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Introduction
The aim of the present paper is to furnish a revised overview of the stratigraphy of strata in the type area of the Maastrichtian Stage (Fig. 1), the youngest time slice of the Cretaceous Period (70.6 ± 0.6 to 65.5 ± 0.3 Ma). On numerous occasions it has been pointed out that strata in the historical type area were affected by regional synsedimentary tectonic movements (Fig. 2; compare Bless et al., 1987; Rossa, 1987; Bless, 1991a, b; Gras, 1995; S. Voigt et al., 2008) and that the refined lithostratigraphical subdivision (W.M. Felder, 1975a, b, 1996; W.M. Felder & Bosch, 2000) was not matched by a comparably detailed biozonation. In general, there is a consensus amongst members of the Maastrichtian Working Group (Subcommission on Cretaceous Stratigraphy) that, for various reasons, sections in the historical type area of the stage cannot be used for the definition of the Campanian/Maastrichtian boundary. This has now been ratified as a GSSP (Global Boundary Stratotype Section and Point) at Tercis les Bains, near Dax (Landes, southwest France; Odin, 1996, 2001). Similarly, the GSSP for the Maastrichtian/Danian boundary has been designated elsewhere, at El Kef (Tunisia), because of the widely held view that the top of the Maastrichtian and the overlying basal portion of the Danian were missing in the type area of the Maastrichtian Stage. In recent years, it has appeared that this is not the case, and that the K/Pg boundary section here is more complete than previously held possible (Brinkhuis & Schiøler, 1996; Jagt, 1996, 1999a, b, 2000a, b, c, d; Kuhnt, 1996; A.J.T. Romein et al., 1996; Schmitz & Speijer, 1996; Smit & Brinkhuis, 1996; Smit & Zachariasse, 1996; Vonhof & Smit, 1996; Willems, 1996; Witte & Schuurman, 1996; Vonhof et al., 2011).
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Fig. 1. Map of southern Limburg (the Netherlands) and contiguous areas in northeast Belgium (Voerstreek, Limburg and Liège) and western Germany (Aachen area), showing the most important localities ([temporary] outcrops and quarries) in the type area of the Maastrichtian Stage. |
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Fig. 2. Structural map and cross sections (A-C) of the Liège-Limburg basin. During mid-Santonian to early Maastrichtian times, the Roer Valley Graben became inverted, while the Brabant and Stavelot massifs formed structural highs. Latin numerals in cross section C refer to bioclast ecozones (after S. Voigt et al., 2008, fig. 15.16). |