Simulating biogeochemical processes with numerical models
Scenarios reconstructed for past microbial processes can always be tested using geochemical models. Using this approach it could be demonstrated that sulphate reducing bacteria do not have the potential to induce carbonate precipitation in microbial mats. This insight has consequences for the interpretation of stromatolites suggested to represent lithified microbial mats as earliest indicators of life on Earth.
Section through a phototrophic microbial mat, Lagoa Vermelha, Brazil. Early lithification (white regions) is generally considered a result of microbial activity, even though the exact mechanism is still poorly understood.
Geochemical models are also used to simulate the effects of microbial processes on alkalinity and carbonate diagenesis in marine sediments (Meister et al., 2013; Contreras et al., 2013).
A geochemical model is currently being developed by Gerhard Herda, as part of his Master Thesis, to simulate the influence of clay mineral alteration on carbonate formation, in particular if the porefluid is acidified due to high pCO2.