Possible impact of a primordial oil slick on atmospheric and chemical evolution.

Low molecular weight liquid hydrocarbons from various sources, could have formed an oil layer covering the primeval ocean (present already 4.0-4.4 x 10(9) yr ago), preventing water from evaporating into the atmosphere. Water from other sources, precipitated by cold traps at higher altitude in the atmosphere, becomes trapped in the ocean. In a thereby more dry and presumably reducing atmosphere (before 3.9 x 10(9) yr ago) even more hydrocarbons, as well as reactive molecules will form. An oil layer can possibly act as a dry solvent for reactions, where the reactive molecules can produce monomers and condensing agents. Monomers and eventual polymers formed could become strongly concentrated at the oil-water interface, favouring molecular interactions at high mobility and low dilution, without exposure to the destructive action of UV-light. Increased water leakiness of the oil layer due to accumulation of polar molecules within, would lead to photooxidation of liquid hydrocarbons, and subsequent emulsification at the oil-water interface, forming cellular structures. The atmosphere would then have lost its reducing character.