Continental Record in the Maaseik Well (49W0220) in the Roer Valley Graben, NE Belgium

KONINKLIJK BELGISCH INSTITUUT INSTITUT ROYAL DES SCIENCES VOOR NATUURWETENSCHAPPEN NATURELLES DE BELGIQUE

ROYAL BELGIAN INSTITUTE OF NATURAL SCIENCES

MEMOIRS OF THE GEOLOGICAL SURVEY OF BELGIUM N. 52 – 2005

Stratigraphic interpretation of the Neogene marine – continental record in the Maaseik well (49W0220) in the Roer Valley Graben, NE Belgium

N. Vandenberghe1, P. Laga2, S. Louwye3, R. Vanhoorne4, R. Marquet4, F. De Meuter1, K. Wouters4 & H.W. Hagemann5

1 K.U.Leuven, Historische Geologie, Redingenstraat 16, B-3000, Leuven 2 KBIN-Geological Survey of Belgium, Jennerstraat 13, B-1000 Brussels 3 U Gent, Paleontology Research Unit, Krijgslaan 281/S8, B-9000 Gent 4 KBIN, Vautierstraat 29, B-1000 Brussels 5 RWTH Aachen, LEK, Lochnerstrasse 4-20, D-52056 Aachen corresponding author: [email protected]

(10 ﬁ gures, 4 tables, 2 photo plates)

Cover illustration : Illustration of sedimentary structures in the lithologically most variable upper part of the Kieseloolith Formation. Different forms of lamination, erosive contacts and eroded clay parts, alternations between clay, sand and lignite are shown. Clockwise from upper left, samples from depths 91,67 m - 68,20 m - 91,55 m - 67,20 m.

Comité éditorial: L. Dejonghe, P. Laga Redactieraad: L. Dejonghe, P. Laga Secrétaire de rédaction: M. Dusar Redactiesecretaris: M. Dusar Service Géologique de Belgique Belgische Geologische Dienst Rue Jenner, 13 - 1000 Bruxelles Jennerstraat 13, 1000 Brussel Belgique België

MEMOIRS OF THE GEOLOGICAL SURVEY OF BELGIUM N. 52 Ð 2005: 1-39

STRATIGRAPHIC INTERPRETATION OF THE NEOGENE MARINE – CONTINENTAL RECORD IN THE MAASEIK WELL (49W0220) IN THE RUR VALLEY GRABEN, NE BELGIUM

N. VANDENBERGHE1, P. LAGA2, S. LOUWYE3, R. VANHOORNE4, R. MARQUET4, F. DE MEUTER1, K. WOUTERS4 & H.W. HAGEMANN5

(10 ﬁ gures, 4 tables, 2 photo plates)

Abstract. A 302 m deep, cored reconnaissance well was drilled in 1980, at Jagersborg to the northwest of Maaseik (49W0220). & e borehole is located north of the Feldbiss fault system, in the Rur Valley Graben. & e top of the section consists of Saalian to Pleni-Weichselian Meuse gravels capped by loam. & e section between 22 and 193 m is identifi ed as the Kieseloolith Formation, consisting mainly of quartzic sands with the intercalation of four lignite and clay intervals. Lithological characteristics and geophysical well logs allow the traditional identifi cation of the Waubach sands and gravels at the base of the Kieseloolith Formation, overlain by the Pey sands between two lignite and clay levels which are interpreted as Brunssum clay; using the same approach, the sands above the upper Brunssum clay are interpreted as the Schinveld/Jagersborg sands. & e palynology, however, suggests a Pliocene age, Reuverian, for the entire quartz sand unit although also a Brunssum age could be accorded to the quartz sand below 90 m depth. Two palynozones occur with a boundary around 57.6 m. & e top of the lower palynozone A, between 57.6 and 87.5 m, has a similar composition as the Mol sand lignites occurring to the west, outside the Rur Valley Graben. & e upper palynozone B between 57.6 m and the top of the sands characterizes the Reuverian C and the clay layers present in this section are consequently interpreted as Reuver clay. & e palynozone A represents a landscape covered by dense forest in contrast to the upper palynozone B during which the clearance of the woods had already started, the forest became less dense and enclosed mires more extensive. & e top of the Kieseloolith Formation marks the transition to the Praetiglian. All lignites show a rank between the brown coals in the Lower- Rhine exploitations and peats. & e interval between 193 and 198 m is a yellow quartzic, mica-containing marine sand of uncertain stratigraphic position; it might correspond to the Syltian, an uppermost Miocene regional North-Sea stage. & e green glauconitic sands between 198 and 302 m are identifi ed as the Breda Formation and can be further subdivided based on grain size and glauconite content. Dinofl agellates and mollusc fragments allow the identifi cation of a lower part between 302 and about 273 m that is biostratigraphically similar to the upper part of the Antwerpen Member and Zonderschot Member of the Berchem Formation to the west. It is considered as Middle Serravallian in age based on dinofl agellates. An upper part between about 235 and 198 m is biostratigraphically equivalent to the Deurne and Dessel Members of the Diest Formation, based on dinofl agellates, molluscs, benthic foraminifera and ostracods. & e age of this upper part is Tortonian. & e interval between these lower and upper parts of the Breda Formation has no facies equivalents in the Campine basin to the west. Key words: palynology, dinofl agellates, molluscs, benthic foraminifera, ostracods.

