Raman spectroscopy of nanocrystals in rock     

G. A. Sobolev  V. I. Vettegren  S. M. Kireenkova  V. B. Kulik  Yu. A. Morozov  A. I. Smul’skaya 《Izvestiya Physics of the Solid Earth》2007,43(6):447-454

Nanocrystals were detected and identified in rocks by the method of Raman spectroscopy. The experiments showed that the Raman scattering spectra of fine-lamellar arkosic sandstone exhibit bands corresponding to lattice vibrations of anatase, α-quartz, and plagioclase. In all spectra of the rock, the bands are displaced towards high frequencies as compared with their position in spectra of single crystals and widen on the same side. These results show that, in all of the studied places of the sample, the particles of anatase, quartz, and plagioclase have nanometer sizes, namely, of the order of 10 nm in anatase and quartz and about 20 nm in plagioclase. Moreover, in different places of the sample, not only the shape and position of the bands under study but also their intensity vary, the latter being directly proportional to the concentration of nanocrystals.  相似文献   

The main structure and tectonic features of the Chernorud-Mukhor site on the western shore of Lake Baikal from TEM and SP measurements     

Nikolai Kozhevnikov  Bülent Tezkan   《Journal of Applied Geophysics》1998,39(4):237-250

Transient electromagnetic (TEM), self-potential (SP) and geoelectrical mapping measurements were carried out at the Chernorud-Mukhor site in the Priolkhonje area on the western shore of the Lake Baikal. All measurements were made along several profiles across the main strike of the regional Primorsky fault. TEM measurements were carried out in a time range from a few tens of microseconds to several tens of milliseconds. The most important result of the 1D modelling of TEM soundings is the discovery of nearly horizontal boundaries that divide high resistive overlying and well conducting underlying rocks. The resistivity of the former is in the range from 100 Ωm to 1000 Ωm, while the resistivity of the latter varies from less than 1 Ωm to several tens of Ωm. This good conductive zone could also be verified by geoelectrical mapping using Schlumberger array (AB/2=100 m). Due to high conductivity of the underlying rocks only the upper boundary of the conductive layer could be determined by TEM soundings. A regional SP anomaly with amplitude of about −450 mV has also been observed above the low resistivity zone indicating the electron nature of its conductance. Geologically, the conductive zone is represented by a graphite-bearing layer within the region of archean rocks. Since that layer extends over a large area, it may be used as a key in studying structures and tectonics of the Priolkhonje area. A 1D TEM geoelectric section shows a wide, gently sloping syncline as a probable base structure of the Chernorud-Mukhor site. Neotectonic faults divide the syncline into vertically displaced blocks that form a wide complicated graben with a total amplitude of about 250 m.  相似文献   

Notes on the variation of magnetization within basalt lava flows and dikes   总被引：2，自引：0，他引：2  

Nikolai Petersen 《Pure and Applied Geophysics》1976,114(2):177-193

Summary The magnetic properties of basaltic rocks are dominated by the contained primary Fe–Ti oxides. At solidus temperature (1000°C) the composition of these primary oxides is restricted to titanomagnetite (Fe_3-xTi_xO₄) and hemoilmenites (Fe_2-yTi_yO₃). The examination of 269 chemical analyses of the primary Fe–Ti oxides in basalts (in sensu lato) gives an average ofx=0.61 (T _c=168°C) for the titanomagnetites andy=0.89 (T _c=–121°C) for the hemoilmenites. If distinction is made between tholeiites, alkali basalts and andesites, a clear difference for thex-values is observed: the average for tholeiitesx=0.64 (T _c=144°C), for alkali basaltsx=0.52 (T _c=253°C), for andesitesx=0.38 (T _c=341°C).Environment of crystallization and cooling rate are major interrelated factors influencing subsequent changes in the mineralogy of the primary Fe–Ti oxides and resulting magnetic properties. This has been tested by studying the variation of magnetization and some of its parameters in three different basalt rock units: a dike, 180 cm, and two lava flows, 3 m and 33 m thick, respectively. Grain size and oxidation state of the titanomagnetites control the variation of magnetization in these basalt units.  相似文献   

The spatial and temporal changes inV p /V s before strong earthquakes in Kamchatka     

G. A. Sobolev  L. B. Slavina 《Pure and Applied Geophysics》1977,115(4):1047-1060

A method was developed to obtain from a signal station the spatial and temporal distribution ofV _p /V _s ratios before earthquakes of magnitude>6. It was shown thatV _p /V _s values strongly depend upon the relative positions of the stations, the future large earthquake and the foci of the smaller earthquakes used forV _p /V _s determination. The appearance of a zone of anomalousV _p /V _s values with linear dimensions of the order of 100 km was noted at least 4 years before a deep earthquake of magnitude 7. Similar size anomalous zones were detected one year before some magnitude 6 earthquakes. V _p /V _s values decreased by a small but distinct amount during this time. Additionally, local short term minima inV _p /V _s ratios were observed some months before the major event. The epicenters of the large earthquakes were located within the 100 km size zone where the gradients of theV _p /V _s field were largest.  相似文献   

