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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

Mucoviscidose : simuler pour mieux soigner

La mucoviscidose est la plus fréquente des maladies rares, touchant principalement les fonctions respiratoires et digestives et affectant en moyenne 1 nouveau né sur 4 500 en France. Cette maladie génétique potentiellement grave est le résultat de mutations affectant la protéine CFTR (Cystic Fibrosis...

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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