Mol inférieur / Mol supérieur unit

The information on this page is a summary description.
The full formal description is available here: Mol inférieur / Mol supérieur unit

Parent unit Mol Formation
Child units
Lithological description In the archives of the Geological Survey of Belgium several borehole descriptions have used a subdivision of the pale grey to white Mol Sand into Mol supérieur and inférieur. The term Mol inférieur was introduced to describe the lower part of the Mol Formation where it picked up some glauconite pellets and mica flakes thereby changing the colour from white to rather grey. The mention in the definition of the Mol Formation by Laga et al. (2001) ‘in the type region, lower part very slightly glauconiferous’, seems to justify the practice of using a distinction between Mol inférieur and supérieur. This mention however follows exactly part of the description of the Sables de Mol by Gulinck (1962) where this author referred to a debatable sand unit in the Mol area below coarser Mol sand; the sand unit was soon interpreted by this author as the lateral extension of the Kasterlee sand (Gulinck,1963) and he continued to do so afterwards (Gulinck and Laga , 1975). This debatable sand unit has been discussed in Vandenberghe et al. (2020) and these authors better defined this sand unit below the coarser sand of the Mol Formation and provisionally named it the ‘lower Mol’ or ‘Kasterlee-sensu-Gulinck’ unit. It is now formally defined as the Retie Member. At the base of the Donk Member and of the Retie Member, some reworked sand from the underlying units can be present, but the less than 2 m thickness at maximum of such reworked base certainly does not require a separate ranking. The term Mol inférieur has never been precisely defined and neither was the boundary with the companion term, the so called Mol supérieur which undoubtedly largely corresponds to the sand of the Donk and/or Maatheide Members. In addition, the term Mol inférieur was confused with the Kasterlee Sand sensu-Gulinck. Therefore the division Mol supérieur–inférieur is obsolete and the term Mol inférieur should not be used any longer.
Age See LIS file Mol Formation for information on the age of the Mol Formation units.
Area of occurrence
Type locality
Alternative names
Authors Vandenberghe, N., Berwouts, I. & Vos, K.
Date 01/09/2023
Cite as Vandenberghe, N., Berwouts, I. & Vos, K., 2023. The Mol inférieur / Mol supérieur unit, 01/09/2023. National Commission for Stratigraphy Belgium.érieur-Mol-supérieur-unit
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