Résonance paramagnétique électronique de biosignatures carbonées au sein de roches siliceuses primitives: De la vie primitive sur Terre à la recherche de traces de vie fossile
The oldest traces of primitive terrestrial life are fossilized form of carbonaceous microstructures
trapped in microcrystalline siliceous rocks (flint , chert in English) . The techniques typically used for
their detection (light and electron microscopy , Raman spectroscopy , . ) mainly the surface ( or near
surface area ) and often require sample preparation. In situ detection of the non-invasive and
primitive carbonaceous material is however possible if spectroscopy penetrating radiation such as
microwave or radio frequencies is used. We have recently shown interest in the electron
paramagnetic resonance (EPR ) for the search of the first traces of primitive life, and to study the
structure and origin of carbonaceous matter in carbonaceous meteorites , among the objects the
most primitive solar system (1-11) . Based on the detection of unpaired electrons in organic radicals
or defects / impurities in the inorganic matrix spins, this technique can detect, analyze and date
without any preparation or extract fossil carbon material , even very scarce within Archean flint (up
to 3.5 billion years) ( 3,10 ) . By means of magnetic field gradients superimposed on the static
magnetic field , it is possible to produce 3D images of the distribution of carbon in the rock ( 5 ) . The
apparatus generally X-band EPR (~ 9.4 GHz ) with a magnetic field ( ~ 350 mT ) requiring a large
electromagnet , so they are well suited to the study of terrestrial rocks or Martian rocks in the
context of a sample return mission . They are absolutely not adapted for spatial uses in this
configuration. With financial support from CNES , we currently carry ( LASIR , Lille) EPR apparatus
operating at very low frequency (250 MHz) with ultra light weight to be adaptable to a lander for a
mission to Mars. However, the large frequency difference between the two devices requires a
thorough study of the EPR at very low frequency of carbonate rocks , for which there is currently no
The thesis proposed several aspects in the study of Archean rocks containing traces of probable or
The goal is to refine the methodology RPE in five directions :
1) Identify indisputable magnetic biosignatures , to distinguish between a biological carbon and
abiotic carbon ( chemical reaction, decomposition of carbonates, meteoritic carbon etc. .) ;
2) Improve the dating method of the RPE that we recently proposed carbonaceous material (3, 10 )
to distinguish between contemporary primitive life of the rock formation , and carbon contamination
from the rear by endolithic bacteria for example ;
3) Identify specific biosignatures primitive metabolism. These studies will require the synthesis of
analogues (encapsulated biomolecules and artificially aged silica and bacteria).
4) Search and study of inorganic paramagnetic potential biosignatures , such as VO2 + ions vanadyles
5) Undertake studies RPE very low frequency (250 MHz) of Archean rocks to assess the potential of
the equipment under construction for the study of carbon and inorganic biosignatures in Martian
Laboratories will be the thesis: This will be done in LASIR Lille (H. Vezin) and Chemistry-ParisTech (D. Gourier) for the RPE, in collaboration with the laboratory of UPMC
BIOEMCO (S. Derenne) for primitive metabolism and the CBM Orleans (F. Westall) for the
Candidate Profile: The candidate should preferably be a physical chemist materials. Interest for spectroscopy is highly desirable. An interest for exobiology is a plus. Financing of the thesis: Centre National d'Etudes Spatiales (CNES), confirmed. Directors of thesis : Laboratoire de chimie de la matière condensée de Paris, UMR CNRS-7574, Chimie-ParisTech, 11 rue Pierre et Marie Curie 75005 Paris, Pr. Didier Gourier, et Laboratoire de spectrochimie infrarouge et Raman, UMR CNRS-8516, Lille, Dr. Hervé Vezin Contacts : [email protected]; [email protected] Références: 1) Extreme deuterium enrichment of organic radicals in the Orgueil meteorite: revisiting the interstellar interpretation ? D. GOURIER, F.
ROBERT, O. DELPOUX, L. BINET, H. VEZIN, A. MOISSETTE, S. DERENNE, Geochim. Cosmochim. Acta. 72 (2008) p. 1914-1923 2) CW and Pulsed-EPR of carbonaceous matter in primitive meteorites: solving the lineshape paradox, O. DELPOUX, D. GOURIER, L. BINET, H. VEZIN, S. DERENNE and F. ROBERT, Spectrochim. Acta Part A69 (2008) p. 1301-1310 3) EPR of radicals in primitive organic matter: a tool for the search of biosignatures of the most ancient traces of life, A. SKRYPCZAK- BONDUELLE, L. BINET, O. DELPOUX, H. VEZIN, S. DERENNE, F. ROBERT and D. GOURIER. Appl. Magn. Reson. 33 (2008) p. 371-397 4) Molecular evidence for life in the 3.5 billion year old Warrawoona chert, S. DERENNE, F. ROBERT, A. SKRZYPCZAK-BONDUELLE, D. GOURIER, L. BINET, J.N. ROUZAUD, Earth Planet Sci. Lett. 272 (2008) p. 476 - 480 5) Potential of EPR imaging to detect traces of life in the oldest sedimentary rocks, L. BINET, D. GOURIER, S. DERENNE, Earth Planet Sci. Lett. 273 (2008) p. 359-366. 6) Proto-Planetary Disk Chemistry Recorded by D-rich Organic Radicals in Carbonaceous Chondrite, L. REMUSAT, F. ROBERT, A. MEIBOM, S. MOSTEFAOUI, O. DELPOUX, L. BINET, D. GOURIER, S. DERENNE, The Astrophysical Journal698 (2009) p. 2087-2092. 7) EPR, ENDOR and HYSCORE study of the structure and the stability of vanadyl-porphyrin complexes encapsulated in silica: Potential paramagnetic biomarkers for the origin of life. D. GOURIER, O. DELPOUX, A. SKRZYPCZAK-BONDUELLE, L. BINET, I. CIOFINI, H. VEZIN. J. Phys. Chem. B114 (2010) p. 3714-3725 8) Biradical character of the D-rich carriers in the insoluble organic matter of carbonaceous chondrites: A relic of the protoplanetary disk chemistry. O. DELPOUX, D. GOURIER, H. VEZIN, L. BINET, S. DERENNE, F. ROBERT, Geochim. Cosmochim. Acta75 (2011) p. 326-336. 9) Electron paramagnetic resonance study of a photosynthetic microbial mat and comparison with Archean cherts, M. BOURBIN, S. DERENNE, F. WESTALL, D. GOURIER, J.N. ROUZAUD, P. GAUTRET, Origin of Life and Evolution of the Biosphere42 (2012) p. 569-585 10) Dating the carbonaceous matter and detection of contamination in Precambrian cherts by Electron Paramagnetic Resonance, M. BOURBIN, D. GOURIER, S. DERENNE, L. BINET, Y. LE DU, F. WESTALL, F. ROBERT, B. KREMER, P. GAUTRET, Astrobiology13 (2013) p. 151-162 11) Nuclear Magnetic signatures of exctinct Life detected by Electron Paramagnetic Resonance in primitive Carbonaceous Matter, D. GOURIER, O. DELPOUX, L. BINET, H. VEZIN, Astrobiology (accepté)
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