Abiotic synthesis of organic molecules from minerals containing traces of dissolved H2O, CO2 and N2 part I: Basic principles

Abstract

Oxides and silicates which crystallize in the presence of H2O, CO2 and N2, especially at high pressures, are expected to dissolve traces of these fluid components. In doing so atomic and electronic rearrangements occur between the host lattice and the dissolved molecules which lead to different solute species. These may be simply hydroxyl OH−, carbonate CO3 2− of similar ions, but other species can also form which are chemically reduced such as molecular H2, CO2 2− and CO− or oxidized such as peroxy ions, O2 2−. When the minerals containing such solute species are decompressed and cooled, they eventually become supersaturated with respect to their dissolved impurities. If the relative mobilities of the different solute species are different, diffusion and subsurface segregation lead to spatial separation: the surface and subsurface zone become enriched in the reduced species while the oxidized species remain in the bulk. Upon heating or during chemical dissolution (weathering) the reduced species contained in the surface react leading to the formation of a wide variety of H−C−O−N molecules: not only H2O, CO2 and possibly N2 but also organic molecules. No external reduced atmosphere is needed, according to this hypothesis.