COG3

Serpentinization of Mantle Peridotite and the Release of Hydrogen Within the Temperature Limits of Life

The exposure of mantle rocks to seawater at crustal levels leads to a cascade of interconnected dissolution-precipitation and reduction-oxidation reactions, with strong implications for seafloor spreading, subduction zone processes, and microbial life. This widespread process (referred to as serpentinization) releases molecular hydrogen that can be exploited by microorganisms to gain metabolic energy; however, the mechanisms that control hydrogen generation during serpentinization remain poorly understood. In this seminar I will discuss recent hydrothermal experiments, theoretical constraints, and field observations to highlight the important roles alteration temperature, protolith composition, and fluid flux play in regulating the release of hydrogen. I will compare mid-ocean ridge serpentinization systems with their counterparts at continental margins and demonstrate that low-temperature serpentinization can release abundant hydrogen within the temperature limits of life.