Detailed oxygen and carbon isotope stratigraphy of the Oxfordian in Central Poland   总被引：1，自引：0，他引：1  

Hubert Wierzbowski 《International Journal of Earth Sciences》2002,91(2):304-314

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The mafic–ultramafic complex of Sikhoran (central Iran): a polygenetic ophiolite complexLe massif basique-ultrabasique de Sikhoran (Iran central) : un complexe ophiolitique polygénétique     

Habibollah Ghasemi  Thierry Juteau  Hervé Bellon  Mossaieb Sabzehei  Hubert Whitechurch  Luc-Emmanuel Ricou 《Comptes Rendus Geoscience》2002,334(6):431-438

The mafic–ultramafic complex of Sikhoran presents a long geological history, marked out by various magmatic, metamorphic and tectonic events. This history is much more complex than a simple ophiolite obduction over a continental margin. As early as the Upper Permian, following a mantle uprise in a Tethysian supra-subduction zone, the opening of a (back-arc?) basin in extensional/transtensional conditions provoked the intrusion of multiple gabbroic dykes, veins and plutons charged with fluids, through a mafic/ultramafic complex and its metamorphic cover. Several basins, characterised by abundant submarine basaltic volcanism developed during Jurassic, whose feeding dykes may be represented by the diabase dyke swarms intruding the whole Sikhoran complex and its metamorphic cover. To cite this article: H. Ghasemi et al., C. R. Geoscience 334 (2002) 431–438.  相似文献   

Dynamical aspects of katabatic wind evolution in the Antarctic coastal zone     

Hubert Gallée  Guy Schayes 《Boundary-Layer Meteorology》1992,59(1-2):141-161

The spatial evolution of katabatic winds along idealized slopes representative of Antarctic terrain is examined using a hydrostatic, two-dimensional primitive equation model with high resolution. A downslope momentum-forces analysis is made of simulations in which katabatic flow reaches steady state, with emphasis on physical mechanisms in the coastal zone. The importance of the reversal of the pressure gradient force in the coastal zone, causing the sudden decay of katabatic winds, is discussed.  相似文献   

Kritische Betrachtungen zum geologischen Zusammenhang zwischen den chilenischen Anden und der Westantarktis     

Dr. Hubert Miller 《International Journal of Earth Sciences》1967,56(1):643-656

Zusammenfassung Die Entwicklung der Westantarktischen Geosynklinale läßt sich eher mit der der Anden-Geosynklinale vergleichen als mit der der Magallanes-Geosynklinale. Südast und Nordast des Südantillen-Bogens gehören verschiedenen Bereichen an. Analogien zum Westindischen Inselbogen werden aufgezeigt.

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Summary The West Antarctic geosyncline is more similar to the Andean geosyncline than to the Magallanes geosyncline. Northern and southern trace of the Scotia Arc form parts of distinct units. Analogies to the West Indian Island Arc are pointed out.

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Resumen El geosinclinal Antártico se asemeja más al geosinclinal Andino que al geosinclinal Magallánico. El brazo meridional y el brazo septentrional del arco de las Antillas Australes, pertenecen a diferentes unidades geológicas. Se señalan algunas analogías con el arco de las Antillas de América Central.

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Résumé Le géosynclinal de l'Antartide Occidentale est comparable avec le géosynclinal des Andes plutôt qu'avec celui de Magallanes. La branche Nord et la branche Sud de l'Arc de Scotia font partie de différentes unités. Des analogies avec l'Archipel des Indes Occidentales sont soulignées.

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Das Grundgebirge der Anden im Chonos-Archipel,Region Aisén,Chile     

Dr. Hubert Miller 《International Journal of Earth Sciences》1979,68(1):428-456

Zusammenfassung Im schwach bis mäßig metamorphen Grundgebirge des Chonos-Archipels in Südchile werden erstmals drei Formationen unterschieden: Die wahrscheinlich kambro-ordovizische Canal-King-Formation besteht überwiegend aus Phylliten und Glimmerschiefern mit Einlagerungen von Grünschiefern. Die schwächer metamorphe Potranca-Formation ist im wesentlichen devonisch und besteht aus Tonschiefern, unreinen Sandsteinen, Phylliten und Quarziten. Die vermutlich jungpaläozoische Canal-Pérez-Sur-Formation besteht aus Tonschiefern und Sandsteinen und zeigt fast gar keine Metamorphose.Das Gebiet ist mehrfach kompliziert gefaltet worden. Nach einer vermutlich vorvariszischen, nur noch stellenweise erkennbaren Faltung und schwachen Metamorphose folgte etwa im Unterkarbon eine kräftige variszische Faltung, die ein NNW—SSE-streichendes Gebirge schuf. Spätere, vermutlich oberpermische bis höchstens mitteltriassische Nachläufer der variszischen Faltung schufen Faltenachsen in NNE—SSW-Richtung.Das Untersuchungsgebiet stellt ein Glied in der Kette von präandinen Orogenen im südlichen Südamerika dar, deren Alter im großen ganzen gesehen nach Süden hin abnimmt.

