Kerniel Member

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

Abbreviation BiKe
Parent unit Bilzen Formation
Child units
Lithological description The Kerniel Sand Member consists of medium-grained, white to yellowish quartz sand with only rare mica and glauconite grains. The sand has been described as clayey at the base and fining towards the top. Occasional layers of Glycymeris obovata (Lamarck, 1819) shells and marine shell imprints have been described in the upper part. Other characteristic species are Arctica islandica rotundata (Agassiz, 1845), Pycnodonte queteleti (Nyst,1853), Hilberia hoeninghausi (Defrance, 1825) (Vervoenen, 1995; Baut & Génault, 1999). Except for some reworked foraminifera, no microfauna has been observed. Small lignite fragments are occasionally present. In Limburg the gravel in the middle of the sand unit is reported to be well developed and consists of rounded quartz and flint pebbles (from Van den Broeck 1893 p 285, 280; Gulinck, 1954; Batjes, 1958; Kruissink et al., 1978; Claes et al., 2001; Claes & Gullentops, 2001). As the Kerniel Sand Member is seldom exposed, the Gellik-Eigenbilzen Albert Canal section in the early 90’s of the previous century is an exceptional outcrop worth mentioning. The section was studied for fossils by Vervoenen (1995) and Baut & Génault (1999). Remarkably in the middle of the 9-10 m thick sand section the last authors describe a dm thick shell grit layer (op.cit. fig.4) with a wavy eroding base (op.cit. fig.3) containing fish and other vertebrate remains and also small white quartz pebbles, undoubtedly the same level described by Steurbaut et al. (1999) with channels, gravel and oblique lamination. This observation seems to fit the subdivision in three units labelled R1d, R2a, R2b by Van den Broeck (1893) as discussed above.
Age The chronostratigraphic position of the Kerniel Sand Member is in the lower part of nannoplankton zone NP23 and is geometrically equivalent to part of the Terhagen Member of the Boom Clay Formation (Figure 4).
Thickness Thickness of the Kerniel Sand Member varies from 5-7 m on average to maximal 10 m (Claes et al., 2001; Claes & Gullentops, 2001).
Area of occurrence The Kerniel Member occurs in South Limburg: northeast and east on the geological map sheet Sint-Truiden and north on the map sheet Tongeren (Claes et al., 2001; Claes & Gullentops, 2001) (Figure 7). Further northwards in the subsurface, the member can be identified on geophysical logs as far north as the boreholes Koewijde-KS2 (Figure 3, 9), Dornerheide-KS6 (Figure 8a), and Ruwmortelsheide-KS22 (063E0222 and Vandenberghe et al. 2001 fig. 9), whilst west of these boreholes the Kerniel Member, as well as the Kleine-Spouwen Member are absent in the Opglabbeek-KS19 borehole (Figure 8a and Vandenberghe et al. 2001 fig. 9).
Type locality Van den Broeck (1883) refers to the railroad Looz (Borgloon)-Kerniel, at Kerniel, a section in which he originally had erroneously taken the Kerniel Sand for ‘boldérien sableux’ (Van den Broeck, 1893 p 270) (an interpretation still held for possible by Gullentops, oral com.). This railroad section is point 163 in Glibert & de Heinzelin (1954, p 299 and map fig.4). In the close vicinity Glibert & de Heinzelin (op. cit.) report an open sand pit in the Kerniel Sand at their point 164 and a few other outcrops.
In the subsurface the sand lithology of the Kerniel Member between the clays of the Kleine Spouwen Member and the Boom Formation is easily recognized on geophysical logs (examples Figures 3, 8b, 9 and Vandenberghe et al., 2001 fig. 9).
Alternative names The labelling of the Kerniel Sand on the 1:40 000 geological map (Anonymous 1909) consists of 3 codes: R1d, R2a and R2b. The reason is that within the Rupelian stage (R), two ‘assises’ were distinguished (R1 & R2); within each of these marine cycles or ‘assises’ a theoretical sedimentary cycle was assumed with successive facies ‘a’ (gravel), ‘b’ (transgressive sand), ‘c’ (deeper marine clay) and ‘d’ (regressive sand) (Rutot, 1883). As the Kerniel Sand at Kerniel near Borgloon (Looz) interpreted by Van den Broeck (1893 p. 270) as a stratigraphically independent sand unit between two deeper marine clay units, the argile à Nucula comta (Kleine Spouwen Member) and the argile à Leda Deshayesiana (Boom Formation), this intermediate Kerniel Sand unit needs to be composed of a succession of regressive sand, a base gravel and an overlying transgressive sand, labelled respectively as R1d, R2a and R2b. In the Stratigraphic Register (Anonymous, 1929,1932) the sand unit corresponding to the Kerniel Sand is not listed. On the recent 1: 50 000 geological maps the coding for the Kerniel Sand is BiKe.
Authors Vandenberghe, N. & Wouters, L.
Date 05/04/2024
Cite as Vandenberghe, N. & Wouters, L., 2024. The Kerniel Member, 05/04/2024. National Commission for Stratigraphy Belgium.


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