| Detailed chemical and X-ray analysis of representative clay fraction samples from the Maldegem and Zelzate Formations (Middle and Upper Eocene) in western Belgium reveal a rather constant clay mineralogy, consisting mainly of kaolinite, smectitic minerals (of the nontronite type) and illite. Glauconite occurs in two different forms, the coarser grained being better crystallized. Local climatic or landscape conditions as inferred from the qualitative clay mineralogical suite point towards a shallow marine sedimentary environment in transgressive phase. A low relief restricted drainage area delivered kaolinite to the basin under moderate weathering conditions, transforming volcanic ash layers into smectites. |
