Diagenetisch gebildeter Magnesit und Dolomit in den Grödener Schichten des Dobratsch im Gailtal,Kärnten — österreich     

Dr. G. Niedermayr  Dr. E. Scheriau-Niedermayr  Dr. A. Beran 《International Journal of Earth Sciences》1979,68(3):979-995

Dolomite, magnesite, calcite and aragonite are described from sandstones and conglomerates of the Grödener Schichten of the Dobratsch in the Gailtal Alps, Carinthia — Austria. The carbonates occur as early and late diagenetic cements, as recrystallized matrix of more or less laminated carbonate layers (up to 0.5 m thick), as concretions, as fillings of early diagenetic shrinkage cracks and late diagenetic fissures and as crystals in open cavities and clefts. The formation of dolomite and magnesite may have been caused by pore solutions highly enriched in magnesium, which are likely to have formed by evaporation in a hypersaline environment. Magnesite and dolomite most probably have been formed diagenetically from aragonite and/or calcite during progressive evaporation cycles. Because of magnesite is a common constituent in Permo-Scythian sediments of the Eastern Alps, its presence is of importance for the evaluation of the environment. Additionally the wide-spread occurrence of magnesite within these post variscian sediments has important implications regarding the paleogeographical reconstruction and the evaluation of diagenetic processes.  相似文献   

A reflected light investigation of ilvaite     

Doz. Dr. A. A. Beran 《Mineralogy and Petrology》1980,27(3):225-230

Summary The reflectance of oriented crystal faces parallel (100) and (001) of ilvaite was measured in air and in oil at different wavelengths with linearly polarized light. Refractive indices and absorption constants were calculated from the reflectance values. In contrast ton andn ,n has a strong dispersion. For the calculation ofn the absorption constant can be neglected. According to the unit cell ofBelov andMokeeva (1954) with the lattice constantsa ₀=8.82,b ₀=13.07,c ₀=5.86 Å,n vibrates parallel to [001]n parallel to [100] andn parallel to [010]. Ilvaite is optically negative.

---

Auflichtuntersuchungen zur Optik des Ilvaits

Zusammenfassung Auf orientiert geschliffenen (100) und (001) Kristallplatten von Ilvait wurde das Reflexionsvermögen in Luft und in Öl mit linear polarisiertem Licht bei verschiedenen Wellenlängen gemessen. Aus den Reflexionswerten wurden die Brechungsindices und Absorptionskonstanten berechnet.n zeigt im Gegensatz zun undn eine auffallend starke Dispersion. Für die Berechnung vonn kann die Absorptionskonstante vernachlässigt werden. Nach der Aufstellung der Elementarzelle vonBelov undMokeeva (1954) mit den Gitterkonstantena ₀=8,82,b ₀=13,07,c ₀=5,86 Å schwingtn parallel [001],n parallel [100] undn parallel [010]. Der Ilvait ist optisch negativ.

---

---

With 2 Figures  相似文献   

UR-spektroskopischer Nachweis von H2O in Nephelin     

Dr. A. Beran 《Mineralogy and Petrology》1974,21(3-4):299-304

  相似文献   

Das Absorptionsspektrum des Benitoits im nahen Ultrarot     

Dr. A. Beran 《Mineralogy and Petrology》1974,21(1):47-51

  相似文献   

Book reviews     

Tlamicha  Antonín  Podolský  Jiří 《Astrophysics and Space Science》1986,120(2):307-308

Astrophysics and Space Science -  相似文献   

A petrological,mineralogical, and chemical analysis of the lunar mare basalt meteorite LaPaz Icefield 02205, 02224, and 02226     

Katherine H. Joy  Ian A. Crawford  Hilary Downes  Sara S. Russell  Anton T. Kearsley 《Meteoritics & planetary science》2006,41(7):1003-1025

Abstract— LaPaz Icefield (LAP) 02205, 02226, and 02224 are paired stones of a crystalline basaltic lunar meteorite with a low‐Ti (3.21–3.43% TiO₂) low‐Al (9.93–10.45% Al₂O₃), and low‐K (0.11–0.12% K₂O) composition. They consist mainly of zoned pyroxene and plagioclase grains, with minor ilmenite, spinel, and mesostasis regions. Large, possibly xenocrystic, forsteritic olivine grains (<3% by mode) contain small trapped multiphase melt inclusions. Accessory mineral and mesostasis composition shows that the samples have experienced residual melt crystallization with silica oversaturation and late‐stage liquid immiscibility. Our section of LAP 02224 has a vesicular fusion crust, implying that it was at one time located sufficiently close to the lunar surface environment to have accumulated solar‐wind‐implanted gases. The stones have a comparable major element composition and petrography to low‐Ti, low‐Al basalts collected at the Apollos 12 and 15 landing sites. However, the LAP stones also have an enriched REE bulk composition and are more ferroan (Mg numbers in the range of 31 to 35) than similar Apollo samples, suggesting that they represent members of a previously unsampled fractionated mare basalt suite that crystallized from a relatively evolved lunar melt.  相似文献   

Pixel-based correction for Charge Transfer Inefficiency in the Hubble Space Telescope Advanced Camera for Surveys     

Richard Massey  Chris Stoughton  Alexie Leauthaud  Jason Rhodes  Anton Koekemoer  Richard Ellis  Edgar Shaghoulian 《Monthly notices of the Royal Astronomical Society》2010,401(1):371-384

