Abiogenic formation of H2, light hydrocarbons and other short-chain organic compounds within the serpentinite mud volcanoes of the Marianna Trench

Olivier Sissmann (1) , Roy Price (2) , Marcus Elvert (3) , Verena B Heuer (3) , Xavier Prieto (3) , Christophe Monnin (4) , Virgile Rouchon (1) , Sonia Noirez (1) , Valérie Beaumont (1) , Jérémie Ammouïal (1) , Eric Kohler (1) , Catriona Menzies (5) , Jeffrey Ryan (6) , Ken Takai (7)

1 IFPEN - IFP Energies nouvelles
2 SBU - Stony Brook University [SUNY]
3 MARUM - Center for Marine Environmental Sciences [Bremen]
4 GET - Géosciences Environnement Toulouse
5 Ocean and Earth Science [Southampton]
6 USF - University of South Florida [Tampa]
7 JAMSTEC - Japan Agency for Marine-Earth Science and Technology

Serpentinite-hosting mud volcanoes, located in the Marianna forearc subduction zone, were drilled during IODP Expedition 366. Recovered samples from Asùt Tesoru seamount provide new insights on the generation of organic matter in deep environments. Short-chain alcohols, volatile fatty acids and light hydrocarbons are produced within hyperalkaline pore fluids (pH 12.5) rich in H2. The stable isotope values of those species show heavy δ 13 C values, suggesting a formation process through Fischer-Tropsch-Type reactions. This close isotopic study brings new constraints on the reaction pathways leading to the formation of not only light hydrocarbons, but also of short-chain organic molecules. These compounds may serve as precursors of building blocks essential to life in deep oceanic settings.

Domaines: Sciences de la Terre

Olivier Sissmann, Roy Price, Marcus Elvert, Verena B Heuer, Xavier Prieto, et al.. Abiogenic formation of H2, light hydrocarbons and other short-chain organic compounds within the serpentinite mud volcanoes of the Marianna Trench. International Symposium on Water-Rock Interaction, Jul 2019, Tomsk, Russia. ⟨10.1051/e3sconf/20199802011⟩. ⟨hal-02395935⟩