Rare earth elements in the clay fraction of coaliferous sediments of the Arkagalinskoe (Magadan district) and Dolinskoe (Sakhalin Island) coalfields

The study of REE distribution in the clay fraction of sedimentary rocks from two coalfields made it possible to distinguish several types of REE distribution, which correlate with their mineral composition. It is shown that the REE fractionation was related to the mineral reconstruction of the primary clay fraction and some detrital minerals in the course of postsedimentary transformations of rocks during diagenesis, early catagenesis, and beginning of late catagenesis. These transformations were governed by several factors, such as the composition of sediments; hydrochemical features of accumulation environment; the chemical composition, dynamics, and feeding sources of pore solutions; the porosity and permeability of sediments and rocks; and the content of organic matter and its reaction ability.     

Copper(II) humate mobility in kaolinite soil

An investigation of the influence of humate on the mobility of copper(II) ions in a kaolinite soil using leaching tests and electrokinetic experiments is reported. The data are interpreted in terms of humate–copper–clay interactions and humate electrical charge. Humate is mostly immobile below pH8 but is more mobile in alkaline conditions (sorption to kaolinite reduces its mobility in neutral conditions). Copper humate complexes are mobile in both acidic and alkaline conditions, but not in neutral conditions where they are sorbed. The dissolved copper humate complexes that form in acidic conditions are positively charged. The net effect of humate is to increase cupric ion mobility in kaolinite soil, especially in alkaline conditions.     

Improved Petrological Modal Analyses from X-ray Powder Diffraction Data by use of the Rietveld Method I. Selected Igneous, Volcanic, and Metamorphic Rocks

Mineral modes have been determined for specimens of eight rocktypes from CuK X-ray powder diffraction data using the Rietveldmethod. The samples include two granites, a granodiorite, adamellite,gabbro, basalt, trachyte, and two granulite-facies metamorphicrocks. Up to eight individual mineral components have been measuredin each sample (no glassy phases were observed), with a detectionlimit of {small tilde}1 wt.%, depending on the mineral assemblage.Marked variations in grain size (i.e., granite vs. trachyte)provide no difficulties for the X-ray method. The X-ray resultscompare very favourably with (1) optical modes determined forthe medium–coarse-grained samples by point counting, (2)normative calculations obtained using locally enhanced catanormand mesonorm software, and (3) corresponding Rietveld modesdetermined, for two samples, from neutron powder data. Wheredifferences occur, these are discussed in relation to the limitationsof each of the methods. The improved accuracy of the X-ray method is due primarily tothe incorporation of the full diffraction profile in the Rietveldanalysis calculations, and the elimination of preferred orientationby collecting the data from samples packed in glass capillaries(i.e., Debye–Scherrer mode). The good agreement of theX-ray and neutron modes shows that the usual problems encounteredwith microabsorption, extinction, and sampling are of littleconcern in these rocks. The results highlight one of the majoradvantages provided by Rietveld modal analysis over the moretraditional ‘reference intensity’ X-ray methods,namely, that the crystal chemistry (and thus the calibrationconstants) of the individual phases can be adjusted dynamicallyduring each individual analysis. This not only provides moreaccurate phase abundances, but also gives important supplementaryinformation about the mineralogy of the major components.     

Discrepancy of masses in double galaxies

The estimations of integral masses of double galaxies are obtained taking as a basis recent observational data on 150 pairs of galaxies with measured radial velocities for both components. It is shown that the mean orbital mass-to-luminosity ratio essentially depends on a morphological type of double galaxies and on a kind of interaction between pair components. Minimal values of mass-to-luminosity ratio take place for double galaxies having linear features of interaction, namely: bridges, tails; as well for pairs with compact and Markarian components, too. The empirical relation between mass-to-luminosity ratio and linear separation of pair components do not indicate on an existence of a hidden stellar coronae around double galaxies.     

