Geochemical applications of quantitative ion-microprobe analysis     

N. Shimizu  M.P. Semet  C.J. Allègre 《Geochimica et cosmochimica acta》1978,42(9):1321-1334

  相似文献   

⁸⁷Rb-⁸⁷Sr studies of waters in a geothermal area: The Cantal,France     

A. Stettler  C.J. Allègre 《Earth and Planetary Science Letters》1978,38(2):364-372

We have determined K, Rb and Sr concentrations and⁸⁷Sr/⁸⁶Sr ratios in fresh surface waters, a rain water sample and five geothermal waters from the Cantal volcanic area in the Massif Central, France. A comparison with appropriate rock types of the region showed no apparent chemical and isotopic fractionation occurring in the fresh water-surface rock system. The thermo-mineral water results suggest that all springs discharge dissolved Sr from the following contributors: Hercynian granito-metamorphic basement, lacustrian sediments underlying the volcano, Miocene-Pliocene volcanic rocks of basaltic to rhyolitic composition.  相似文献   

Alkali feldspar liquid equilibrium relationships in peralkaline oversaturated systems and volcanic rocks     

Jacques Roux  Jacques Varet 《Contributions to Mineralogy and Petrology》1975,49(1):67-81

A critical review of both experimental data and natural rock sequences allows a comparison of liquid lines of descent in peralkaline oversaturated systems. Available experimental data have been used to draw the liquidus surfaces and the fractionation curves in various planes including the alkali feldspar join. The thermal valley becomes steeper, the fractionation curves being channeled faster towards the thermal valley with increasing alkali-silica ratio. The slope of the thermal valley varies so that the higher the peralkalinity, the more sodic the most fractionated liquids. Rock series from Easter Island, Gran Canaria, Pantellaria Island, Boina (Afar), Fantale (Ethiopia) and Menengai (Kenya) in which there is good evidence for alkali feldspar fractionation, show that such variations do occur in nature. Factors other than the peralkalinity of the series, such as additional components and changes in the confining pressure are shown to affect the orientation and location of the thermal valley.  相似文献   

A study of the formation and history of a piece of continental crust by 87Rb-87Sr method: The case of the French oriental Pyrénées     

Annie Vitrac Michard  Claude J. Allègre 《Contributions to Mineralogy and Petrology》1975,50(4):257-285

Rb-Sr whole rock data for gneisses and granites from the oriental Pyrénées yield cadomian ages for the basement gneisses and hercynian ages for the granites. Granites occur in two generations. An alkaline granite dated at 335±15 m.y. is syn.—or slightly post-tectonic, and a later calcalkaline granite dated at 275±12 m.y, is clearly intrusive and marks the end of hercynian tectono-metamorphism. Initial ⁸⁷Sr/⁸⁶Sr ratios of the granites put limits on the proportion of juvenile contribution from the mantle to their formation. Petrogenetic models are tested using Rb and Sr as tracers.  相似文献   

Utilisation du radon comme indicateur de l'intensite des echanges pres du sol (0–100 M)     

Aimé Druilhet  Jacques Fontan 《Boundary-Layer Meteorology》1974,6(3-4):387-411

Resumé Les donées moyennes relatives à deux années de mesures continues du radon à 1.5–30 et 100 m au-dessus du sol sont présentées sous forme de variations diurnes standard; ces dernières sont étudiées par une analyse de Fourier (amplitude et phase). On précise l'évolution des variations au cours du cycle annuel.Le but de l'étude des donées moyennes étant d'accéder aux informations relatives à la variation diurne des échanges, on a recherché des relations entre la variation diurne standard des concentrations et celles des échanges; d'autre part on a défini des critères, déduits des paramètres météorologiques, classiques susceptibles de caracteriser l'intensité de la variation diurne des échanges.

