Approximately quantitative values are presented on the mineral content of the clay and silt fractions of marine sediments from the Wadden Sea. Considering the extent of clay mineral transformation and neoformation in a marine environment, it is believed to be insignificant, because of the sea water and pore solutions of the sediments seem to represent - with the exception of a small Mg-surplus - a kind of equilibrium solution for three- and four-layer minerals, which neither favors a considerable base fixation nor base release. Therefore, illite neoformation during halmyrolysis or early diagenesis seems to be impossible, especially because of unfavourable relations of potassium to all other cations in the sea water. Obviously the neoformation of illite takes place only during later diagenetic stages. The processes of clay mineral neoformation in a marine environment are probably restricted to the formation of amorphous (Mg-)Fe-Si-particles which may be first steps in the formation of chamosites, chlorites or smectites.

The concentration values were originally given in per mil and were transformed to percent by dividing by 10.

Supplement to: Brümmer, Gerhard; Schroeder, Diedrich (1976): Bestand, Umwandlung und Neubildung von Tonmineralen in küstennahen Sedimenten der Nordsee. Meyniana, 28, 19-28