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Three formations are distinguished for the first time within the weakly to moderately metamorphic basement of the Chonos Archipelago in southern Chile: The probably Cambro-Ordovician Canal King Formation consists mainly of phyllites and micaschists with intercalations of greenschists. The less metamorphic Potranca Formation is essentially of Devonian age and consists of slates, impure sandstones, phyllites and quartzites. The Canal Pérez Sur Formation is probably of Upper Paleozoic age; it consists of slates and sandstones and shows nearly no metamorphism at all.The area has been folded complexly several times. After a supposed pre-Hercynian folding and metamorphism which can be recognized only in places, about in the Lower Carboniferous a strong Hercynian folding occurred, causing a NNW—SSE striking mountain chain. Possibly between Upper Permian and Middle Triassic times, late phases of the Hercynian folding created NNE—SSW striking fold axes.The investigated area forms a part of the pre-andine orogenic chains of southern South America, whose ages are on the whole decreasing from North to South.

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Resumen En el basamento débil a moderadamente metamórfico del Archipiélago de los Chonos en Chile Austral, por primera vez se distinguen tres formaciones: La Formación Canal King, de probable edad cambroordovícica, contiene mayormente filitas y micaesquistos con algunas intercalaciones de esquistos verdes. La Formación Potranca, de edad esencialmente devónica, consiste de pizarras, areniscas impuras, filitas y cuarcitas. La Formación Canal Pérez Sur, de presunta edad permocarbonífera, consiste de pizarras y areniscas, y aparentemente no muestra metamorfismo.La región ha sido plegada varias veces y de manera compleja. Después de un plegamiento probablemente pre-varíscico y un metamorfismo débil que sólo en ciertas partes se reconocen, alrededor del Carbónico inferior un plegamiento fuerte varíscico produjo un orógeno de rumbo NNW—SSE. Fases tardías del ciclo varíscico, acontecidas probablemente entre el Pérmico superior y el Triásico medio, crearon ejes de pliegues en dirección NNE—SSW.El área investigada forma un eslabón de la cadena de orógenos pre-andinos en el cono Sur de Sudamérica cuya edad en grandes rasgos disminuye hacia el Sur.

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The control of alkalies and uranium in seawater by ocean crust alteration     

Stanley R. Hart  Hubert Staudigel 《Earth and Planetary Science Letters》1982,58(2):202-212

Alteration of the oceanic crust during hydrothermal circulation of seawater produces fluxes of K, Rb and Cs between these reservoirs which are significant compared to the river input of these elements. The ocean crust U flux, on the other hand, is probably not significant. The upper crust, altered at low temperature, is a sink for all of these elements (as shown by direct analysis of upper crustal materials). The lower crust is a source for K, Rb, and Cs, based on the observation that high-temperature fluids exiting the crust as “host springs” are enhanced over seawater in K, Rb and Cs concentration. While the sign of the hot spring fluxes may be correct, the absolute magnitudes cannot be, as the calculated yearly hot spring flux of Rb and Cs significantly exceeds the total Rb and Cs inventory of newly formed unaltered crust. By modelling the crust as a melt/cumulate combination, we show that the crust as a whole is a sink for K, Rb, Cs, and probably U, with yearly fluxes of1.1 × 10¹³, 2.6 ×10¹⁰, 6.0 × 10⁸ and 1.0 × 10⁹g, respectively (com to yearly river dissolved fluxes of7.4 × 10¹³, 3.5 × 10¹⁰, 6.4 × 10⁸and1.0 × 10¹⁰g, respectively). The alteratio oceanic crust appears capable of quantitatively balancing the river inputs of Rb and Cs. For K, an additional sink comprising～ 85% of the river input is necessary. Because this missing K sink cannot be arbitrarily manipulated without destroying the Rb and Cs balances, a sink with K/Rb higher than the continental crust is required, and may possible be found in the sediments of the continental shelves.  相似文献   

Isotope and trace element geochemistry of young Pacific seamounts: implications for the scale of upper mantle heterogeneity   总被引：2，自引：0，他引：2  

Alan Zindler  Hubert Staudigel  Rodey Batiza 《Earth and Planetary Science Letters》1984,70(2):175-195

Basalts from young seamounts situated within 6.8 m.y. of the East Pacific Rise, between 9° and 14°N latitude, display significant variations in ¹⁴³Nd/¹⁴⁴Nd (0.51295–0.51321), ⁸⁷Sr/⁸⁶Sr (0.7025–0.7031), and(La/Sm)_N (0.415–3.270). Nd and Sr isotope ratios are anti-correlated and form a trend roughly parallel to the “mantle array” on a¹⁴³Nd/¹⁴⁴Nd vs.⁸⁷Sr/⁸⁶Sr variation diagram. Nd and Sr isotope ratios display negative and positive correlations, respectively, with(La/Sm)_N. The geochemical variations observed at the seamounts are nearly as great or greater than those observed over several hundred kilometers of the Reykjanes Ridge, or at the islands of Iceland or Hawaii.

