METABOLIC POTENTIALS IN SOILS DERIVED FROM ULTRAMAFIC BEDROCK

Ultramafic rocks, rich in Fe and Mg and other metals, alter to serpentine mineral-rich assemblages in the presence of water. The rocks so produced weather further to diverse clay minerals, Fe oxyhydroxides, carbonate group minerals, and relict spinel and crystalline Fe-oxide phases. Through these transformations, soil microbial communities gain access to a changing mineral backdrop offering diverse redox gradients. Metabolic potential, considered as the collection of thermodynamically feasible metabolic strategies at a given reaction step, shifts in concert. Here, I consider the weathering serpentine-rich soil unit as a habitat, and describe the changes in energy yielding reactions over the course of the environmental reaction. The implications for environments in continent-hosted ophiolites, in subseafloor settings, and planetary sites in which serpentine has been detected, are discussed.