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| Toner, Brandy M.; Rouxel, Olivier; Santelli, Cara M.; Bach, Wolfgang; Edwards, Katrina J.. |
| Hydrothermal sulfide chimneys located along the global system of oceanic spreading centers are habitats for microbial life during active venting. Hydrothermally extinct, or inactive, sulfide deposits also host microbial communities at globally distributed sites. The main goal of this study is to describe Fe transformation pathways, through precipitation and oxidation-reduction (redox) reactions, and examine transformation products for signatures of biological activity using Fe mineralogy and stable isotope approaches. The study includes active and inactive sulfides from the East Pacific Rise 9 degrees 50'N vent field. First, the mineralogy of Fe(III)-bearing precipitates is investigated using microprobe X-ray absorption spectroscopy (RXAS) and X-ray... |
| Tipo: Text |
Palavras-chave: Hydrothermal; East Pacific Rise; X-ray absorption spectroscopy; Stable isotopes; Micro-environment; Mineral alteration; Iron; Biosignature. |
| Ano: 2016 |
URL: http://archimer.ifremer.fr/doc/00337/44810/44375.pdf |
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| Gong, Jian; Myers, Kimberly D.; Munoz-saez, Carolina; Homann, Martin; Rouillard, Joti; Wirth, Richard; Schreiber, Anja; Van Zuilen, Mark A.. |
| Palisade fabric is a ubiquitous texture of silica sinter found in low temperature (<40 degrees C) regimes of hot spring environments, and it is formed when populations of filamentous microorganisms act as templates for silica polymerization. Although it is known that postdepositional processes such as biological degradation and dewatering can strongly affect preservation of these fabrics, the impact of extreme aridity has so far not been studied in detail. Here, we report a detailed analysis of recently silicified palisade fabrics from a geyser in El Tatio, Chile, tracing the progressive degradation of microorganisms within the silica matrix. This is complemented by heating experiments of natural sinter samples to assess the role of diagenesis. Sheathed... |
| Tipo: Text |
Palavras-chave: Silica sinter; Biosignature; El Tatio; Sheathed cyanobacteria; Experimental diagenesis; Mars. |
| Ano: 2020 |
URL: https://archimer.ifremer.fr/doc/00637/74902/76135.pdf |
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