| Title | Interplay between abiotic and microbial biofilm-mediated processes for travertine formation: Insights from a thermal spring (Piscine Carletti, Viterbo, Italy) |
| Abstract | Most Neoproterozoic iron formations (NIF) are closely associated with global or near-global "Snowball Earth" glaciations. Increasingly, however, studies indicate that some NIFs show no robust evidence of glacial association. Many aspects of non-glacial NIF genesis, including the paleo-environmental setting, Fe(II) source, and oxidation mechanisms, are poorly understood. Here, we present a detailed case study of the Jiapigou NIF, a major non-glacial NIF within a Neoproterozoic volcano-sedimentary sequence in North Qilian, northwestern China. New U-Pb geochronological data place the depositional age of the Jiapigou NIF at ~600 Ma. Petrographic and geochemical evidence supports its identification as a primary chemical sediment with significant detrital input. Major and trace element concentrations, REE + Y systematics, and epsilonNd(t) values indicate that iron was sourced from mixed seawater and hydrothermal fluids. Iron isotopic values (delta56Fe = -0.04%O-1.43%O) are indicative of partial oxidation of an Fe(II) reservoir. We infer that the Jiapigou NIF was deposited in a redox stratified water column, where hydrothermally sourced Fe(II)-rich fluids underwent oxidation under suboxic conditions. Lastly, the Jiapigou NIF has strong phosphorous enrichments, which in other iron formations are typically interpreted as signals for high marine phosphate concentrations. This suggests that oceanic phosphorus concentrations could have been enriched throughout the Neoproterozoic, as opposed to simply during glacial intervals. |
| Source | Geobiology (Online) 20 (6), pp. 837–856 |
| Keywords | biofilms; gypsum; hot spring; microbial mat; travertine |
| Journal | Geobiology (Online) |
| Editor | Blackwell., Oxford, Regno Unito |
| Year | 2022 |
| Type | Articolo in rivista |
| DOI | 10.1111/gbi.12516 |
| Authors | Venturi S.[1,2], Crognale S.[3], Di Benedetto F.[4], Montegrossi G.[2], Casentini B.[3], Amalfitano S.[3], Baroni T.[1], Rossetti S.[3], Tassi F.[1,2], Capecchiacci F.[1,2,5], Vaselli O.[1,2], Fazi S.[3] |
| Text | 472683 2022 10.1111/gbi.12516 Scopus 2 s2.0 85135558443 biofilms; gypsum; hot spring; microbial mat; travertine Interplay between abiotic and microbial biofilm mediated processes for travertine formation Insights from a thermal spring Piscine Carletti, Viterbo, Italy Venturi S. 1,2 , Crognale S. 3 , Di Benedetto F. 4 , Montegrossi G. 2 , Casentini B. 3 , Amalfitano S. 3 , Baroni T. 1 , Rossetti S. 3 , Tassi F. 1,2 , Capecchiacci F. 1,2,5 , Vaselli O. 1,2 , Fazi S. 3 1 Department of Earth Sciences, University of Florence, Florence, Italy; 2 Institute of Geosciences and Earth Resources IGG , National Research Council of Italy CNR , Florence, Italy; 3 Water Research Institute IRSA , National Research Council of Italy CNR , Rome, Italy; 4 Department of Physics and Earth Sciences, University of Ferrara, Ferrara, Italy; 5 Istituto Nazionale di Geofisica e Vulcanologia, Sezione di Napoli, Osservatorio Vesuviano, Naples, Italy Most Neoproterozoic iron formations NIF are closely associated with global or near global Snowball Earth glaciations. Increasingly, however, studies indicate that some NIFs show no robust evidence of glacial association. Many aspects of non glacial NIF genesis, including the paleo environmental setting, Fe II source, and oxidation mechanisms, are poorly understood. Here, we present a detailed case study of the Jiapigou NIF, a major non glacial NIF within a Neoproterozoic volcano sedimentary sequence in North Qilian, northwestern China. New U Pb geochronological data place the depositional age of the Jiapigou NIF at 600 Ma. Petrographic and geochemical evidence supports its identification as a primary chemical sediment with significant detrital input. Major and trace element concentrations, REE Y systematics, and epsilonNd t values indicate that iron was sourced from mixed seawater and hydrothermal fluids. Iron isotopic values delta56Fe = 0.04%O 1.43%O are indicative of partial oxidation of an Fe II reservoir. We infer that the Jiapigou NIF was deposited in a redox stratified water column, where hydrothermally sourced Fe II rich fluids underwent oxidation under suboxic conditions. Lastly, the Jiapigou NIF has strong phosphorous enrichments, which in other iron formations are typically interpreted as signals for high marine phosphate concentrations. This suggests that oceanic phosphorus concentrations could have been enriched throughout the Neoproterozoic, as opposed to simply during glacial intervals. 20 Published version https //onlinelibrary.wiley.com/journal/14724669 Interplay between abiotic and microbial biofilm mediated processes for travertine formation Insights from a thermal ... VENTURI_November_2022.pdf Articolo in rivista Blackwell. 1472 4669 Geobiology Online Geobiology Online Geobiol. Online Geobiology. Online orlandovaselli VASELLI ORLANDO francotassi TASSI FRANCO francescocapecchiacci CAPECCHIACCI FRANCESCO VENTURI STEFANIA simona.rossetti ROSSETTI SIMONA giordano.montegrossi MONTEGROSSI GIORDANO stefano.fazi FAZI STEFANO stefano.amalfitano AMALFITANO STEFANO barbara.casentini CASENTINI BARBARA simona.crognale CROGNALE SIMONA |
