Just to build up on my previous success with oxygen origin in the atmosphere, I want to expand the question as was advised in the answers. The official heresy, despite denied in the comments and answers here, says that the atmosphere oxygen was produced by plants. Meantime, the oxidation of the atmosphere was delayed by oxidation of the iron, which was free at that time. Yet, if we look at the geology, we find very few Fe oxides in the crust. There is much more aluminium oxide Al2O3 (aka clay) and quartz (SiO2 aka sand). I wonder, when did the clay with sand were formed so that no phytoplankton was necessary for their formation and why was iron delayed its oxidation?
PS I have later realized that Ca oxidation is also an issue of this kind.