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Contents to Volume 7 相似文献3.
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Contents to Volume 5 相似文献7.
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Contents of Volume 30 相似文献8.
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Contents Volume 21 (2003) 相似文献9.
C. Emdad Haque Dale Dominey-Howes Nuray Karanci Gerassimos Papadopoulos Ahmet Yalciner 《Natural Hazards》2003,29(3):603-606
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Contents of Volume 29 相似文献10.
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Contents of Volume 24 相似文献15.
H. Alawaji 《Geotechnical and Geological Engineering》2001,19(1):85-86
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Volume contents 57 nos. 1-4 相似文献17.
《Physics and Chemistry of Minerals》2005,31(10):659-659
Referee Acknowledgement
Referee Acknowledgement Volume 31, 2004 相似文献18.
Heiner Flick H. Dieter Nesbor Roman Behnisch 《International Journal of Earth Sciences》1990,79(2):401-415
Investigations on the reconstruction of processes and facies relationships from submarine volcanics of Devonian age in the Lahn syncline (Rhenish Mountains, Western Germany) reveal a complex development of secondary alteration. This is well illustrated by a mafic pyroclastic sequence (»Schalstein«) at the Gänsberg near Weilburg where alteration processes are visible by petrographic and geochemical means and can be further classified by cathodoluminescence. Iron ore formation of Lahn-Dill type is recognized as part of this alteration process, resulting from diagenetic seeping. Until recently a direct magmatic source for the Lahn-Dill type iron ore has been the generally accepted model. These bodies have therefore been viewed as a rather unique stratiform deposit, whose occurrence was virtually confined to this type area. However, it is here considered that the formation of the iron ore corresponds well with existing models of alteration processes within recent oceanic environments which are of a more universal occurrence.
Zusammenfassung Untersuchungen zur Rekonstruktion der Abläufe an und in den submarinen Vulkangebäuden des Devons (Givet/Adorf-Phase) der Lahnmulde (südliches Rheinisches Schiefergebirge) schließen die sekundäre Alteration mit ein und werden an dem ausschließlich aus basischen Pyroklastiten (Schalstein) aufgebauten Profil am Gänsberg bei Weilburg exemplarisch vorgestellt. Diese anhand petrographischer und geochemischer Kriterien erkennbaren sekundären Prozesse zeigen eine mehrphasige Entwicklung auf, die durch Kathodenlumineszenz-Untersuchungen der Karbonatzemente bestätigt und zeitlich geordnet werden kann. Die an die pyroklastische Abfolge gebundene Roteisensteinvererzung vom Lahn-Dill-Typ läßt sich mit der bei diesen Vorgängen erfolgten Wanderung verschiedener Elemente korrelieren. Damit wird die Vererzung zu einem Produkt der diagenetischen Alteration und nicht der magmatischen Differentiation, wodurch sie mit rezent im ozeanischen Raum beobachteten Prozessen vergleichbar ist. Diese Vorstellungen fügen die Lahn-Dill-Erze in aktualistisch begründete Modelle zur Genese von Erzen ein. Damit erscheint die Besonderheit und fast nur auf den rhenoherzynischen Raum beschränkte Verbreitung dieses Typus hinfällig.
Résumé L'étude de la succession des phénomènes et des relations facielles dans les volcanites sous-marines d'âge dévonien du synclinal de la Lahn (Massif schisteux rhénan) fait apparaître des processus complexes d'altération secondaire. Ceci est particulièrement bien illustré par la séquence pyroclastique («Schalstein») du Gänsberg près de Weilburg: les processus secondaires, identifiables par des critères pétrographiques et géochimiques y présentent un développement polyphasé dont l'histoire peut être reconstituée par application de la cathodo-luminescence au ciment carbonaté. Les minéralisations en fer associées à la série pyroclastique peuvent être corrélées avec les migrations de divers éléments impliqués dans ces processus. Ces minéralisations apparaissent ainsi comme le produit d'une altération diagénétique et ne correspondent donc pas au modèle généralement admis d'une différenciation magmatique. Cette genèse par altération est d'ailleurs conforme à ce qu'on observe dans les domaines océaniques récents de sorte que les gisements de la région Lahn-Dill doiventêtre considérés non pas comme une singularité du massif schisteux rhénan, mais comme l'expression d'un phénomène plus général à caractère actualiste.
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19.
