Fossilization of bacteria in microbialites

Finding traces of intracellular CaCO₃ biomineralization in the geological record requires to better understand the fossilization processes prevailing in environments where these cyanobacteria are found. By studying microbialites forming in several Mexican lakes and populated by cyanobacteria forming intracellular CaCO₃, we showed the importance of (extracellular) fine grained and poorly crystallized Mg-silicate precipitation in these lakes (Zeyen et al., 2015). These authigenic and early precipitating phases have a high fossilization potential for a diversity of microorganisms and may have been overlooked in the geological record (Iniesto et al., 2015; Zeyen et al., in prep).

Scanning electron microscopy image of cells fossilized by Mg-silicates.