Experimental investigation of zoisite–clinozoisite phase equilibria in the system CaO–Fe2O3–Al2O3–SiO2–H2O     

A. Brunsmann  G. Franz  W. Heinrich 《Contributions to Mineralogy and Petrology》2002,143(1):115-130

The system Ca₂Al₃Si₃O₁₁(O/OH)-Ca₂Al₂FeSi₃O₁₁(O/OH), with emphasis on the Al-rich portion, was investigated by synthesis experiments at 0.5 and 2.0 GPa, 500-800 °C, using the technique of producing overgrowths on natural seed crystals. Electron microprobe analyses of overgrowths up to >100 µm wide have located the phase transition from clinozoisite to zoisite as a function of P-T-X_ps and a miscibility gap in the clinozoisite solid solution. The experiments confirm a narrow, steep zoisite-clinozoisite two-phase loop in T-X_ps section. Maximum and minimum iron contents in coexisting zoisite and clinozoisite are given by X_ps^zo (max) = 1.9*10 ^{- 4} T+ 3.1*10 ^{- 2} P - 5.36*10 ^{- 2}{\rm X}_{{\rm ps}}^{{\rm zo}} {\rm (max) = 1}{\rm .9*10}^{ - 4} T{\rm + 3}{\rm .1*10}^{ - 2} P - {\rm 5}{\rm .36*10}^{ - 2} and X_ps^czo (min) = (4.6 * 10 ^{- 4} - 4 * 10 ^{- 5} P)T + 3.82 * 10 ^{- 2} P - 8.76 * 10 ^{- 2}{\rm X}_{{\rm ps}}^{{\rm czo}} {\rm (min)} = {\rm (4}{\rm .6} * {\rm 10}^{ - {\rm 4}} - 4 * {\rm 10}^{ - {\rm 5}} P{\rm )}T + {\rm 3}{\rm .82} * {\rm 10}^{ - {\rm 2}} P - {\rm 8}{\rm .76} * {\rm 10}^{ - {\rm 2}} (P in GPa, T in °C). The iron-free end member reaction clinozoisite = zoisite has equilibrium temperatures of 185ᇆ °C at 0.5 GPa and 0ᇆ °C at 2.0 GPa, with (H_r⁰=2.8ǃ.3 kJ/mol and (S_r⁰=4.5ǃ.4 J/mol2K. At 0.5 GPa, two clinozoisite modifications exist, which have compositions of clinozoisite I ~0.15 to 0.25 X_ps and clinozoisite II >0.55 X_ps. The upper thermal stability of clinozoisite I at 0.5 GPa lies slightly above 600 °C, whereas Fe-rich clinozoisite II is stable at 650 °C. The schematic phase relations between epidote minerals, grossular-andradite solid solutions and other phases in the system CaO-Al₂O₃-Fe₂O₃-SiO₂-H₂O are shown.  相似文献   

Die Abhängigkeit des Großwetters von solaren Erscheinungen     

Baur  Franz 《Meteorology and Atmospheric Physics》1953,6(2):129-152

Zusammenfassung Im ersten Abschnitt werden Einwände gegen die bisherigen Untersuchungen entkräftet. Im zweiten Abschnitt werden neue Belege für die doppelte Schwankung des Großwetters in der gemäßigten Zone während des Sonnenfleckenzyklus erbracht. Es wird gezeigt, daß die Sommer in Neuengland, die 3 bis 1 1/2 Jahre vor einem Fleckenminimum liegen, fast durchweg wärmer als normal sind und alle Hochsommer, die 2,8 bis 1,9 Jahre vor einem Fleckenextrem (Minimum oder Maximum) liegen und in denen weitere solare Bedingungen erfüllt sind, in Mitteleuropa trockener und wärmer als normal sind und übernormalen Luftdruck in Mittel- und Westeuropa aufweisen. Das gleiche gilt in den meisten dieser Jahre auch für den ganzen Sommer und auch für die südlicheren Teile Nordeuropas. Die relative Häufigkeit des Zusammentreffens dieser Großwettererscheinungen mit bestimmten solaren Bedingungen wird als überzufällig erwiesen; die Zusammenhänge werden physikalisch gedeutet.Im dritten Abschnitt wird ein überzufälliger Zusammenhang des Verlaufs der Sonnenflecken vom Vorwinter bis zum Herbst mit dem Temperaturgepräge des Folgewinters in Mitteleuropa dargestellt und erklärt.Im vierten Abschnitt wird aus der zur Erklärung der Doppelschwankung des Großwetters innerhalb des Sonnenfleckenzyklus aufgestellten Hypothese eine logische Folgerung gezogen, die sich auf die Stärke der zonalen Zirkulation in den gemäßigten Breiten in der Höhe der 500 mb-Flächevor einer länger anhaltenden Vermehrung der Sonnenflecken bis zur nächsten Sonnenrotation bezieht. Es wird festgestellt, daß diese rein theoretisch gezogene Schlußfolgerung in der Wirklichkeit mindestens im Winterhalbjahr tatsächlich erfüllt ist, womit ein neues Argument für die Richtigkeit der aufgestellten Theorie des Einflusses der von der Sonne ausgehenden Strahlungsschwankungen auf das Großwetter gewonnen wird. Die Beeinflussung des Großwetters geschieht nicht durch die korpuskularen Strahlungen der Sonne, die auf ionosphärische Vorgänge und dadurch auch auf den Erdmagnetismus wirken, sondern durch länger anhaltende Intensitätsänderungen der Wellenstrahlung, vor allem der ultravioletten Strahlung der Sonne.

