Kieseloolite Formation

The information on this page is a summary description.
The full formal description is available here: Kieseloolite Formation

Abbreviation Kz
Parent unit
Child units Waubach Member, op-den-Berg Facies, Brunssum Member, Jagersborg Member
Lithological description The Kieseloolite Formation in Belgium is limited to the Belgian part of the Roer Valley Graben (Laga et al., 2001). The main lithology in the formation is a white quartz-enriched sand. The grain-size varies from fine to coarse, in particular in the lower part of the formation. The marked difference in log resistivities measured at different current penetration depths points to a permeable sand. The sand contains small lignitic fragments and ripped up clay clasts. Lignite, clay and lignitic clay horizons varying in thickness from a few cm to 2 to 4 m in thickness occur in the sand. Subdivisions in the formation are based on the presence of some of the thicker lignite and clay beds which could be aquitards at least at local scale. The subdivisions identified from bottom to top are: the Waubach sand, Brunssum II clay, Pey sand , Brunssum I clay and Schinveld/Jagersborg sand. Except for Jagersborg , these subdivisions and their nomenclature in the Belgian part of the RVG are based on the stratigraphy in the Dutch RVG published a.o. by Wong et al. (2007, fig. 13) as illustrated below (Figure 39 1).
Age Detailed chronostratigraphy of the Kieseloolite Formation is poorly documented. The age of the lowest lithostratigraphic unit of the Kieseloolite Formation, the Waubach Member, is latest Miocene while the Brunssum and Jagersborg members probably are continuously formed during the Pliocene. The transition to the Pleistocene is uncertain. The introduction of an alternative lithostratigraphic subdivision including the Stramproy Formation above the Kieseloolite Formation places the Kieseloolite definitely in the Pliocene and the Stramproy Formation in the early Pleistocene – Middle Pleistocene (Tiglian – early Cromerian) (TNO-GDN (2022)).
Thickness In the Maaseik borehole the thickness is 144 m. Van der Sluys (2000) reports a fairly constant thickness between 130 and 160 m of the Kieseloolite Formation including the now recognized Inden Formation (formerly also described as lower Waubach unit) but strongly varying thicknesses for its members (see also Vandenberghe et al., 2020, fig. 6).
Area of occurrence By definition the Kieseloolite Formation in the Belgian RVG is limited to the RVG east of the Heerlerheide-Reppel boundary faults.
Type locality The reference borehole for the Kieseloolite Formation in the Belgian Roer Valley Graben is the cored and geophysically logged Maaseik borehole (049W0220) between 22 and 166 m, studied by Vandenberghe et al. (2005) and revised by Louwye & Vandenberghe (2020).
It should be noted that the coarse sand below 166 m was originally considered as part of the Kieseloolite Formation but is now identified as the Inden Formation as discussed in Louwye & Vandenberghe (2020).
Alternative names Several ways to spell the name of this unit occur in literature in different languages:
– Kieseloolite (in Westerhoff , 2009),
– Kiezeloolith (in Vandenberghe et al. , 2020 & Vandenberghe et al., 2005) ),
– Kiezeloöliet ( H3O projects Flanders-the Netherlands (Vernes et al., 2009), in Laga et al. ,2001),
– Kieseloolith ( German stratigraphic table,
– les Kiezeloolithes (Gulinck ,1960)).
In the Neogene 2020 Geologica Belgica Volume the Westerhoff (2009) spelling is mostly used and is also followed in the present LIS.
Authors Vandenberghe, N., & Dusar, M.
Date 01/09/2023
Cite as Vandenberghe, N., & Dusar, M., 2023. The Kieseloolite Formation, 01/09/2023. National Commission for Stratigraphy Belgium.
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