Introduction

& e Maaseik well in northeast Limburg (Fig. 1) was & e total depth of the well is 302 m. Except for the upper drilled in 1980 as a reconnaissance borehole at the initia- 30 m, the whole borehole was cored with a core diameter tive of the Geological Survey of Belgium. & e borehole of 10 cm. & e upper 30 m of the well is cased. Open hole is located about 5 km to the northwest of Maaseik, in geophysical logs are available between 30 m and total the industrial zone named Jagersborg. & e Lambert depth, recording resistivity, spontaneous potential, natural coordinates of the well are 246 636 (x), 200 835 (y) and gamma ray and caliper (Fig. 2). the topographic height is +33.14 m TAW (z). 2 VANDENBERGHE, LAGA, LOUWYE, VANHOORNE, MARQUET, DE MEUTER, WOUTERS & HAGEMANN

0100 Km The NETHERLANDS NORTH SEA a C AM P b Antwerpen INE Maaseik

Brussels GERMANY

F R A N C E a GR. DUCHY LUX.

ROER VALLEY GRABEN

C AM PI NE N

0 5 10 km

Molenbeersel

Kessenich Kinrooi Ophoven

Maaseik Neeroeteren 012 kmb

Figure 1. Situation of the Maaseik well ( Ma / 49W0220) in northeast Belgium on a regional fault map. All boreholes indicated on the map have been been stratigraphically interpreted and correlated in Figure 10. The faults and their nomenclature have been taken from Gullentops and Vandenberghe (1995), Langenaeker (2000) and Van der Sluys (2000). STRATIGRAPHIC INTERPRETATION OF THE NEOGENE MARINE Ð CONTINENTAL RECORD IN THE MAASEIK WELL 3

SP RES. GAMMA

10 Lanklaar Fm

sn REUVERIAN C REUVERIAN

palynozone B palynozone 50 'MERKSEMIAN' REUVER CLAY ? # lignite 1

# lignite 2 REUVERIAN 'SCALDISIAN'

? ! #

sensu de Heinzelin 1963 sensudeHeinzelin lignite 3 MAASEIK 49W - 220

100

!! lignite 4 POSSIBLYBRUNSSUMIAN ? ?

P L I O C E N E 150 palynozone A palynozone

GL ground level

cased interval 'SUSTERIAN'? cored interval interval without core cored interval WAUBACHSANDAND GRAVEL

dinoflagellates

? UNIT X yellow, mica rich pollen

Sylt ? Sylt SAMPLES green molluscs

# brown coal Lingula pyrite

loose sand muscovite

fining up 'Deurne-DesselSand' cycle (benth.foram.-ostracoden) (dinofl.) 'DeurneSand' clay TORTONIAN thin clay laminae

loam mica clayey sand

BREDA Fm BREDA very fine sand

fine sand Langenfelde Gram medium sand unknownfaciesCampine in coarse sand pale very coarse sand

lowermollusc association gravel

peat fossil debris

? DN 6&78 DN 9 DN shell

SERRAVALLIAN sandstone

30 mV 0 200"m 400 50 CPS

Figure 2. Geophysical well logs and synthesis of the stratigraphic results of the Maaseik borehole (49W0220), based on core description, geophysical well logs, sediment analysis and biostratigraphy (palynology, dinoﬂ agellates, molluscs, ostracodes and benthic foraminifera). The stratigraphic interpretations are discussed in the text. 4 VANDENBERGHE, LAGA, LOUWYE, VANHOORNE, MARQUET, DE MEUTER, WOUTERS & HAGEMANN

& e cores have been described by Vandenberghe, Laga scale sand laminae between 45 and 46 m. Some levels and Vandormael already in 1981 and their full detailed are coarse grained. Several erosional surfaces interrupt description is kept in the fi les of the Geological Sur- the sedimentation and lignite and clay fragments occur vey of Belgium by the number 49W0220 (VIII, b). as eroded lumps in the sediment. Small synsedimentary & e borehole description is on-line available via the deformational features occur. Clay laminae of over 10 cm subsurface borehole database of the Flemish Ministry thickness occur and some levels have a characteristic http://dov.vlaanderen.be. A synthetic overview litholog gamma ray log clay response (Fig. 2). Clays can be pale is represented in Fig. 2. grey, pale greenish or black with admixture of plant Hammenecker (1980) initiated a regional study of remains. Sediment transport sometimes concentrated Plio-Pleistocene of the area and Van der Sluys (2000) mica fl akes. & e sand is often purple stained because of reviewed the borehole data in the Belgian part of the Rur the admixture of plant remains. At 34.8 m even a black Valley Graben. & e detailed stratigraphy of the borehole gyttja type mud occurs. Maaseik 49W0220, penetrating through the Pleistocene into the Neogene, however has not been published. Since In the interval between 35.45 m and 37.65 m metallic the cores became available for further research, several spherules with diameters between 50 µm and 1700 µm paleontological analyses have been carried out and as were detected. Mineralogical and chemical analysis in the Maaseik borehole is one of the few cored wells north several laboratories concluded that the magnetite spher- of the Feldbiss fault system in Belgium, its stratigraphy ules are artifi cial and probably produced by a welding-arc can contribute in linking the Belgian and the Dutch at the well site (see De Geyter, 1989). traditions in stratigraphic nomenclature (see also Sels et al., 2001). Between 50.5 m and 52.5 m grey and bluish clay oc- As the lithological column can be subdivided in Meuse curs with some thin lignitic layers. & e clay is underlain, sediments at the top (0-22 m), a quartz dominated sand between 52.5 m and 56 m, by a thick brown coal layer complex below (22-198 m) and a glauconitic green sand (lignite 1 on Fig. 2). Wood fragments can still be recog- at the bottom (198-302 m), and as the biostratigraphic nised in this brown coal layer. techniques for the study of the quartz sands and the & e interval between 56 m and 62 m consists of similar glauconitic sands are diff erent, the paper is subdivided grey sands as occur above the overlying clay and brown according to these three lithological types. coal layer. Also the resistivity logs, pointing to permeable sands, and the low gamma-ray log are similar to the sands higher up in the borehole (Fig. 2). Some sands in 1. Pleistocene loam and Meuse gravel (0 – 22 m) this interval are laminated and some show the prominent presence of eroded lumps. & e uppermost 6 m consists of loam. In the area it is known as a usually thinly laminated loam of fl uvio-lacus- & e 62 m – 76 m interval consists of less permeable sands, trine to lacustro-eolian origin, the Molenbeersel Member as indicated by the similar resistivity values measured by (Kinrooi Formation), of Pleni-Weichselian age. Below long- and short-spaced electrodes. & is interval is char- the loam occur, till 22 m, Meuse river gravels with loam acterised by the systematic presence of thin clay layers of and carbonate at their base. & e higher gamma ray signals 5 to 10 cm thickness. & e clays are coloured green, pale (Fig. 2) probably represent clayey intervals. & e gravels brown and black. & e black colour points to the presence belong to the Lanklaar Formation and are Saalian and of vegetal organic matter and within this interval, at 71 m Pleni-Weichselian in age. & e lithostratigraphic nomen- depth, a 40 cm thick brown coal layer occurs (lignite 2 clature system used here has been developed during the on Fig. 2). Several erosional surfaces occur and clays are Quaternary mapping organized by the Flemish Ministry sometimes ripped up into clasts, apparently by strong (see Beerten et al., 2000). current activity.

