Solubility of tin,tungsten and molybdenum oxides in felsic magmas

Saturation versus undersaturation of granitic melts in tin, tungsten and molybdenum oxides is discussed on the basis of experimental data. Results of dry and hydrothermal experiments are evaluated under the assumption of ideal solubility of Sn, W and Mo oxides in granitic melts. A conservative interpretation arrives at concentration levels of 1000 ppm SnO₂, WO₃ and MoO₃ respectively, considered as the maximum solubility of these components in granitic melts at 750°C-800 °C. Such values are never reached in natural granites unaffected by hydrothermal alteration and therefore even highly evolved granites are expected to be undersaturated in these metals. Consequently cassiterite and scheelite are neither common liquidus minerals of ore-bearing granites nor restite minerals from partial melting events.     

Textural evidence of magma decompression, devolatilization and disequilibrium quenching: an example from the Western Krušné hory/Erzgebirge granite pluton

We report new occurrences of “two-phase” granitic textures from the Western Krušné hory/Erzgebirge pluton (central Europe) and use crystal-size distribution data and thermodynamic modeling to interpret their crystallization conditions. The two-phase texture consists of (1) early phenocrysts of quartz, plagioclase, K-feldspar and biotite, (2) medium-grained matrix of the same phases and (3) interstitial channels and patches of a late-stage, very fine-grained matrix. The porphyritic two-mica microgranites, which host two-phase textures, occur as minor intrusions in early low-F biotite granites or as marginal parts of evolved high-F Li-mica granites. Measurements of the crystal-size distribution of quartz revealed three grain populations: (1) early phenocrysts (0.5–3.0 mm) showing partial resorption by residual melt, (2) a medium-grained population of the equigranular rock matrix (0.05–0.50 mm) that experienced minor coarsening by subsolidus annealing and (3) a fine-grained population (<0.03 mm) in the interstitial channels and patches formed during rapid devolatilization; this quartz group shows no or poor grain coarsening. All samples exhibit similar fraction of the fine-grained population (44–52%) but proportions of phenocrysts to medium-grained matrix vary significantly. Thermodynamic modeling of liquidus equilibria and experimental data in the hydrous haplogranite system require: (1) ascent of a granitic suspension (15–25% phenocrysts) under H₂O-undersaturated conditions at 25–45 bar/°C and a cooling rate of 40 J/(g kbar) in order to produce partial resorption of quartz phenocrysts and continued growth of feldspar phenocrysts, followed by (2) emplacement as discrete intrusions or bodies along pluton roof accompanied by sudden devolatilization. At the onset of matrix nucleation, disequilibrium undercooling of 70–85°C was inferred from the presence of micrographic intergrowths of quartz and K-feldspar. The two-phase granites in the Western Krušné hory/Erzgebirge pluton and in the Southeast Asian batholith form compositionally narrow groups with high-silica and moderate volatile enrichments but they differ in peraluminosity and phosphorus concentrations. Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

Study of the post-flare loops on 29 July 1973

We present revised values of temperature and density for the flare loops of 29 July 1973 and compare the revised parameters with those obtained aboard the SMM for the two-ribbon flare of 21 May 1980. The 21 May flare occurred in a developed sunspot group; the 29 July event was a spotless two-ribbon flare. We find that the loops in the spotless flare extended higher (by a factor of 1.4–2.2), were less dense (by a factor of 5 or more in the first hour of development), were generally hotter, and the whole loop system decayed much slower than in the spotted flare (i.e. staying at higher temperature for a longer time). We also align the hot X-ray loops of the 29 July flare with the bright H ribbons and show that the H emission is brightest at the places where the spatial density of the hot elementary loops is enhanced.presently at Big Bear Solar Observatory, Caltech, California, U.S.A.presently at The Marshall Space Flight Center, Huntsville, Alabama, U.S.A.     

Seismic events with non-shear component: II. Rock bursts with implosive source component

The rock burst mechanism of an implosive character is introduced and discussed; it is based on the idea that the compressional component of the stress field around the loaded stress concentrator can participate in the rock burst event. For easier classification of the rock burst from this viewpoint, a set of P-wave radiation patterns of the rock burst with a varying portion of the implosive component and varying propagation velocity of the displacements is presented and discussed. To support the credibility of the rock burst mechanism of an implosive character the seismic signals of the rock bursts from the mid-Bohemian coal district with negative signs of the P-wave first onsets are presented.     

Closed formulae for transformation of the cartesian coordinate system into a system of geodetic coordinates

Summary Relations for the direct transformation of the Cartesian coordinate system into a system of geodetic coordinates.

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u ¶rt;u , , z ¶rt;uu , , h.

     

Resonance frequencies in the sun's motion

Summary The position of the Sun with respect to the gravity centre of the Solar System for the beginning of every year of a 3100 — year time series was determined and the harmonic analysis of the parameters of the Sun's motion about the gravity centre was carried out.

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unu u u ¶rt; ¶rt;¶rt; u ¶rt; ¶rt;u 3100 u c¶rt;uu u n ¶rt;uu u.

     

Calculation of temperature distribution in two-dimensional geothermal profile

Summary The temperature-depth distribution along the 250 km long Czechoslovak part of DSS profile VII was calculated to a depth of 40 km. The two-dimensional solution of the steadystate equation of heat conduction in an inhomogeneous medium, obtained by means of the finite difference method, was used. By resolving the observed surface heat flow into two components, one of which is generated by heat sources inside the model and the other is connected with the heat flow from deeper parts of the Earth, the heat flow at the lower boundary of the model was estimated and used here as a boundary condition in the numerical solution. To reduce the differences between the calculated and observed surface heat flow, the heat sources in the upper 10 km of model were optimized. A regularization process, in which the variation of the sought function was limited, was used both to estimate the heat flow and to optimize the sources.

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u n¶rt;u n ¶rt; (¶rt;u 250 ) nu . . VII ¶rt;u 40 . un ¶rt; u u nn¶rt;u ¶rt; u ¶rt;¶rt; ¶rt; ¶rt; . n u u n n n ¶rt; u, ¶rt; u u uuu n u ¶rt;u, a u n, n uu ¶rt;u u un ¶rt; u u nu u uu u. u na¶rt;u ¶rt; u u u nu nu ¶rt; nuuu uu n u 10 ¶rt;u. nu , u nu nuuuu uu n un n uuu, uuu uau u uu .

     

Precession-nutation torque from the tidal potential

aam, m nu-mau m nuuau u m n¶rt;u ¶rt;a an¶rt;uu nmm . ¶rt; a u m nm u u nuua ma (, a) u naam, n¶rt;u au nu m u unu¶rt; uuu u u nuua ma.     

On the determination of the non-linearity of the gravimeter scale

Summary The results of two different methods of the determination of the non-linearity of the gravimeter scale are compared; the economy is discussed as well.