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Summary In the first part objections against the former investigations are refuted. In the second part new arguments are given for the double variation of the large scale weather conditions (Großwetter) in the temperate zone during the sun spot cycle. It is shown that the summers in New England which lie 3 to 1 1/2 years before a sun spot minimum are almost without exception warmer than normal, and all midsummers which lie 2,8 to 1,9 years before a sun spot extremum (minimum or maximum) and in which further solar conditions are satisfied are drier and warmer than normal in Central Europe and show supernormal atmospheric pressure in Central and Western Europe. The same is true during most of the years also for the whole summer and also for the more southern parts of Northern Europe. The relative frequency of meeting of these large scale occurences with certain solar conditions are proved to be beyond chance; the relations are physically interpreted.In the third part a relation beyond chance of the course of the sun spots from the foregoing winter until autumn with the temperature-character of the following winter in Central Europe is described and explained.In the fourth part a logical conclusion is drawn from the hypothesis for explaining the double oscillation of the Großwetter within the sun spot cycle. This conclusion regards to the strength of the zonal circulation in the middle latitudes in the height of the 500 mb-area before a longer increasing of the sun spots until the next rotation of the sun. It is stated that this conclusion is fulfilled in the reality. This is a new argument for the correctness of the used theory concerning the influence of the variations of the sun's radiation upon the Großwetter. This influence is not caused by the corpuscular radiations of the sun which have an effect on the ionospheric occurences and by these also on the terrestrial magnetism, but by assiduous changes of the intensity of the undulatory radiation, especially of the ultra-violet radiation of the sun.

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Résumé La première partie de l'article réfute des objections soulevées par les études précédentes. La deuxième partie apporte de nouvelles preuves de la double variation du temps (à grande échelle) de la zone tempérée pendant le cycle des taches solaires. On montre qu'en Nouvelle-Angleterre les étés précédant de 3 à 1,5 ans un minimum de taches sont presque tous trop chauds et que tous les pleins-étés précédant de 2,8 à 1,9 ans un extremum de taches (minimum ou maximum) et pour lesquels d'autres conditions solaires sont remplies sont en Europe centrale trop secs et trop chauds avec pression supra-normale sur le centre et l'Ouest de l'Europe. La même relation existe dans la plupart de ces années également pour tout l'été et dans les régions plus méridionales de l'Europe septentrionale. La fréquence relative de ces conjonctures s'avère comme supérieure à celle du hasard pur; l'auteur en expose les bases physiques.La troisième partie traite d'une relation signifiante entre l'évolution des taches solaires du début de l'hiver à l'automne et l'allure de la température de l'hiver suivant en Europe centrale.Dans la quatrième partie, l'auteur tire de l'hypothèse expliquant la variation double du temps dans l'espace du cycle solaire une conséquence logique se rapportant à l'intensité de la circulation zonale aux latitudes moyennes, à l'altitude de la surface de 500 mb, avant l'augmentation durable des taches solaires jusqu'à la rotation suivante du soleil. Il montre que cette conséquence purement théorique se réalise en fait, au moins pendant le semestre hivernal, et qu'elle fournit ainsi un nouvel argument en faveur de la théorie qui prétend une influence des variations du rayonnement solaire sur la situation météorologique générale. Cette situation n'est pas influencée par le rayonnement corpusculaire du soleil qui intervient dans les phénomènes ionosphériques et dans le magnétisme terrestre, mais bien par les variations à longue période du rayonnement ondulatoire, et avant tout de l'ultra-violet solaire.