Between 76 m and 88 m clay layers, black clayey brown 2. The complex of quartz-rich sands, clays coal and black gyttja type muds are dominating the lithol- and brown coal (22 – 198 m) ogy. Also some thin sand layers occur and silt layers are present within the clays. & is alternation of lithologies 2.1. Lithological description explains the rapid changes in the spontaneous potential, the resistivity, caliper and gamma-ray logs (Fig. 2). & e & e 22-50.5 m interval can be individualised on the two brown coals at the base of this interval are labelled geophysical logs and it is composed dominantly of a as lignite 3 on Fig. 2. fine-grained to medium-sized sand. The dominant structure in the sand is a horizontal lamination but also Geophysical well logs show a permeable sand unit be- oblique stratifi cation and clay drapes over sand ripples tween 88 m and 125 m. & e sediment contains milky occur. Typical mm laminated clays alternate with cm quartz grains, small transported lignite fragments, thin STRATIGRAPHIC INTERPRETATION OF THE NEOGENE MARINE Ð CONTINENTAL RECORD IN THE MAASEIK WELL 5 erent forms of Figure 2. Diff 2. Figure der is referred to the original description of the loolith Formation between 36 and 109 m depth. e detailed stratigraphic position of each core can be found on elow surface. & elow surface. s between clay, sand and s lignite between details For are clay, the shown. rea res res of the lithologically most variable upper part of the Kiese les of the Geological Survey of Belgium. e number above each core is the depth of the top of the core b cores kept in the fi cores lamination, erosive contacts lamination, and eroded clay alternation parts, Photo plate 1 Illustration of the sedimentary structures in a selection of co & 6 VANDENBERGHE, LAGA, LOUWYE, VANHOORNE, MARQUET, DE MEUTER, WOUTERS & HAGEMANN the es ternations between clay erosive contacts and and sand, elow surface and the cm scale along each core identifi core each along scale cm the and surface elow Figure 2. Figure erent types of horizontal and oblique types al of laminations, b core the of top the of depth the is core each above number e can of each core be found e detailed stratigraphic position on Photo plate 2 Details from the cores in Photo displaying plate diff 1, clay pellets derived from disrupted clay laminae. & fromderivedclay pellets disruptedclaylaminae. exact depth of each core fragment shown. & fragment depth of each core exact shown. STRATIGRAPHIC INTERPRETATION OF THE NEOGENE MARINE Ð CONTINENTAL RECORD IN THE MAASEIK WELL 7

