Objectif The appearance of microbial life on Earth is manifested by stromatolites in ~3.5 billion year (Ga) old marine sediments in Pilbara, Australia. The processes involved in the mineralisation and preservation of these earliest signatures of life remain incompletely understood. It has been observed that the stromatolites are mineralised by several generations of carbonate and silica phases, but when and how the different cement phases formed is under debate. Knowing the time and conditions of mineralisation of the stromatolites is necessary to evaluate whether the cements represent primary phases truly indicative of past environmental conditions or a post-depositional overprint. As some of the mineral phases have been suggested to represent reliable archives of ancient Pilbara seawater, they can be used to reconstruct the habitats of the earliest life on Earth. The goal of project ELEMIN is to reconstruct the syn- and post-depositional history of the Pilbara stromatolites and differentiate between primary and later-stage carbonate/silica mineral phases. High-resolution petrographic methods, such as electron backscatter diffraction mapping, in combination with radiometric isotope dating will be applied to date individual mineral phases and to identify pristine mineral phases that were directly precipitated from seawater ~3.5 Ga ago. Trace elements and neodymium isotope compositions of these pristine mineral phases yield detailed insights into the local physico-chemical conditions prevailing at the site of stromatolite growth, such as redox conditions and the source(s) of elements dissolved in Pilbara seawater. Both proxies trace the origin of elements to either continental weathering or to submarine hydrothermal systems. This distinction is essential as it allows us to evaluate contrasting models for early life, suggesting either a peculiar ocean chemistry or submarine hydrothermal systems as the cradle of life. Champ scientifique humanitieshistory and archaeologyhistorynatural scienceschemical sciencesinorganic chemistryinorganic compoundsnatural sciencesphysical sciencesastronomyplanetary sciencesplanetsnatural sciencesearth and related environmental sciencesoceanographyocean chemistry Programme(s) H2020-EU.1.3. - EXCELLENT SCIENCE - Marie Skłodowska-Curie Actions Main Programme H2020-EU.1.3.2. - Nurturing excellence by means of cross-border and cross-sector mobility Thème(s) MSCA-IF-2016 - Individual Fellowships Appel à propositions H2020-MSCA-IF-2016 Voir d’autres projets de cet appel Régime de financement MSCA-IF-EF-ST - Standard EF Coordinateur UNIVERSITAT WIEN Contribution nette de l'UE € 166 156,80 Adresse UNIVERSITATSRING 1 1010 Wien Autriche Voir sur la carte Région Ostösterreich Wien Wien Type d’activité Higher or Secondary Education Establishments Liens Contacter l’organisation Opens in new window Site web Opens in new window Participation aux programmes de R&I de l'UE Opens in new window Réseau de collaboration HORIZON Opens in new window Coût total € 166 156,80