EGU General Assembly 2020
© Author(s) 2020. This work is distributed under
the Creative Commons Attribution 4.0 License.

Effect of serpentinization on carbon speciation: an experiment with formic acid

Samuel Barbier1,2, Muriel Andreani1, Eric C. Gaucher2, Isabelle Daniel1, Bénédicte Ménez3, Vincent Grossi1, Ingrid Antheaume1, Emmanuelle Albalat1, Clémentine Fellah1, Hervé Cardon1, Patrick Jame4, Xavier Saupin4, and Erik Bonjour4
Samuel Barbier et al.
  • 1Laboratoire de géologie de Lyon Terre, planètes et environnement (LGL-TPE), UMR 5276 CNRS, Université de Lyon, Université Lyon 1, Ens de Lyon, Villeurbanne, France (;; isabelle.daniel@univ-lyon1.f
  • 2Total CSTJF, Pau, France (
  • 3Institut de Physique du Globe de Paris, Sorbonne Paris Cité, Université Paris Diderot, CNRS, Paris, France (
  • 4Institute des Sciences Analytiques (ISA), UMR 5280 CNRS, Université de Lyon, Université Lyon 1, Ens de Lyon, Villeurbanne, France (;;

One of the principal theories about the origin of life is based on the abiotic reduction of carbon oxides to various organic molecules in hydrothermal systems. This synthesis is most favored in ultramafic environments undergoing hydrothermal alteration where the serpentinization reaction efficiently produces H2. Nevertheless, decades of hydrothermal experiments have hardly succeeded in producing abundant organic volatiles such as CH4 and short-chain hydrocarbons. On another hand, natural observations have shown the occurrence of other abiotic compounds such as organic acids in fluids and carbonaceous matter (CM) within serpentinized rocks. But organic acids as carbon source and CM as product have not been investigated so far in experiments reproducing hydrothermal peridotite alteration. Here, we explored the effect of formic acid (HCOOH) on the serpentinization reaction and possible feedback effects on carbon speciation in both fluid and solid. We performed reactions at 300°C and 250 bar using peridotite powder (<40 microns) in the presence of  0.1 M formic acid. A temperature of 300°C has been shown to be optimal for olivine serpentinization, while formic acid should partly decomposed into H2, CO, and CO2. After 4 months, H2, CO, CO2, CH4 and short-chain alkanes (mainly ethane) were measured in the fluid, and the powder was completely indurated. The solidified powder displayed a black and white layering perpendicular to fluid diffusion. Its analysis showed the advancement of the serpentinization reaction, and the incorporation of carbon compounds into the solid phase. XRD analysis indicated 70% of serpentinization. SEM-EDX observations showed peculiar texture with large and localized euhedral magnetite grains alternating with larger magnetite grains mixed with C-enriched areas of long chrysotile fibers. FT-IR measurement attested of the widespread formation of carbonaceous material in the solid. Liquid analyses are under progress. Those first results suggest that serpentine formation not only provides additional H2 to the system, but also mineral surfaces that could play a role in the precipitation of carbonaceous material and carbon speciation in natural systems. The nature and formation mechanisms of this latter remain to be addressed but this opens new paths for abiotic organic synthesis under hydrothermal conditions. In addition to their implications as an abiotic carbon source for deep hydrocarbon degraders ecosystems, it could have important implications for the total carbon cycle.

How to cite: Barbier, S., Andreani, M., Gaucher, E. C., Daniel, I., Ménez, B., Grossi, V., Antheaume, I., Albalat, E., Fellah, C., Cardon, H., Jame, P., Saupin, X., and Bonjour, E.: Effect of serpentinization on carbon speciation: an experiment with formic acid , EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-20924,, 2020

This abstract will not be presented.