Directional dependence of P- and S-wave propagation and polarization in foliated rocks from the Kola superdeep well: Evidence from laboratory measurements and calculations based on TOF neutron diffraction

We have measured P- and S-wave velocities on two amphibolite and two gneiss samples from the Kola superdeep borehole as a function of pressure (up to 600 MPa) and temperature (up to 600 °C). The velocity measurements include compressional (Vp) and shear wave velocities (Vs1, Vs2) propagating in three orthogonal directions which were in general not parallel to inherent rock symmetry axes or planes. The measurements are accompanied by 3D-velocities calculations based on lattice preferred orientation (LPO) obtained by TOF (Time Of Flight) neutron diffraction analysis which allows the investigation of bulk volumes up to several cubic centimetres due to the high penetration depth of neutrons. The LPO-based numerical velocity calculations give important information on the different contribution of the various rock-forming minerals to bulk elastic anisotropy and on the relations of seismic anisotropy, shear wave splitting, and shear wave polarization to the structural reference frame (foliation and lineation). Comparison with measured velocities obtained for the three propagation directions that were not in accordance with the structural frame of the rocks (foliation and lineation) demonstrate that for shear waves propagating through anisotropic rocks the vibration directions are as important as the propagation directions. The study demonstrates that proper measurement of shear wave splitting by means of two orthogonal polarized sending and receiving shear wave transducers is only possible when their propagation and polarization directions are parallel and normal to foliation and lineation, respectively.     

Geology and activity around volcanoes on Io from the analysis of NIMS spectral images

The last two successful flybys of Io by Galileo in 2001 (orbits I31, I32) allowed the Near Infrared Mapping Spectrometer to enrich its collection of IR spectral image cubes of the satellite. These data cover hemispheric portions of Io, several volcanic centers as well as their surroundings with a spatial resolution ranging from 2 to 93 km pixel⁻¹. They map thermal emission from the hot-spots and the distribution of solid SO₂ in the 1.0-4.7 μm spectral range. We obtain maps of SO₂ abundance and granularity from the NIMS data using the method of Douté et al. (2002, Icarus 158, 460-482). The maps are correlated to distinguish four different physical units that indicate zones of SO₂ condensation, metamorphism and sublimation. We relate these information with visible images from Galileo's Solid State Imaging System and with detailed mapping of the thermal emission produced by Io's surface. Our principal goal is to understand the mechanisms controlling how lava, pyroclastics and gas are emitted by different types of volcanoes and how these products evolve. The 800 km diameter white ring of fallout created by a violent “Pillanian” eruption during summer of 2001 is at least partly composed of solid SO₂ and has enriched preexisting regional deposits. Orange materials have been recently or are currently emplaced 240 km south from the main eruption site, possibly as sulfur flows. A similar event may have taken place in the past at Ababinili Patera (12.5° N, 142° W). Carefull study of SO₂ maps covering the Emakong region also suggests that sulfur forms the bright channel-fed flow emerging from the south eastern side of the caldera. Within the main caldera of Tvashtar Catena completely cooled patches of crust exist. Elsewhere, the caldera is still cooling from previous episodes of flooding. We confirm that Amirani emits constantly large amount of SO₂ gas by interaction of fresh lava with the volatiles of the underlying plains. Nevertheless SO₂ frost is not the major component of the bright white ring seen in the SSI images. Over the whole Gish Bar region, SO₂ frost seems barely stable and is constantly regenerated. The stability increases along gray filamentary structures which could be faults filled with materials having peculiar thermal properties. Northwest of Gish Bar Patera, a localized bright deposit shows an unusual spectral signature potentially indicative of H₂O molecules forming ice crystals or being trapped in a nonidentified matrix. The Chaac region may present a thickened old crust reducing the geothermal flux to levels lower than 0.5 W m⁻² and thus creating a cold trap for SO₂. Looking at the abundance and degree of metamorphose of SO₂, we establish the relative age of different flows and ejecta for the Sobo Fluctus. Finally the assumption that the white patches in visible images indicate SO₂ rich deposits is once again challenged. In the Camaxtli region we identify a topographically controlled compact white deposit showing only moderate SO₂ abundance. In contrast, we detect two spots of quite pure SO₂ ice on the gray flanks of Emakong. Furthermore, the close association of fumarolic SO₂ and red S₂ already noted for several volcanic centers is observed at Tupan.     

