2.11.1.2. Kleine-Spouwen Member
Name
The name was introduced by Van Den Broeck (1883) in an explanatory note of the geological map Bilzen (scale 1/20.000). The name is here used in the sense defined by Van Den Broeck (1883). Formerly, the term was used for a unit comprising the Berg Sands and, as well, the late Tongrian Oude-Biezen Sands (Vieux-Joncs) (de Heinzelin & Glibert, 1956, p. 96). Kleine-Spouwen is a village in South East Limburg, and is now a dependent municipality of Bilzen.
The spelling Kleine-Spauwen or Klein-Spauwen was often used in the French literature.
General characteristics
The member consists of greenish to yellowish grey clay, sometimes brownish at the top because of the oxidation. The member is frequently calcareous with numerous Nucula compta. The occurrence of calcareous concretions has been described. The fossils indicate a fully marine depositional environment.
Occurrence
The clay occurs in South Limburg (Sint-Truiden-Tongeren as far as Genk, Water-schei, Winterslag) and East Limburg (Maasmechtelen-Eisden).
The lower boundary of the member is with the Berg Member and the upper boundary is with the Kerniel Member or the Boom Clay in the Genk, Waterschei and Winterslag area (Gulinck, 1975, Belgian Geological Survey document MG/75/338). The member is also present - although reduced in thickness - in the Roelants Quarry in Lubbeek-Pellenberg (between Leuven and Tienen), where it is barely distinguishable from the overlying Terhagen Member (Boom Formation). The member has a maxi-mum thickness of 5 m.
Stratotype
Van Den Broeck (1883) refers to the top of the hill of Kleine-Spouwen. This site was already described by Ortlieb & Dolfuss (1873) and by Rutot (1873). A lithological profile of the site was given by Glibert & de Heinzelin (1954, fig. 12, p. 306) and by Van Den Broeck (1883, p. 44, fig. 4).
Profile of the outcrop at Kleine-Spouwen between points A and B: sheet 34/1-2 (Bilzen-Veldwezelt).
Co-ordinates point A: X = 233.18, Y = 170.42, Z = + 117 m.
Co-ordinates point B: X = 232.860, Y = 170.250, Z = + 122 m.
Former designations
Bosquet (1851): Clay with Nucula compta (or comta)
Geological map 1/40.000: R1c
Stratigraphical register (1929, 1932): R2a
New geological map 1/50.000: BiKs.