Charge Transfer Inefficiency (CTI) due to radiation damage above the Earth's atmosphere creates spurious trailing in Hubble Space Telescope ( HST ) images. Radiation damage also creates unrelated warm pixels – but these happen to be perfect for measuring CTI. We model CTI in the Advanced Camera for Surveys (ACS)/Wide Field Channel and construct a physically motivated correction scheme. This operates on raw data, rather than secondary science products, by returning individual electrons to pixels from which they were unintentionally dragged during readout. We apply our correction to images from the HST Cosmic Evolution Survey (COSMOS), successfully reducing the CTI trails by a factor of ∼30 everywhere in the CCD and at all flux levels. We quantify changes in galaxy photometry, astrometry and shape. The remarkable 97 per cent level of correction is more than sufficient to enable a (forthcoming) reanalysis of downstream science products and the collection of larger surveys.  相似文献   

On the peculiarities in the rotational frequency evolution of isolated neutron stars     

Anton Biryukov  Gregory Beskin  Sergey Karpov 《Astrophysics and Space Science》2007,308(1-4):551-555

The measurements of pulsar frequency second derivatives have shown that they are 10²−10⁶ times larger than expected for standard pulsar spin-down law, and are even negative for about half of pulsars. We explain these paradoxical results on the basis of the statistical analysis of the rotational parameters ν, and of the subset of 295 pulsars taken mostly from the ATNF database. We have found a strong correlation between and for both and , as well as between ν and . We interpret these dependencies as evolutionary ones due to being nearly proportional to the pulsars’ age. The derived statistical relations as well as “anomalous” values of are well described by assuming the long-time variations of the spin-down rate. The pulsar frequency evolution, therefore, consists of secular change of ν _ev(t), and according to the power law with n≈5, the irregularities, observed within a timespan as a timing noise, and the variations on the timescale larger than that—several decades. This work has been supported by the Russian Foundation for Basic Research (grant No 04-02-17555), Russian Academy of Sciences (program “Evolution of Stars and Galaxies”), and by the Russian Science Support Foundation. The authors would also like to thank the anonymous referee for valuable comments.  相似文献   

Traces of structural H2O molecules in baryte     

Anton Beran  Dominik Talla  Zdenek Losos  Jiri Pinkas 《Physics and Chemistry of Minerals》2010,37(3):159-166

The infrared (IR) spectra of gem-quality baryte crystals from different occurrences are characterized by relatively weak but strongly pleochroic absorption bands at 3,280, 3,220, 3,155, and 3,115 cm⁻¹. These bands are assigned to anti-symmetric and symmetric OH stretching vibrations of two types of H₂O molecules localized on vacant Ba sites. The H–H axis of the H₂O I molecule is slightly tilted from the a-axis direction, its twofold axis being nearly parallel to the b-axis, thus defining the plane of the H₂O molecule practically parallel to (001). The H₂O II molecule has its H–H axis parallel to the b-axis direction, with its plane lying approximately parallel to (101). The values of the total water contents of the baryte crystals, calculated on the basis of IR spectroscopic data, are ranging from about 1.7–3.8 wt.ppm. The possible presence of H₃O⁺ ions is also discussed.  相似文献   

Trace-element study and uranium-lead dating of perovskite from the Afrikanda plutonic complex, Kola Peninsula (Russia) using LA-ICP-MS     

Ekaterina P. Reguir  Alfredo Camacho  Panseok Yang  Anton R. Chakhmouradian  Vadim S. Kamenetsky  Norman M. Halden 《Mineralogy and Petrology》2010,100(3-4):95-103

The U-Pb geochronology of perovskite is a powerful tool in constraining the emplacement age of silica-undersaturated rocks. The trace-element and U-Pb isotopic compositions of perovskite from clinopyroxenite and silicocarbonatite from the Afrikanda plutonic complex (Kola, Russia) were determined by laser-ablation inductively-coupled mass-spectrometry (LA-ICP-MS). In addition, the Sr isotopic composition of perovskite was measured by isotope-dilution mass-spectrometry to better constrain the relations between its host rocks. Perovskite from the two rock types shows a different degree of enrichment in Na, Mg, Mn, Pb, Fe, Al, V, rare-earth elements, Zr, Hf, Th, U and Ta. The perovskite ⁸⁷Sr/⁸⁶Sr values are within analytical uncertainty of one another and fall within the range of mantle values. The ²⁰⁶Pb/²³⁸U ages (corrected for common lead using ²⁰⁷Pb-method) of perovskite from silicocarbonatite statistically yield a single population with a weighted mean of 371?±?8 Ma (2σ; MSWD?=?0.071). This age is indistinguishable, within uncertainty, to the clinopyroxenite weighted mean ²⁰⁶Pb/²³⁸U age of 374?±?10 Ma (2σ; MSWD?=?0.18). Our data are in good agreement with the previous geochronological study of the Afrikanda complex. The observed variations in trace-element composition of perovskite from silicocarbonatite and clinopyroxenite indicate that these rocks are not related by crystal fractionation. The Sr isotopic ratios and the fact that the two rocks are coeval suggest that they were either produced from a single parental melt by liquid immiscibility, or from two separate magmas derived at different degrees of partial melting from an isotopically equilibrated, but modally complex mantle source.  相似文献