Redox states of lithospheric and asthenospheric upper mantle 总被引：31，自引：7，他引：24
C. Ballhaus 《Contributions to Mineralogy and Petrology》1993,114(3):331-348
The oxidation state of lithospheric upper mantle is heterogeneous on a scale of at least four log units. Oxygen fugacities (
) relative to the FMQ buffer using the olivine-orthopyroxene-spinel equilibrium range from about FMQ-3 to FMQ+1. Isolated samples from cratonic Archaean lithosphere may plot as low as FMQ-5. In shallow Proterozoic and Phanerozoic lithosphere, the relative
is predominantly controlled by sliding Fe3+-Fe2+ equilibria. Spinel peridotite xenoliths in continental basalts follow a trend of increasing
with increasing refractoriness, to a relative
well above graphite stability. This suggests that any relative reduction in lithospheric upper mantle that may occur as a result of stripping lithosphere of its basaltic component is overprinted by later metasomatism and relative oxidation. With increasing pressure and depth in lithosphere, elemental carbon becomes progressively refractory and carbon-bearing equilibria more important for
control. The solubility of carbon in H2O-rich fluid (and presumably in H2O-rich small-degree melts) under the P,T conditions of Archaean lithosphere is about an order of magnitude lower than in shallow modern lithosphere, indicating that high-pressure metasomatism may take place under carbon-saturated conditions. The maximum
in deep Archaen lithosphere must be constrained by equilibria such as EMOG/D. If the marked chemical depletion and the orthopyroxene-rich nature of Archaean lithospheric xenoliths is caused by carbonatite (as opposed to komatiite) melt segregation, as suggested here, then a realistic lower
limit may be given by the H2O +C=CH4+O2 (C-H2O) equilibrium. Below C –H2O a fluid becomes CH4 rather than CO2-bearing and carbonatitic melt presumably unstable. The actual
in deep Archaean lithosphere is then a function of the activities of CO2 and MgCO3. Basaltic melts are more oxidized than samples from lithospheric upper mantle. Mid-ocean ridge (MORB) and ocean-island basalts (OIB) range between FMQ-1 (N-MORB) and about FMQ +2 (OIB). The most oxidized basaltic melts are primitive island-arc basalts (IAB) that may fall above FMQ+3. If basalts are accurate
probes of their mantle sources, then asthenospheric upper mantle is more oxidized than lithosphere. However, there is a wide range of processes that may alter melt
relative to that of the mantle source. These include partial melting, melt segregation, shifts in Fe3+/Fe2+ melt ratios upon decompression, oxygen exchange with ambient mantle during ascent, and low-pressure volatile degassing. Degassing is not very effective in causing large-scale and uniform
shifts, while the elimination of buffering equilibria during partial melting is. Upwelling graphite-bearing asthenosphere will decompress along
-pressure paths approximately parallel to the graphite saturation surface, involving reduction relative to FMQ. The relative
will be constrained to below the CCO equilibrium and will be a function of
. Upwelling asthenosphere whose graphite content has been exhausted by partial melting, or melts that have segregated and chemically decoupled from a graphite-bearing residuum will decompress along
-decompression paths controlled by continuous Fe3+-Fe2+ solid-melt equilibria. These equilibria will involve increases in
relative to the graphite saturation surface and relative to FMQ. Melts that finally segregate from that source and erupt on the earth's surface may then be significantly more oxidized than their mantle sources at depth prior to partial melting. The extent of melt oxidation relative to the mantle source may be directly proportional to the depth of graphite exhaustion in the mantle source. 相似文献
20.
The results of an analysis of the activity of the young stars with planetary systems EPIC 211901114 and K2–33 based on observational data obtained over 70 days with the Kepler Space Telescope are presented. The rotation periods of EPIC 211901114 (8.56±0.60d) and K2–33 (6.29±0.50d) have been found. Maps of temperature inhomogeneities on the surfaces of EPIC 211901114 and K2–33 have been constructed. No relative displacements of the active regions on the stellar surface have been foundfor EPIC 211901114. The differential-rotation parameter has been estimated for K2–33, ΔΩ = 0.0039±(0.0020–0.0012) rad/day. The fractional spotted area S on the surface of EPIC 211901114 reaches about 5% of its total visible surface. For K2–33, S is 3.8% of its total visible surface, on average. On the whole, the positions of EPIC 211901114 and K2–33 on S–age, S–rotation period, and S–Rossby number diagrams match the general character of the dependence found earlier for M dwarfs. The flare activity of EPIC 211901114 and K2–33 has been studied, based on 32 flares of EPIC 211901114 and 7 flares of K2–33. The flare frequencies and amplitudes for EPIC 211901114 and K2–33 have been estimated, together with the time scales for their rise and decay. The flare energies have also been estimated, 1032.1?33.4 and 1032.2?33.3 erg for EPIC 211901114 and K2–33, respectively. 相似文献