Lime mud production: the microbial biofilm connection
|Starts:||13:00 14 Mar 2018|
|Ends:||14:00 14 Mar 2018|
|What is it:||Seminar|
|Organiser:||Department of Earth and Environmental Sciences|
|Who is it for:||University staff, Adults, Alumni, Current University students, General public|
Join Emeritus Reader at the University of Hull Martyn Pedley as he discusses microbial biofilms.
Microbial biofilms are ubiquitous in aqueous environments and have probably been so since the Early Proterozoic. They are capable of constructing 'stromatolites' that can be conveniently gathered into two groups: those that stick and bind pre-existing sediment particles into mats, and those associated with internal precipitates (most skeletal stromatolites). A third (pelagic) microbial association is dispersed within shallow waters. These drive precipitation within the water column to form whitings.
This presentation focuses on microbial biofilms in which peloidal calcium carbonate precipitation dominates (thrombolite microherms). It explores novel ways of studying biofilm process and product using freshwater lab-based mesocosm experiments. The effects of light, temperature, pH and turbulence on biofilm metabolism were investigated from the viewpoint of biofilm structure and calcium carbonate precipitation. In particular, the importance of EPS (extracellular metabolic substances) in precipitating spherules, micropeloids, micrite and microspar was studied. Much of the precipitate was incorporated into thrombolite skeletal micro-fabrics, but significant amounts were also shed to the surrounding environment as peloids and ultrafine lime mud particles.
Conclusions from these studies have been applied to resolving lime mud production problems associated with two contrasting geological case studies:
- a freshwater lake (phytoherm and ramp) association from the Quaternary of Central Spain;
- a marine ramp and sea mount example from the Quaternary of Sicily, Italy.
Collectively these illustrate that very significant quantities of calcium carbonate are generated within microbial mats within the photic zone and that up to 70% of the carbonate product is resedimented downslope and into the basins.
This seminar is open to all and tea and coffee will be served from 12.30pm in the lobby on the first floor of the Williamson Building.
Role: Emeritus Reader
Organisation: The University of Hull
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