Microbes and volcanoes: A tale from the oceans, ophiolites, and greenstone belts

Abstract

Submarine volcanic glass alteration displays two easily discernable types of textures, one that is best interpreted as the result of an abiotic diffusive exchange process and another that involves microbial activity. Glass bioalteration textures dominate in the upper 300 m of the oceanic crust and have been found in nearly all ocean basins and in many ophiolites and greenstone belts back to 3.5 Ga. Bioalteration may involve a globally significant biomass and may influence geochemical fluxes from seafloor alteration. Glass bioalteration creates an entirely new discipline of research that involves microbiologists and volcanologists working in active volcanic systems and in the geologic record. Submarine volcanoes exposed on the ocean floor are studied along with ophiolites and greenstone belts to understand Earth not only as a physical and chemical heat engine but also as a bioreactor.