Carbonate Mounds as a Possible Example for Microbial Activity in Geological Processes

Carbonate mounds from the geological record provide ample evidence of microbial mediation in mound buildup and stabilization. Advanced models argue for the prominent role which biofilms may have played at the interface between the fluid and mineral phases. While up to the early nineties, there was little evidence of mud-mound formation from Late Cretaceous times onwards, recent investigations have increasingly reported occurrences of large mound clusters on modern ocean margins, in particular in basins rich in hydrocarbons. Mound provinces are significant ocean margin systems, up to now largely overlooked. How do such recent mound provinces relate to the fossil examples, and do the modern mound provinces provide a new window on the microbiota that were instrumental in building giant mounds throughout Phanerozoic times? These are burning questions, and the answer will only come through a new dialogue between experts of the past, explorationists of the recent ocean, and microbiologists. An example is given of the power of new exploration tools, which can highlight controls on mound nucleation and patterns of early diagenesis — typically microbially driven processes. New insights can pave the way for new sampling opportunities, both by targeted surface sampling and controlled subsurface sampling through drilling.