Evolution comparée de deux séries alcalines du Pacifique Central: Rôle de la fugacité d’oxygène et de la pression d’eau     

R. C. Maury  R. Andriambololona  C. Dupuy 《Bulletin of Volcanology》1978,41(2):97-118

A comparative mineralogical and geochemical study of two alkali-basalt series from French Polynesia (Rapa and Nuku-Hiva islands) reveals several important differences, particularly in the degree of Fe enrichment in ferromagnesian minerals and the behaviour of Ti, V and Zn. These differences appear to be connected with the onset of magnetite crystallization, which is early in the Nuku-Hiva suite but later in that of Rapa. The variable influence of this phase is ascribed to differences in IO₂, which is probably ultimately dependent on variations in P_{H 2 O}. In both cases, observed chemical variations may be explained in terms of fractional crystallization, with the occurrence of some oversaturated residual liquids resulting from the separation of mica.  相似文献   

Trace element geochemistry of paleozoic amphibolites from S. W. Spain     

Dr. C. Dupuy  Dr. J. Dostal  Dr. J. P. Bard 《Mineralogy and Petrology》1979,26(1-2):87-93

Summary Mid-grade low P/high T Paleozoic amphibolites from Acebuches (S. W. Spain) represent a mostly isochemically metamorphosed basaltic suite which is partly cumulative and partly differentiated. They have chemical compositions and element variations similar to ocean-floor tholeiites. The amphibolites may be related to the early stages of rapid rifting during the formation of the Variscan belt.

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Geochemie der Spurenelemente in Paläozoischen Amphiboliten aus Südwest-Spanien

Zusammenfassung Amphibolite mittleren Metamorphose-Grades (niedrige Drucke, hohe Temperaturen) von Acebuches, Südwest-Spanien, repräsentieren eine weithin isochemisch metamorphosierte Abfolge von Basalten, die teils differenzierte und teils Cumulus-Gesteine waren. Chemismus und Element-Variationen entsprechen den Tholeiiten von Ozeanböden. Diese Amphibolite können den Frühstadien intensiver Grabenbildung im Zuge der Entstehung des Varistischen Gürtels zugeordnet werden.

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Geochemistry and petrogenesis of late proterozoic volcanic rocks from north-western Africa     

M. Chikhaoui  C. Dupuy  J. Dostal 《Contributions to Mineralogy and Petrology》1980,73(4):375-388

The Upper Proterozoic volcanism of northwestern Africa is characterized by the predominance of calc-alkaline rocks. Volcanics with tholeiitic affinities and alkali basalts are rare. The geochemistry and the relative proportions of calc-alkaline rocktypes in the Silet zone (Algeria) and the Ouarzazate formation (Morocco) are similar to those of recent island arc suites where basalts are most abundant while in the Tassendjanet and Gara Akofo zones (Algeria) they resemble contintal margin volcanic suites with a predominance of andesites. The volcanic rocks have undergone low-grade metamorphism which strongly affected alkali and alkali-earth elements and also to a smaller degree, the less mobile elements such as REE, Zr, Hf, Nb, and P. The geochemistry of the calc-alkaline rocks point to a complex origin involving low-pressure fractional crystallization, crustal contamination and derivation from a source already enriched in LILE.  相似文献   

Uranium and potassium in calc-alkaline volcanic rocks from Sardinia     

J Dostal  S Capedri  C Dupuy 《Lithos》1976,9(3):179-183

The U content of major rock-forming minerals in a suite of calc-alkaline volcanic rocks from Sardinia is very low and their partition coefficient of U (D^U = C^S/C^L) is smaller than 0.1. The values of D^U of the mineral phases decrease from basalt to dacite and, in all rocks, the bulk of U and K is present in the groundmass. The apparent close association between K and U in basic and intermediate rocks probably reflects the fact that most of their rock-forming minerals are relatively ‘inert’ with respect to both of these elements.  相似文献   

K,U and Li abundances in ultramafic rocks of the Tethyan ophiolites     

Dr. J. Dostal  Dr. C. Dupuy  Dr. S. Capedri 《Mineralogy and Petrology》1977,24(3):161-168

Summary K, U and Li have been determined in 28 ultramafic rocks of the Tethyan ophiolites from the Northern Apennines (Italy), the Hellenides (Greece) and the Dinarides (Yugoslavia). The analyzed rocks show a variable degree of serpentinization, which leads to an increase in the content of these elements. The behaviour of U during alteration of the ultramafic rocks differs from that of K and Li. The average original content of K, Li and U in the ultramafic rocks was about 15 ppm, 0.91 ppm, and <10 ppb.

