Comparative study of modern Sardinian stromatolites with Messinian fossil ones

PhD Student Juliette Debrie (Supervisors : Karim Benzerara - IMPMC, Jean Paul Saint Martin - CR2P, DIM Grant)

Stromatolites, i.e. macroscopically laminated carbonate rocks formed by diverse microbial communities, are particularly emblematic geobiological materials since they are the oldest evidence of life-mineral interactions, dated up to 3.5 Gyrs ago. have received strong attention because of the information they provide about microbial paleobiodiversity and paleoenvironments. However, while this information is interpreted based on our knowledge about modern analogues, the latter remains very incomplete. The present PhD project aims at studying the mineralogical, geochemical, textural and biological properties of modern coastal pond stromatolites recently discovered in Sardinia from the field- to the nano-scale. Sardinian stromatolites may become a unique model of stromatolites subjected to severe environmental variations, in particular in terms of salinity. They will be compared to fossil stromatolites from the Messinian (~6 Ma old) which are abundant in the Mediterranean basin and the coastal origin of which remains uncertain.