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| Marin-carbonne, Johanna; Rollion-bard, Claire; Bekker, Andrey; Rouxel, Olivier; Agangi, Andrea; Cavalazzi, Barbara; Wohlgemuth-ueberwasser, Cora C.; Hofmann, Axel; Mckeegan, Kevin D.. |
| Iron and sulfur isotope compositions recorded in ancient rocks and minerals such as pyrite (FeS2) have been widely used as a proxy for early microbial metabolisms and redox evolution of the oceans. However, most previous studies focused on only one of these isotopic systems. Herein, we illustrate the importance of in-situ and coupled study of Fe and S isotopes on two pyrite nodules in a c. 2.7 Ga shale from the Bubi Greenstone Belt (Zimbabwe). Fe and S isotope compositions were measured both by bulk-sample mass spectrometry techniques and by ion microprobe in-situ methods (Secondary Ion Mass Spectrometry, SIMS). Spatially-resolved analysis across the nodules shows a large range of variations at micrometer-scale for both Fe and S isotope compositions, with... |
| Tipo: Text |
Palavras-chave: Pyrite nodules; Fe and S isotopes; Archean; SIMS. |
| Ano: 2014 |
URL: http://archimer.ifremer.fr/doc/00177/28824/27324.pdf |
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| Hickman-lewis, Keyron; Gautret, Pascale; Arbaret, Laurent; Sorieul, Stéphanie; De Wit, Rutger; Foucher, Frédéric; Cavalazzi, Barbara; Westall, Frances. |
| Morphologically diverse organo-sedimentary structures (including microbial mats and stromatolites) provide a palaeobiological record through more than three billion years of Earth history. Since understanding much of the Archaean fossil record is contingent upon proving the biogenicity of such structures, mechanistic interpretations of well-preserved fossil microbialites can reinforce our understanding of their biogeochemistry and distinguish unambiguous biological characteristics in these structures, which represent some of the earliest records of life. Mechanistic morphogenetic understanding relies upon the analysis of geomicrobiological experiments. Herein, we report morphological-biogeochemical comparisons between micromorphologies observed in growth... |
| Tipo: Text |
Palavras-chave: Microbial mat; Stromatolite; Anoxygenic photosynthesis; X-ray micro-scale computed tomography; Archaean; Early life; Dresser Formation; Middle Marker horizon. |
| Ano: 2019 |
URL: https://archimer.ifremer.fr/doc/00512/62323/66580.pdf |
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| Jebbar, Mohamed; Hickman-lewis, Keyron; Cavalazzi, Barbara; Taubner, Ruth-sophie; Rittmann, Simon K.-m. R.; Antunes, Andre. |
| The icy moons of the outer Solar System harbor potentially habitable environments for life, however, compared to the terrestrial biosphere, these environments are characterized by extremes in temperature, pressure, pH, and other physico-chemical conditions. Therefore, the search for life on these icy worlds is anchored on the study of terrestrial extreme environments (termed “analogue sites”), which harbor microorganisms at the frontiers of polyextremophily. These so-called extremophiles have been found in areas previously considered sterile: hot springs, hydrothermal vents, acidic or alkaline lakes, hypersaline environments, deep sea sediments, glaciers, and arid areas, amongst others. Such model systems and communities in extreme terrestrial environments... |
| Tipo: Text |
Palavras-chave: Extremophiles; Prokaryotes; Metabolism; Diversity; Adaptation; Space explorat. |
| Ano: 2020 |
URL: https://archimer.ifremer.fr/doc/00606/71771/70275.pdf |
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