Multidisciplinary investigations of the white sea during the period of the summer low water in 2009 onboard the R/V Ekolog     

Shevchenko  V. P.  Zdorovennov  R. E.  Kravchishina  M. D.  Kutcheva  I. P.  Novigatskii  A. N.  Politova  N. V.  Potapova  I. Yu.  Prikhod’ko  D. I.  Slastina  Yu. L.  Tekanova  E. V.  Tolstikov  A. V.  Filippov  A. S.  Chul’tsova  A. L.  Shcherbakov  K. A. 《Oceanology》2010,50(4):630-634

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On the intensity of the geomagnetic field in the geological past     

V. P. Shcherbakov  N. K. Sycheva 《Izvestiya Physics of the Solid Earth》2013,49(5):699-717

A detailed analysis of the data on the intensity of the geomagnetic dipole and frequency of its reversals presented in the world’s paleointensity databases provided the arguments in favor of the hypothesis of the negative correlation between the average virtual dipole moment (VDM) and the frequency of the reversals on the interval from 5 Ma to 100 Ma ago. However, the statistical confidence level of this hypothesis is only 60–70%, which is far below 95%, the standard required confidence level of a hypothesis to be considered statistically reliable. At a high level of confidence (above 99%), the presence of a positive correlation between the mean value and variance of VDM for a number of intervals of stable polarity in the Cenozoic and Mesozoic is confirmed. This finding means that the distribution of VDM on these time intervals is certainly non-Gaussian and is rather described by the gamma- or lognormal law. At the same time, in contrast to the earlier intervals, the histogram of VDM for the Brunhes epoch is closer to the normal distribution. Compared our conclusions with the published results on the numerical modeling of the geodynamo, we found that they are consistent in terms of a probable negative correlation between the average VDM and reversal frequency, as well as the lack of correlation between the average VDM and the length of the interval of stable polarity.  相似文献   

The Properties of Thermochemical Remanent Magnetization Acquired by Slow Laboratory Cooling of Titanomagnetite-Bearing Basalt Samples from Different Temperatures and the Results of the Thellier Method     

Gribov  S. K.  Shcherbakov  V. P.  Tsel’movich  V. A.  Aphinogenova  N. A. 《Izvestiya Physics of the Solid Earth》2021,57(6):913-926

Izvestiya, Physics of the Solid Earth - Abstract—The experiments have been carried out on the acquisition of thermochemical remanent magnetization (TCRM) in basalt samples containing...  相似文献   

Nanocracks upon Fracture of Oligoclase     

Vettegren  V. I.  Ponomarev  A. V.  Mamalimov  R. I.  Shcherbakov  I. P. 《Izvestiya Physics of the Solid Earth》2021,57(6):894-899

Izvestiya, Physics of the Solid Earth - Abstract—The spectrum of fractoluminescence (FL) upon fracture of the surface of oligoclase is obtained. The analysis of the spectrum has shown that...  相似文献   

On the theory of low-temperature oxidation of titanomagnetite grains     

V.P. Shcherbakov 《Physics of the Earth and Planetary Interiors》1982,30(4):324-329

It is shown that the space-time distribution of vacancies in the process of formation of cation-deficient spinels is determined mainly by the boundary kinetics. At low rates of vacancy appearance in the surface layer (e.g., owing to oxygen deficit), the degree of grain oxidation remains invariant over the entire volume. The rate of oxidation in this case does not depend on the diffusion coefficient, but is determined by the boundary processes. With an excess of oxygen, the process of oxidation occurs inhomogeneously over the grain volume. In this case the rate of oxidation is determined by the diffusion coefficient. Approximate estimates have been made of the physical parameters characterising the two types of oxidation.  相似文献   