Diffuse reflection of light from a spherical nebula     

A. K. Kolesov  V. V. Sobolev 《Astrophysics》1990,32(2):154-162

Leningrad State University. Translated from Astrofizika, Vol. 32, No. 2, pp. 277–289, March–April, 1990.  相似文献   

Continuum in night airglow between 8000 and 11, 000 Å     

V.G. Sobolev 《Planetary and Space Science》1978,26(7):703-704

According to observations in the Crimea and in Zvenigorod the continuum in the night airglow from 8000 to 11,000 Å has values of about $\text{1–2 R}\text{A}\text{?}$ and does not rise markedly with the increase in the wavelength.  相似文献   

Measurement and implication of "effective" viscosity for rhyolite flow emplacement   总被引：1，自引：0，他引：1  

Richard J. Stevenson †  Donald B. Dingwell  Nikolai S. Bagdassarov  Curtis R. Manley 《Bulletin of Volcanology》2001,63(4):227-237

Hazardous explosive activity may sporadically accompany the extrusion of silicic lava domes. Modelling of the emplacement of silicic domes is therefore an important task for volcanic hazard assessment. Such modelling has been hampered by a lack of a sufficiently accurate rheological database for silicic lavas with crystals and vesicles. In the present study, the parallel-plate viscometry method was applied to determine the shear viscosity of five natural rhyolitic samples from a vertical section through the Ben Lomond lava dome, Taupo Volcanic Centre, New Zealand. Rheological measurements were performed at volcanologically relevant temperatures (780-950°C) and strain rates (10^-5-10^-7 s^-1). Although these samples are in the metastable state, viscosity determinations, melt composition, as well as water and crystal contents of samples were demonstrably stable during experiments. For samples containing up to 5 vol.% microlites, the composition of the melt, rather than the physical effect of suspended crystals, had greater influence on the effective viscosity of the silicic magma. Samples with 10 vol.% microlites and containing a flow banding defined by microlites show no significant orientational effects on apparent viscosity. The rheological measurements were used together with a simple cooling model to construct thermal and viscosity profiles revealing conditions during the emplacement of the Ben Lomond lava dome.  相似文献   

Polarization and brightness opposition effects for the E-type Asteroid 64 Angelina     

Vera K. Rosenbush  Nikolai N. Kiselev  Klaus Jockers  Yuriy S. Efimov 《Icarus》2005,178(1):222-234

We present new polarimetric and photometric observations of the high-albedo Asteroid 64 Angelina in the UBVRI wavebands at phase angles ranging from 0.43° to 13.02° during oppositions in 1995, 1999, and 2000/2001. The polarization opposition effect has been observed in the form of a sharp peak of negative polarization with amplitude of about −0.4% centered at αmin≈1.8°, which is superimposed on the regular negative polarization branch. The amplitude of the polarization opposition effect appears to be apparition-dependent. Our photometric data confirm the early detected by Harris et al. [1989. Phase relations of high-albedo asteroids: The unusual opposition brightening of 44 Nysa and 64 Angelina. Icarus 81, 365-374] of a very strong and unusually narrow opposition spike, i.e., brightness opposition effect, for Angelina. Thus, 64 Angelina is the first asteroid for which both the polarization opposition effect and the brightness opposition effect have been detected. We observed that the polarization opposition effect as well as the regular negative polarization branch depends on the wavelength of scattered light, but in different manners. In addition, the colors B-V and V-R show little phase-angle dependence, while the color U-B increases with increasing phase angle, thus indicating that the amplitude of the brightness opposition effect is larger in the U band and almost the same in the B, V, and R bands. It appears that all colors indices begin to increase with decreasing phase angle to zero. The composite lightcurve computed with a period of 8.752 h has amplitude of 0.13 magnitude.  相似文献   

On Some Issues of Cross-Identification of Astronomical Catalogs     

Ladeyschikov  D. A.  Sobolev  A. M. 《Astronomy Reports》2022,66(11):1082-1097

Astronomy Reports - The paper deals with the issues of cross-identification of sources from various astronomical catalogs. One of the main problems under consideration is how to cross-identify a...  相似文献   

Application of Synthetic Doppler Tomography to Investigation of Eclipsing Polar V808 Aur     

Sytov  A. Yu.  Sobolev  A. V. 《Astronomy Reports》2022,66(11):936-952

Astronomy Reports - The paper describes three methods for constructing synthetic Doppler tomograms. These methods are applied to the results of MHD simulation of the V808 Aur polar, and the...  相似文献