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Mit 3 Textabbildungen.  相似文献   

Über den „Taucheffekt” bei der Lichtmessung über und unter Wasser     

Franz Berger 《Theoretical and Applied Climatology》1961,11(2):224-240

Zusammenfassung Das Verhältnis der meßbaren Intensitäten in einem Lichtmeßgerät flacher Bauart dicht unter und über Wasser wird Taucheffekt genannt. Dieses Verhältnis weicht von der wahren Relation der Lichtintensitäten innerhalb weiter Grenzen ab. Entsprechend den verschiedenen optisch-geometrischen Bedingungen bei Opal-, Klarglas- und Mattscheiben gibt es drei verschiedenartige Taucheffekte.Opal- und Mattscheiben verhalten sich gegensätzlich, ihre Taucheffektbereiche liegen unterhalb, bzw. oberhalb des gut definierbaren Klarglaswertes. Dieser bildet für Opalglas die obere, für Mattglas die untere Grenze. Die untere Grenze für Opalglas ist annähernd bestimmt, die obere Grenze für Mattglas nicht. Kunststoffgläser mit ihren niedrigeren Brechungszahlen ergeben noch breitere Taucheffektbereiche als Silikatgläser.Das Verhältnis der tatsächlichen Intensitäten liegt im Bereich des Opalglas-Taucheffekts. Es muß daher möglich sein, ein Opalglas herzustellen, mit dem ein Lichtmeßgerät über und unter Wasser richtig zeigt.Opal- und Mattgläser weisen einen Oberflächeneffekt, d. h. einen Totalreflexionsfehler in der Nähe der Wasseroberfläche auf, dessen Zusammenhang mit dem Taucheffekt geklärt wird.Es wird eine einfache Vorrichtung angegeben, um bei Taucheffekt-Bestimmungen den Totalreflexionsfehler zu vermeiden.

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Summary The ratio of light intensities just below and above a water surface as measured by a light meter of disk-shaped design is called immersion effect. This ratio differs within a wide margin from the ratio of the true intensities. According to the different optical-geometrical conditions of light transmission through opal, clear and ground glass three different types of the immersion effect can be distinguished.The immersion effect of opal glass is lower, and that of ground glass higher than the (well defined) value for clear glass. The latter is the upper margin for opal glass, and the lower margin for ground glass. The lower margin for opal glass is approximately defined while the upper margin for ground glass is indefinite. Plastic glasses with their low index of refraction cause an even wider range of the immersion effect than silicate glasses.The true ratio of light intensities lies within the range of the immersion effect of opal glass. Therefore, it should be possible to design a light meter with an opal filter which gives correct readings above and below the water surface.When placed closely beneath the water surface opal and ground glass show an additional surface effect. It is caused by total reflection at the water surface. Its relation to the immersion effect is discussed.A simple device is described which eliminates the surface effect and permits accurate determinations of the immersion effect.

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Résumé Le rapport entre les intensités mesurées par un photomètre plat directement sous la surface de l'eau et au-dessus de celle-ci est appelé «effet de plongée»; il diffère de la relation véritable des intensités lumineuses dans de larges limites. Par suite des propriétés optiques différentes des disques de verre opalin, transparent ou mat, il existe trois effets de plongée différents.Les disques opalins et mats se comportent de façon contraire; leurs domaines d'effet de plongée se trouvent au-dessous et au-dessus de la valeur bien définie correspondant au verre transparent. Celle-ci constitute pour le verre opalin la limite supérieure, pour le verre mat la limite inférieure. La limite inférieure pour le verre opalin est à peu près définie, la limite supérieure pour le verre mat ne l'est pas. Les verres synthétiques à indices bas ont des domaines d'effet de plongée encore plus larges que les verres à silicates.Le rapport véritable des intensités se trouve dans le domaine de l'effet de plongée du verre opalin. Il doit donc être possible de préparer un verre opalin à l'aide duquel un photomètre fonctionne correctement dans et sur l'eau.Les verres opalins et mats présentent un «effet de surface», c'est-àdire une erreur de réflexion totale au voisinage de la surface de l'eau, dont on explique la relation avec l'effet de plongée.On donne un dispositif simple permettant d'éviter l'erreur de réflexion totale.

