Fluorine and boron distribution in sections of clay from Kroening Upper Freshwater Molasse (Lower Bavaria)

The fluorine and boron concentrations of Upper Tertiary clays from Kroning are connected with the grain-size distribution and the quantitative mode. The concentrations of both elements is positively correlated with increasing proportions of the clay and silt fraction. In the case of fluorine the surface bounding is the essential factor. The clay minerals illite, chlorite, kaolinite and montmorillonite detected by XRD, control the fluorine and boron abundances in different manner: while fluorine is predominantly enriched in montmorillonite and illite, chlorite and illite are the main boron-bearing phases.