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SUMMARY:EESS talk on "Sub-micrometer pyrites in stromatolites recorded iso
 topic fingerprints of microbial activities through time "
DTSTART:20210316T121500
DTEND:20210316T130000
DTSTAMP:20260602T070927Z
UID:703e46779d87a767bb297c67a33fcbdfd43cd0d0fcd1e3991e1976b7
CATEGORIES:Conferences - Seminars
DESCRIPTION:Dr Johanna Marin Carbonne\, Tenure Track Assistant Professor\,
  Institute of Earth Sciences (ISTE)\, Faculty of Geosciences and Environme
 nt\, UNIL\nAbstract:\nThe identification of microbial signatures preserved
  in the geological record is crucial for understanding life evolution in t
 he Early Earth. Iron and sulfur isotope composition offer the most direct 
 means to track the biogeochemical cycling of these elements through time\,
  but their joint use as biomarker of specific metabolic activity has been 
 relatively limited to date. Archean stromatolites and modern microbialite
 s contain small sulfides\, that can be formed either by abiotic processes 
 (reaction between H2S and Fe(II)) or by metabolic activity like microbial 
 sulfate reduction (MSR) or dissimilatory iron reduction (DIR). We have dev
 eloped a microscale approach using correlative microscopy\, SIMS and NanoS
 IMS analyses. In situ Fe and S isotope analyses as well as high-resolutio
 n mineralogy of pyrites in Archean stromatolites from the Tumbiana Formati
 on (2.7 Ga\, Australia) and microbialites from Atexcac Lake (Mexico) and C
 ayo Coco Lagoon (Cuba) reveal well-preserved primary microbial signature i
 nherited from biomineralization process. This microscale approach allows 
 us to distinguish microbial signatures from late overprints in the geologi
 cal record but also provide implications on the evolution of redox conditi
 ons as well as on sulfate concentration evolution through time. \n\nShort
  biography:\nDr Johanna Marin Carbonne graduated from the National School 
 of Geology in Nancy (France) in 2006. The same year\, she obtained another
  Masters in geosciences\, planetology and cosmochemistry. In 2009\, she su
 ccessfully obtained her PhD at the Petrographic and Geochemical Research C
 enter (CRPG\, Nancy) with a thesis entitled "Silicon and oxygen isotopic c
 omposition of Precambrian cherts: paleo environmental implications".\n \n
 Between 2010 and 2014\, Johanna Marin Carbonne spent two post-doctoral per
 iods\, one at UCLA between 2010 and 2012\, and the second at the Institut 
 de physique du globe\, attached to the University of Paris Diderot before 
 being appointed assistant professor at the 'Jean Monnet University in Sain
 t-Etienne in France and attached to the Magmas and Volcanoes Laboratory of
  Clermont-Ferrand. She is currently a recipient of an European grant\, ERC
  Starting Grant\, obtained for the period 2018-2023 for her STROMATA proje
 ct. This project aims to define new biogenicity tracers through the study 
 of micropyrites associated with organic matter in old stromatolites and is
  hosted at the UNIL in Lausanne\, at the Institute of Earth Sciences where
  she is assistant tenure track professor.\n\nHer research aims to quantita
 tively reconstruct the surface conditions of the early Earth and to better
  understand the evolution of life during this period.Her research foIt com
 bines a detailed mineralogy approach associated with high spatial resoluti
 on analyzes of traditional and non-traditional stable isotopes by Secondar
 y Ion Mass Spectrometry\, SIMS. \n 
LOCATION:ZOOM https://epfl.zoom.us/j/84677261593
STATUS:CONFIRMED
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