Opgrimbie Facies

The information on this page is a summary description.
The full formal description is available here: Opgrimbie Facies

Abbreviation BbOg
Parent unit Genk Member
Child units
Lithological description A medium-grained, white sandy unit holding a lignite seam (Kikbeek Lignite) and a quartzite layer (a silcrete cemented by originally opal bioliths) (Gullentops, 1963, 1972-1973; Matthijs, 1999). The white sand of the Opgrimbie Facies has in the type locality (Opgrimbie quarry) a modal grain size of approximately 215 µm. A sample from this facies in the Wijshagen borehole has a modal grain size of 296 µm, a clay content of only 0.7 % and a D90 of 433 µm. (Gullentops, 1963, 1973; see also Adriaens, 2015).
Age No precise absolute or relative dating of the Opgrimbie Facies is available. The Genk Member has been relatively dated through biostratigraphy as Langhian to early Serravallian (Louwye et al., 2020).
Thickness The thickness of the Opgrimbie Facies ranges between 10 and 15 m. The lignite seam has a thickness of about 3 m. The precise lateral and vertical limits of this facies remain to be determined (Louwye et al., 2020).
Area of occurrence The Opgrimbie Facies occurs in the eastern part of the Limburg province.
Type locality Sibelco sand pit at Opgrimbie in eastern part of the Limburg province (Gulinck, 1961; Wouters & Vandenberghe, 1994; Van Loon, 2009).
Alternative names Miocene glass sand of Maasmechelen (Gullentops, 1972-1973); Maasmechelen Silver Sands (Sels et al., 2001; Buffel et al., 2001), ‘Mechelen aan de Maas sand’ (Laga, 1973). This unit includes the Terlamen gravel at its base. It is topped by the Opgrimbie gravel.
Authors Louwye, S., Adriaens, R., Deckers, J. Vandenberghe, N. & Verhaegen, J.
Date 01/09/2023
Cite as Louwye, S., Adriaens, R., Deckers, J. Vandenberghe, N. & Verhaegen, J., 2023. The Opgrimbie Facies, 01/09/2023. National Commission for Stratigraphy Belgium. http://ncs.naturalsciences.be/lithostratigraphy/Opgrimbie-Facies
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