The role and environmental significance of microbial communities in the construction of Cryogenian and Late Devonian carbonate reef complexes in Australian basins.

Cryogenian and Late Devonian reef complexes of Australian basins were studied to examine the roles microbial communities played in ancient reef construction including carbonate production. Microbial communities fill various roles in reef framework building and imparting rigidity, while showing great resilience to environmental changes through ecological adaptability. Certaincalcimicrobes seek shelter in crypts (e.g. Frutexites) whereas others apply morphological adaptability to cope with a wide range of environmental conditions (e.g. Girvanella). Morphological and geochemical characterisation of the biotic-mineralogic interface suggests bacterial surfaces werenucleation sites for the precipitation of carbonates and authigenic clays forming a primary microframework upon synsedimentary organomineralisation.