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Diese Arbeit ist dem Andenken anFranz Sauberer gewidmet. Sie enthält manche Antwort auf methodische Grundfragen, um deren KlärungSauberer stets gewissenhaft bemüht war. Dem lieben, unvergessenen Kollegen sei damit wenigstens in memoriam der Dank erstattet, den ihm der Verfasser für Anregung und Kritik schuldet.  相似文献   

New 40Ar/39Ar age constraints on the timing of magmatic events in the Panagyurishte region, Bulgaria     

Andrea B. Rieser  Franz Neubauer  Robert Handler  Svetlana H. Velichkova  Zivko Ivanov 《Swiss Journal of Geoscience》2008,101(1):107-123

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The XMM-Large Scale Structure catalogue: X-ray sources and associated optical data. Version I     

M. Pierre  L. Chiappetti  F. Pacaud  A. Gueguen  C. Libbrecht  B. Altieri  H. Aussel  P. Gandhi †  O. Garcet  E. Gosset  L. Paioro  T. J. Ponman  A. M. Read  A. Refregier  J.-L. Starck  J. Surdej  I. Valtchanov  C. Adami  D. Alloin  A. Alshino  S. Andreon  M. Birkinshaw  M. Bremer  A. Detal  P.-A. Duc  G. Galaz  L. Jones  J.-P. Le Fèvre  O. Le Fèvre  D. Maccagni  A. Mazure  H. Quintana  H. J. A. Röttgering  P.-G. Sprimont  C. Tasse  G. Trinchieri  J. P. Willis 《Monthly notices of the Royal Astronomical Society》2007,382(1):279-290

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Mineralogical alteration of artificial meteorites during atmospheric entry. The STONE-5 experiment     

Franz Brandsttter  Andr Brack  Pietro Baglioni  Charles S. Cockell  Ren Demets  Howell G.M. Edwards  Gero Kurat  Gordon R. Osinski  Judith M. Pillinger  Claude-Alain Roten  Suzy Sancisi-Frey 《Planetary and Space Science》2008,56(7):976-984

The generic concept of the artificial meteorite experiment STONE is to fix rock samples bearing microorganisms on the heat shield of a recoverable space capsule and to study their modifications during atmospheric re-entry. The STONE-5 experiment was performed mainly to answer astrobiological questions. The rock samples mounted on the heat shield were used (i) as a carrier for microorganisms and (ii) as internal control to verify whether physical conditions during atmospheric re-entry were comparable to those experienced by “real” meteorites. Samples of dolerite (an igneous rock), sandstone (a sedimentary rock), and gneiss impactite from Haughton Crater carrying endolithic cyanobacteria were fixed to the heat shield of the unmanned recoverable capsule FOTON-M2. Holes drilled on the back side of each rock sample were loaded with bacterial and fungal spores and with dried vegetative cryptoendoliths. The front of the gneissic sample was also soaked with cryptoendoliths.

The mineralogical differences between pre- and post-flight samples are detailed. Despite intense ablation resulting in deeply eroded samples, all rocks in part survived atmospheric re-entry. Temperatures attained during re-entry were high enough to melt dolerite, silica, and the gneiss impactite sample. The formation of fusion crusts in STONE-5 was a real novelty and strengthens the link with real meteorites. The exposed part of the dolerite is covered by a fusion crust consisting of silicate glass formed from the rock sample with an admixture of holder material (silica). Compositionally, the fusion crust varies from silica-rich areas (undissolved silica fibres of the holder material) to areas whose composition is “basaltic”. Likewise, the fusion crust on the exposed gneiss surface was formed from gneiss with an admixture of holder material. The corresponding composition of the fusion crust varies from silica-rich areas to areas with “gneiss” composition (main component potassium-rich feldspar). The sandstone sample was retrieved intact and did not develop a fusion crust. Thermal decomposition of the calcite matrix followed by disintegration and liberation of the silicate grains prevented the formation of a melt.

