Icarus http://doi.org/ngw (2013)

Credit: © NASA/JPL/USGS

The surface of Saturn's moon Titan is dotted with dry lake beds and lakes thought to be filled with liquid hydrocarbons. Geochemical modelling suggests that the surface of the dry lake beds could be enriched in butane and acetylene.

Daniel Cordier of the Institut UTINAM/OSU THETA, Besançon, France, and colleagues simulated the geochemical evolution of a hydrocarbon lake similar to those thought to occur on Titan. The modelled lake consisted of liquid ethane, methane and nitrogen, with a suite of organic compounds in solution. The simulated evaporation of the lake concentrated the dissolved species, particularly acetylene and butane. The relative abundance of each compound was temperature dependent, with butane favoured under warmer conditions. According to the simulations, surficial evaporites in dry lake beds should be predominantly composed of acetylene and butane.

However, the modelling did not account for the presence of sediments, which could affect the formation of solids from solutions. The researchers suggest that the amount of sediments in the lake could affect the composition of the evaporite deposits, leading to variations in the overall chemical composition according to the sediment dynamics within each lake.