HR: 0800h
AN: B21B-0890 [Abstracts]
TI: Silicate-carbonate-microorganism interface studied by high resolution TEM and electron energy loss
spectroscopy
AU: * MENGUY, N
EM: menguy@lmcp.jussieu.fr
AF: Laboratoire de Mineralogie Cristallographie, UMR 7590 CNRS Universite PARIS 7 & IPGP, 4 place Jussieu,
PARIS, 75252
France
AU: Benzerara, K
EM: benzerar@stanford.edu
AF: Surface & Aqueous Geochemistry Group, Department of Geological and Environmental Sciences, Stanford
University, Stanford, CA 94305-2115
United States
AU: Guyot, F
EM: guyot@lmcp.jussieu.fr
AF: Laboratoire de Mineralogie Cristallographie, UMR 7590 CNRS Universite PARIS 7 & IPGP, 4 place Jussieu,
PARIS, 75252
France
AU: Vanni, C
EM: christian.vanni@univ-mrs.fr
AF: Centre Pluridisciplinaire de Microscopie et de Microanalyse, case 151,Faculte des Sciences et Techniques
de Saint Jerome
Universite Paul Cezanne, Marseille, 13397
France
AB:
The biogeochemical alteration of an Mg-Fe orthopyroxene (Tatahouine meteorite) reacted under arid conditions in a desert
environment was studied by transmission electron microscopy (TEM).
The focused ion beam method has been used to prepare an electron transparent cross section of the interface between a single
microorganism, an orthopyroxene and nanometer-sized calcite crystals.
The microorganism en route to fossilization and the nanometer-sized calcite crystals were identified using X-ray energy
dispersive spectroscopy and electron energy loss spectroscopy (EELS). High resolution TEM observations reveal a close
relationship between the microorganism and the surface of the orthopyroxene. Moreover, a 100 nm deep depression was observed
in the orthopyroxene close to the microorganism, suggesting an enhanced dissolution mediated by the microbe. EELS
measurements have also shown the existence of carbonyl or carboxyl groups associated with the calcite nano-crystals that
could be related to the unusual morphology and structure of these calcite crystals.
DE: 3954 X ray, neutron, and electron spectroscopy and diffraction
DE: 0400 Biogeosciences
SC: Biogeosciences [B]
MN: 2004 AGU Fall Meeting