Furthermore, the non-exposed surface of all samples experienced strong thermal alterations. Hot gases released during ablation pervaded the empty space between sample and sample holder leading to intense local heating. The intense heating below the protective sample holder led to surface melting of the dolerite rock and to the formation of calcium-silicate rims on quartz grains in the sandstone sample.  相似文献   

M dwarfs at large heliocentric distances     

Elizabeth R. Stanway  Malcolm N. Bremer  Matthew D. Lehnert  John J. Eldridge 《Monthly notices of the Royal Astronomical Society》2008,384(1):348-360

We present an analysis of the faint M star population seen as foreground contaminants in deep extragalactic surveys. We use space-based data to separate such stars from high-redshift galaxies in a publicly available data set, and consider the photometric properties of the resulting sample in the optical and infrared. The inferred distances place these stars well beyond the scaleheight of the thick disc. We find strong similarities between this faint sample (reaching   i '_AB= 25  ) and the brighter disc M dwarf population studied by other authors. The optical–infrared properties of the bulk of our sources spanning 6000 Å-4.5 μm are consistent with those 5–10 mag brighter. We also present deep spectroscopy of faint M dwarf stars reaching continuum limits of i '_AB≈ 26, and measure absorption-line strengths in the CaH2 and TiO5 bands. Both photometrically and spectroscopically, our sources are consistent with metallicities as low as a tenth solar: metal-rich compared with halo stars at similar heliocentric distances. We comment on the possible massive astrophysical compact halo object (MACHO) identification of M stars at faint magnitudes.  相似文献   

On contamination and completeness in z≥ 5 Lyman-break galaxy surveys     

Elizabeth R. Stanway  Malcolm N. Bremer  Matthew D. Lehnert 《Monthly notices of the Royal Astronomical Society》2008,385(1):493-510

A large population of z > 5 Lyman-break galaxies has been identified in recent years. However, the high-redshift galaxies selected by different surveys are subject to a variety of selection effects – some overt, others more subtle. We present an analysis of sample completeness and contamination issues in high-redshift surveys, focusing on surveys at z ≈ 5 and using a spectroscopically confirmed low-redshift sample from the DEEP2 survey in order to characterize contaminant galaxies. We find that most surveys underestimate their contamination from highly clustered galaxies at z ≈ 1 and stars. We consider the consequences of this for both the rest-frame ultraviolet luminosity function and the clustering signal from z ≈ 5 galaxies. We also find that sources with moderate strength Lyman α emission lines can be omitted from dropout surveys due to their blue colours, again effecting the derived luminosity functions. We discuss the points of comparison between different samples, and the applicability of survey-specific results to the population at z > 5 in general.  相似文献   

The evolution of the brightest cluster galaxies since z∼ 1 from the ESO Distant Cluster Survey (EDisCS)     

I. M. Whiley  A. Aragón-Salamanca  G. De Lucia  A. von der Linden  S. P. Bamford  P. Best  M. N. Bremer  P. Jablonka  O. Johnson  B. Milvang-Jensen  S. Noll  B. M. Poggianti  G. Rudnick  R. Saglia  S. White  D. Zaritsky 《Monthly notices of the Royal Astronomical Society》2008,387(3):1253-1263

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Dating of soil layers in a young floodplain using iron oxide crystallinity   总被引：1，自引：0，他引：1  

Georg J. Lair  Franz Zehetner  Markus Hrachowitz  Nikolaus Franz  Franz-Josef Maringer  Martin H. Gerzabek 《Quaternary Geochronology》2009,4(3):260-266

Dating of fluvial deposits is essential for a more quantitative understanding of landscape evolution and soil development in floodplain environments. We collected soil layers in defined depth intervals down to 60 cm along a substrate age gradient in a floodplain of the Danube River near Vienna, Austria. Depth profiles of fallout ¹³⁷Cs were used to assess short-term sedimentation, and optically stimulated luminescence (OSL) dating was used to attribute sediment deposits to time periods between the early last millennium BC and the 18th century AD. In the studied soils, the ratio of oxalate- to dithionite-extractable iron (Fe_o/Fe_d), which indicates the degree of iron oxide crystallinity, progressively decreased from ratios greater than 0.5 to values less than 0.2 with increasing soil age and proved to be a reliable indicator of soil maturity. We linked the observed Fe_o/Fe_d ratios to the radiometric and OSL ages in a chronofunction, which allows to approximately date soil layers that lack an independent age control. The soil ages calculated with this chronofunction accurately reflected their geomorphological position, resulted in consistent age trends with depth, and highlighted the active morphodynamics of the studied floodplain. The chronofunction was further validated by dating a soil profile near the studied chronosequence that contained an archaeological find dated to the La Tène period (5th to 1st century BC).  相似文献