planet

Alkaline hydrothermal vent

A seafloor vent where warm alkaline fluid (roughly 40–90 °C, pH 9–11) seeps out of serpentinizing mantle rock, building porous chimneys of iron sulfide. It is sharply distinct from a magmatic black smoker at 300–400 °C and acidic — that heat shreds RNA and peptides. It is the alkaline vent, not the black smoker, that origin-of-life models rely on, because the pH difference across a thin mineral wall is itself a voltage.