Sprecher
Beschreibung
Bénédicte Ménez
Institut de physique du globe de Paris, Université Paris Cité, France
Geogenic molecular hydrogen (H2), produced through water-rock reactions, is a persistent and widespread source of reducing power in Earth’s lithosphere. In the presence of inorganic carbon, H2 can promote the abiotic synthesis of organic compounds. Yet, the mechanisms controlling the diversity, spatial distribution, and evolution of these compounds in natural settings remain poorly understood, limiting our understanding of how lithosphere-derived H₂ may have contributed to the emergence of life and the establishment of the first metabolisms on the early Earth.
Here, we investigate how geodynamics-driven fluid circulation and rock-forming minerals regulate coupled H2–carbon chemistry using a multimodal approach combining ultrahigh-resolution mass spectrometry and microscale imaging. Focusing on deep subsurface environments, including active and ancient hydrothermal systems along ocean ridges as well as subduction zones, we reveal chemically diverse and spatially structured organic assemblages displaying pronounced microscale heterogeneity and intimate associations with mineral phases.
Our observations provide direct evidence from natural systems—beyond laboratory experiments and numerical models—that minerals locally govern not only H₂ generation but also the formation, transformation, and preservation of organic compounds. Rather than acting as passive substrates, minerals and organics appear to co-evolve during fluid–rock interactions and metamorphic processes, with changing redox conditions and water-rock ratios driving increasing molecular complexity over time.
We propose that these mineral-guided processes generate a sustained endogenous reservoir of reduced carbon in the deep subsurface, largely decoupled from surface-derived inputs. Together, these findings portray the lithosphere as a self-sustained reactive environment in which mineral-driven H₂ production and organic synthesis can support microbial ecosystems. More broadly, they point to a mineral-controlled “dark” hydrogen and carbon cycle with profound implications for the emergence, persistence, and distribution of life in the deep Earth and beyond.