Kiel Member

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

Abbreviation BcKi
Parent unit Berchem Formation
Child units
Lithological description The Kiel Member was originally described as a non-fossiliferous (i.e. decalcified), grey-green medium fine-grained to coarse-grained sand (mode 248 μm ± 51 μm), very rich in glauconite, sometimes concentrated in patches, with rare clay streaks and sandstones. The clay content is 2.5 ± 1.3% and the D90 of the grain size distribution of 404 ± 108 μm, making the Kiel Member less clayey and with a larger coarse fraction compared to the underlying Edegem Member and overlying Antwerpen Member (De Meuter & Laga, 1976; Verhaegen, 2020). This facies occurs in the south and central part of the city of Antwerp (De Meuter & Laga, 1976). To the north and east of Antwerp this member becomes fossiliferous (Everaert et al., 2020). Everaert et al. (2020) studied several temporary outcrops of the Kiel Member in Antwerp and could distinguish the fossiliferous Kiel and Antwerpen members by a slight but marked color difference (greyish versus blackish) due to a somewhat lower clay and glauconite content and a coarser sand fraction in the Kiel Member. The glauconite content ranges from 28% to 54% and is on average 38% (Adriaens, 2015). The Kiel Member is characterized by a different ichnofacies, with the almost continuous presence of bioturbation. Everaert et al. (2020) described furthermore in great detail sandstone layers and shell layers (Glycymeris, Cordiopsis, Cyrtodaria), intercalated between several metres of loose grey sand, seemingly devoid of calcareous fossils. In contrast to the Antwerpen Member, the recorded molluscs are worn and very fragile due to heavy decalcification.
Age The radiometric dating of glauconites show diverging K-Ar ages (23 to 25.3 Ma; Chattian) and Rb-Sr ages (30 Ma; Rupelian) (Odin et al., 1974; Odin & Kreuzer, 1988, Vandenberghe et al., 2014) indicative of presumed reworking. This is underscored by the grain-size distribution curves (Adriaens, 2015). The Kiel Member holds the dinoflagellate cyst zones Exochosphaeridium insigne and Cousteaudinium aubryae, inferring a middle to late Burdigalian age (Louwye et al., 2000). An analysis of the dinoflagellate cysts of the Kiel Member by Everaert et al. (2020) indicates a similar age for the deposits, apart from a sample at the very base of a studied outcrop that yielded a deviating age (late Aquitanian) that needs further elucidation.
Thickness Based on the outcrop drawings by De Meuter et al. (1976) and CPTs, the Kiel Member has an approximate thickness of 10 m in the type area.
Area of occurrence Deposits coeval with the Kiel Member are recorded in several boreholes north and east of the type area (Antwerp Campine area, Figure 0-2) reaching a thickness of circa 20 m (Louwye et al., 2020).
Type locality De Meuter & Laga (1976) mentioned Kiel, suburb of the city of Antwerp, as the type locality. No permanent outcropping type section for the member exists. The lithology of the member was described in following temporary outcrops in the Antwerpen area (see Figure 0-2 for a synthetic overview):
Antwerpen – Van Rijswijcklaan AV (De Meuter et al., 1976)
Antwerpen – Nachtegalenpark AN (De Meuter et al., 1976)
Berchem – Grote Steenweg AG (De Meuter et al., 1976)
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 Kiel Member, 01/09/2023. National Commission for Stratigraphy Belgium.
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