Samples from one particular seamount, Seamount 6, display nearly the entire observed range of chemical variations, offering an ideal opportunity to constrain the nature of heterogeneities in the source mantle. Systematics indicative of magma mixing are recognized when major elements, trace elements, trace element ratios, and isotope ratios are compared with each other in all possible permutations. The source materials required to produce the end-member magmas are: (1) a typical MORB-source-depleted peridotite; and (2) a relatively enriched material which may represent ancient mantle segregations of basaltic melt, incompletely mixed remnants of subducted ocean crust, or metasomatized peridotite such as that found at St. Paul's Rocks or Zabargad Island. Due to the proximity of the seamounts to the East Pacific Rise (EPR), the source materials are thought to comprise an intimate mixture in the mantle immediately underlying the seamounts and the adjacent EPR. Lavas erupted at the ridge axis display a small range of isotopic and incompatible trace element compositions because the large degrees of melting and presence of magma chambers tend to average the chemical characteristics of large volumes of mantle.

If the postulated mantle materials, with large magnitude, small-scale heterogeneities, are ubiquitous in the upper mantle, chemical variations in basalts ranging from MOR tholeiites to island alkali basalts may reflect sampling differences rather than changes in bulk mantle chemistry.  相似文献   

Exploitation d''un système de deux puits en situation de compétition et en situation de coordination     

P. Hubert 《Journal of Hydrology》1984,70(1-4):353-367

We propose to study two different ways of exploiting a two-well system in steady state. In the first case, two different economical agents manage one well each (competition). In the second case, both of the wells are managed by the same economical agent (coordination). These problems are special cases of an oligopoly game. In both cases, the hydrogeologic conditions are assumed to be favourable for groundwater exploitation and its only limiting factor of economic origin. It is shown that an equilibrium is always reached, but that, in the case of coordinated exploitation, at least one of the wells is operated at a lower production rate than in the case of competitive exploitation. Finally, a numerical application is made on a simplified example.

Résumé

On se propose d'étudier l'exploitation en régime permanent d'un système de deux puits dans deux situations. Dans la première situation, deux agents économiques gèrent chacun un puits (compétition). Dans la seconde situation, les deux puits sont gérés par un même agent économique (coordination). Ces problèmes sont des cas particuliers de jeu oligopolistique. Dans tous les cas, les conditions hydrogéologiques sont supposées suffisamment favorables pour que la seule limite à l'exploitation des eaux souterraines soit de nature économique. On démontre qu'un équilibre stable est toujours atteint, mais que, dans la situation de coordination, un puits au moins est utilisé avec un débit moindre que dans la situation de compétition. Une application numérique a été effectuée sur un exemple simple.  相似文献   

Large scale isotopic Sr, Nd and O isotopic anatomy of altered oceanic crust: DSDP/ODP sites417/418   总被引：3，自引：0，他引：3  

Hubert Staudigel  G.R. Davies  Stanley R. Hart  K.M. Marchant  Brian. M. Smith 《Earth and Planetary Science Letters》1995,130(1-4):169-185

Large-scale compositional domains at DSDP/ODP drill sites 417A, 417D and 418A were analyzed for O, Sr and Nd isotope ratios, and REE, U, K, Rb and Sr abundances, to constrain the bulk chemical composition of the oceanic crust that is recycled at subduction zones. The combination of the three sites gives the composition of the upper oceanic crust in this region over a distance of about 8 km. The δ¹⁸O_SMOW and⁸⁷Sr/⁸⁶Sr_meas of compositional domains 10–100 m in size correlate well, with a range of 7.7–19.2 and 0.70364–0.70744, and mean of 9.96 and 0.70475, respectively. The Rb inventory of the upper crust increases by about an order of magnitude, while Sr contents remain constant. U abundances increase moderately under oxidizing alteration conditions and nearly triple in the commonly reducing alteration environments of the upper oceanic crust. REEs are influenced by alteration only to a small extent, and recycled oceanic crust is similar to MORB with respect to¹⁴³Nd/¹⁴⁴Nd. Even though the average composition of the upper oceanic crust is well defined, the large scale composition varies widely. Highly altered compositional domains may not have a large impact on the average composition of the oceanic crust, but they may preferentially contribute to fluids or partial melts derived from the crust by prograde metamorphic reactions.  相似文献   

The Electromagnetic Borehole Flowmeter: Description and Application   总被引：2，自引：0，他引：2  

Steven C. Young  Hubert S. Pearson 《Ground Water Monitoring & Remediation》1995,15(4):138-147

Borehole flowmeters are downhole tools that measure axial flow in a well or borehole. Desirable flowmeter characteristics include low detection limit, a wide range of operation, accuracy, durability, reliable performance, and a small diameter and length. The recently developed electromagnetic (F.M) flowmeter has these trails. The first portion of this paper presents the MM flowmeter design, provides laboratory calibration data, and compares the performance characteristics of MM flowmeters 10 those of impeller and thermal pulse flowmeters. The second portion of the paper discusses applications of the MM flowmeter.  相似文献