The information on this page is a summary description.
The full formal description is available here: Wurfeld Formation
Abbreviation
Wu
Parent unit
Child units
Lithological description
In the Maaseik borehole (049W0220), quartz-enriched pale coloured sand occurs above green glauconite enriched sand. Above the latter, the basal part of the pale-colored sand between 192.7 m and 198 m depth is singled out because of its finer grain size – modal size between 128 and 174 µm-, high mica content, faint lamination, a few percentages of glauconite pellets (1.7 -3.5 %) and as an interval with a more elevated natural gamma ray (GR) signature. The basal part of this pale-colored sand above 198 m was interpreted as a shallow marine deposit.
Age
Dinoflagellate cysts biostratigraphy shows all samples of the Wurfeld Formation hold the H. obscura Zone, age calibrated between 7.6 and 8.8 Ma indicating a mid-late Tortonian age (7.246 to 11.63 Ma) (Louwye & Vandenberghe, 2020).
Thickness
The thickness is 5,3 m in the Maaseik reference borehole. Because of its limited thickness and its high gamma-ray signature the unit was included in the underlying Diest Formation in the H30-project (Vernes et al., 2018).
Area of occurrence
Until now the Wurfeld Formation has only been described in cores of the Maaseik borehole (049W0220). However, based on the gamma ray signal, it is suspected that the formation can be more generally present in the Belgian part of the Roer Valley Graben (see logs in Vandenberghe et al., 2005, fig.10). It should be noted however that the use of the jump to higher gamma ray values needs to be interpreted with caution as in the Maaseik well within the RVG its lithological significance is different compared to the area Dessel-Mol where the top of this gamma-ray signal corresponds to the clayey glauconite sand of the Heist-op-den-Berg Member of the Kasterlee Formation (‘clayey Kasterlee’ in the Geologica Belgica, 2020 Neogene volume).
Type locality
Until now the Wurfeld Formation has only been positively identified in the Maaseik borehole (049W0220) between 192.7 m and 198 m, consequently making this borehole the reference.(Vandenberghe et al., 2005 ; Louwye & Vandenberghe, 2020).
Alternative names
unit X : This name has been used in literature since the unit was first described by Vandenberghe et al. (2005) and in the review of its stratigraphic position by Louwye & Vandenberghe (2020).
Authors
Vandenberghe, N., & Dusar, M.
Date
01/09/2023
Cite as
Vandenberghe, N., & Dusar, M., 2023. The Wurfeld Formation, 01/09/2023. National Commission for Stratigraphy Belgium. http://ncs.naturalsciences.be/lithostratigraphy/Wurfeld-Formation
