GEOLOGICA BELGICA (2004) 7/1-2: 27-39 GEOLOGY AND PALAEONTOLOGY OF A TEMPORARY EXPOSURE OF THE LATE MIOCENE DEURNE SAND MEMBER IN ANTWERPEN (N. BELGIUM) Mark BOSSELAERS1, Jacques HERMAN2, Kristiaan HOEDEMAKERS3, Olivier LAMBERT4,*, Robert MARQUET4 & Karel WOUTERS5,6 (9 figures, 2 tables) 1. Lode Van Berckenlaan, 90, B-2600 Berchem, Antwerpen, Belgium. E-mail: [email protected] 2. Royal Belgian Institute of Natural Sciences, Geological Survey of Belgium, rue Jenner, 13, B-1000 Brussels, Belgium 3. Minervastraat 23, B-2640 Mortsel, Belgium 4. Royal Belgian Institute of Natural Sciences, Department of Palaeontology, rue Vautier, 29, B-1000 Brussels, Belgium 5. Royal Belgian Institute of Natural Sciences, Department of Invertebrates, id. 6. K.U.Leuven, Department of Biology, Laboratory of Comparative anatomy and Biodiversity, De Bériotstraat 32, B-3000 Leuven, Belgium * F.R.I.A Doctoral fellow ABSTRACT. A section of 6.10 m through the Deurne Sand Member (Diest Formation, Late Miocene) in Antwerpen (Antwerp) is described, which has been observed during the construction works of a new hospital building in the southern part of Deurne, and here called “Middelares Hospital Section” after that location. This temporary outcrop section can well be correlated with a similar one which was outcropping some 35 years ago, and was located at some 1.5 km to the NE. It was studied in detail by De Meuter et al. (1967), who called it the “Borgerhout-Rivierenhof VII B.R.” section. Since that section was the most relevant of the previously described sections in the Deurne Sand Member, it is here suggested to designate that section as stratotype for the member. Part of the fossil content, mainly the macrofossils (Brachiopoda, Mollusca, Ostracoda, Thoracica, Pisces, Reptilia and Mammalia) is listed. Two species of Terebratulidae (Pliothyrina sowerbyana (Nyst, 1843) and Terebratula cf. ampulla Brocchi, 1814) were recognized. The Mollusca are represented by 24 taxa, of which the Pectinidae are the most common. One undescribed ostracod taxon (Thaerocythere sp.) is restricted to the Deurne Sands and can be considered a stratigraphic marker for this member. Fossil Lepadomorpha are recorded for the first time from the Belgian Late Miocene. The Squalus sp. from the Deurne Sands closely resembles the Squalus sp. from the Gramian of Denmark. Preliminary data about a fairly complete skeleton of a Mysticete whale, probably belonging to the genus Plesiocetus Van Beneden (in Van Beneden & Gervais, 1880) are given. The recovered specimen of Ziphirostrum is characteristic of Z. laevigatum and is probably different from Z. belgicus. The molluscan fauna seems to point to a shallow environment with swiftly changing currents, moving sand bars or megaripples subjected to tidal currents. Palaeoclimatological data cannot be deducted from the fossils encountered. KEY-WORDS: Deurne Sand Member, Late Miocene, Antwerpen, Cetacea, Plesiocetus, Brachiopoda, Mollusca, Ostracoda, Crustacea, Pisces. 1. Introduction been exposed since the construction of the Main Ring Road ("Grote Ring" [Fig.1: "R1"]) around Antwerpen The Deurne Sand Member of the Diest Formation (Fm), in the 1960s. In April 2001 the Deurne Sand member Late Miocene, was formally described by De Meuter & was observed in the construction pit for new hospital Laga (1970, 1976), who also analysed its foraminiferal buildings on the Herentalsebaan in Antwerpen (Fig. content. The invertebrate macrofossils were listed 2). One of the important discoveries was a more or less by Glibert & de Heinzelin de Braucourt (1955a, b). complete skeleton of a mysticete whale. Besides this This member is found only in a very limited area to one, parts of other cetacean skeletons were recovered. the East of the centre of the city of Antwerpen, in the Although the aquatic mammal fauna of the region districts Borgerhout and Deurne. Most of this area is around Antwerpen is extraordinarily rich, this is one of now covered with buildings and this member has not the few skeletal remains whose exact stratigraphy and 28 M. BOSSELAERS, J. HERMAN, K. HOEDEMAKERS, O. LAMBERT, R. MARQUET & K. WOUTERS � � � � � � � � � � � � � � � taphonomy was recorded. A preliminary report of this ������� discovery as well as further observations on the Deurne ������� � � � � � � � � Sand Member are presented. ��� The locality investigated is a building site for a ���� new wing of the Algemeen Ziekenhuis Monica v.z.w., �� ��� ����� campus Onze Lieve Vrouw Middelares Deurne (in the ���������� ������ present text cited as Middelares Hospital Section), on �������� the Herentalsebaan in the district Deurne, Antwerpen ���������� ����� ������� �������� ������������ (Fig. 1). The Lambert coordinates of the section are ��� ���� ���������� ����������� �������� x = 157.080, y = 210.700; altitude 7.5 metres NOP ������ ����������� ����� ������� ��� (sheet Borgerhout 15/4, 1969, scale 1:10.000). ������� �� ������ ������� ������� ����� ������� �������� ���� ��� ������ 2. Material and methods �� ������ ��� ���� The section was measured in the eastern part of the ���� construction pit and was completed by a boring with ���� an Edelman auger to a depth of 10.80 m (Fig. 3). Thirty ���� ������������ ������ nine samples for microfossils were taken at intervals of 10 to 20 cm throughout the section, starting below the reworked Lillo Fm. downwards. Their contents of Foraminifera and of some further microfossils are to be described in following reports. Here we describe the occurrences of Brachiopoda, Mollusca, Ostracoda, Crustacea, Pisces, Reptilia and Cetacea. Large samples were taken near the top of the Deurne Sand Member and �������� ������� at the bottom of the construction pit at 6.80 m below ����� surface. �������������������������������������������������et al.�������� The most complete whale skeleton was found at a ������������������������������������ depth of 2 m below the top of the Deurne Sand Member, ����������������������������������� in the southeastern section of the construction pit, in two ��������������� clusters of bones at short distances from each other. Its Figure 1: Location of sections with Deurne Sands. ������� � � ������ �� ���� � ����� Ziphirostrum ��� ���� �� Plesiocetus ��� ���������� ���� � ���� �������� Plesiocetus ��� ����������� � ���� ���������������� ���������� � Plesiocetus ��� �������� ������ � �������� �� Figure 2: Location of section and vertebrate remains. EXPOSURE OF THE LATE MIOCENE DEURNE SAND MEMBER IN ANTWERPEN 29 position in the sediment was recorded on drawings and 0m photographs. The skeleton is now being cleaned and consolidated; it will be exhibited in the new hospital. a 3. The section 3.30 m 3.1 Description b 4 m The lithological section was exposed to a depth of 6.80 c m; a hand boring was performed from 6.80 m to 10.80 m. The following levels were distinguished from top to 5 m basis (Fig. 3). PR 13 d level a: 0.00 - 3.30 m Remnants of buildings. level b: 3.30 - 4.00 m Grey to red-brown loam without fossils. 6 m level c: 4.00 - 4.20 m Crag in matrix of clayey sand to clay, greyish to red coloured, with mostly e broken shells and at its base derived whale bones, shark 6.80 m f (bottom pit) teeth and light grey sandstones; this level is variable in 7 m thickness. level d: 4.20 - 5.80 m Rather coarse grey-green glauconitic sand, strongly bioturbated (ichnogenus Ophiomorpha), containing lenticles of clay and pure 8 m glauconite as well as abundant Bryozoa, tubes of the polychaete Ditrupa sp., Echinoidea, Crustacea g (Thoracica, Lepadomorpha), scarce otoliths, very scarce Gastropoda, more numerous Bivalvia and driftwood. 9 m level e: 5.80 - 6.60 m Rather coarse grey-green glauconitic sand with dispersed fossils, not bioturbated, with scattered light grey friable sandstones, and locally h in its lower part concentrations of shark teeth and 10 m phosphatic nodules. level f: 6.60 - 6.70 m Rather coarse grey-green 10.80 m (depth of boring) i glauconitic sand containing lots of Brachiopoda (mainly Pliothyrina sowerbyana (Nyst, 1843), as sand described by Van Roy (1980)) and Bivalvia (mainly Pectinidae, which were dispersed in pockets), scarce Ditrupa and Bryozoa shark teeth, whale bones, driftwood and scattered light grey, friable sandstones. level g: 6.70 - 9.30 m Rather coarse grey-green burrows glauconitic decalcified sand. level h: 9.30 - 9.80 m Rather coarse grey-green shells glauconitic sand with dispersed gravel and phosphatic nodules. vertebrate remains level i: 9.80 - 10.80 m Very fine, dark grey glauconitic sand with remains of Glycymeris sp. phosphoritic nodules Interpretation / Stratigraphy Plesiocetus bones Levels a to b Pleistocene to Recent. Level c Reworked Kattendijk and Lillo Fms, Mimachlamys angalonii level Pliocene. Levels d to f Deurne Sand Member, Diest Fm., Late Miocene. Figure 3: Section at Middelares Hospital. Upper parts: Level g Supposedly Deurne Sand Member, Diest exposed in construction pit. Lower part: Edelman boring. Fm., Late Miocene. 30 M. BOSSELAERS, J. HERMAN, K. HOEDEMAKERS, O. LAMBERT, R. MARQUET & K. WOUTERS Level h Supposedly base of the Deurne Sand Indeed, Glibert & de Heinzelin de Braucourt (1955a, Fig. Member, Diest Fm., Late Miocene. 2) only gave a composite section, based on observations Level i Antwerpen Sand Member, Berchem Fm., of Mourlon (1876) at four different locations in Middle Miocene. Borgerhout and Deurne. De Meuter & Laga (1976) mentioned “Deurne” as type-locality and “temporary Level d is characterized by Bryozoa and concentrations exposures of shallow excavations at Deurne” as type-