clay laminae, ripped up clay fragments, and concentration 2.2. The depositional environment of mica fl akes in thin laminae. & e sands are often purple stained by colloidal organic matter. Lignitic fragments & e mica-rich sediments between 198 and 193 m are are sometimes washed together in thin laminae; larger interpreted as undeep marine sediments, seen their fi ne lignitic fragments show bio-perforations and several homogeneous nature, the presence of some glauconite lignite fragments contain pyrite. At 116 m depth a clay grains and also their dinofl agellate content (see further). horizon occurs. & e sand between 88 m and 116 m can Between the underlying green sand with abundant glau- be subdivided in two fi ning upwards cycles which have conite grains and marine molluscs, a continental phase at about 103 m and 117 m a coarse basal level (Fig. 2, see must have occurred as shown by the peat fragments at resistivity log and litholog). Both cycles end in clay and the base of the unit. lignite at their top. & e overlying coarse sediments between 193 and 148 m Below the clay horizon at 116 m, the sand unit, which are interpreted as riverplain deposits. & e coarse levels and extends till 125 m depth, is more homogeneous and has rip-up clasts represent the stream channel deposits whilst typical low gamma ray intensities compared to higher the more clayey and sometimes humic horizons represent readings above 116 m. Some of the more variable litholo- fl oodplain deposits. From the relative proportion of both gies above 116 m are shown in two photoplates (Plate lithologies, it can be concluded that the landscape was 1, 2). dominated at that time by a high sand load braided river system and some swampy areas in which humic clays were Between 125 m and 127 m a clay and brown coal layer deposited. & e repetition of several meter-scale fi ning-up occurs, indicated as lignite 4 on Fig. 2. cycles suggests that the channels were laterally shifting, turning into swampy lakes or ponds when abandoned. & e 127 m to 193 m interval consists of pale to whit- From 148 to 116 m the quartz sands are rather homoge- ish grey sands. & e top part, down to 148 m is medium neous compared to the underlying and overlying sands grained and very permeable; based on the log data a and between 138 and 116 m the sands are characterized further subdivision can be made at about 138 m, with by a distinctive low gamma ray signal. & e landscape a lower part being more clay rich and less permeable. was still dominated by sandy plains but the draining Below 148 m the sand is coarse and even contains gravel, waters had lower energy than before. At 125-127 m the especially between 156 m and 170 m. Several, meter-scale, landscape had turned into a swampy vegetated area for a fi ning-upward cycles can be distinguished. Many thin short time (lignite 4). clay laminae exist in the sand, often ripped up into clasts. Coarser river sands are appearing again during a short Colloidal organic matter has stained the sand purple. time at 116 and 106 m, to fi ne up and fi ll in the river Many lignite fragments occur in the sand, especially in the plain with sand and evolving at the top in a swamp with coarser horizons; also clay fragments occur in the coarse abundant vegetation. Vegetation must have been fairly sands. For this reason, the coarse level at 165 m – 166 m widespread seen the many lignitic fragments dispersed appears rather as a more clayey interval on the resistivity in the sand. At the top of the second cycle the swampy and gamma ray logs. vegetation conditions stay for a longer period, from 88 In the relatively coarse sands below 166 m, the change in to 76 m (lignite 3). the patterns of the resistivity and spontaneous-potential From that time on, swampy conditions with abundant logs, without a noticeable change in the accompanying vegetation dominated the landscape as shown by the gamma-ray pattern, could suggest a more saline ground- regular occurrence of black clay and lignitic layers between water; however this geophysical log pattern is generally 76 and 20 m. Twice, an extensive lignite (lignites 1 & observed in neighbouring water wells without any indica- 2) has developed. However a fi nely laminated clay sand tion of increasing salinities in the producing water (Van facies, pointing to tidal infl uences indicates that the sea der Sluys, oral.com). Small quantities of glauconite grains shore was not very far northwards of the area. Also river or other particularities in the mineralogical composition channels were crossing the area as indicated by the many of the sand could have a similar eff ect. A few thin clay ho- erosional surfaces and eroded clasts. rizons occur at the base of the interval around 190 m. 2.3. The lithostratigraphy & e interval between 192.70 m and 198 m is an intermediate to fi ne pale yellowish grey sand; a modal size & e stratigraphic signifi cance of the 193-198 m marine between 128 and 174 µm is measured on three samples. interval is not clear. & e unit is not formally named in It contains small glauconite grains (1.7 to 3.5 % glauco- the area. nite measured in three samples). & e sand is rich in mica In the tradition of the lithostratigraphy in the Rur Val- fl akes, also expressed by the high gamma ray signal. & e ley Graben, the continental quartz sands with a mixture sand is faintly laminated and contains towards the base of river, swamp and coastal plain facies and the occur- greenish clay, peat fragments, some small gravels and a rence of lignite layers between 22 and 193 m belong to 3 cm large pebble. the Kieseloolith Formation (Westerhoff et al., 2003). 8 VANDENBERGHE, LAGA, LOUWYE, VANHOORNE, MARQUET, DE MEUTER, WOUTERS & HAGEMANN 6% 0.2 0.8 0.2 0.3 0.7 0.26 0.4 0.9 0.5 0.2 0.2 0.2 4.6 0.2 0.6 0.7 0.4 8.3 0.2 0.9 0.11 0.5 0.12 0.2 0.5 0.4 0.4 0.5 0.8 0.2 0.28 0.2 0.2 0.26 MAASEIK BOREHOLE 220 (part 1) (part 220 BOREHOLE MAASEIK 0.2 0.8 0.1 0.2 0.2 0.1 0.6 0.2 0.1 0.3 0.85 0.5 0.7 0.6 0.1 3.8 0.4 0.5 0.4 0.9 55 6 10 1

0% 40 35 2 10 20 5 1 10 10 10 10 5 1 0.5 1 5 5 20 5 10 5 5 1 0.5 2 2.5 2 0.5 20

BELOW SURFACE BELOW DEPTH (m) DEPTH 30 m 32.50 57.57 67.58 77.50 34.80 41.25 50.25 70.10 85.90 89.80 116.40 100.25 109.80 119.30 123.88 143.75 152.65 158.85 172.45 172.60 183.93 197.9 m 197.9 50 100 150 200 STRATIGRAPHIC INTERPRETATION OF THE NEOGENE MARINE Ð CONTINENTAL RECORD IN THE MAASEIK WELL 9 1% 51.51.51.5 0 84 17.8 95 29.1 52 23 29 17.2 19 15.7 885 1.9 524 3.3 164 1.8 350 1.7 374 7.7 250 32.4 174 30.1 338 16.5 233 29.7 371 41.1 148 15 123 20.1 460 39.2 862 2.5 617 7.4 688 22.7 337 31.4 344 24.7 MAASEIK BOREHOLE 220 (part 2) (part 220 BOREHOLE MAASEIK 0.1 0 0.5 0.5 0.5 0.5 0.5 0.5 0.5 2.5 1 1 0.5 0.5 50 0.5 2 1 2% 1 10 5 15 1 2 1 2 0.5 0.5 1.5 0.

