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Resume Les gisements epithermaux de type low-sulfidation a Au et Pb Zn de Troita, Trestia et Magura (monts Apuseni, Roumanie) sont spatialement associes au porphyre cuprifere de Bolcana. Dans l'objectif d'etudier la connexion entre ces mineralisations, une etude geometrique a ete realisee a partir de mesures structurales et d'une representation 3D des differents gisements a l'aide du geomodeleur GOCAD © . Cette etude montre qu'il existe une repartition zonaire des differents filons epithermaux a Au et Pb Zn autour du porphyre, qui ne peut etre due a un telescopage des differents systemes. Pour citer cet article : O. Cardon et al., C. R. Geoscience 337 (2005).

The granitic plutons located north of the Kwyjibo property in Quebec's Grenville Province are of Mesoproterozoic age and belong to the granitic Canatiche Complex . The rocks in these plutons are calc-alkalic, K-rich, and meta- to peraluminous. They belong to the magnetite series and their trace element characteristics link them to intraplate granites. They were emplaced in an anorogenic, subvolcanic environment, but they subsequently underwent significant ductile deformation. The magnetite, copper, and fluorite showings on the Kwyjibo property are polyphased and premetamorphic; their formation began with the emplacement of hydraulic, magnetite-bearing breccias, followed by impregnations and veins of chalcopyrite, pyrite, and fluorite, and ended with a late phase of mineralization, during which uraninite, rare earths, and hematite were emplaced along brittle structures. The plutons belong to two families: biotite-amphibole granites and leucogranites. The biotite-amphibole granites are rich in iron and represent a potential heat and metal source for the first, iron oxide phase of mineralization. The leucogranites show a primary enrichment in REE (rare-earth elements), F, and U, carried mainly in Y-, U-, and REE-bearing niobotitanates. They are metamict and underwent a postmagmatic alteration that remobilized the uranium and the rare earths. The leucogranites could also be a source of rare earths and uranium for the latest mineralizing events.[Traduit par la Rédaction]

Foraminifera representing two species are decalcified by E.D.T.A. and then allowed to mineralize by removing E.D.T.A. of the sea water medium. This mineralization occurs under usual conditions for the control group and under induced radial acceleration of 1.6 G for the experimental group (resulting acceleration 1.9 G). Atomic Ca and Mg distribution is analyzed by means of X-ray microprobe. Interplanar d values of the calcite unit-cell and peak broadenings are determined by X-ray diffraction. In one species increased gravity has no influence upon variation of Mg/Ca concentration ratio and d values but increases peak broadening. In the other species increased gravity decreases Mg/Ca concentration ratio, increases some d values and decreases the width of some peaks. Mechanism at cell membrane level is proposed., Deux espèces de Foraminifères ont été décalcifiées à l'E.D.T.A. pour permettre la reminéralisation du test après remplacement du chélateur par de l'eau de mer. Cette minéralisation a lieu sous des conditions normales d'élevage pour le groupe témoin, et sous une accélération de 1,6 G pour le groupe expérimental (accélération résultante de 1,9 G). La distribution des atomes de Ca et de Mg est analysée à l'aide de la microsonde à rayons X. Les distances interréticulaires d ainsi que les largeurs des pics de diffraction sont mesurées par diffractométrie X. L'effet de l'augmentation de la gravité se traduit différemment chez les deux espèces considérées : absence de variation du rapport de concentration Mg/Ca, absence de variation des distances interréticulaires d et accroissement des valeurs des pics de diffraction chez l'une, diminution du rapport Mg/Ca, augmentation des valeurs de d et diminution des largeurs des pics chez l'autre. Une action au niveau de la membrane cellulaire est proposée., Very Jean-Michel, Le Campion Joël. Effect of increased gravity on calcitic mineralization of test of foraminifera (protozoa). In: Bulletin de Minéralogie, volume 105, 3, 1982. pp. 280-283.

Tin-bearing alluvial deposits and cassiterite-bearing kaolinized granulite have been discovered at La Villefoucre near Nozay, west of the area of tin mineralization of the Abbaretz district, France. The alluvial deposits are not important, but this is the first time a cassiterite-bearing kaolinized granulite has been reported in the Armorican massif; only vein occurrences of tin have been known previously. A connection between the veins and the extension in depth of the Nozay granulite is established.