Abiotic photosynthesis from ferrous carbonate (siderite) and water

Anoxic photochemical oxidation of siderite generates molecular hydrogen and iron oxides

“…Indeed, siderite is found in rocks as old as 3.8 Ga, and its abundance suggests it was a prevalent ferrous species during Archean time (17)(18)(19)(20)(21). Although UV photooxidation of siderite is possible (22), and may have implications for the early hydrogen cycle, the rates and mechanisms of hydrogen production by this potential geochemical pathway have not been experimentally elucidated.…”

Marine Hydrothermal Systems and the Origin of Life

“…CH20 and higher aldehydes are also formed by the photolysis of H20 in the presence of C~ (Ferris and Chen, 1975b;Bar-Nun and Chang, 1983), the photolysis of CO-H20 mixtures (park and Getoff, 1988) and the photolysis of methanol (Allamandola et al, 1988). It has been tentatively identified as a product of the photolysis of ferrous carbonate (Joe et al, 1986) and~-irradiation of calcium carbonate (Albarran et al, 1987). Formaldehyde has been detected in the interstellar medium (Mann and Williams, 1980) and the presence of polyoxymethylene, a polymeric form of formaldehyde, on Comet Halley has been inferred, but not proven, from mass spectral data (Huebner, 1987).…”

Photoprecipitation and the banded iron-formations — Some quantitative aspects

“…Cairns-Smith's suggestion (1978) that oxidizing power could have come from sunlight has received support from our findings (Braterman et al, 1983(Braterman et al, , 1984 that the photo-oxidation of Fe(II) to Fe(III) proceeds more rapidly in neutral than in acid solution, because of the photosensitivity of FeOH ÷ in the near uv. Schrauzer and Guth (1976) described the evolution of hydrogen from precipitated Fe(II) hydroxide under the influence of light, or even in the dark, while Borowska and Mauzerall (1986) (Joe et al, 1986) been shown to undergo photo-oxidation, and the photochemistry of Fe(II) silicates would clearly repay further investigation). We have therefore estimated the possible rate of abiotic photoprecipitation from an ocean surface continuously replenished in iron using the following assumptions (for a more detailed discussion of these assumptions, and of the method of calculation, see Braterman and Cairns-Smith, in the press):…”