Disused Neogene and Quaternary Regional
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GEOLOGICA BELGICA (2006) 9/1-2: 215-224 DISUSED NEOGENE AND QUATERNARY REGIONAL STAGES FROM BELGIUM: BOLDERIAN, HOUTHALENIAN, ANTWERPIAN, DIESTIAN, DEURNIAN, KASTERLIAN, KATTENDIJKIAN, SCALDISIAN, POEDERLIAN, MERKSEMIAN AND FLANDRIAN Pieter LAGA1 & Stephen LOUWYE2 with a contribution of Frank MOSTAERT3 concerning the Flandrian Quaternary stage (1 fi gure, 1 table) 1. Geological Survey of Belgium, Royal Belgian Insitute of Natural Sciences, Jennerstraat 13, B-1000 Brussels, Belgium; E-mail: [email protected]. 2. Research Unit Palaeontology, Ghent University, Krijgslaan 281/S8, B-9000 Gent, Belgium; E-mail: [email protected]. 3. Geology and Soil Science Department, Ghent University, Krijgslaan 281/S8, B-9000 Gent, Belgium. Limburgs Universitair Centrum, Universitaire Campus Diepenbeek, B-3590 Diepenbeek, Belgium; E-mail: [email protected]. ABSTRACT. An overview of eleven disused Neogene regional stages from Belgium is presented. Some of the regional stages were already brought into use in the nineteenth century, but are nowadays considered ill defi ned and of no use in the light of the modern stratigraphic concepts. An overview of their defi nition and history is given, together with the argumentation for the abandonment of each unit and its present status. S e disused chronostratigraphic units belonged to the Miocene, the Pliocene and the Holocene series. KEYWORDS: Belgium, Neogene, Holocene, regional stages, disused chronostratigraphic units Reference to this paper: Laga, P. & Louwye, S.(coll. Mostaert, F.), 2006. Disused Neogene and Quaternary regional stages from Belgium: Bolderian, Houthalenian, Antwerpian, Diestian, Deurnian, Kasterlian, Kattendijkian, Scaldisian, Poederlian, Merksemian and Flandrian. In Dejonghe, ed., Current status of chronostratigraphic units named from Belgium and adjacent areas, Geologica Belgica, Brussels, 9/1-2: 215-224. 1. Introduction 5°E S e study of the Neogene deposits of northern Belgium southern started during the nineteenth century and was mainly North Sea The Netherlands Antwerp Campine based on outcrops in quarries in the Campine area (Fig. area Campine 1) and on temporary outcrops made for the construction area of military defences around the city of Antwerp and the Belgium 51°N expansion of the harbour. Many regional stages were 2IVER3CHELDT 0OEDERLEE defi ned and in use for many years. However, during the +ATTENDIJK +ASTERLEE -ERKSEM $IEST last decades it became clear that these Neogene regional $EURNE "OLDERBERG 0 20 km N stages do not meet the modern criteria for stratigraphic !NTWERP (OUTHALEN classifi cation. Consequently the usage of these regional southern limit of Neogene deposits in northern Belgium stages should be abandoned, and replaced by the inter- Figure 1. Overview of the localities after which the disused nationally accepted stages. A historical overview together Neogene regional stages in northern Belgium were named. with an analysis of the validity of each regional stage is Inset: southern North Sea Basin. given in stratigraphic order. 216 PIETER LAGA & STEPHEN LOUWYE (CONTRIBUTION OF FRANK MOSTAERT) 2. Bolderian 2.3. Status of the name 2.1. Defi nition and history According to modern stratigraphic criterions, the stage name Bolderian should not be used anymore. Actually, S is stage name (“Boldérien”) was established by Dumont the geographic name Bolderberg is used as a lithostrati- (1850) as the youngest Miocene stage, which, in his graphic term for the Bolderberg Formation (De Meuter opinion, consisted of the Bolderian, Rupelian and Ton- & Laga, 1976; Laga et al., 2001) and is used on the re- grian stages. With the Bolderian stage, he designated the gional geological map at a 1:50,000 scale. An overview sediments nowadays known as the Bolderberg Formation, of the members included in the Bolderberg Formation which was known at that time from the Bolderberg sec- is summarised in Laga et al. (2001). tion (Fig. 1), situated near Zolder. S e section contained two gravel levels: a lower gravel bed with well preserved silicifi ed molluscs (a concentration of fossils belonging 3. Houthalenian to the Bolderberg Sands), and an upper gravel bed with limonitic fossils, actually belonging to the Diest Sands. 3.1. Defi nition and history Nyst (1861), who discovered the Edegem Sands over- lying the Boom Clay, takes the view that the Edegem S is stage name “Houthaléen” was established by Hinsch Sands, with Panopaea menardii and other mollusc spe- (1952) after the “Horizon de Houthalen” from which cies occurring in the “Crag noir“ near Antwerp, actually Glibert (1945) had studied the Miocene mollusc fauna. belongs to the Diestian. In his opinion, the Bolderian of S e name is derived from the village of Houthalen (Fig. Dumont (1850) has to be considered as the base of the 1), situated 12 km north of Hasselt. S is horizon was Diestian stage. found above the Voort Sands (Chattian) during the con- During several decades, diff erent authors discussed the struction of a mineshaft at the colliery of Houthalen. stratigraphic position