Molecular preservation of 1.88 Ga Gunflint organic microfossils as a function of temperature and mineralogy.
The significant degradation that fossilized biomolecules may experience during burial makes it challenging to assess the biogenicity of organic microstructures in ancient rocks. Here we investigate the molecular signatures of 1.88 Ga Gunflint organic microfossils as a function of their diagenetic history. Synchrotron-based XANES data collected in situ on individual microfossils, at the submicrometre scale, are compared with data collected on modern microorganisms. Despite diagenetic temperatures of ∼150-170 °C deduced from Raman data, the molecular signatures of some Gunflint organic microfossils have been exceptionally well preserved. Remarkably, amide groups derived from protein compounds can still be detected. We also demonstrate that an additional increase of diagenetic temperature of only 50 °C and the nanoscale association with carbonate minerals have significantly altered the molecular signatures of Gunflint organic microfossils from other localities. Altogether, the present study provides key insights for eventually decoding the earliest fossil record.
Institut de Minéralogie, de Physique des Matériaux et de Cosmochimie (IMPMC), Sorbonne Universités - CNRS UMR 7590, Muséum National d'Histoire Naturelle, UPMC Univ Paris 06, IRD UMR 206, 61 rue Buffon, 75005 Paris, France.
Julien
J
Alleon
Institut de Minéralogie, de Physique des Matériaux et de Cosmochimie (IMPMC), Sorbonne Universités - CNRS UMR 7590, Muséum National d'Histoire Naturelle, UPMC Univ Paris 06, IRD UMR 206, 61 rue Buffon, 75005 Paris, France.
Sylvain
S
Bernard
Institut de Minéralogie, de Physique des Matériaux et de Cosmochimie (IMPMC), Sorbonne Universités - CNRS UMR 7590, Muséum National d'Histoire Naturelle, UPMC Univ Paris 06, IRD UMR 206, 61 rue Buffon, 75005 Paris, France.
Corentin
C
Le Guillou
Univ Lyon, UJM Saint Etienne, Laboratoire Magma et Volcans, UBP, CNRS, IRD, 23 rue Dr Paul Michelon, 42100 St Etienne, France.
Johanna
J
Marin-Carbonne
Institut de Minéralogie, de Physique des Matériaux et de Cosmochimie (IMPMC), Sorbonne Universités - CNRS UMR 7590, Muséum National d'Histoire Naturelle, UPMC Univ Paris 06, IRD UMR 206, 61 rue Buffon, 75005 Paris, France.
Sylvain
S
Pont
Institut de Minéralogie, de Physique des Matériaux et de Cosmochimie (IMPMC), Sorbonne Universités - CNRS UMR 7590, Muséum National d'Histoire Naturelle, UPMC Univ Paris 06, IRD UMR 206, 61 rue Buffon, 75005 Paris, France.
Olivier
O
Beyssac
Department of Earth, Planetary and Space Sciences, University of California-Los Angeles, 595 Charles Young Drive East, Los Angeles, California 90095-1567, USA.
Kevin D
KD
McKeegan
Institut de Minéralogie, de Physique des Matériaux et de Cosmochimie (IMPMC), Sorbonne Universités - CNRS UMR 7590, Muséum National d'Histoire Naturelle, UPMC Univ Paris 06, IRD UMR 206, 61 rue Buffon, 75005 Paris, France.
François
F
Robert
D002254:Carbonates / Q000032:analysis*; D005580:Fossils / Q000648:ultrastructure*; D019015:Geologic Sediments / Q000032:analysis*; D046529:Microscopy, Electron, Transmission; D008910:Minnesota; D009864:Ontario; D010163:Paleontology / Q000295:instrumentation / Q000379:methods; D011309:Preservation, Biological; D011791:Quartz / Q000032:analysis*; D012822:Silicon Dioxide / Q000032:analysis*; D013059:Spectrum Analysis, Raman; D013696:Temperature; D056928:X-Ray Absorption Spectroscopy; D014961:X-Ray Diffraction
D002254:Carbonates; D011791:Quartz; D012822:Silicon Dioxide