Investigating geochemistry and habitability of continental sites of serpentinization: the Cedars, California, USA and the Tablelands, Newfoundland, CAN

Abstract

This study investigates the geochemistry and habitability of spring fluids associated with active continental serpentinization at The Cedars, California, USA and the Tablelands, Newfoundland, CAN. These ophiolite complexes were host to several springs discharging ultra-basic (>11) and highly reducing (<-400 mV) fluids rich in H2 gas that were geochemically distinct from the surrounding groundwater. C2+ hydrocarbons at both ophiolite complexes suggest hydrocarbons were thermogenic in origin; however, an abiogenic contribution could not be ruled out. Methane at The Cedars was dominated by a microbial origin with a contribution of non-microbial sources, while methane at the Tablelands was dominated by a non-microbial source (i.e. thermogenic or abiogenic or mixture of the two). Spring fluids lacked electron acceptors and nutrients which adds further complications to the already unusually high pH and limited carbon fixation possibilities in this extreme environment.