Discovery of an alternative organic synthesis route in hydrothermal environments

Publication of the LGL-TPE in the journal Nature Communications on January 21, 2023. Communication of the CNRS-INSU on February 3, 2023.

The abiotic reactions that allow the formation of complex, potentially prebiotic organic molecules are a missing key to determining where life may have emerged. The limited variety and simplicity of the abiotic organic molecules observed have long discredited the theory of a hydrothermal origin for the emergence of life on Earth. A research team, involving scientists from the LGL-TPE, proposes an alternative hypothesis.

How simple abiotic organic compounds evolve toward more complex molecules of potentially prebiotic importance remains a missing key to establish where life possibly emerged. The limited variety of abiotic organics, their low concentrations and the possible pathways identified so far in hydrothermal fluids have long hampered a unifying theory of a hydrothermal origin for the emergence of life on Earth. Here we present an alternative road to abiotic organic synthesis and diversification in hydrothermal environments, which involves magmatic degassing and water-consuming mineral reactions occurring in mineral microcavities. This combination gathers key gases (N2, H2, CH4, CH3SH) and various polyaromatic materials associated with nanodiamonds and mineral products of olivine hydration (serpentinization). This endogenous assemblage results from re-speciation and drying of cooling C’O-S-H-N fluids entrapped below 600 °C-2 kbars in rocks forming the present-day oceanic lithosphere. Serpentinization dries out the system toward macromolecular carbon condensation, while olivine pods keep ingredients trapped until they are remobilized for further reactions at shallower levels. Results greatly extend our understanding of the forms of abiotic organic carbon available in hydrothermal environments and open new pathways for organic synthesis encompassing the role of minerals and drying. Such processes are expected in other planetary bodies wherever olivine-rich magmatic systems get cooled down and hydrated.

Reference : The rocky road to organics needs drying . Muriel Andreani, Gilles Montagnac, Clémentine Fellah, Jihua Hao, Flore Vandier, Isabelle Daniel, Céline Pisapia, Jules Galipaud, Marvin D. Lilley, Gretchen L. Früh Green, Stéphane Borensztajn and Bénédicte Ménez. DOI : 10.1038/s41467’023 -36038-6

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