Figure 3.

A surface hydrothermal vent fed by a carbon-rich nitrogen-rich magma. The edges of the pool may expand and recede, providing dry-wet cycles. The water of the pool would plausibly be enriched by sulfites (SO₃²⁻), sulfates (SO₄²⁻), and Iron(II). Various amounts of diacetylene (C₄H₂), acetylene (C₂H₂), cyanoacetylene (HC₃N), hydrogen cyanide (HCN), hydrogen (H₂) and methane (CH₄) bubble up out of the pool in ratios determined by the depth at which the gas is quenched. One released into the air above the pool, these species are photolysed and react to produce small amounts of cyanamide. The cyanide in the pool will react with the sulfates to slowly form thiocyanate (CNS⁻), and will react with solvated electrons to produce simple sugars and amino-acid precursors.