BELOW SURFACE BELOW DEPTH (m) DEPTH 30 m 30 32.50 57.57 67.58 77.50 85.90 34.80 41.25 50.25 70.10 85.90 89.80 116.40 100.25 109.80 119.30 123.88 143.75 152.65 158.85 172.45 172.60 183.93 197.9 m 197.9 50 100 150 200

Figure 3. Diagram of the palynological counts (parts 1 & 2) in the section between 30 and 197.9 m. The lithological column and its legend are the same as in Fig.2. 10 VANDENBERGHE, LAGA, LOUWYE, VANHOORNE, MARQUET, DE MEUTER, WOUTERS & HAGEMANN

Within this formation several members can be distin- log correlations and calibration of the log signatures with guished. & e lower coarse gravelly river-facies sands the cored and analysed wells of Maaseik (49W-220) (this between 193 and 148 m represent the Waubach Member, paper) and Bocholt (33W-153) (Van der Sluys, 2000), oldest member of the Kieseloolith Formation (Westerhoff the 1:50.000 Flemish Geological maps of the area and et al., op.cit.). On the 1:50.000 geological map Maaseik, information from NITG-TNO for the Dutch boreholes based on the geophysical well log pattern and the cor- (Westerhoff , oral com.). & e Sterksel Fm (see Gullen- relation with neighbouring wells, Sels et al. (2001, fi g. 11 tops et al., 2001) is characterised by a high gamma-ray and geological map profi le 3) erroneously interpreted the signal, the Stramproy Formation (including the former 168 to 193 m section as Kasterlee Sand, a marine sand of Kedichem) (Westerhoff et al., 2003, p.343-344) by a very earliest Pliocene (Laga et al., 2001). low gamma-ray signal, and the Kieseloolith Formation In the Dutch southern Limburg and the southern part shows characteristic log signatures for its diff erent mem- of the Rur Valley Graben, the Brunssum Clay Member bers; the Jagersborg/Shinveld sands with clay and lignitic occurs above the fl uviatile Waubach Member. It has a horizons have an irregular but relatively high gamma-ray maximum thickness of some tens of meter (Westerhoff signal with moderate separation between the resistivity logs et al., op.cit.). A lithologically similar clay overlies the with diff erent-spacing, the Brunssum clay packages have Brunssum Clay, namely the Reuver Clay occurring in peak gamma-ray values and the Pey (between Brunssum the top of the Kieseloolith Formation and deposited in packages) and Waubach (below lowest Brunssum clay) alluvial plains near the coast; Reuver clay is generally thin- sands have a more regular gamma-ray signal and a high ner than 10 m thick (Westerhoff et al., op.cit.). Based on separation between the resistivity logs with diff erent-spac- lithology alone, it is not possible to precisely diff erentiate ing. High gamma-ray values in the Jagersborg/Shinveld between both clay members. However, as tidal infl uences sands could point to Reuver clays (Westerhoff et al., 2003, are observed towards the top of the section in the Maa- p.319). & e unit X is the pale yellowish mica rich marine seik well, it is expected that the upper clays could belong sand between 193 and 198 m in the Maaseik well and to the Reuver Member. & e lower boundary can not be characterized by a markedly higher gamma-ray signal. precisely determined. & e Breda Formation is characterised by green glauconitic In the practice of well descriptions in the southern part of sands and a very low resistivity signal. the Rur Valley Graben, a coarse permeable sand between two lignitic clay layers is described and mapped as Pey 2.5. Palynological investigations Sands and the boundary lignitic clays are described as lower and upper Brunssum clay (see Zagwijn and van 2.5.1. & e samples and the pollendiagram Staalduinen 1975, fi g. 2.1.47; van Adrichem Bogaert & Kouwe 1993, section I, p.33). Although these subdivi- In the lignitic seams of the uppermost 200 m fi fty samples sions are not precisely defi ned, the sands between lignite were taken for palynological investigation, thirty-one of 3 and lignite 4 fi t the description of the Pey Sand and which yielded a reliable pollen assemblage. & e chemi- therefore lignites 3 and 4 are described as Brunssum I and cal treatment of the samples consists of boiling in 10% II clays in the Maaseik well (Fig. 2). Lithologically, the KOH aqueous solution followed by acetolysis. & e results sand below lignite 4 till 148 m, ressembles more the Pey are represented in Fig. 3 and Fig. 4. & e taxa percentages Sand than the Waubach Sand. & is regional practice of are based on a sum containing the pollen grains of trees, lithostratigraphic interpretation has also been systemati- shrubs and herbaceous plants except waterplants and cally applied by Van der Sluys (2000). spores. & e number of pollen grains counted and the In the Dutch stratigraphic practice the sands above the percentages of the Tertiary types are arranged in two Brunssum Clay are called the Schinveld Sands. Vanhoo- columns in the middle of the diagram in Fig. 3, separating rne et al. (1999) have proposed for the white quartz sands the summed pollen and the taxa excluded from the sum under the Meuse gravel deposits in the area, the name to the right. & e Tertiary types comprise Tsuga, Sequoia, Jagersborg Sand, which they consider as a member of the Taxodium, Sciadopitys, Cupressaceae, Podocarpus, Pterocarya, Mol Formation in the Kieseloolith Group. Unfortunately Juglans, Carya, Ostrya, Castanea, Eucomnia, Liquidamba, the base of the Jagersborg Sand was not formally defi ned. Nyssa, Cyrillaceae and Symplocos (Zagwijn, 1960). In Fig. Sels et al. (2001) and Laga et al. (2001, p.146) continue 4 the relative importance of these Tertiary types is indi- to rank the Kieseloolith as a formation. cated with respect to the total vegetation cover unveiled by pollen analysis. 2.4. Geophysical log characterisation of the units and their correlation in the area. 2.5.2. & e description of the diagram

