Japan Geoscience Union Meeting 2023

Presentation information

[J] Oral

M (Multidisciplinary and Interdisciplinary) » M-IS Intersection

[M-IS20] Aqua planetology

Thu. May 25, 2023 3:30 PM - 4:45 PM 304 (International Conference Hall, Makuhari Messe)

convener:Yasuhito Sekine(Earth-Life Science Insitute, Tokyo Institute of Technology), Hidenori Genda(Earth-Life Science Institute, Tokyo Institute of Technology), Keisuke Fukushi(Institute of Nature & Environmental Technology, Kanazawa University), Takazo Shibuya(Japan Agency for Marine-Earth Science and Technology), Chairperson:Hidenori Genda(Earth-Life Science Institute, Tokyo Institute of Technology), Keisuke Fukushi(Institute of Nature & Environmental Technology, Kanazawa University), Tomohiro Usui(Japan Aerospace Exploration Agency), Takazo Shibuya(Japan Agency for Marine-Earth Science and Technology)

4:30 PM - 4:45 PM

[MIS20-10] Liquid and supercritical CO2 as an organic solvent in Hadean seafloor hydrothermal systems

*Takazo Shibuya1, Ken Takai1 (1.Japan Agency for Marine-Earth Science and Technology)

Prebiotic chemical evolution and the emergence of life in the seafloor hydrothermal systems of Hadean Earth is one of the most plausible and popular hypotheses for the origin of life on Earth. In contrast, many studies indicated that this hypothesis intrinsically harbors a critical unsolved problem called the “water paradox”: abundant water limits synthetic dehydration and facilitates hydrolysis of organic molecules during the early stage of chemical evolution. Nevertheless, many of these criticisms have not referred to the presence of abundant liquid/supercritical CO2 (L/SC-CO2) fluids and pools in modern hydrothermal systems. Indeed, the L/SC-CO2 fluids and pools create dry environments and behave as hydrophobic solvents at and beneath the seafloor. In this work, we theorize the generation and preservation mechanisms of a L/SC-CO2 pool in modern seafloor hydrothermal systems then reinterpret the fossil hydrothermal systems preserved in early Archean seafloor basalts. The theoretical consideration of subseafloor phase separation and phase segregation of CO2-rich hydrothermal fluids points to the presence of L/SC-CO2 fluids and pools also in Hadean seafloor hydrothermal systems. Because they behave as hydrophobic organic solvents, L/SC-CO2 has the great potential to drive the dehydration synthesis of organic molecules in seafloor hydrothermal systems. Furthermore, at the interface between L/SC-CO2 and H2O-rich fluid (seawater or hydrothermal fluid), amphiphilic molecules might be generated and triggered into self-assembled growth. Based on the abundant occurrence and physico-chemical properties of L/SC-CO2 fluids, we propose a new stepwise concept for the origin of life, whereby prebiotic chemical evolution was co-hosted and facilitated by L/SC-CO2 in Hadean water-rich seafloor hydrothermal systems. This “liquid/supercritical CO2 hypothesis” probably overcomes the water paradox and strengthens the idea that earthly life was hatched in deep-sea hydrothermal systems.