| Autor: |
Thomazo C; Biogéosciences, UMR6282, CNRS, Université Bourgogne Franche-Comté, Dijon, France., Couradeau E; Joint Genome Institute, Lawrence Berkeley National Lab, Walnut Creek, California., Giraldo-Silva A; Center for Fundamental and Applied Microbiomics, Biodesign Institute, and School of Life Sciences, Arizona State University, Tempe, Arizona., Marin-Carbonne J; Institut des Sciences de la Terre, Université de Lausanne, Lausanne, Suisse., Brayard A; Biogéosciences, UMR6282, CNRS, Université Bourgogne Franche-Comté, Dijon, France., Homann M; European Institute for Marine Studies, CNRS-UMR6538, Laboratoire Géosciences Océan, Technopôle Brest-Iroise, Plouzané, France.; Department of Earth Sciences, University College London, London, United Kingdom., Sansjofre P; European Institute for Marine Studies, CNRS-UMR6538, Laboratoire Géosciences Océan, Technopôle Brest-Iroise, Plouzané, France.; MNHN, Sorbonne Université, CNRS UMR 7590, IRD, Institut de Minéralogie, de Physique des Matériaux et de Cosmochimie, Paris, France., Lalonde SV; European Institute for Marine Studies, CNRS-UMR6538, Laboratoire Géosciences Océan, Technopôle Brest-Iroise, Plouzané, France., Garcia-Pichel F; Center for Fundamental and Applied Microbiomics, Biodesign Institute, and School of Life Sciences, Arizona State University, Tempe, Arizona. |
| Abstrakt: |
Stable isotope signatures of elements related to life such as carbon and nitrogen can be powerful biomarkers that provide key information on the biological origin of organic remains and their paleoenvironments. Marked advances have been achieved in the last decade in our understanding of the coupled evolution of biological carbon and nitrogen cycling and the chemical evolution of the early Earth thanks, in part, to isotopic signatures preserved in fossilized microbial mats and organic matter of marine origin. However, the geologic record of the early continental biosphere, as well as its evolution and biosignatures, is still poorly constrained. Following a recent report of direct fossil evidence of life on land at 3.22 Ga, we compare here the carbon and nitrogen isotopic signals of this continental Archean biosphere with biosignatures of cyanobacteria biological soil crusts (cyanoBSCs) colonizing modern arid environments. We report the first extended δ 13 C and δ 15 N data set from modern cyanoBSCs and show that these modern communities harbor specific isotopic biosignatures that compare well with continental Archean organic remains. We therefore suggest that cyanoBSCs are likely relevant analogs for the earliest continental ecosystems. As such, they can provide key information on the timing, extent, and possibly mechanism of colonization of the early Earth's emergent landmasses. |