& is lithostratigraphic interpretation of the Maaseik well & e pollen diagram in Figs. 3 & 4 shows a predominance leads to a consistent stratigraphic frame in the area, strad- of arboreal pollen (A.P.) except at depths of 85.90 m and dling the Dutch-Belgian border (Fig. 10). In ﬁ gure 10, the 70.10 m as well as at the levels 34.80 m, 32.50 m, 30.00 m lithostratigraphic interpretations are based on geophysical where the non arboreal pollen (N.A.P.) are dominant. STRATIGRAPHIC INTERPRETATION OF THE NEOGENE MARINE Ð CONTINENTAL RECORD IN THE MAASEIK WELL 11

Figure 4. The relative importance of deciduous and coniferous trees, herbs, Ericales and Tertiary types in the section between 30 and 197.9 m. The subdivision in palynozone A, lower and upper part, and B is discussed in the text.The lithological column and its legend are the same as in Fig.2. 12 VANDENBERGHE, LAGA, LOUWYE, VANHOORNE, MARQUET, DE MEUTER, WOUTERS & HAGEMANN

& e coniferous pollen constitutes the most important ent species (Fig. 3): Pinus diploxylon (sylvestris-type) with component of the A.P. group except at 87.60 m and the pollen grains of 60-80 µm total length, Pinus diploxylon levels 32.50 m (only represented in Fig. 4) and 30.00 m displaying a total length varying between 80 and 100 µm where Angiosperm tree pollen are slightly more numer- and a pollen structure at the limit of the diploxylon and the ous. haploxylon type, and ﬁ nely the scarcely represented Pinus haploxylon where the sacci are attached to the corpus of Pinus is the most abundant tree taxon, even at those the pollen grain along a straight line and have the same depths where the Angiosperm trees exceed the Gym- height as the corpus. Scoring best after Pinus, are Sequoia nosperm trees, namely 30.00 m and 116.40 m (only and Cupressaceae which are especially well represented in represented in Fig. 4). & is taxon comprises three diﬀ er- the lowermost part of the diagram (Fig. 3). Pollen of other coniferous trees such as Abies, Tsuga, Picea, Taxodium, Sciadopitys, Podocarpus and Taxus are scarce; their frequencies remain below 4%.

Concerning the Angiosperm trees, Alnus pollen is an important component of the pollen rain especially between 109.80 m and 158.85 m. Also Nyssa is regularly present in the lower part of the diagram (Fig. 3) reaching even more than 15% at 152.65 m depth. & e pollen of other Angiosperm trees, including Juglans, Salix, Betula, Carpinus, Ostrya, Fagus, Castanea, Quercus, Ulmus, Eucommia, Liquidambar, Acer, Ilex, Cornaceae, Cyrillaceae and Fraxinus occur in minor quantities.

At 150.20 m (Fig. 4) four pollen grains of Mastixia are identiﬁ ed, with a diameter of 31 to 41 µm (type 1 in Fig. 5), while at 183.93 m and 197.90 m one pollen grain of the same genus with a diameter of 45 to 58 µm is found (type 2 in Fig. 5). & e pollen spectrum at 150.20 m is not represented in Figure 3. Both types are tricolporate with a perforated tectum and clearly discernible baculae in the ektexine. Endexine and ektexine have about the same thickness. & e amb is triangular with slightly con- vex sides. Each of the long, tapering colpi is bordered by thinnings in the endexine, running parallel to the colpi (Fig. 5). & e genus Mastixia is abundantly represented in Miocene deposits but is also recorded in small amounts in the Pliocene. & is is also the case for Symplocos which occurs at 70.10 m depth (Mai, 1995).

