The information on this page is a summary description.
The full formal description is available here: Hageland Diest Member
| Abbreviation | DiHa |
| Parent unit | Diest Formation |
| Child units | |
| Lithological description | The member is created to accommodate the poorly sorted medium to coarse, very glauconiferous, grey green to brownish, Diest Sand that crops out in between Brussels and Leuven, in Hageland, Zuiderkempen and western-central Limburg (Houthuys et al., 2020). In the outcrop area, the sand is often loosely or firmly limonite-cemented. Hageland ironstone has been used as iron ore and as building stones. Glauconite content varies from 25% to 60%. The coarse beds often contain a subpopulation of 0.5 to 2 mm (sub)angular quartz grains. In the vertical direction, grain size is either constant or coarsening upwards. The sand shows various primary structures: large and small-scale cross-bedding, massive sand, spaced planar lamination, all of which can display scarce to abundant biogenic burrows, and homogenization by bioturbation. The cross-bedded facies may contain isolated or bundled clay laminae. The sand is non-calcareous and only occasionally contains limonite fossil prints. |
| Age | There is no direct proof of the age of the member, except its relative position in the lithostratigraphy of the area. Awaiting further proof, the age is assumed to be late Miocene: Tortonian, biochron DN8. |
| Thickness | General evolution from less than 10 m near the south and west margins of its extent to several 10s of metres in the centre of its extent. Important thickness variations in Hageland and Zuiderkempen are related to the incised nature of the member base. The thickness reaches more than 100 m in the centre of some incisions. |
| Area of occurrence | Outcrop area between Brussels, Leuven, Diest, Heusden-Zolder, Geel and Heist-op-den-Berg (Hageland and Zuiderkempen), Subcrop area to the northeast of the outcrop area, in central and possibly into north-Limburg and continuing into SE-Netherlands. |
| Type locality | The type locality is Diest, where exposures were available at the former town fortress. Hageland and Zuiderkempen can be considered as the type area. Numerous small and larger outcrops are found in the sunken roads. The Kesselberg geosite 2 km NE of Leuven and disused quarries 0.5 km NE of Wezemaal are well-known exposures. Additional exposures are temporarily offered at construction sites. |
| Alternative names | in the past, Diest Formation (De Meuter & Laga, 1976; after Dumont, 1839) was often used for only this member |
| Authors | Houthuys, R., Adriaens, R., Goolaerts, S., Laga, P., Louwye, S., Matthijs, J., Vandenberghe, N. & Verhaegen, J. |
| Date | 01/09/2023 |
| Cite as | Houthuys, R., Adriaens, R., Goolaerts, S., Laga, P., Louwye, S., Matthijs, J., Vandenberghe, N. & Verhaegen, J., 2023. The Hageland Diest Member, 01/09/2023. National Commission for Stratigraphy Belgium. http://ncs.naturalsciences.be/lithostratigraphy/Hageland-Diest-Member |
