Gulpen Formation - GUL
Authors: Netherlands Geological Survey (1957), W.M. Felder (1975).
Description: Five members are distinguished as follows from the base to the top:
- Zeven Wegen Member (thickness up to about 30 m): white to light grey, fine-grained chalks with basal layer of glauconitic zones, towards the west with randomly distributed black, fine-grained flints with glassy fracture.
- Beutenaken Member (thickness up to about 10 m): light greyish to whitish yellow, glauconitic fine- grained clayey and calcareous marls, with glauconite concentration in lowermost metre.
- Vijlen Member (thickness generally between 15 and 25 m, but locally up to about 100 m): yellowish grey, glauconitic fine-grained chalks, with basal glauconite-rich portion, subdivided into seven intervals by P. J. Felder & Bless (1994), each with distinctive fossil assemblages.
- Lixhe Member: (total thickness of Lixhe 1-3members up to 25 m) white, fine-grained chalks with irregular dark blue-grey to black flint nodules. West of the River Maas (Meuse) threefold subdivision possible on flint type and abundance.
- Lanaye Member (thickness c. 20 m) white, fine-grained chalks with irregular light to dark blue-grey flint nodules; west of River Maas with 23 flint bands, east of river bedding the Lixhe Member is absent and only randomly distributed flint nodules occur.
legend : Diesberg Sluizen. Former Diesberg quarry, Sluizen (Tongeren commune), GeoDoc 107W0160, showing continuous layers of rather coarse grey flint in coarse whitish chalk, characteristic for the Lanaye Member of the Gulpen Formation. The flint makes up to 25% of the sediment composition (photo M. Dusar).
Stratotypes:
- Zeven Wegen Member: road cutting along tourist road Vaals-Epen, near Zeven Wegen (Vijlenerbosch), Limburg, The Netherlands (co-ordinates 308.550/194.940)
- Beutenaken Member: disused Habets quarry, Beutenaken, Limburg, The Netherlands (co-ordinates 309.270/188.250).
- Vijlen Member: road cutting between Mamelis and Bocholtzerheide, on the Dutch-German boundary (co-ordinates 312.330/196.450).
- Lixhe 1-3 members: disused Dierkx quarry, Lixhe; Liège province (Dutch co-ordinates 308.400/174.500).
- Lanaye Member: west bank of Albert Canal outcrop, north of bridge at Lanaye, Liège province (Dutch co-ordinates 311.000/176.150).
Area: In southern Limburg, confined to area south of Benzenrade and Schin op Geul faults; well developed in Haccourt-Eben Emael area (Liège).
Thickness: Up to about 175 m.
Age: Earliest Late Campanian to early Late Maastrichtian by: coleoid and ammonoid cephalopods: Scaphites gibbus, Trachyscaphites spiniger, Acanthoscaphites (A.) tridens, A. (Euroscaphites) varians blaszkiewiczi, Pachydiscus neubergicus, Belemnella (B.) inflata, Bn. (Pachybelemnella) obtusa, Bn. (P.) sumensis, Bn. (P.) cimbrica, Belemnitella pulchra, Bt. junior, Bt. minor II, Bt. najdini, andBt. woodi.
Foraminifera: Bolivinoides delicatulus regularis, B. australis, B. d. draco, B. draco miliaris, Neoflabellina permutata.
Remarks: - Formerly described as "Gulpens Krijt" (Netherlands Geological Survey, 1957), "Craie grise" auctorum, "Craie blanche" auctorum, "Craie tigrée" auctorum, "Tijgerkrijt" auctorum.
- Recent references: P. J. Felder & Bless (1994), P.J. Felder (1996, 1997), Keutgen & Jagt (1999), Keutgen (1996, 1997), Jagt (1999), Jagt et al. (1999).
Complementary data (M. Dusar, 2011):
The subcrop area of the Gulpen Formation extends over the eastern part of the Brabant Massif and the Campine Basin. The lower Campanian Vaals Formation becomes chalky towards the west to the point that the succession of the Vaals and Gulpen formations merges into a chalk sequence to form the Nevele Formation on the Brabant Massif (see separate description). The Gulpen Formation and time-equivalent strata are largely absent in the Rur Valley Graben. In the northeastern Campine, the Gulpen Formation laterally grades in the new Dorne Formation, equivalent of the Benzenrade Member of the Vaals Formation as defined by Felder & Bosch (2000).
Combining geophysical well logs, the ecozonation established by P.J. Felder and dinoflagellate cyst biostratigraphy allowed to elucidate problems of lateral facies persistence within the Gulpen Formation of the Campine Basin, resulting in some shifts with respect to the standad zonation in the type localities south and east of Maastricht. The white chalk facies, expressed in the Zeven Wegen Member in the type area, strongly increases in thickness and also incorporates the Beutenaken -1 Member of the type area. The Campanian/Maastrichtian boundary is included in the hiatus marked by the Froidmont Hardground on top of this unit. The overlying Beutenaken-2 Member, absent in the type area is widespread over the Campine basin and forms a continuous sedimentary sequence with the Vijlen and Lixhe Chalks. Noteworthy is the less pronounced facies variation and the delayed facies change in the western Campine compared to the type area: so are the Lixhe-1 equivalent strata indistinguishable from the underlying Vijlen Chalk. The Lanaye Chalk on the other hand, is developed in calcarenite facies.
Felder, P.J., 2001. Bioklasten-stratigrafie of ecozonatie voor het Krijt (Santoniaan-Campaniaan-Maastrichtiaan) van Zuid-Limburg en oostelijk België. Memoirs of the Geological Survey of Belgium 47: 141 p.
Slimani, H.; Louwye, S.; Dusar, M. & Lagrou, D., 2011. Connecting the Chalk Group of the Campine Basin to the dinoflagellate cyst biostratigraphy of the Campanian to Danian in borehole Meer (northern Belgium). In: Jagt, J.W.M., Jagt-Yazykova, E.A. & Schins, W.J.H. (eds): A tribute to the late Felder brothers - pioneers of Limburg geology and prehistoric archaeology. Netherlands Journal of Geosciences / Geologie en Mijnbouw 90 - 2/3: 120-164.
legend : top layer: displaced cover strata - upper bench: Lanaye (with regular flint layers) and top Lixhe members - middle bench: Lixhe member (small flint without layered appearance from this angle) and Vijlen member (grey chalk) - lowermost bench: Zeven Wegen member (white chalk) - 107E0215 - Hallembaye CPL groeve