& e N.A.P. are dominant at the depths of 85.90 m and 70.10 m but especially at the top levels of the diagram in Fig. 3. & is pollen group is mainly composed of represent- atives of Ericales except at 123.88 m where herbs, mainly composed of grasses exceed the Ericales (Fig. 4). At the Figure 5. Photographs of pollen grains of Mastixia (type 1 & 2). top of the diagram, the Ericales display high percentages, 1a & 1b: Pollen grain in oblique polar view of Mastixia (Type 1) from depth 150.20 m. Note the endexine thinnings, indicated in attaining at two levels more than 70% (Fig. 4). Spores of 1a by arrows in 1a and the perforate tectum and baculae in 1b. Sphagnum continuously accompany the tetrads of Ericales 2a & 2b: Pollen grain in oblique equatorial view of Mastixia but they are less numerous with maximal percentages of (type 1) from depth 150.20 m. Note the perforate tectum in 2a more than 20% at 34.80 m and 85.90 m. and the tapering colpi in 2b. 3a, 3b & 3c: Pollen grains in oblique equatorial view of Mas- 2.5.3. & e botanical interpretation tixia (type 2) from depth 183.93 m. Note the perforate tectum in 3a, the endexine thinnings indicated by an arrow in 3b, the Based on the frequency of the Ericales, but especially of baculae in 3b and the tapering colpi in 3c. the Tertiary types, the pollen diagram can be subdivided 4: Pollen grain in slightly oblique polar view of Mastixia (type 2) from depth 197.90 m. Note the perforate tectum, the baculae and into two parts, the limit lying probably just above 57.57 the rounded triangular amb. m. In the lower part, called palynozone A, the A.P.-group STRATIGRAPHIC INTERPRETATION OF THE NEOGENE MARINE Ð CONTINENTAL RECORD IN THE MAASEIK WELL 13

dominates and the Tertiary types are abundantly repre- contiguous oligotrophic mires, Ericales may attain in the sented; in the upper part, called palynozone B the N.A.P. peat samples from the mires high percentages exceeding group dominates in the upper levels and the Tertiary types even the A.P. values and may vary as a function of the undergo a substantial decrease. & is subdivision may not distance to the wooded upland. be confused with that of Zagwijn, who subdivided the For the two palynozones in the Maaseik borehole it can be Reuverian into three stages A, B and C (Zagwijn, 1960, concluded that in the upper B zone a wooded landscape fi g 5). existed enclosing oligotrophic mires and that, compared & e pollen assemblages of the lower palynozone A refl ect to the older zone A, the forest was less dense and the a mixed, mesophytic forest dominated by coniferous trees, enclosed mires more extensive. especially Pinus. & e accompanying Ericales tetrads may In the Maaseik section the clearance of the woods had derive from the undergrowth of the forest, established already started as is documented by the presence of two on the quartz-rich upland or from enclosed oligotrophic light demanding plants growing on mineral soils: the mires without or with scattered trees. continuous curve of Artemisia from 50.25 m to the top & e upper palynozone B is characterized by a decrease of the section and the appearance of Plantago at the very towards the top of the A.P. percentages and by high top level of the pollen diagram. frequencies of the N.A.P., of which the great majority is composed of Ericales. Pinus remains the dominant tree 2.5.4. Palyno-stratigraphic interpretation and the thermophilous trees such as Carpinus, Quercus, Ulmus as well as the Tertiary elements including Tsuga, & e tree pollen in the diagram originating from exotic Podocarpus, Cupressaceae, Pterocarya, Carya and Ostrya are taxa, belong to East Asian genera including Sciadopitys still present but in smaller quantities than in the underly- and Eucommia, to North American genera including ing palynozone A. However, the Tertiary types including Sequoia and Taxodium and to genera occurring in both Sequoia, Sciadopitys, Taxodium, Nyssa and Symplocos are regions including Tsuga, Carya and Nyssa. & eir coexist- lacking from 50.25 m till the top of the section. ence with genera extant in Europe including Pinus, Salix, Alnus, Betula, Carpinus, Corylus, Fagus, Quercus, Acer and As the analysed samples are taken in peat layers, the Fraxinus pleads for a Pliocene age of the deposit. & is con- Ericales may originate to a large extend from oligo- clusion is not contended by the occurrence of Symplocos trophic mires in which they throve. On the other hand and Mastixia, appearing a few times in small quantities, the presence of thermophilous and some Tertiary types as these genera which are abundantly represented in Mi- trees which do not grow in such oligotrophic marshes, ocene deposits, are regularly recorded in the Pliocene. & e suggests that the surrounding mineral soils were covered lack of Tricolporopollenites villensis, Tricolpopollinites micro- by trees. In order to check if high percentages of Ericales henrici and liblarensis, which are abundantly represented in a pollen spectrum are not only owing to a deteriora- in Miocene deposits, could confi rm the Pliocene age. tion of the climate, but can also be found in a wooded area with enclosed oligotrophic mires, a comparison is & e palynozone A is characterised by a dominance of tree made with the pollen analytical results of peat samples pollen among which the Tertiary types play an important collected in a comparable landscape. For comparison, a role. From the A.P. / N.A.P. ratio it may be concluded Holocene peat deposit is chosen from the coastal plain that the landscape at that time was covered by a dense, which developed along the NW European coast from mixed, mesophytic forest dominated by coniferous trees, Calais in NW France to Denmark. Along the Belgian especially Pinus. & e regular trend of the tree pollen coast, this peat was growing between the North Sea curves shows no major change in the composition and and the densely wooded, contiguous, sandy upland from therefore hardly allows any subdivision of the palyno- Late Atlantic to Subatlantic times. At some places the zone A. If however the moderate but clear increase of peat evolved into a raised bog where the Ericales were Sequoia observed below 87.5 m depth would correspond abundant as demonstrated by the twigs and seeds of to the high Sequoia values considered by Zagwijn (1960) Ericales in the peat. Published pollen diagrams (Stock- as characteristic for the Brunssumian, the lower part of mans & Vanhoorne, 1954) cannot be used as such and the palynozone A could correspond to this stage; if not, percentage recalculations have to be made in order to the whole palynozone A would correspond to the Reu- obtain comparable pollen diagrams as used in the present verian, a possibility supported by the rarity of Symplocos study. Recalculated pollen spectra could be obtained at and Mastixia which occur regularly in the Brunssumian distances of 7.6 km, 4 km, 3.7 km and 2.3 km from the pollen assemblages, as well as by the lack of Tricolpopol- limit of the wooded upland, and maximal Ericales values lenites liblarensis, which can attain up to 13% in the Dutch at these distances are respectively 58%, 54%, 37% and Brunssumian. 35%. & ese percentages, decreasing when approaching the wooded upland, are lower than in the palynozone B & e upper part of the palynozone A above 87.5 m resem- in the Maaseik borehole but some exceed the A.P. values. bles fairly well the pollen spectra of the borings 49W0206 & ese pollen data indicate that in a wooded area with and 49W0208 (fi les Geological Survey of Belgium) near 14 VANDENBERGHE, LAGA, LOUWYE, VANHOORNE, MARQUET, DE MEUTER, WOUTERS & HAGEMANN

