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Institut de minéralogie, de physique des matériaux et de cosmochimie
UMR 7590 - UPMC/CNRS/IRD/MNHN

PhD Thesis - Nina Zeyen

Study of modern microbialites from Mexican crater lakes

ERC Calcyan - Advisor K. Benzerara (Geobio-IMPMC)

 

Microbialites are organo-sedimentary rocks found in abundance throughout the geological record back to ~3.5 Ga. Interpretations on how and under which conditions ancient microbialites formed are based on actualism, i.e., a comparison with modern microbialites. Therefore, a better characterization of diverse modern microbialites is crucial to improve such interpretations. For this purpose, we studied modern microbialites from several Mexican alkaline crater lakes located in the Trans-Mexican Volcanic Belt. One of the objectives is to characterize microbialites and better understand the relationship between their composition and the chemical composition of the lakes as well as document the spatial associations of organic polymers with mineral phases down to the nm-scale and the possible traces of life preserved in the mineral part of the microbialites. For that purpose, we combined a geochemical characterization of the surface water of the lakes with bulk x-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR) and electron and x-ray microscopy analyses of the microbialites. Altogether, these analyses reveal the pervasiveness of an authigenic poorly crystalline silicate phase, rich in Mg and sometimes Fe and/or Mn Moreover, these results showed that organic carbon is pervasively associated with kerolite. Overall, it is suggested that the poorly-crystalline hydrated magnesium-rich silicate may result from a biomineralization process. The conditions and mechanisms of its formation as well as its importance in the fossilization of microbial communities in lacustrine microbialites are studied. Finally, the frequent occurrence of such an authigenic silicate phase in modern lacustrine microbialites calls for a reappraisal of its potential presence in ancient rocks.

Sylvain Bernard - 17/02/16

Traductions :

    Stabilité des pigments au chrome dans les glaçures de la Manufacture de Sèvres

    Dès sa découverte, le chrome a été utilisé pour colorer des céramiques. En effet, les oxydes de chrome permettent d’obtenir une large variété de couleurs et sont ainsi utilisés comme pigments. Par exemple, en substitution de l’aluminium dans les structures spinelles ZnAl2O4 ou corindon Al2O3, des composés...

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    Contact

    Guillaume Fiquet (Guillaume.Fiquet @ impmc.upmc.fr)

    Directeur de l'institut

    33 +1 44 27 52 17

     

    Nalini Loret (Nalini.Loret @ impmc.upmc.fr)

    Attachée de direction

    33 +1 44 27 52 17

     

    Dany Thomas-Emery (danielle.thomas @ impmc.upmc.fr)

    Gestion du personnel

    33 +1 44 27 74 99

     

    Danielle Raddas (cecile.duflot @ impmc.upmc.fr)

    Gestion financière

    33 +1 44 27 56 82

     

    Cécile Duflot (cecile.duflot @ impmc.upmc.fr)

    Chargée de communication

    33 +1 44 27 46 86

     

    Adresse postale

    Institut de minéralogie, de physique des matériaux et de cosmochimie - UMR 7590

    Université Pierre et Marie Curie - 4, place Jussieu - BC 115 - 75252 Paris Cedex 5

     

    Adresse physique

    Institut de minéralogie, de physique des matériaux et de cosmochimie - UMR 7590

    Université Pierre et Marie Curie - 4, place Jussieu - Tour 23 - Barre 22-23, 4e étage - 75252 Paris Cedex 5

     

    Adresse de livraison

    Accès : 7 quai Saint Bernard - 75005 Paris, Tour 22.

    Contact : Antonella Intili : Barre 22-23, 4e étage, pièce 420, 33 +1 44 27 25 61

     

     

    Fax : 33 +1 44 27 51 52

    Geobio Team @ IMPMC

    The Geobio Team @ IMPMC brings together :

     - 10 permanent members

     - 3 postdoctoral fellows

     - 6 PhD students