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K-, U- und Li-Häufigkeiten in ultramafischen Gesteinen der Tethys-Ophiolithe

Zusammenfassung In 28 ultramafischen Gesteinen von Tethys-Ophiolithen aus dem nördlichen Appenin (Italien), den Helleniden (Griechenland) und den Dinariden (Jugoslawien) wurde K, U und Li bestimmt. Die analysierten Gesteine zeigen unterschiedliche Serpentinisierung, die zu einem Anstieg des Gehaltes an diesen Elementen führt. Das Verhalten des U während der Umwandlung der ultramafischen Gesteine unterscheidet sich von dem des K und Li. Der ursprüngliche Durchschnittsgehalt an K, Li und U in den ultramafischen Gesteinen war ungefähr 15 ppm, 0,91 ppm und <10 ppb.

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Upper proterozoic volcanic graywackes from northwestern Hoggar (Algeria) — geology and geochemistry     

R. Caby  J. Dostal  C. Dupuy 《Precambrian Research》1977,5(3):283-297

Late-Proterozoic volcanic graywackes from the NW Hoggar (Algeria) have been investigated from geological and petrological points of view. Thirty-five samples have been analysed for major elements and the following trace elements: Li, Rb, Sr, Ba, Ni, Co, Cr, V, Zn, Cu.These graywackes constitutes a thick flysch-like formation deposited in a marine environment. They are composed of volcanic (mainly andesites) and plutonic detritus. The chemical analyses confirm this observation and demonstrate the very immature character of these rocks.The composition of the NW Hoggar graywackes differs chemically from other investigated graywackes in that they have a higher Ca, Na content and lower SiO₂, Ni content.Several geological observations suggest that the average Hoggar graywacke composition approaches the composition of the W Hoggar Late Precambrian upper crust. The graywackes were formed as a result of erosion of penecontemporaneous calc-alkali volcanic suite, emplaced after widespread mafic intrusions in the Upper Proterozoic shelf deposits.  相似文献   

Détermination de ${}^{87}\text{Sr}{}^{86}$Sr dans les andésites cénozoïques et les laves associées de Sardaigne Nord occidentale (Italie)     

C Dupuy  R.H McNutt  C Coulon 《Geochimica et cosmochimica acta》1974,38(8):1287-1296

Initial isotopic ratios of strontium have been determined in some calc-alkali rocks of Sardinia. The values of these ratios are from 0.7044 and 0.7047 in two basalts, and from 0.7063 to 0.7081 in five andesites. A dacite and a rhyolite have intermediate values of 0.7056 and 0.7058.It is suggested that increase of radiogenic strontium in andesite is most likely related to a contamination process involving water expelled from an underthrusting plate. This water also contributes to the increase in the potassium and related trace element contents in andesites.In spite of the${}^{87}\text{Sr}{}^{86}$Sr difference between basalt and andesite, a cogenetic relationship between these two kinds of rocks cannot be precluded  相似文献   

Origin and recharge mechanisms of groundwater in the upper part of the Awaj River (Syria) based on hydrochemistry and environmental isotope techniques   总被引：1，自引：0，他引：1  

N. M. Asmael  F. Huneau  E. Garel  H. Celle-Jeanton  P. Le Coustumer  A Dupuy  S. Hamid 《Arabian Journal of Geosciences》2015,8(12):10521-10542

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Michel Dupuy 《Journal of Geodesy》1952,26(3):345-357

Résumé La simplicité du calcul de la réduction au plan est une des qualités pratiques les plus importantes dans toute projection géodésique. Comme les calculs sont à l'heure actuelle entièrement effectués en coordonnés rectangulaires, la réduction au plan demande à être calculée exclusivement à partir des dits éléments: telle est bien du reste la situation en ce qui concerne la projection de Mercator Transverse, communément employée. Pour la projection conique conforme deLambert, officiellement employée pour la triangulation fran?aise, on obtient une formule commode en introduisant l'aire triangulaire comprise entre le sommet de la projection conique (image du p?le) et les stations AB à relier. Le présent acticle justifie cette formule, décrit son application par la section de Géodésie de l'Institut Géographique National, et spécifie les formules de moyenne à employer: cette note forme un ensemble avec l'article suivant deM. Dufour.

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Summary Simplicity of calculation in the plane is one of the most important characteristics of any surveyor's projection. Since all calculation is today carried out in terms of rectangular coordinates, any reduction to the plane should involve only these coordinates: and this is, in fact, the situation in the commonly employed Transverse Mercator projection. For theLambert Conical orthomorphic projection, officially used for the French triangulation, a convenient formula is obtained in terms of the area of the triangle formed by the two points concerned and the vertex of the projection (which represents the pole in the plane). This paper justifies the use of the formula; describes its application by the Institut Géographique National; and discusses the different mean value formulae which are suited to the various grades of accuracy desired. This paper should be considered together with that ofM. Dufour.

