MODELING WATER-ROCK REACTIONS IN OPHIOLITE-HOSTED PERIDOTITES

The aqueous alteration of peridotites is an exothermic, volume-increasing process that produces a serpentine-dominated mineral assemblage, with mineral proportions and ambient aqueous geochemistry strongly dependent on protolith composition. Serpentinization thus takes on different characteristics in marine and continental settings, with initial rock compositions ranging from peridotite to pyroxenite, and produces predictably different sets of secondary minerals. I model the alteration of peridotites of the Coast Range Ophiolite in Northern California to determine the mineralogical range of related serpentinites, identifying how different budgets of entrained seawater and meteoric influx impact reaction progress, in systems open and closed to atmospheric CO₂.