Kleine-Spouwen Member

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

Abbreviation BiKs
Parent unit Bilzen Formation
Child units
Lithological description The member consists of greenish to yellowish grey clay, turning brownish when oxidized. The member is frequently calcareous, rich in foraminifera and with numerous Nucula comta accompanied by some more rare shells. Calcareous concretions have been described by Gulinck (1954). The fossils indicate a fully marine depositional environment (see also Janssen, 1979). The presence of sand has been described by several authors and Gulinck (1954) even reports that it may grade into the underlying sand of the Berg Member accompanied with a thickness reduction.
Age Paleontological data show that the Kleine Spouwen Clay Member falls within the same biozonation as the interval between the top of the Belsele-Waas Member and the Terhagen Member clay around septaria level S10 (Steurbaut et al., 1999; Vandenberghe et al., 2001 p71).
Thickness The member has a reported maximum thickness of 10 m (Claes et al. , 2001). Gulinck (1954) notes that the development of the clay unit is very irregular.
Area of occurrence The Kleine Spouwen Clay Member occurs in the shallow subsurface of the Sint-Truiden–Tongeren area in South Limburg (Claes et al., 2001; Claes & Gullentops, 2001), and is known northwards as far as Genk, Waterschei, Winterslag, Maasmechelen–Eisden (map Figure 7) (see also 3.). On the Hasselt geological map sheet, Matthijs (1999) reports thickness between 6 and 9 m and notes that variations in thickness suggest tectonic activity in the area.
Type locality
Alternative names A short historical review of the stratigraphic classification of the clay unit called nowadays the Kleine Spouwen Member is given in Glibert & de Heinzelin (1954 p 283-284 and Tableau I). Based on his mapping of the Bilzen 1:20 000 sheet, Van den Broeck (1883a,b) individualized the now-named Kleine Spouwen clay unit and separated it from underlying units. This clay unit was labelled as R1c on the geological maps 1:40 000 ( Anonymous, 1892,1896, 1900, 1909). However the name used to refer to the clay unit, already as long ago as Bosquet (1851), was ‘the clay with Nucula comta (or compta)’ as this shell is commonly present in the clay. In the Legend of the geological map 1:40 000 the clay is described as ‘argile en masse lenticulaire à Nucula compta’ (Anonymous 1909), as ‘clays with Nucules’ in the Stratigraphic register (Anonymous, 1929,1932) where it is labeled R2a and as ‘Argile sableuse à nucules’ in Glibert & de Heinzelin (1954). Gulinck (1954) reports on ‘l’argile à Nucula comta, dite aussi argile de Klein-Spauwen’. ‘Argile sableuse à Nucula comta’ is also reported by de Heinzelin & Glibert in the Lexique Stratigraphique International (Denizot, 1957 p 142). At the occasion of their study in the Sint-Truiden area Bor et al. (1980) have also presented a detailed historical nomenclature review used for the clay unit and concluded with the proposition to use the name Nucula Clay Lyell,1852, emend. However in the logic of naming lithostratigraphic units with reference to a locus typicus, the Nationale Stratigrafische Commissie (1988) decided to further use the term Kleine Spouwen Member. On the recent 1:50 000 geological maps the Kleine Spouwen Clay Member is coded BiKs. Note that several spelling variants have been used in literature used (Kleine-Spauwen, Klein-Spauwen, Kleyn-Spauwen,…).
Authors Vandenberghe, N. & Wouters, L.
Date 05/04/2024
Cite as Vandenberghe, N. & Wouters, L., 2024. The Kleine-Spouwen Member, 05/04/2024. National Commission for Stratigraphy Belgium. http://ncs.naturalsciences.be/lithostratigraphy/Kleine-Spouwen-Member


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