Geochemistry of carbonate microbialites through time and space: Insights from the microbialite collection of the Muséum National d'Histoire Naturelle (MNHN), France

• Published in: Chemical Geology
• Main Authors: Fogret, Laurane, Sansjofre, Pierre, Lalonde, Stefan, V
• Other Authors: Institut de minéralogie, de physique des matériaux et de cosmochimie (IMPMC), Muséum national d'Histoire naturelle (MNHN)-Institut de recherche pour le développement IRD : UR206-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), Geo-Ocean (GEO-OCEAN), Université de Bretagne Sud (UBS)-Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS), MNHN Transhumance support, Origin and Evolution department of the MNHN, M-FED 2021 and CNRS-INSU Tellus fundings., European Project: 716515
• Format: Article in Journal/Newspaper
• Language: English
• Published: HAL CCSD 2024
• Subjects: Microbialite; Stromatolite; Geochemistry; Paleoenvironments; Museum collection; Sample curation; [SDU.STU.GC]Sciences of the Universe [physics]/Earth Sciences/Geochemistry; Antarc*; Antarctica
• Online Access: https://hal.science/hal-04682046; https://hal.science/hal-04682046/document; https://hal.science/hal-04682046/file/Fogret_et_al_2024.pdf; https://doi.org/10.1016/j.chemgeo.2024.122239

International audience Microbialites are microbial sedimentary structures that constitute some of the oldest traces of life on Earth. By their deposition in a wide range of sedimentary environments and their presence throughout most of geological time, the sedimentological and geochemical signatures they preserve represent important paleoenvironmental archives for understanding Earth's biological and geochemical co-evolution. Here we present a large microbialite collection containing >1370 curated specimens, covering all continents except Antarctica and spanning >3.5 Ga of Earth history, that is accessible to the international scientific community for examination and sampling at the Muséum National d'Histoire Naturelle (MNHN) in Paris, France. After cataloguing and evaluating the samples for their lithology, biogenicity, and inferred depositional environments, we characterized the collection for selected geochemical parameters, notably carbonate stable carbon and oxygen isotope ratios, as well as major, trace, and rare earth element compositions. Finally, we explore the different geochemical proxies analyzed with regards to their utility for reconstructing evolving Earth surface environments and/or microbial metabolisms via comparison of geochemical data from the MNHN Microbialite Collection to a compilation of similar proxy data for carbonates worldwide. We demonstrate that certain temporal trends previously recognized in carbonates worldwide (e.g., with respect to variations in C and O stable isotope compositions and redox sensitive trace element enrichments) are well reflected in this collection. Our findings highlight the utility of the MNHN Microbialite Collection and microbialites more generally for reconstructing the conditions associated with habitable environments in deep time and for tracing the response of microbial communities to the geochemical evolution of Earth's surface.