Maastricht Formation - MAA
Authors: Dumont (1849), W.M. Felder (1975).
Description: Six members are distinguished, as follows from the base to the top:
-Valkenburg Member (thickness between about 2.5 and 45 m): poorly indurated, white-yellowish to yellowish grey, fine- to coarse-grained "chalk" with greyish brown flint nodules of varying size in the west. In the east, sequence changes into alternation of poorly and more intensely indurated chalk beds, part of so-called 'Kunrade limestone'. Flints, where occurring, are crumbly, light grey nodules. Base with coarse-grained, phosphatic/glauconitic and pyritic bioclastic sand.
- Gronsveld Member (thickness between 4.5 and about 10 m): poorly indurated, white- yellowish to yellowish grey, fine to coarse-grained "chalk". In its lower portion, small, light to dark greyish brown flint nodules of varying size and shape, in its higher portion arranged in more or less regular beds of nodules. Towards the east the higher portion is missing, where the "chalk" changes into cyclic alternation of more or less indurated chalk beds, part of the so-called 'Kunrade limestone'.
- Schiepersberg Member (thickness 5 to 6 m): poorly indurated, white yellowish, fine- to coarse-grained, homogeneous "chalk" with numerous regular beds and randomly distributed, light-grey to bluish-grey flint nodules. Homogeneous "chalk" changes towards the east into alternation of chalk beds of varying induration, part of the so-called 'Kunrade limestone'.
- Emael Member (thickness between about 5 and 7.5 m): poorly indurated white-yellowish and yellowish-brown, fine- to coarse-grained, homogeneous "chalk", in its lower portion with numerous light grey flint nodules; typical are large, regular flat and pipe-shaped flint bodies. In the east, this homogeneous "chalk" changes into alternation of more or less indurated chalk beds, which form the highest part of the so-called 'Kunrade limestone'.
- Nekum Member (thickness between about 7 and 15 m): poorly indurated, white yellowish, coarse-grained, homogeneous "chalk", in its lower part with few randomly distributed greyish brown flint nodules. Locally with coarse-grained fossil hash lenses and beds.
- Meerssen Member (thickness between about 15 and 20 m): poorly indurated white yellowish, coarse- to very coarse-grained "chalk" with clearly developed hardgrounds and fossil hash layers and omission surfaces.
Stratotypes:
-Valkenburg Member: disused quarry east of Valkenburg aan de Geul, Limburg, The Netherlands (co-ordinates 318.520/186.770).
-Gronsveld Member: quarries Wijngaardsberg and Varkensgat at Riesenberg, east of Gronsveld, Limburg, The Netherlands (co-ordinates 314.050/180.150).
-Schiepersberg Member: disused Schiepersberg quarry, Cadier en Keer, Limburg, The Netherlands (co-ordinates 315.880/182.680).
-Emael Member: Marnebel quarry, Emael, Bassenge, Liège (co-ordinates 310.850/175.050).
-Nekum Member: disused de Tombe Quarry, St Pietersberg, Maastricht, Limburg, The Netherlands (co-ordinates 315.130/175.350).
-Meerssen Member: Ankerpoort-Curfs quarry, Geulhem, Limburg, The Netherlands (co-ordinates 320.120/182.100).
Area: With the exception of the area south of the line St Geertruid-Gulpen-Vaals and north of the Heerlerheide fault, where the formation is absent due to erosion, the unit occurs throughout southern Limburg and contiguous areas of Belgian Limburg and Liège.
Thickness: Between about 45 and 90 m.
Age: Early Late to latest Maastrichtian by: coleoid and ammonoid cephalopods: Belemnitella junior, Belemnella (Neobelemnella) kazimiroviensis, Baculites vertebralis, Pachydiscus gollevillensis, P. jacquoti, Sphenodiscus binckhorsti, Menuites terminus, M. fresvillensis andHoploscaphites constrictus.
Inoceramid bivalve: Tenuipteria argentea.
Microfauna/flora: Thalassiphora pelagica, Palynodinium grallator.
Remarks: - Formerly known as "Calcaire de Maestricht" auctorum, "Maastrichtien" (sensu Dumont, 1849), "Maastrichts Krijt (Tufkrijt)" (Netherlands Geological Survey, 1957).
- Recent references: W.M. Felder (1975), Zijlstra (1994), Vonhof & Smit (1996), Schiøler et al., 1997, Machalski & Jagt (1998), Jagt (1999).
Complementary data (M. Dusar, 2011): The Maastricht Formation has its largest extension in the Campine basin and also occurs in the Belgian part of the Roer Valley Graben. Although the distinction of the members defined in the type area is generally not feasible it is obvious that their equivalents are generally present and that defining alternative units is not advantageous. The hiatus at the Paleocene-Cretaceous boundary is persistent over the Campine and the Roer Valley Graben. However, in the eastern Campine and the Roer Valley Graben, the Kunrade facies has been recognized. After consultation with the Dutch stratigraphers it was decided to formalise the status of the Kunrade as a new formation (see separate description on this website).
Type profile of the Maastricht Formation in the ENCI quarry (Maastricht, the Netherlands), with succession of members and contacts with under- and overlying units (modified from Geological Survey of Belgium Professional Paper 301).
Legend : Yellowish fine grained calcarenite with layered flint nodules, characteristic for lower part of Maastricht Formation (Gronsveld Member). Roosburg underground quarry, commune of Riemst (photo M. Dusar).