The information on this page is a summary description.
The full formal description is available here: Aalterbrugge Member
| Abbreviation | GeAb |
| Parent unit | Gentbrugge Formation |
| Child units | |
| Lithological description | The Bed consists of clays and sand occurring in a complex geometrical relationship like usually encountered in continental deposits; also lignite beds and drift wood, sometimes silicified, occur. It occurs between the Vlierzele Member and the Aalter Formation (Zenne Formation) (Maréchal & Laga, 1988; Steurbaut, 2006), both more homogeneous, glauconitic, marine sediments. In the synthesis on Belgian geology (P. Fourmarier, 1954, Prodrome d’une description géologique de la Belgique, Soc. Géol. Belg.) Gulinck & Hacquaert (1954) describe in the chapter XIV the Complexe d’Aalterbrugge occurring in the top of the Vlierzele sand unit as follows: “Ces sables prennent souvent dans les zones supérieures, quelquefois aussi dans les parties moyennes, un facies plus grossier, pauvre en galuconie, parfois ligniteux, avec bois flottés percés de tarets et souvent silicifiés. On y rencontre également des niveaux de galets de glaise, spécialement dans la région de Torhout (Rutot [explic.carte géologique 1:40 000]) et d’Aalter (Hacquaert, [1939]). Les bois flottés sont parfois très volumineux. Leur nature fragmentaire permet rarement une détermination précise, mais on a pu y distinguer une dizaine d’espèces (F. Stockmans [région de Bruxelles])”. The Aalterbrugge unit as represented on the section in De Moor & Geets (1973, fig.4) attains 10m thickness. The temporary exposure described by Jacobs (2015 p 137) was at maximum 3m thick (Steurbaut or. com.). Van Simaeys (1999) shows the presence of the Aalterbrugge Complex in the Hijfte borehole (040E0373) section between 46.1 and 53.1 m depth. No Aalterbrugge unit is reported in Geets et al. (2000) and also in the explanatory notes of the 1:50 000 map sheet 22 Gent, the Aalterbrugge unit is not reported (Jacobs et al., 1996). From his extensive data review, Fobe (1995) even concludes that the Aalterbrugge layer does not exist as a separate facies and has been confused with lignitic rich zones occurring at different levels in the Vlierzele unit. The Aalterbrugge unit is well documented and analysed by Van Simaeys (1999) in the Hijfte borehole 040E0373 in which it is 7m thick. Because of this thickness the member rank is justified for the Aalterbrugge Member. A several meter thick similar unit was also exposed during the construction of the pedestrian bridge over the E40 motorway in Wetteren. |
| Age | |
| Thickness | |
| Area of occurrence | The Aalterbrugge Member is most often reported between Aalterbrugge and Beernem (Jacobs, 2015). It was also described in the Hijfte borehole ? 040E0373 northeast of Gent. A recent outcrop along the E40 in Wetteren also showed the presence of the Aalterbrugge Member. Roche (1988?1991, p 375) and DeConinck (1988?1991, fig. 9 p 304) report the presence of the Aalterbrugge Complex in the boreholes Kallo ? 027E0148 (level 203 m) and Woensdrecht (NL) (level 385 m). |
| Type locality | Sections along the Gent?Brugge canal (Hacquaert 1939 section). Parastratotype in the Hijfte borehole (040E0373) section between 46,1 and 53,1 m depth (Van Simaeys, 1999). Remark : The Aalterbrugge Member of the Hijfte borehole (Van Simaeys, 1999) contains isolated records of the freshwater fern Azolla sp. which occurs massively in the North Sea and even the Atlantic Ocean at the base of chron C21r (Vandenberghe et al., 2004). |
| Alternative names | |
| Authors | Steurbaut, E., De Ceukelaire, M., Lanckacker, T., Matthijs, J., Stassen, P., Van Baelen, H. & Vandenberghe, N. |
| Date | 09/01/2017 |
| Cite as | Steurbaut, E., De Ceukelaire, M., Lanckacker, T., Matthijs, J., Stassen, P., Van Baelen, H. & Vandenberghe, N., 2017. The Aalterbrugge Member, 09/01/2017. National Commission for Stratigraphy Belgium. http://ncs.naturalsciences.be/lithostratigraphy/Aalterbrugge-Member |