---

Continuous measurement of radon concentrations at, 1.5, 30 and 100 m has been carried out for 2 years, from October 1966 to October 1968. The mean diurnal variations of the concentrations are characterized in a simple manner using a Fourier analysis, revealing the diurnal and annual waves, and showing the variations with altitude of the radon concentrations. The amplitude of this diurnal wave can be considered as representative of the mean diurnal variation of the intensity of the vertical exchange processes.This method of analysis is applied to the study of influence of standard meteorological elements measured at the site on the diurnal variation of the exchanges. Additional indicators are derived from temperature, humidity and wind (speed and direction) measurements, and their daily cycles (mean winds, mean direction, temperature diurnal variation amplitude...) are shown to be related to the cycles of radon concentrations.The mean diurnal variations of the radon concentrations classified according to several meteorological parameters are used to characterize the intensity of mixing, in terms of a mixing coefficient.This characterization is achieved both from the average gradients (local value) and from the diurnal wave at the soil.

---

---

Equipe de Recherche Associée au CNRS, No. 378.  相似文献   

L'évolution magmatique du Complexe de Morin et son apport au problème des anorthosites     

Jacques Martignole 《Contributions to Mineralogy and Petrology》1974,44(2):117-137

The Morin Plutonic Complex, in the southern part of the Grenville tectonic province (Canadian Shield) consists of a rock suite ranging from troctolite to farsundite. The centre of the complex is a large domical anorthosite body. Twenty-six chemical analyses have been carried out in order to compare the Morin Complex with similar complexes in the Grenville and Nain provinces. Variation diagrams constructed by plotting the major oxides vs. the differentiation index Al₂O₃+CaO+MgO show a gap between troctolite and anorthosite in the Morin Complex whereas this gap is absent in the anorogenic complexes of Labrador (Nain province). It is inferred that this gap is the result of intrusion, from the same magma chamber, of two distinct pulses separated by an intervening period of crustal uplift.A second gap occurs between anorthosites and farsundites in all complexes as yet investigated. This gap is an argument for an independent, possibly anatectic, origin of the farsundites.Mineral assemblages in the Morin Complex are compatible with cooling in the lower crust, at a depth of approximately 30 km.  相似文献   

L’utilisation des volcans pour accroître la pluviosité dans le Sahara est-elle utopique?     

Bernard Gèze 《Bulletin of Volcanology》1960,23(1):213-217

  相似文献   

The gravitational potential and its vertical derivatives     

Prof K. Kántás 《Pure and Applied Geophysics》1959,44(1):20-24

Summary The vertical gradient of gravitational field is derived by a corollary ofGreen's theorem from the gravitational potential. For the solving of the integral defined the vertical gradient is given a simple approximation. For practical computation are presented the numerical values of coefficients.

---

Zusammenfassung Der vertikale Gradient des Gravitationsfeldes ist vom Gravitationspotentials als Folgensatz desGreen-Theorems abgeleitet. Zur Lösung des den vertikalen Gradienten definierenden Integrals wurde ein einfaches Annäherungsverfahren angewandt. Für praktische Berechnungen sind die numerischen Werte der Koeffizienten gegeben.

  相似文献   

The microbial sulfur cycle and some of its implications for the geochemistry of sulfur isotopes     

Dr. J. W. M. la Rivière 《International Journal of Earth Sciences》1966,55(3):568-582

Qualitatively most microbial processes of the sulfur cycle are well known, but the extent to which specific groups of microbes take part in sulfate reduction and sulfide oxidation is at present difficult to estimate and the same holds for the role played by purely chemical sulfide oxidation.The capacity of an organism to differentiate between sulfur isotopes is genetically determined and probably strain-specific; whether or not, and to what extent, fractionation actually occurs is codetermined by physiological conditions inside the cell and by ecological conditions, i.e. the parameters of the environment.For conclusive interpretation of sulfur fractionation data of natural deposits further microbiological studies on the enzymatic, cellular and ecological level are necessary; such studies would be technically feasible today. The study of isotope effects of relevant, purely chemical reactions should not be neglected.