Study of the Galactic Rotation Based on Masers and Radio Stars with VLBI Measurements of Their Parallaxes

Astronomy Letters - Based on published data, we have produced a sample of 256 radio sources whose trigonometric parallaxes and proper motions were measured by VLBI. This sample contains Galactic...     

Numerical Modeling of the Observed Wiechert Seismograph Magnification

—The paper presents results of experiments designed to measure the actual dynamic magnification of the Wiechert 1000 kg horizontal seismometer when excited by seismic waves. This is accomplished by comparing 51 digital records of seismic events recorded by the Wiechert and a well calibrated reference seismometer. The results obtained indicate that the magnification of the Wiechert seismometer is influenced by the interaction of its mass and frame, especially for high frequencies. This interaction has been modeled by considering a system of two coupled pendulums, yielding a theoretical dynamic magnification curve which exhibits main features of the observed magnification. The dis crepancy between the nominal and the actual response of the Wiechert seismograph may lead to errors in studies involving spectral analyses of recorded seismograms, and to overestimation of local earth quake magnitudes.     

Spectrophotometric Variability of Mira

Data from the Pulkovo spectrophotometric data base on the absolute quasimonochromatic fluxes from oCet in the 320–1080 nm range are used to determine the physical parameters of this star in different phases of its light curve. The continuum emission layer is found to expand between the phases of the cycle corresponding to the rising and falling branches of the light curve. The average expansion velocity is 32 km/s. By the time the star’s brightness has fallen by roughly three magnitudes, its radius has increased by almost a factor of three. Over this same time the temperature of the layer has fallen from 3000 K to 2200 K. For this expansion velocity, the calculated mass rate loss is ⊙ M /year.__________Translated from Astrofizika, Vol. 48, No. 2, pp. 175–189 (May 2005).     

Platinum-group elements in alpine-type ultramafic rocks and related chromite ores of the main ophiolite belt of the Urals

On the basis of a representative collection of ultramafic rocks and chromite ores and a series of technological samples from the largest (Central and Western) deposits in the Rai-Iz massif of the Polar Urals and the Almaz-Zhemchuzhina and Poiskovy deposits in the Kempirsai massif of the southern Urals, the distribution and speciation of platinum-group elements (PGE) in various type sections of mafic-ultramafic massifs of the Main ophiolite belt of the Urals have been studied. Spectral-chemical and spectrophotometric analyses were carried out to estimate PGE in 700 samples of ultramafic rocks and chromite ores; 400 analyses of minerals from rocks, ores, and concentrates and 100 analyses of PGE minerals (PGM) in chromite ores and concentrates were performed using an electron microprobe. Near-chondritic and nonchondritic PGE patterns in chromitebearing sections have been identified. PGE mineralization has been established to occur in chromite ore from all parts of the mafic-ultramafic massifs in the Main ophiolite belt of the Urals. The PGE deposits and occurrences discovered therein are attributed to four types (Kraka, Kempirsai, Nurali-Upper Neiva, and Shandasha), which are different in mode of geological occurrence, geochemical specialization, and placer-forming capability. Fluid-bearing minerals of the pargasite-edenite series have been identified for the first time in the matrix of chromite ore of the Kempirsai massif (the Almaz-Zhemchuzhina deposit) and Voikar-Syn’ya massif (the Kershor deposit). The PGE grade in various types of chromite ore ranges from 0.1–0.2 to 1–2 g/t or higher. According to technological sampling, the average PGE grade in the largest deposits of the southeastern ore field of the Kempirsai massif is 0.5–0.7 g/t. Due to the occurrence of most PGE as PGM 10–100 mm in size and the proved feasibility of their recovery into nickel alloys, chromites of the Kempirsai massif can be considered a complex ore with elevated and locally high Os, Ir, and Ru contents. The Nurali-Upper Neiva type of ore is characterized by small-sized primary deposits, which nevertheless are the main source of large Os-Ir placers in the Miass and Nev’yansk districts of the southern and central Urals, respectively.