Gravel- to sand-sized vivianite components in a Saalian till layer near Borne (The Netherlands)

Abstract

Vivianite particles have been found within the gravel and sand fractions of a specific level of a Saalian till layer. Besides with gravel constituents, which are common in Dutch till deposits, the vivianite granules are associated with sedimentary rock fragments containing a.o. glauconite and a kind of phosphoritic grains that are cemented by carbonates. The vivianite aggregates can be observed inside this carbonate matrix. Individual vivianite granules were studied in thin section and by SEM, X-ray diffraction, microprobe and differential thermal analyses. Only the monoclinic phase of Fe3(PO4)2.8H2O could be established with certainty. The vivianite of the granules contains lower Ca, Mn, Mg, Si and Al abundances than the vivianite of the aggregates included in the carbonate matrix. It is concluded that the vivianite granules are of nondetrital origin.