---

Zusammenfassung In qualitativer Hinsicht sind die meisten mikrobiellen Vorgänge des Schwefelkreislaufs gut bekannt. Jedoch ist es gegenwärtig noch schwierig zu sagen, in welchem Ausmaß die verschiedenen Mikroorganismengruppen an der Reduktion der Sulfate und an der Oxidation der Sulfide teilnehmen. In wieweit die Oxidation der Sulfide rein chemisch erfolgt, ist ebenso schwer einzuschätzen.Die Fähigkeit einer Mikrobe zwischen verschiedenen Schwefelisotopen zu unterscheiden, ist genetisch festgelegt und ist wahrscheinlich stammspezifisch. Ob überhaupt und, wenn ja, in welchem Ausmaß eine Fraktionierung tatsächlich stattfindet, wird von den physiologischen Verhältnissen innerhalb der Zelle und von ökologischen Verhältnissen, d. h. den Parametern der Umwelt, mitbestimmt.Um eine endgültige Interpretation der Fraktionierungsdata in der Natur abgelagerter Schwefelverbindungen zu ermöglichen, sind weitere mikrobiologische Forschungen auf enzymatischer, zellularer und ökologischer Stufe erforderlich, die heute ohne weiteres durchgeführt werden könnten. Isotopeneffekte bei rein chemischen Reaktionen sollten dabei ebenfalls untersucht werden.

---

Résumé La plupart des processus microbiologiques du cycle du soufre est qualitativement assez connue mais il est encore difficile de déterminer quantitativement dans quelle mesure des microbes spécifiques contribuent à la réduction des sulfates et à l'oxidation des sulfides. La même difficulté se présente quant à l'oxidation des sulfides purement chimique.Le pouvoir d'un organisme de distinguer entre les isotopes de soufre est déterminé par voie génétique et probablement est spécifique pour la souche individuelle. Dans quelle mesure un fractionnement des isotopes est vraiment réalisé sous les conditions expérimentales ou. naturelles est déterminé par des conditions physiologiques dans les cellules et des conditions écologiques, c'est à dire par les paramètres du milieu.Pour une interprétation conclusive des dates de fractionnement du soufre des dépôts naturels, il est nécessaire d'étudier les processus microbiens relevants au niveau enzymatique, cellulaire et écologique, des études qui sont aujourd'hui tout à fait réalisables. D'autre part, l'étude des effets isotopiques des réactions purement chimiques ne devrait pas être négligée.

---

, . .

---

---

Edited version of a lecture held at the Colloquium on the Geochemistry of Sulfur Isotopes, Bad Sooden-Allendorf, 1964; the references given provide entrances to the literature of the topics discussed rather than exhaustive documentation.  相似文献   

The surface seiches of Lake of Lugano     

PD. Dr. K. Hutter  Dr. G. Raggio  PD. Dr. C. Bucher  Dr. G. Salvadè  Dr. F. Zamboni 《Aquatic Sciences - Research Across Boundaries》1982,44(2):455-484

A computational analysis of the periods and structure of surface seiches of the southern basin of Lake of Lugano and its experimental verification from three simultaneous water gauge recordings, mounted along the shores in Agno, Morcote and Riva S. Vitale, is given. The first five theoretical modes are calculated with a finite element code of the tidal equations; it yields the eigenperiods and co-range and co-tidal lines, which are graphically displayed and discussed in detail. Experimental verification is from recordings taken during February/March 1982. Inspection by eye allows identification of the five lowest order modes, partly including interstation phase shift. Power spectral analysis of three-time series and interstation phase difference and coherence spectra allow identification of higher order modes, probably up to order 13. Agreement between the theoretically predicted and the experimentally determined periods is excellent for all calculated modes. Computational results for the four lowest modes and their structure of the northern basin of Lake of Lugano are also presented and experimentally verified with records taken from an event in August 1979. Agreement is again excellent.  相似文献