Both autotrophic and heterotrophic metabolic processes have been linked to biologically induced carbonate precipitation. The controls on precipitation in the Cariboo Plateau microbial mats are unknown. Microelectrode studies show that photosynthetic oxygen production occurs in the upper 5 mm of the mat resulting in supersaturation of oxygen in surface waters. Depletion of this oxygen generally occurs just below 5 mm and sulfide production begins at 10 - 15 mm from the mats surface. Methane concentrations vary depending on lake geochemistry as lakes with high sulphate (>5 mM) show low methane production and lakes with low sulphate concentrations have high levels of methane production with highly depleted 13C values.
Variations in microbial phospholipid fatty acid (PLFA) distribution demonstrate that Cariboo Plateau microbial mat community structure varies seasonally and spatially. Isotopic analyses (δ13C) were used to investigate the potential for microbial biosignatures in these carbonate rich systems. Bulk cell analysis of microbial mats show non-CO2 limited inorganic to organic offsets of 23-25 . Some Cariboo Plateau lakes and microbial mats demonstrate 13C-enriched DIC and carbonate resulting from photosynthetic drawdown of 12C. Biologically induced 13C-enrichment of the local residual DIC pool has the potential to be preserved in ancient carbonate structures.