georefid:1994-048565SEDIS Publication Catalogueana.macario@awi.dehttp://sedis.iodp.org/pub-catalogue/informationpointOfContact2011-06-23T00:00:00Zhttp://sedis.iodp.org/pub-catalogue/index.php?id=1994-048565<gco:CharacterString>Mecanismes de formation des argiles des halos noirs de basaltes oceaniques Formation mechanism of clays in the oceanic basaltic black halos</gco:CharacterString>1990-01-01publicationgeorefid:1994-048565Buatier, M.Inst. Geologie, Strasbourg, FranceauthorHonnorez, J.authorGauthier-Villars, Montrouge, FrancepublisherdocumentHardcopyComptes Rendus de l'Academie des Sciences, Serie 2, Mecanique, Physique, Chimie, Sciences de l'Univers, Sciences de la Terre310 (11)1497-1503Clay minerals in vesicles and miarolitic voids form black halos in zero age oceanic basalts. They correspond to mixtures of Fe-smectites with celadonite or glauconite. They are Fe-rich and present variable Al, Mg and K contents. The observation of these clay minerals at scales ranging from that of petrographic microscope to that of high resolution transmission electron microscope indicates that their formation mechanisms are very complex : they form not only by precipitating directly from hydrothermal fluids mixed with seawater but also by replacing basalt primary pyroxene and mesostasiscompletedMineralogy of silicatesIgneous and metamorphic petrologybasaltsceladoniteCenozoicchemical compositionclay mineralsDeep Sea Drilling ProjectEast Pacific Ocean Islandsfluid phaseGalapagos Islandsglauconitehydrothermal alterationigneous rocksiron-rich compositionmelangemetasomatismmica groupmid-ocean ridgesNeogeneocean floorsPleistocenePlioceneQuaternarysea watersheet silicatessilicatessmectiteTEM dataTertiarytholeiitic basaltvolcanic rocksX-ray diffraction dataFrenchgeoscientificInformation-92.0000-89.0000-1.30001.0000Galapagos Islands