My research interest is the understanding of the microbially-mediated carbon cycle at the biosphere-lithosphere interface with a specific focus on the microbe-mineral interaction (especially carbonates). The domains of investigation range from the early Earth History to modern environments and requires the interaction between geologists, biologists, biogeochemists, and computer scientists. My personal expertise is in geology (carbonate sedimentology and paleoecology) and in geomicrobiology (study of microbial carbonate formation) using various microscopy techniques (e.g., ESEM, low-temperature cryo SEM). This research has potential for interpreting the rock record, understanding life in extreme environments, investigating organically-mediated carbon sinks and even searching for extraterrestrial life (exobiology). This research program includes studies in both fossil and recent ecosystems and takes place in various environments (open-marine, hypersaline, freshwater and terrestrial environments).

Geomicrobiology of lithifying microbial mats 

The microbial communities are playing a key role in the redox processes that control the cycling of the major elements (C, N, O, S, etc.) sustaining life in virtually all earth-based ecosystems and likely beyond. The microbial ecosystem is able to obtain energy from element cycles, influencing the balance between the more reduced (organic C) and the more oxidized (the carbonates) species of carbon. The understanding of the mechanisms regulating carbonate mineral precipitation in microbially-active sediments thus requires knowledge of the microbial populations, their often complex metabolisms, as well as the properties of the organic matrix (EPS), the global environment and finally a detailed characterization of the mineral product. This research is producing models for microbialite formation in various environments and is furnishing insight in the modern carbon cycle and in the past as microbially-induced biomineralization of carbonate mineral is playing a key role in virtually all past and modern carbonate environment. 

Simulation of stromatolite formation

Stromatolites can be compared to a ‘biogeochemical engine’ that translates energy in morphology. The top active surface at water-sediment interface represents the boundary where energy and nutrient fluxes are translated into morphologies through iterative processes. The emergence of stromatolite thus results from interactions and balance between intrinsic (microbial mat or biofilm) and extrinsic factors (environmental conditions) that are responsible of the explosion of the morphological space in the fossil record. In collaboration with developers the aim of this research is the investigation of this morphological space using various modeling approaches such as DLA-CA ('Diffusion Limited Aggregation' associated to a 'Cellular Automata"), 3D DLA-CA, and multi-agent platforms.

Microbial processes during early diagenesis of carbonate reservoirs

Diagenesis characterizes physicochemical processes that alter sediments following deposition until final lithification. These processes involve compaction, induration, cementation and lithification. Although diagenesis is generally related to burial processes involving temperature and pressure modifications and fluid circulation, alteration starts immediately following sedimentation. Early diagenesis commences in depositional environments, where life and especially that of microbes can be involved. Situated at the lithosphere-biosphere interface, the “microbial interface” can induce stabilization, early lithification, and geochemical fractionation of deposited sediments through ‘trapping and binding’ and in situ precipitation of carbonates. The resulting benthic microbial deposits are defined as microbialites, or as ‘microbially-induced sedimentary structure’ (MISS). When considering the formation of carbonate reservoirs, initial microbial processes that can strongly influence the following steps of diagenesis are often overlooked. Microbial activity may also alter geochemical proxies for palaeoceanography.