What is the likely source of methane in mars atmosphere?

 UV can also generate methane from organic materials in the Martian surface. Other possible sources for methane on Mars include reactions between water and olivine, and, hypothetically, microbes. Methane generated underground in the distant or recent past might be stored within lattice-structured methane hydrates called clathrates, and released by the clathrates at a later time, so that methane being released to the atmosphere today might have formed in the past.