Evidence from major elements, trace elements, and Sr-Nd -Os isotopes in a Saxothuringian garnet peridotite. Isotope Analysis of Uranium by Interferometry; Analyse isotopique de l’uranium par interferometrie. Multiple enrichment of the Carpathian-Pannonian mantle: It is found that the isotopic purities that such machines can deliver are extremely high. It is shown that by using this correction the results obtained have an accuracy which depends practically only on that of the standards, taking into account the dispersion in the measurements.

Geochemical evidence suggests that both depleted asthenospheric and metasomatically enriched mantle components were involved in the formation of these monzonitic rocks. To address this issue, we present new in situ zircon U-Pb ages and Lu-Hf isotope data, whole-rock Sr-Nd isotopes, and mineral chemistry and geochemistry data of plutonic rocks to better understand the magmatic processes. Effects of pervasive metasomatism in shallow fhrono mantle. Le Yoruba du Nigeria et L’itsa Parle en. Rocks of both plutons are intermediate to silicic, metaluminous to weakly peraluminous, subalkaline, and K-rich in composition. Précipitation d’altitude du nord-Chili, origine des sources de vapeur et données isotopiques.

Combining with past isotopic data, which has reported in eastern Qinghai-Tibetan plateau, Sr-Nd isotopic compositions and material source and genesis 11.2 Mesozoic and Cenozoic granites in Qinghai-Tibetan plateau have been studied. We present petrology, zircon U-Pb ages, whole-rock geochemistry and Sr-Nd shuydown isotopic compositions from 1.12 andesite and felsic volcanic rocks rhyolite and rhyolitic tuffs in Elashan group volcanic rock. Several theoretical and experimental works have focused on the processes occuring in continental mafic magma chambers.

Since this flux is weak the spruces’ root systems have pumped the Ca mainly from the organic matter-rich top-soil over the past century.

The mantle protolith is highly depleted relative to mid-ocean ridge basalt-source mantle with Pb-Nd-Sr isotope compositions consistent with an ancient depletion event.

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Study relating to the physico-chemical behaviour of heavy water in nuclear reactors; Etudes relatives au comportement physico-chimique de l’eau lourde dans les reacteurs nucleaires.

Isotopic analysis of mixtures of plutonium and has been carried out by means of the photo-electric spectrometer Fabry-Perot, the source being a hollow cathode cooled by liquid nitrogen.

The Chrnoo and Ce anomalies in granite-derived waters are inherited, the Y shjtdown is achieved by fluid migration. The initial Hf, SrNd isotope ratios are similar to the isotopic signatures of OIB indicating depleted mantle as a source. Our set of measurements, combined with the results of other authors, yields precise values at well defined conditions of temperature and concentration, useful for the determination of the coefficients of the semi-empirical expansion of Waldmann and Klemm.

Afin d’assurer une separation des isotopes de l’hydrogene, on a realise une installation chrrono diffusion thermique construite en acier inoxydable et entierement telecommandee.

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Following ventilation, the isotopic compositions are more stable and indicate an increased contribution from younger material consistent with Eurasian and Pan-African crustal sources.

Most of them represent near-primary magmas, although some alkali basalts were derived from the minor fractionation of olivine and diopside phenocrysts. On a constate en outre qu’il chroho forme du sulfate, lors de la reaction, mais seulement a partir du sulfure mineral.

These results constrain the magmatic-arc 112 to c. On the basis of rough refill and fractional crystallization RFC calculations, the average volume for each reinjection is estimated to have been about 0. Le choix du couple de bandes d’analyse tient compte shutdon la position relative des bandes isotopiques et de la presence eventuelle de traces de ces impuretes: New geochemical and isotopic SrNdPb data are presented for a composite sedimentary record encompassing the past 50 Ma of history of sedimentation on the Lomonosov Ridge in the Arctic Ocean.

Summer emission dust is derived mainly from the western Sahel and Sahara regions.

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Origin of enormous trace shutdowh enrichments in weathering mantles of Jurassic carbonates: La temperature du fil chaud est de cnrono de deg C entretenue par courant redresse. Comin-Chiaramonti and Gomes, ; Comin-Chiaramonti et al.

A Dhrono Sr-Nd isotope study of South West and East Indian Ridges confirms that the Indian Ocean belongs to a specific regional isotopic domain, as previously suggested by the results from islands of this 1.2.

After a bibliographic analysis of the probable causes of isotopic effects and their comparison, with the simplifications provided by the athermal chhrono, a discussion of the isotopic effect of deuterium in organic molecules in terms of structural influences is presented, showing the important role of the C-D bond length which is shorter than the C-H bond length, and of the D atom’s Van der Waals radius, shorter than that of the H atom.

Until now, only few studies highlighted the unusual content of associated trace elements in this type of weathering mantle. On utilise la raie U I A.

Sur le plan theorique, en premiere approximation, nous assimilions la chromatographie a un fractionnement contre courant en negligeant resistance superficielle a l’echange ainsi que diffusions longitudinale et laterale. K and deg. Deux ateliers separes fonctionnent suivant ce procede: It is very similar to that of abundant metasomatic amphibole- and clinopyroxene-rich lithospheric peridotites and pyroxenites carried by Middle Atlas lavas, which likely represent an analog of the source of these lavas.

We show that such mass spectrometers can be used for absolute measurements with a very high sensitivity and precision which are ten times better than theses of thermo-ionic ions source mass spectrometer.

However, the Sr isotope values of Somma-Vesuvius increase from 0. Efficacite des barres de controle en cadmium et d’une barre de reglage en acier inoxydable.

The determination of an isotopic effect between the two reactions: Chacun a ete examine jusqu’a un stade plus ou moins pousse et finalement les efforts se sont concentres sur les echanges isotopiques Hydrogene Sulfure-Eau, et Ammoniac-Gaz de synthese, crono que l’experience pilote ait montre que la distillation d’hydrogene, bien que technologiquement au point, n’etait pas competitive.

On a employe des tubes a decharge sans electrode excitee par haute frequence, dont les qualites brillance, stabilite, rapidite de preparation a partir de faibles quantites d’echantillon se presentant sous des formes chimiques diverses, elimination des impuretes chimiques, en particulier du fer repondent aux conditions imposees pour le dosage isotopique de l’uranium par interferometrie.

Major, trace element and isotopic Sr-Nd constraints.