1. Genesis of the formation of solid fossil fuels

1.1 Carbon cycles

Organic matter is condemned to perish and be reborn in the perpetual renewal that characterizes the biosphere's cycles. For carbon, a distinction is made between :

• the short cycle, in which the deposited plant material is transformed directly by aerobic bacterial oxidation into carbon dioxide and water, which is by far the most prevalent;

• the middle cycle, in which part of the organic sediments has escaped total oxidation and is buried in the subsoil, leading to the formation of dispersed sedimentary organic matter or kerogen [1] and, exceptionally, to the formation of concentrated, exploitable deposits of solid fuels;...