Beerzel Member

The information on this page is a summary description.
The full formal description is available here: Beerzel Member

Abbreviation KlBe
Parent unit Kasterlee Formation
Child units
Lithological description The Beerzel Member in the type area can be recognized by its yellow to white colour and low glauconite and clay content, and is consistently underlain by a more glauconite-rich unit – the Hallaar Member, and overlain by a unit with clay-sand alternations – the Heist-op-den-Berg Member. It has a homogeneous appearance, except for possible irregular brownish intercalations due to oxidation above the groundwater table, linked to groundwater fluctuations. Glauconite content is significantly lower in the Beerzel Member compared to the underlying Hallaar Member (2–6%, glauconite/quartz ratio of 0.02–0.08). The grain size distribution curves show a very well sorted sediment with a modal grain size between 185 and 204 µm and only a small amount of material outside of the 100 to 300 µm range. The content of dioctahedral 2:1 Al-rich layer silicates (3–9%, 2:1 Al-clay/quartz ratio of 0.03–0.11) is lower than in the Hallaar Member and similar to the sandy layers of the overlying Heist-op-den-Berg Member, and there is an overall decrease to the top. Feldspar content remains largely constant within the member (4–6%, feldspar/quartz ratio of 0.05– 0.08). On CPT’s, the Beerzel Member can be identified based on an interval with constant qc values, a bit higher than in the underlying and overlying members. Based on CPT profiles, the Beerzel Member also occurs further north, such as near Kasterlee, though not consistently (Vandenberghe et al., 2020).
Age No age data are available for the Beerzel Member, yet it is underlain by the late Tortonian to Messinian Campine Diest Sand and overlain by the Heist-op-den-Berg Member in which dinoflagellate cyst biozone DN10 of late Tortonian to Messinian Miocene age was identified.
Thickness In the type section, the Beerzel Member has a thickness of 4 m. Where the Beerzel Member occurs towards the north, the thickness fluctuates but is generally less than 4 m.
Area of occurrence The Beerzel Member occurs consistently in the southern occurrence area of the Kasterlee Formation, in the area Beerzel – Heist-op-den-Berg – Olen. Towards the northeast, in the area Geel-Kasterlee-Retie, the member occurs locally. It appears to be absent in the area Mol-Dessel and further to the east, as well as in the northwestern occurrence area of the Kasterlee Formation.
Type locality The proposed type section of the lower three members of the Kasterlee Formation, including the Beerzel Member, is the sunken lane atop the hill of Heist-op-den-Berg (DOV TO-20140919 and TO-20190617). The type section is described in detail in Verhaegen et al. (2014) and Verhaegen et al. (2020). The member name was originally proposed after a study of this section by Fobe (1995).
Alternative names Formerly part of the at the time not yet subdivided Kasterlee Formation sensu De Meuter and Laga (1976) and Laga et al. (2001).
Authors Verhaegen, J. & Vandenberghe, N.
Date 01/09/2023
Cite as Verhaegen, J. & Vandenberghe, N., 2023. The Beerzel Member, 01/09/2023. National Commission for Stratigraphy Belgium.
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