55th Anniversary of Ivan Barnes: Microbial Communities of Serpentinite-Hosted Ecosystems

Book excerpt: Serpentinization is a reaction that involves the hydration of ferromagnesium minerals (e.g., olivine, pyroxenes), resulting in the production of hydrogen gas and reduced carbon compounds. This reaction also leads to the formation of mineral carbonates, and highly alkaline and reducing fluids. Microorganisms have adapted to such extremes and robust microbial communities were discovered at several locations, including the Mid-Atlantic Ridge, Mariana Forearc, the Cabeço de Vide Aquifer, the Cedars, the Coast Range Ophiolite Microbial Observatory, Hakuba Happo, the Samail ophiolite, the Voltri Massif, and the Zambales ophiolite. These locations represent a range of pressure and temperature conditions, demonstrating that serpentinization is a ubiquitous geologic process occurring at subduction zones, mid-ocean ridges, and passive margins. This process is also thought to have supported early life because of the availability of reduced products and the presence of geochemical disequilibria.