Geological framework for the origin of life in the early continental crust

The development of the first cells on a young Earth presupposes the existence of stable conditions in an environment over an extended period, where unlimited primary gaseous reactants were available. Additional prerequisites include a broad range of physicochemical parameters such as pressure, temperature, states of matter, and pH values. Cyclical processes that enable chemical evolution and a transport system for the supply and removal of substances involved in reactions were also necessary. Corresponding conditions were and still are present in open, water-filled fault zones in the continental crust, where CO2, N2, H2, H2S, NH3, and trace gases ascend. Within these zones, synthesis processes occur that are analogous to Fischer/Tropsch and Haber/Bosch syntheses. Variable pressure/temperature conditions in the upper crust create a unique situation likely crucial for the development of life. Above 1000 meters crustal depth, pressure fluctuations, induced by cold-water geysers, cause CO2 to transition from supercritical to subcritical states. For pure N2, the transition occurs approximately 600 meters higher. The phase transition, which is accompanied by a significant increase in entropy, leads to the localized enrichment of organic molecules in cavities within faults, facilitating a multitude of chemical reactions. The transport of organic molecules from deeper formation areas involves a flotation process through supercritical CO2/N2 bubbles. These bubbles directly capture nonpolar molecules or attach certain amphiphiles to the bubble surface, acting as collector molecules for specific RNA molecules, for example. Flotation results in an initial selection of organic molecules and is complemented by surface effects on fault walls. During ascent, specific molecules adhere to changing mineral surfaces such as lead-zinc or iron-sulfide ores, quartz, or clay minerals. Variations in temperature occurred through adiabatic state changes and the influx of hotter deep-seated water or cooler artesian water, simultaneously influencing the pH value. References Schreiber, U. (2023): Storage of Biochemical Information as the Start of Life: A Hypothetical Model for the Development of the First Cell, preprints.org > chemistry and materials science > organic chemistry > doi: 10.20944/preprints202201.0364.v2