In sea-marginal pools of the Red Sea, algal (cyanophyte) stromatolites floor the pools and subbottom sediments consist of intercalated cyanophyte mats and laminites of gypsum. Chemical analyses show that the mats contain appreciable amounts of extractable organic matter which is of the kind, if preserved, that may serve as important source material for hydrocarbons.

Cores of undeformed and non-recrystallized evaporite deposits including salt rock, from the Zechstein (Permian) salt section of the North Sea and of the Silurian deposits of the Appalachian and Michigan basins display stromatolitic textures of the kind found in the modern sea-marginal pools. The stromatolitic laminae are usually preserved as anhydrite. Brine occupied the spaces between the stromatolites and salt precipitated into the brine-logged voids. The presence of such abundant organic matter in the evaporite deposits provides convincing evidence that evaporites may be considered potential source rock.