BIOFILMS AND MICROBIAL MATS - THEIR CONTRIBUTIONS TO SEDIMENT GENESIS

Biofilms and microbial mats consist of communities of microorganisms exhibiting a great array of metabolisms (autotrophic or heterotrophic species, aerobic or anaerobic species...). They have been colonizing the earth's surface since 3,5 billion years. Producing copious mucus and including filamentous microbes, they trap and bind detrital grains, strengthen the cohesion of sediments and iinitiate biolaminated deposits. They build bioconstructions and maintain anoxic conditions on the substrate of water bodies. Inducing mineralizations (carbonates, phosphates, iron oxides...), they pray a leading part during the first steps of diagenesis and during fossilization, particularly by promoting the preservation of soft-bodied organisms.