Bestand, Umwandlung und Neubildung von Tonmineralen in küstennahen Sedimenten der Nordsee

Abstract

Content, Transformation and Neoformation of Clay Minerals in near shore Sediments of the North SeaFrom literature and our own results, approximate quantitative values are given on the mineral content of clay and silt fractions of marine sediments from the Wadden Sea. Besides this, the extent of clay mineral transformation and neoformation in a marine environment is discussed.According to our knowledge, the extent of clay mineral transformation and neoformation must be unimportant because the sea water and pore solution of the sediments seems to be ‐ with the exception of a small Mg‐surplus — something like an equilibrium solution for three‐and fourlayer minerals, which neither favors a considerable base fixation nor base release. Therefore illite neoformation during halmyrolysis or early diagenesis seems to be impossible because of unfavourable relations of potassium to all other cations in the sea water. Obviously the neoformation of illite is connected with later diagenesis. The processes of clay mineral neoformation in a marine evironment 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.