The presence of hydrocarbons would be useful to potential future settlers too, since it can be used as feedstock for things like plastics and petrochemicals.
It can be made from CO2 + H2O with a lot of energy, but it'd be easier to have at least some ready-made to get started.
Does anyone know if these hydrocarbons are in "useful" concentrations, or "detectable" concentrations (ppb).