In situ and laboratory investigation of the alteration of Boom Clay (Oligocene) at the air-geological barrier interface within the Mol underground facility (Belgium): Consequences on kerogen and bitumen compositions

► Comparison of in situ and experimental air oxidation consequences on organic matter. ► The major alteration process of organic matter in the gallery is air oxidation. ► Artificial air oxidation at 80 °C in a ventilated oven simulate the natural oxidation. ► These experiments can be used to assess the long term evolution of the organic matter.