Serpentinization and its link to microbial activity

During alteration of ultramafic rocks hydrogen is produced as a consequence of Fe-oxidation in primary olivine and pyroxene. This induces highly reducing conditions during water-rock interaction, stabilizing native metals and metal alloys, as well as providing an energy source for microbial communities living in these environments. One of the main research aims of our group is to link the mineral reactions to the abundance of microbial activity. For example, recent investigations have shown that sulfate-reducing microbes are abundant during stages of low-temperature water-rock interaction in seafloor hydrothermal systems, but that high-temperature fluids and magmatic activity can – at least temporarily – limit biogenic activity (e.g., Schwarzenbach et al., 2018, GCA; Liebmann et al., 2018, G-cubed).

Similarly, in continental sites of active serpentinization biogenic activity is most likely active within the subsurface and facilitated by methane- and hydrogen-rich vents. Our current research focuses on the impact of such reducing fluids on the stability of sulfide minerals and how their decomposition potentially serves as an additional sulfur and metal source for biogenic communities living in these systems.