of the Bolderberg section (see De Heinzelin (1955) considers the Houthalenian, spelt Tavernier, 1954 and de Heinzelin & Glibert, 1956 for wrongly “Houthaléen” by Hinsch (1952), as a more ad- an overview) in relation to the stratigraphic units near equate stage name to replace the Bolderian because of the Antwerp area. The attribution of the Bolderian the reworked fossils in the type locality of the Bolderian, stage to a series (Oligocene, Miocene or Pliocene) was the lack of well-preserved in situ fossils in the Bolderian constantly modifi ed according to new discoveries and Sands and fi nally the confusion between the Antwerpian interpretations. In the legend of the geological map of (=Anversien) and the Bolderian stages on the geological Belgium (Commission géologique, 1896), the Bolderian map. S is opinion is also expressed in Tavernier & de includes the Edegem Sands, the Antwerpen Sands and Heinzelin (1963). S e (molluscan) fauna of the Houtha- the Bolderberg Sands. lenian is comparable with the fauna from the German During the exploration of Limburg for the development Hemmoorian. of the coal exploitation, the Elsloo gravel was mapped as the basal gravel of the Neogene (Halet, 1921, 1936b; 3.2. Why the Houthalian stage is not an international Gulinck, 1970). In the Limburg mining district, this stage gravel is the base of a pale to dark brownish, often very micaceous, very slightly lignitic, glauconitic, medium S e type locality of the Houthalen Sands is only known fi ne-grained sand with dispersed or concentrated occur- from wells. S e upper and lower boundaries are erosional rences of molluscs. Tavernier and de Heinzelin (1963) levels (the Elsloo gravel at the base and the basal gravel introduced the name Houthalen Sands after the name of the Diest Formation at the top) and consequently “Horizon de Houthaelen” given by Glibert (1945). De they cannot be used as chronological boundaries. S e Heinzelin (1955) considers the “Houthaléen”, introduced calcareous fossil content (planktonic foraminifer and by Hinsch (1952) as a more adequate stage name (with the nannoplankton associations) does not allow unequivocal correct spelling Houthalenian) to replace the Bolderian, correlation with the international chronostratigraphy because of the reworked fossils in the type-locality of (Vandenberghe et al., 1998). the Bolderian. S is opinion is included in Tavernier & de Heinzelin (1963). 3.3. Status of the name 2.2. Why the Bolderian is not an international stage S e stage name Houthalenian has been proposed, but was in fact never used. Nowadays, the geographic name S e type locality of the Bolderian Sands is an oxidized Houthalen is in use for a lithostratigraphic term: the section and contains very few, mainly reworked and poorly Houthalen Member of the Bolderberg Formation (De preserved fossils. S e upper and the lower boundaries are Meuter & Laga, 1976; Laga et al., 2001). S e term lithological boundaries. Houthalenian is obsolete. DISUSED NEOGENE AND QUATERNARY REGIONAL STAGES FROM BELGIUM 217 4. Antwerpian 4.3. Status of the name 4.1. Defi nition and history S e stage name Antwerpian (or Anversien) should be avoided in the future, because the boundaries of the S e stage name “Anversien” (= Antwerpian is the actual original sequence, indicated by the term Antwerpian, correct spelling according to the procedures for establish- are erosional surfaces and do not defi ne chronological ing stratigraphic units) was proposed by Cogels in Van boundaries. Actually, the geographic name Antwerpen is Ertborn (1879), as a “système” belonging to the Miocene. in use as a lithostratigraphic term: the Antwerpen Sands S e name is derived from the city of Antwerp (Fig. 1) Member (De Meuter & Laga, 1976; Laga et al., 2001). (French: Anvers, Dutch: Antwerpen). It was meant to comprise the “Sands with Panopaea menardi” and the “Black sands with Pectunculus pilosus”. It is the sequence 5. Diestian described by several authors as the lower Crag of Antwerp, which consists mainly of dark green to black very glauco- 5.1. Defi nition and history nitic sands. S e creation of this Antwerpian stage consid- erably restricted the Diestian stage. In Cogels’ opinion, the S is stage name (“Diestien”) was defi ned by Dumont sediments with the fossils at Bolderberg, the “Sands with (1839, 1850), after the town of Diest (Fig. 1), situated Panopaea menardi” and the Sands with Pectunculus pilosus approximately 50 km ENE of Brussels. It was meant to are superimposed and without parallel equivalent units. comprise the Diest Sands and the “lower Crag Sands of Vanden Broeck (1879, 1880) accepted the Antwerpian Antwerp”, consisting mainly of dark green to black, very stage, which is stratigraphically older than the Diestian glauconitic sands. According to this defi nition, the Kat- stage, but he and Mourlon (1880, 1881) considered the tendijk Formation should be included in the Diestian. age of the Antwerpian as Mio–Pliocene. Later, Vanden However, Dumont has never observed deposits corre- Broeck (1884) equates the Antwerpian and the Bold- sponding to the actual Kattendijk Formation due to a lack erian.