Flow diagram illustrating the geochemical drive toward the onset of life. There are two pathways to consider - the provision of energy and the fixation of carbon.
Here we focus on the simplest of processes, the fixing of carbon from CO ultimately derived from the mantle. The chemical energy is provided by the oxidation of residual native iron and ferrous iron in minerals in the hot crust, such as olivine (Mg1.8Fe0.2SiO4) to magnetite (Fe3O4), by convecting ocean waters of moderate temperature.
The hydrogen (plus aldhydes, alcohols, thiols and acetate) evolved in this process is activated as electrons are conducted to oxidise FeIII (produced by photolysis of oceanic FeOH+) on the outside of the electrocatalytic mackinawite boundary (modified from Russell and Hall 1999; and see Chen and Bahnemann 2000).
