Waubach Member

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

Abbreviation KzWb
Parent unit Kieseloolite Formation
Child units
Lithological description The main lithology is pale grey to white quartz-enriched sand. The sand is fine to medium grained and becomes coarse to even gravelly, especially at the base of the member. Thin clay laminae, ripped up clasts and some lignitic particles may be present and organic colloids can stain parts of the sand purple. Van der Sluys (2000) notes that gravel is rare in the Belgian RVG and that from top to base, the resistivity decreases and the difference between short and deep resistivity values decreases as well as can also be observed on the resistivity logs of the Maaseik borehole ( 049W0220) (Vandenberghe et al., 2005, fig.2).
Age Vandenberghe & Louwye (2020, fig. 3) and Louwye & Vandenberghe (2020, fig.3) (Figure 40 2) have integrated the available stratigraphic information of the upper Miocene units. They concluded that in the RVG the presently defined Waubach Member is probably a time equivalent facies of the clayey part of the Kasterlee Formation and of the overlying Retie Member of the Mol Formation ( see LIS Mol Formation). This Retie Member is the now formalised ‘lower Mol’ or ‘Kasterlee-sensu-Gulinck’ lithostratigraphic unit described in the Neogene-2020 volume. The Retie Member is for lithological reasons ranked in the Mol Formation. The Waubach Member probably correlates with the Hauptkies in the Lower Rhine area however , detailed correlations between both areas remain hypothetical.
Thickness The thickness is 25- 55 m, based on Vandenberghe et al. (2020, fig. 6).
Area of occurrence The Waubach Member as defined in the Maaseik reference borehole occurs in the Belgian part of the RVG east of the main bordering faults of Heerlerheide and Reppel.
Type locality The 127- 166 m interval in the Maaseik borehole (049W0220) ( Vandenberghe et al., 2005) is chosen as the reference section.
Alternative names As it became clear that the originally described Waubach sand and gravel in the Belgian part of the Roer Valley Graben (RVG) as in Vandenberghe et al. (2005, fig.10) could be systematically split up in 2 parts based on geophysical logs signals (Vandenberghe et al. 2020 fig. 6), the terms Lower and Upper Waubach Member were used (Louwye & Vandenberghe, 2020, fig. 3); since it became clear that the lower part of Waubach sand and gravel could be identified as the Inden Formation, the name Waubach Member is now reserved for its former upper part, but without the prefix upper. It is not clear how the upper and lower Waubach terms used above the Inden Formation in the scheme by Wong et al. (2007) in the adjacent Dutch RVG (Figure 40 1) correspond to parts of the Waubach Sand as described above. Probably the clay shown at the contact between the two parts on the scheme is related to the clay horizon labelled Ki-k-4 and underlain by a sand unit Ki-z-5 by Dusar et al. (2014) Ki-k-4 and Ki-z-5 are absent in the Belgian part of the RVG . The Waubach Sand Member present in the Belgian RVG is labelled Ki-z-4 by Dusar et al. (2014) (see Figure 39 3 in LIS Kieseloolite Formation).
Authors Vandenberghe, N., & Dusar, M.
Date 01/09/2023
Cite as Vandenberghe, N., & Dusar, M., 2023. The Waubach Member, 01/09/2023. National Commission for Stratigraphy Belgium. http://ncs.naturalsciences.be/lithostratigraphy/Waubach-Member
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