THE ROLE OF ARCHAEAL METHANOGENS IN BIOMINERALIZATION AND METAL CYCLING: FROM THE MICROSCOPIC TO THE GLOBAL SCALE

Abstract

Archaea, including methanogens, comprise 20% of microbial biomass in global oceans. This study examines the role of Archaeal cell walls in primary low-temperature (30oC) dolomite formation, the impact of biogenic methane generation on the diagenetic history of dolomite reservoirs, and the role of Ni and H2 on methane production rates. Archaeal cell walls are fundamental in precipitating dolomite due to high carboxyl group density, which desolvate the Mg cation, facilitating nucleation. Therefore biogenic dolomite may be associated with methane production, which decreases effective hydraulic conductivity at high concentrations and is one means of preserving porosity in dolomite reservoirs. While Ni and H2 are two controls on methane generation rates, Ni can be acquired from solid-phases and is not likely limited in modern or ancient environments. Archaea play a fundamental role in biomineralization and metal mobilization, linking these processes to carbon cycling through their metabolic production of an important greenhouse gas.