Polarimetry of stellar active regions and flares     

I. Tuominen  J. Huovelin  Yu. S. Efimov  N. M. Shakhovskoy  A. G. Shcherbakov 《Solar physics》1989,121(1-2):419-429

Observations of regular and irregular polarimetric variability in late-type stars are reviewed, and the related physical and geometrical effects are discussed. There are indications that the irregular part of the variability could be caused by transient events, possibly associated with flares. Polarimetric observations during flares are reviewed, and preliminary results of new observations of a well-known flare star, YY Geminorum, are presented. The results show that the small flare in YY Gem did not cause any significant variations in linear polarization, while the binary eclipse evidently causes an enhancement in the polarization. The reasons for the difficulties in stellar flare polarimetry are discussed. Finally, future prospects for the observations of flaring stars and for the utilization of linear polarimetry as a complementary method to other techniques of surface imaging of stellar activity and flares are presented.  相似文献   

Determination of the paleointensity in the early proterozoic from granitoids of the Shumikhinskii complex of the Siberian craton     

V. V. Shcherbakova  V. P. Shcherbakov  A. N. Didenko  Yu. K. Vinogradov 《Izvestiya Physics of the Solid Earth》2006,42(6):521-529

The extreme scarcity of data on the behavior of the paleointensity H _an in the geological past from rocks older than 400 Ma significantly hinders the development of our ideas of the geomagnetic field evolution and the geological history of the Earth as a planet. This work presents H _an determinations for the Early Proterozoic using the Thellier method and meeting modern requirements for their reliability. The data are obtained from 1850-Ma rocks of granite intrusions sampled in the south of the Siberian platform. The rocks are virtually unaltered granites and granitoids. The paleointensity was determined on 15 samples; results from 11 samples were found to be suitable for the calculation of H _an, which is good for experiments of this type. The common feature in the behavior of the natural remanent magnetization (NRM) is a very narrow interval of blocking temperatures: destruction of (60–90)% NRM often took place between 500 and 550°C. Because of the large thickness of the sampled magmatic body, the paleointensity estimates were corrected for its slow cooling rate. With regard for this correction, the probable value of the virtual dipole moment (VDM) from the given collection amounts to 5 × 10²² A m². Analysis of all published data obtained by the Thellier method for the Precambrian and satisfying the well-known minimal criteria of reliability showed that the average VDM value is about 2 × 10²² A m², which is four times smaller than the VDM value of the last million years. This phenomenon can be interpreted in terms of the hypothesis that the solid inner core formed only in Proterozoic and, in its absence, the generation of the geomagnetic field was relatively weak, which yielded a small intensity value of the geomagnetic field at early stages of the Earth’s evolution.  相似文献   

On the theory of depositional remanent magnetization in sedimentary rocks     

V. P. Shcherbakov  V. V. Shcherbakova 《Surveys in Geophysics》1983,5(4):369-380

The effects of various factors such as thermal agitation, coagulation, anisotropy of susceptibility, and shape irregularity on the alignment of magnetic carrier grains during the process of acquisition of depositional remanent magnetization in sedimentary rocks is discussed.  相似文献   

A Damage Mechanics Model for Aftershocks     

Robert Shcherbakov  Donald L. Turcotte 《Pure and Applied Geophysics》2004,161(11-12):2379-2391

— All earthquakes are followed by an aftershock sequence. A universal feature of aftershock sequences is that they decay in time according to the modified Omori’s law, a power-law decay. In this paper we consider the applicability of damage mechanics to earthquake aftershocks. The damage variable introduced in damage mechanics quantifies the deviation of a brittle solid from linear elasticity. We draw an analogy between the metastable behavior of a stressed brittle solid and the metastable behavior of a superheated liquid. The nucleation of microcracks is analogous to the nucleation of bubbles in the superheated liquid. In this paper we obtain a solution for the evolution of damage after the instantaneous application of a constant strain to a rod. We show that the subsequent stress relaxation can reproduce the modified Omori’s law. It is argued that the aftershocks themselves cause random fluctuations similar to the thermal fluctuations associated with phase transitions.  相似文献   

Domain state stabilization by iterated thermal magnetization processes     

Karl Fabian  Valera P. Shcherbakov 《Geophysical Journal International》2004,159(2):486-494

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