of mature carbonate mounds induced by deep-water coral growth. Stable isotope data show no evidence of methane-derived carbon in the carbonates and lithified sediments of the Porcupine Bank Canyon mounds.  相似文献   

Solar proton increases and dynamics of the electron outer radiation belt during solar events in December 2006     

L. V. Tverskaya  S. V. Balashov  N. N. Vedenkin  V. V. Ivanov  T. A. Ivanova  D. S. Karpenko  S. G. Kochura  I. A. Maksimov  N. N. Pavlov  I. A. Rubinstein  M. V. Tel’tsov  D. A. Trofimchuk  V. I. Tulupov  V. V. Khartov 《Geomagnetism and Aeronomy》2008,48(6):719-726

Increases in solar protons and variations in the electron and proton fluxes from the outer radiation belt are studied based on the GLONASS satellite measurements (the circular orbit at an altitude of ～20000 km with an inclination of ～65°) performed in December 2006. Indications in the channels, registered protons with energies of Ep = 3–70 MeV and electrons with energies of Ee > 0.04 and >0.8 MeV, are analyzed. The data on electrons with Ee = 0.8–1.2 MeV, measured on the Express-A3 geostationary satellite, are also presented. Before the strong magnetic storm of December 14 (|Dst|_max = 146 nT), the maximum of the outer belt electrons with the energy >0.7 MeV was observed at L ～ 4.5. After the storm, the fluxes of these electrons increased by more than an order of magnitude as compared to the prestorm level, and the maximum of a “new” belt shifted to L < 4 (minimal L reached by the GLONASS orbit). Under quiet geomagnetic conditions, solar protons with the energies >3 MeV fill only high-latitude legs of the GLONASS orbit. During the strong magnetic storm of December 15, the boundary of proton penetration into the magnetosphere almost merged with the orbital maximum of the proton radiation belt.  相似文献   

The Influence of Atmospheric Fronts on Free and Forced Oscillations of the Water Level in the Sea of Azov     

Ivanov  V. A.  Shul’ga  T. Ya. 《Doklady Earth Sciences》2019,486(2):737-740

Doklady Earth Sciences - The influence of inhomogeneous moving atmospheric pressure fields on currents and free and forced oscillations of the level of the Sea of Azov, induced by constant wind, is...  相似文献   

Finding of Refractory Inclusions in the North Kolchim Meteorite (H3)     

Berzin  S. V.  Ivanov  K. S.  Burlakov  E. V. 《Doklady Earth Sciences》2019,487(2):908-910

Doklady Earth Sciences - For the first time among Russian meteorites, refractory forsterite-rich inclusions are determined in the North Kolchim meteorite (H3). Forsterite-rich inclusions are found...  相似文献   

Spectrum and Variability of the Supernova Remnant G21.5-0.9     

Ivanov  V. P.  Ipatov  A. V.  Rakhimov  I. A.  Grenkov  S. A.  Andreeva  T. S. 《Astronomy Reports》2019,63(8):642-651

Measurements of the flux densities of the supernova remnant G21.5-0.9 at 4840 and 8450 MHz were performed in 2013–2018 on the 32-m telescope of the Svetloe Observatory of the Institute of Applied Astronomy, Russian Academy of Sciences. Multiple measurements revealed source variability. The flux densities of G21.5-0.9 for 1967–2010 from previously published data are used to compare the intensity of G21.5-0.9 and standard sources. An artificial-Moon flux scale is used to bring all the data into a single system and determine a refined spectrum. Analysis of the resulting data indicates that, first, the observed break in the source spectrum is not associated with energy losses of relativistic electrons due to synchrotron emission and, second, the source variability is manifest as flux-density changes described by one of two power-law dependencies for the flux versus frequency. The spectral indices of each of these dependencies have one of two constant values. Possible origins of the detected changes in the spectrum of G21.5-0.9 are discussed.

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Timing of Back–Arc Spreading of the Paleozoic Island Arc of the Urals: Implication of Sm–Nd and U–Pb Dating of Dolerites and the Composition of Inclusions in Zircon     

Ivanov  K. S.  Berzin  S. V.  Erokhin  Yu. V.  Ronkin  Yu. L.  Khiller  V. V. 《Doklady Earth Sciences》2019,484(1):97-100

Doklady Earth Sciences - Dolerites of the parallel dikes formed in a back-arc spreading setting have been dated by Sm–Nd to the Silurian (426 ± 34 Ma) for Mount Azov in the Central...  相似文献   

Ten-antenna prototype of a radio heliograph based on the Siberian Solar Radio Telescope     

S. V. Lesovoy  A. T. Altyntsev  V. G. Zandanov  E. F. Ivanov  A. V. Gubin  A. I. Maslov 《Geomagnetism and Aeronomy》2009,49(8):1125-1127

An upgrade of the Siberian Solar Radio Telescope (SSRT) [Smolkov et al., 1986; Grechnev et al., 2003] to a multiwave radio heliograph has been started. The radio heliograph being created will be designed mainly to measure coronal magnetic fields, to determine the locations of solar-flare energy release, and to investigate coronal mass ejections. These tasks define the parameters of next-generation radio heliographs. A high spatial resolution, a high image acquisition rate, and a high sensitivity are required simultaneously. All these parameters should be realized in the widest possible frequency range—from fractions to tens of GHz). The expected parameters of the future SSRT-based radio heliograph are listed below: spatial resolution 12″–24″, temporal resolution 0.02–1.0 s, frequency range 4–8 GHz, sensitivity up to 100 K, left-hand and right-hand circular polarizations, data rate 0.5–20 Mb s⁻¹ (normal and flare modes). In this paper, we describe the broadband antennas, analog optical data transmission lines, and correlator used in the 10-antenna radio heliograph prototype.  相似文献   

Displacement of large-scale open solar magnetic fields from the zone of active longitudes and the heliospheric storm of November 3–10, 2004: 2. “Explosion” of singularity and dynamics of sunspot formation and energy release     

K. G. Ivanov 《Geomagnetism and Aeronomy》2010,50(6):695-710

A more detailed scenario of one stage (August–November 2004) of the quasibiennial MHD process “Origination ... and dissipation of the four-sector structure of the solar magnetic field” during the decline phase of cycle 23 has been constructed. It has been indicated that the following working hypothesis on the propagation of an MHD disturbance westward (in the direction of solar rotation) and eastward (toward the zone of active longitudes) with the displacement of the large-scale open solar magnetic field (LOSMF) from this zone can be constructed based on LOSMF model representations and data on sunspot formation, flares, active filaments, and coronal ejections as well as on the estimated contribution of sporadic energy release to the flare luminosity and kinetic energy of ejections: (1) The “explosion” of the LOSMF singularity and the formation in the explosion zone of an anemone active region (AR), which produced the satellite sunspot formation that continued west and east of the “anemone,” represented a powerful and energy-intensive source of MHD processes at this stage. (2) This resulted in the origination of two “governing” large-scale MHD processes, which regulated various usual manifestations of solar activity: the fast LOSMF along the neutral line in the solar atmosphere, strongly affecting the zone of active longitudes, and the slow LOSMF in the outer layers of the convection zone. The fronts of these processes were identified by powerful (about 10³¹ erg) coronal ejections. (3) The collision of a wave reflected from the zone of active longitudes with the eastern front of the hydromagnetic impulse of the convection zone resulted in an increase in LOSMF magnetic fluxes, origination of an active sector boundary in the zone of active longitudes, shear-convergent motions, and generation and destabilization of the flare-productive AR 10696 responsible for the heliospheric storm of November 3–10, 2004.  相似文献