Metazoan-microbial framework fabrics in a Mississippian (Carboniferous) coral-sponge-microbial reef, Monto, Queensland, Australia

Although these reefs grew following Late Devonian extinction events that affected skeletal reef builders, the dominance of microbialites is difficult to attribute to the absence of appropriate skeletal reef builders. The reefs occurred ∼20 million years after the Devonian-Mississippian transition, and diverse, potentially reef-building corals and algae occur throughout the reefs, but never rose to dominate framework construction. High siliciclastic flux, turbidity, abnormal salinity, low oxygen levels, low light penetration, and climatic deterioration can be eliminated as limiting factors for skeletal organisms in the reefs suggesting either that: 1) subtle nutrient or ecological factors governed the community membership; or 2) that the microbial biofilms competed well for reef substrate.