Figure 5
Couple of ToF–SIMS red/green/blue (RGB) overlays for (a) G3, G6 and G5 and (b) G1, G3, and G8 resulting in two different microstructure associations. The first RGB association (a) could correspond to compositional variations in plants (G5, G6, and G3) or to plant fragments (G5, and G6) affected by microbial activity (G3). Interestingly, G4 appears as a compositional variation in the G3 structure. The second RGB association (b) could include three different groups, namely, G1, G3 and G8 that could correspond to a microbial structure such as a biofilm in which the biomass is dominated by microbial forms biomineralizing sulfate. G3 structures interlock empty complementary areas in G1, suggesting that these areas could be the remains of different biological entities, while G8 branched microstructures merge with some filamentous units in G1, suggesting compositional variations in some specific zones of the filamentous mass of G1.
