Sem and light microscopic observations of minerals in bog-ores of the belgian campine

Soft bog-ore deposits are frequently present in alluvial soils of the Nete Valley, Province of Antwerp, Belgium. A profile was studied consisting of four layers of which the upper three were analyzed with the light microscope and SEM (scanning electron microscope). The top layer consisted mainly of clay and fragmented diatom shells. Isotropic Fe-oxihydrates and radiating goethite needles were present in the underlying limonitic layer. Siderite and vivianite were found in the third layer, the former often present in the wall of root channels, whereas the latter was frequently found within the channels. Vivianite was also found associated with decaying roots or alone inside root channels. Pyrite framboids were also found in the lower part of the profile.

The presence, close to each other, of different minerals such as goethite, pyrite, siderite and vivianite cannot be explained by macroenvironmental mineral equilibria alone. It requires the existence of different microenvironments which can vary in time and place. The study of such microenvironments, however, requires additional in situ microchemical submicroscopic techniques.