A somewhat speculative hypothesis of petroleum genesis in the upper lithosphere is proposed, based on Fischer-Tropsch synthesis. This hypothesis is distinct from both the organic (biogenic) model and the inorganic model of hydrocarbon degassing from the Earth's interior.

Fischer-Tropsch synthesis is a well-known industrial process whereby millions of tons of hydrocarbon oil resembling petroleum are produced annually from carbon monoxide or carbon dioxide and hydrogen gases reacting on a metallic iron or iron-oxide catalyst. Like natural petroleum, this synthetic oil consists of gas, gasoline, diesel oil, and wax fractions, all rich in saturated aliphatic hydrocarbons and enriched in the light ¹²C isotope.

The hypothesis presented in this paper proposes that petroleum liquids form by Fischer-Tropsch synthesis on magnetite and hematite catalysts when carbon dioxide (derived by massive metamorphic or igneous decarbonation of subducted sedimentary carbonates) reacts with hydrogen generated by the serpentinization (in the absence of air) of shallow-mantle lithosphere and ophiolite thrust sheets. Oblique plate movements may favor hydrocarbon formation by creating deep faults that aid fluid flow and serpentinization. The world's richest oil provinces, including those of the Middle East, may be tentatively interpreted to have formed by this mechanism.