Skip directly to content

2.1 Introduction


(2 figures &1 table)


Permian to Lower  Jurassic strata, deposited between Variscan and Cimmerian deformation phases , subcrop in the northeastern Campine basin and Roer Valley Graben (NE Belgium). Total preserved thickness attains 550 m (of which 520 m drilled) in the Campine basin and ca. 1500 m (of which 1250 m drilled) in the Roer Valley Graben. Discovery of these concealed deposits is due to coal exploration of the Campine basin; further interest is linked to their potential for energy production or storage. Permo-Triassic sediments displaying Germanic facies were deposited on the southern margin of the Southern Permian Basin; Pangaea break-up associated with opening of the North Atlantic created conditions for deposition of the fully marine Jurassic sediments. Therefore, the stratigraphical succession in north-eastern Belgium is closely related to the Dutch stratigraphical nomenclature.

Keywords: Permian,Triassic, Jurassic, NE Belgium, lithostratigraphy

Reference to this volume: Dusar, M., Langenaeker, V. & Wouters, L., 2001.Permian-Triassic-Jurassic lithostratigraphicunits in the Campine basin and the Roer Valley Graben (NE Belgium). In Bultynck & Dejonghe, eds. Guide to a revised lithostratigraphic scale of Belgium, Geologica Belgica, 4/1-2: 107-112.


1. Introduction

Triassic red beds were first encountered in the Campine subsurface in 1899, when Andre Dumont jr. drilled his first coal exploration well at Elen. Although he failed to bring up coal, he immediately grasped the importance of these red beds and consecutively drilled in 1900 his second well further to the south, closer to the Brabant Massif, near As. Here he struck coal of the right quality for the metallurgical industry directly underneath the subhorizontal Tertiary-Cretaceous cover, without intercepting the red beds. Hence the presence of red beds or "Roches rouges" or "Rode Gesteenten " as they were known , was considered as a nuisance for the coal miners and the Campine coal field developed immediately south of the subcrop wedge of the red beds (Tys, 1980).

The presence of a thick deposit of Permian to Jurassic age in the Campine also gave rise to expectations of salt deposits on Belgian territory. A drilling campaign by Solvay in 1908 - 1911 failed to fulfil this hope but brought additional information on the younger strata in the Roer Valley Graben. In fact the Upper Permian Zech­ stein salt basin extends towards the Rhine, some 50 km north of the Belgian boundary (Stainier, 1907, 1911, 1943).

The stratigraphic interpretation of these older boreholes was summarised by Antun (1954) and Legrand (1959; in Delmer,  1963).

Seismic surveys revealed  that Permian  to Jurassic beds unconformably overly the Carboniferous Coal Measures and  gradually  wedge  out towards  the  south  below  the Cretaceous unconformity, albeit displaced along normal faults. This implied that the coal bearing strata underlying the red bed s may occur at conventionally mineable depths (Bouckaert , Dusar & Van de Velde, 1981). Consequently new coal or gas exploration boreholes drilled in the period 1979 – 1993 extended over the subcrop area of the Permian to Jurassic beds (Fig. 1).

In total 20 wells provide the base for the stratigraphic framework of the Permian to Jurassic. Cuttings or core descriptions, coupled with log interpretation and seismic stratigraphy allowed a correlation with the older boreholes as well as a partial facies reconstruction and diagenetic evolution (cf. Dusar et al., 1987).

As already been introduced by Wouters & Vandenberghe (1994) and Langenaeker (2000), the present update of stratigraphical subdivision of the Permian to Jurassic proposes a new lithostratigraphic subdivision of the Buntsandstein and Zechstein, which are sufficiently covered by boreholes (Tab. 1, Fig. 2). All wellsite information comes from the southern fringe of the Permian to Jurassic subcrop. The Permian to Lower Jurassic deposits probably had a much larger southwards extension and even covered the eastern part of the Brabant Massif, until they were removed by erosion following the Kimmerian Uplift of the Brabant Massif during the Late Jurassic (Van den haute & Vercoutere, 1990). The Stratigraphic Nomenclature of The Netherlands is hereby used as the reference for the stratigraphic subdivision of the Campine (van Adrichem Boogaert & Kouwe, 1993; NITG-TNO, 2001), the Geological Atlas of Western and Central Europe for the palaeogeographical reconstruction (Ziegler, 1990).

2. Description of formations

Table 1: stratigraphic subdivision of the Perrnian to Jurassic sequence in the Campine basin and Roer Valley Graben (Belgian part). Correspondence of lithostratigraphic units to chronostratigraphic units is only assumed. Boundaries between successive lithologic units do not exactly coincide with chronostratigraphic boundaries.





Figure 1. Subcrop map of Permian to Jurassic formations in the Campine basin and Roer Valley graben (northeastern Belgium), compiled at Geological Survey of Belgium, first published in Wouters & Vandenberge (1994), reworked by P. Vancampenhout with location of boreholes discussed.


Figure 2. Chronostratigraphy and lithostratigraphy of Permian - Triassic - Jurassic deposits in NE Belgium (reprint from Dusar et al., 2001).