Antwerpen Member

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

Abbreviation BcAn
Parent unit Berchem Formation
Child units
Lithological description The Antwerpen Member consists of dark green to blackish, medium fine-grained, slightly clayey and very glauconitic sand with a mode of 219 µm ± 61 µm. The dispersed clay content is 3.7 ± 2.3% and the D90 of the grain size distribution is 352 ± 102 µm (De Meuter & Laga, 1976; Verhaegen, 2020). Characteristic are shell layers strongly dominated by Glycymeris baldii with a varying thickness. Some of these shell beds can be traced continuously across the entire type area (Deckers & Everaert, 2022). Layers with phosphatic concretions, friable sandstones, bones and shark teeth are present towards the base of the member. No clear basal gravel is present. The glauconite content ranges from 28% to locally as high as 85% and is on average 47%, which is the highest amount in any unit in the Campine Basin (Adriaens, 2015; Adriaens & Vandenberghe, 2020). The Antwerpen Member contains mostly authigenic glauconite (Vandenberghe et al., 2014; Odin & Kreuzer, 1988).
Age The planktonic foraminifers from the Antwerpen Member indicate the presence of the NPF12 Globogineroides trilobus Zone to the NPF13 Globorotalia praescitula Zone defined by Spiegler et al. (1988), and point towards a late Burdigalian to Langhian age. The benthic foraminifera from the Antwerpen Member are indicative for the mid-Miocene Uvigerina tenuipustulata – Elphidium inflatum Assemblage Zone (De Meuter & Laga, 1976), while the calcareous nannoplanton proposes a correlation with the late Burdigalian to Langhian NN4 Zone (Martini & Müller, 1973). Dinoflagellate cyst analysis demonstrates the presence of the Labyrinthodinium truncatum Zone, the Unipontidinium aquaeductus Zone and the Achomosphaera andalousiensis Zone and suggests deposition between 15.97 Ma and 12.8 Ma (Langhian – mid-Serravallian) (Louwye et al., 2000) (Figure 0‑2). The radiometric datings of glauconites from the Antwerpen Member give a K-Ar age of 20 Ma and a Rb-Sr age of 18.5 Ma to 21.5 Ma (Odin & Kreuzer, 1988), i.e. a latest Aquitanian to mid-Burdigalian age. Vandenberghe et al. (2014) and Adriaens (2015) attribute the diverging age assessment to the presence of reworked glauconite pellets.
Thickness Based on (sometimes lithostratigraphically revised) outcrop drawings by De Meuter et al. (1976) and correlations with nearby CPTs, the Antwerpen Member has an approximate thickness of 7 m in the type area.
Area of occurrence Deposits coeval with the Antwerpen Member are recorded in several boreholes north (Antwerp Campine area) and east (Campine area) of the type area reaching a maximum thickness of c. 5 to 10 m (Louwye et al., 2020).
Type locality According to De Meuter & Laga (1976), the type locality of the member is the city centre of Antwerp. The original, and now disappeared, type section of the member was described during the excavations works for a fort at Antwerp (Nyst, 1845). Nowadays no permanent outcropping type section for the member exist. The lithology of the member was described in following temporary outcrops in the Antwerpen area (see Figure 0 1 for a synthetic overview):
Antwerpen – Berchem Station AM (De Meuter et al., 1976)
Antwerpen – Borbeeksepoort II BP (De Meuter et al., 1976)
Borgerhout – Stenen Brug I SB (De Meuter et al., 1976), revised by Deckers and Everaert (2022)
Borgerhout – Rivierenhof XI BR (De Meuter et al., 1976) correlated to CPT GEO-07/154-S11 by Deckers and Everaert (2022)
Antwerpen – Kievitstraat II, V, VI AK (De Meuter et al., 1976), revised by Everaert et al. (2020)
Posthofbrug (Louwye et al., 2010) correlated to CPT GEO-68/101-SVII by Deckers and Everaert (2022)
Posthofbrug 2-3 (Hoedemakers & Dufraing, 2018)
Tweelingenstraat (Everaert et al., 2020)
Argenta (Everaert et al., 2020)
Post X (Everaert et al., 2020)
Alternative names
Authors Louwye, S., Adriaens, R., Deckers, J., Everaert, S., Vandenberghe, N. & Verhaegen, J.
Date 01/09/2023
Cite as Louwye, S., Adriaens, R., Deckers, J., Everaert, S., Vandenberghe, N. & Verhaegen, J., 2023. The Antwerpen Member, 01/09/2023. National Commission for Stratigraphy Belgium.
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