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Zusammenfassung In jeder geod?tischen Projektion besteht das Haupterfordernis für eine praktische Durchführung darin, da? die Berechnung der Reduktionen auf die Ebene m?glichst einfach sei. Da gegenw?rtig alle Rechnungen mit Hilfe von rechtwinkligen Koordinaten durchgeführt werden, mu? die Reduktion auf die Ebene ausschlie?lich von den genannten Elementen ausgehen. So liegen jedenfalls die Dinge bei der gemeinhin verwendeten Transversalen Mercator-Projektion. Für die Lambertsche konforme Kegelprojektion, die amtliche Projektion für das franz?sische Dreiecksnetz, erh?lt man eine zweckdienliche Formel, wenn man die Dreiecksfl?che zwischen dem Scheitelpunkt der Kegelprojektion (Bildpunkt des Poles) und den zu verbindenden Stationen A B benutzt. Der vorliegende Artikel begründet diese Formel, beschreibt ihre Verwendung durch die Geod?tische Abteilung des Franz?sischen Instituts für Geographie (Section de Géodésie de l'Institut Géographique National) und erl?utert die zu verwendenden Mittelwert-Formeln. Der Aufsatz geh?rt mit dem folgenden vonM. Dufour geschriebenen eng zusammen.

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Resumen La sencillez del cálculo de la reducción al plano es una de las condiciones prácticas más importantes en toda proyección geodésica. Como actualmente están efectuados los cálculos en coordenadas rectangulares, la reducción al plano exige ser calculada exclusivamente a partir de dichos elementos; tal es por lo demás la situación en lo que concierne a la proyección deMercator Transverse, comúnmente empleada. Para la proyección cónica conforme deLambert, oficialmente empleada para la triangulación francesa, se obtiene una fórmula cómoda introduciendo el área triangular comprendida entre el vértice de la proyección cónica (imagen del polo) y las estaciones A y B a enlazar. El presente articulo justifica esta fórmula, y describe su aplicación por la Sección de Geodesia del Instituto Geogróafico Nacional.

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Sommario La semplicità del calcolo delle riduzioni al piano è una delle qualià pratiche più importanti in ogni proiezione geodetica. Poichè attualmente tutti i calcoli di una triangolazione vengono effettuati sul piano, in coordinate rettangolari, è essenziale che tali riduzioni possano avvenire facendo ricorso ai soli elementi piani; come accade in particolare per la proiezione trasversa di Mercatore. Per la proiezione conica conforme diLambert, usata ufficialmente uella triangolazione francese, si ottiene una formula comoda per la riduzione alla corda introducendo l'area del triangolo formalo dall' immagine del polo, e dai due punti da collegare. L'articolo giustifica questa formula, ne descrive la sua applicazione da parte della Sezione Geodetica dell' Istituto Geografico Nazionale, e precisa le formule da impiegare. Esso è collegato con l'articolo seguente del sig.Dufour, col quale forma un tutto unico.

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Estimating River Conductance from Prior Information to Improve Surface‐Subsurface Model Calibration          下载免费PDF全文

Yohann Cousquer  Alexandre Pryet  Nicolas Flipo  Célestine Delbart  Alain Dupuy 《Ground water》2017,55(3):408-418

Most groundwater models simulate stream‐aquifer interactions with a head‐dependent flux boundary condition based on a river conductance (CRIV). CRIV is usually calibrated with other parameters by history matching. However, the inverse problem of groundwater models is often ill‐posed and individual model parameters are likely to be poorly constrained. Ill‐posedness can be addressed by Tikhonov regularization with prior knowledge on parameter values. The difficulty with a lumped parameter like CRIV, which cannot be measured in the field, is to find suitable initial and regularization values. Several formulations have been proposed for the estimation of CRIV from physical parameters. However, these methods are either too simple to provide a reliable estimate of CRIV, or too complex to be easily implemented by groundwater modelers. This paper addresses the issue with a flexible and operational tool based on a 2D numerical model in a local vertical cross section, where the river conductance is computed from selected geometric and hydrodynamic parameters. Contrary to other approaches, the grid size of the regional model and the anisotropy of the aquifer hydraulic conductivity are also taken into account. A global sensitivity analysis indicates the strong sensitivity of CRIV to these parameters. This enhancement for the prior estimation of CRIV is a step forward for the calibration and uncertainty analysis of surface‐subsurface models. It is especially useful for modeling objectives that require CRIV to be well known such as conjunctive surface water‐groundwater use.  相似文献