Formation of stromatolite lamina at the interface of oxygenic–anoxygenic photosynthesis |
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| Authors: | A Pace R Bourillot A Bouton E Vennin O Braissant C Dupraz T Duteil I Bundeleva P Patrier S Galaup Y Yokoyama M Franceschi A Virgone P T Visscher |
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| Institution: | 1. EA 4592, Géoressources & Environnement, Ensegid, Bordeaux INP, Pessac, France;2. Université Bordeaux Montaigne, Pessac, France;3. Laboratoire Biogéosciences, UMR 6282 UBFC/CNRS, Université Bourgogne Franche‐Comté, Dijon, France;4. Total, CSTJF, Pau, France;5. Center for Biomechanics and Biocalorimetry, University of Basel, Basel, Switzerland;6. Department of Geological Sciences, Stockholm University, Stockholm, Sweden;7. UMR 7285 CNRS IC2MP, Université de Poitiers, Poitiers, France;8. Department of Earth and Planetary Sciences, Atmosphere and Ocean Research Institute, University of Tokyo, Chiba, Japan;9. Department of Marine Sciences, University of Connecticut, Groton, CT, USA |
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| Abstract: | In modern stromatolites, mineralization results from a complex interplay between microbial metabolisms, the organic matrix, and environmental parameters. Here, we combined biogeochemical, mineralogical, and microscopic analyses with measurements of metabolic activity to characterize the mineralization processes and products in an emergent (<18 months) hypersaline microbial mat. While the nucleation of Mg silicates is ubiquitous in the mat, the initial formation of a Ca‐Mg carbonate lamina depends on (i) the creation of a high‐pH interface combined with a major change in properties of the exopolymeric substances at the interface of the oxygenic and anoxygenic photoautotrophic layers and (ii) the synergy between two major players of sulfur cycle, purple sulfur bacteria, and sulfate‐reducing bacteria. The repetition of this process over time combined with upward growth of the mat is a possible pathway leading to the formation of a stromatolite. |
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| Keywords: | anoxygenic photosynthesis oxygenic photosynthesis stromatolite |
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