Table 1. The values of the elemental ratios (H,C,O,N) in the lignite 1 (52.5-57.0 m), lignite 2 (68.7-71.0 m) and lignite 3 (81.0-87.0 m) (see also Fig. 6a).

Maaseik in the Rur Valley Graben and described by Vanhoorne (1979). At the top of borehole 0206 the fi rst signs of climate cooling appear, suggesting that this top level may be considered as the onset of the palynozone B or of the Praetiglian. Outside the Rur Valley Graben to Figure 6. (a) The elemental ratios H/C, O/C and N/C in samples the west, lignite occurring in the Sands of Mol (Gulinck, of lignite 1, 2 and 3 (see Fig. 2). (b) Van Krevelen diagram of 1963) also has pollen spectra comparable to the upper part elemental ratios of H, C, O, showing the Maaseik brown coals intermediate between peat samples and brown coal from Lower of the palynozone A (Vanhoorne, 1973). Rhine exploitations (Hagemann, 1981). & e upper levels of palynozone B are dominated by N.A.P. pollen, mostly consisting of Ericales while the lower levels of zone B display 50 % and less. In the A.P. group, Pinus, zone, characterized by the disappearance of subtropical Alnus and Betula are best represented, while thermophil- taxa such as Sequoia, Nyssa, Eucommia, Pterocarya and ous trees and Tertiary types are still present but less than in Sciadopitys is dated from 2.721 to 2.676 Ma. palynozone A. & e pollen assemblages evoke a less dense & e regular occurrence of Ilex, Myrica and Osmunda sug- forest with enclosed oligotrophic mires. Notwithstand- gests oceanic climatic conditions, while Chenopodiaceae ing the high amounts of NAP, especially at the top, the may betray the proximity of the sea. Such conditions could correlation of the palynozone B with the Late Pliocene be expected as to the west time-equivalent marine sedi- or the Reuverian C in the Netherlands is preferred above ments are deposited during the later part of the Reuverian the Praetiglian, because thermophilous trees and Tertiary (Merksem Sands, Zandvliet Sands, Sands with Corbula types continuously occur and the Ericales are considered complanata SOW., see also Vanhoorne, 1963; Buff el et al., to originate for a great part from enclosed oligotrophic 2001, Vandenberghe et al., 2000). Taking into account mires in the forest. Willis et al. (1999) have found a similar the environmental diff erences, the palynozones B and zone in an annually layered sequence of the Late Pliocene A seem to correspond reasonably well with the former lake sediments from Pula maar in Central Hungary marine regional stages, respectively the Merksemian and and considered it as transitional to the next glacial. & is the Scaldisian, sensu de Heinzelin (1963). STRATIGRAPHIC INTERPRETATION OF THE NEOGENE MARINE Ð CONTINENTAL RECORD IN THE MAASEIK WELL 15

2.6. Brown coal characterisation & e 225.5 m to 234 m interval contains slightly fi ner sand than above and is characterized by 5 to 10% clay fraction, In the depth ranges 52.5-57 m (lignite 1 on Fig. 2) , 68.7- as also expressed on the gamma-ray log. & e glauconite 71 m (lignite 2 on Fig. 2), and 81-87 m (lignite 3 on Fig. 2), content is relatively high and increases towards the top. 16 brown coal samples of about 50 cm length were taken Shell debris is present. amongst which 1 xylith sample. During subsampling care & e 234 m to 240 m interval is characterized by a cycle was taken to obtain representative samples for the analyses of coarser sand, less than 5% clay fraction and relatively (Hagemann, 1981). high glauconite contents (Fig. 7). & e water content of the samples, at the time of sampling At about 249-250 m a change in grain-size properties the cores, varied between 29 and 59% whilst the satura- and a glauconite-rich level subdivides a low-glauconite tion water content varied between 57 and 65%. & ese sand interval between 240 m and 261 m, in two parts. & e fi gures point to weakly evolved soft brown coal, similar interval between 240 and 248 m is enriched in mica. to the Oberfl öz–Group in the Lower Rhine brown coal & e underlying interval between 261 m and 273 m is exploitation area at Eschweiler (Kothen & Reichenbach, fi ne-grained and slightly richer in clay content than the 1981). & e ash content, based on water free coal samples, under- and overlying intervals (Fig. 7) as also expressed varied between 10 and 66 weight %. & e xylith sample on the gamma-ray and resistivity logs (Fig. 2). only has 3.1% ash content. & ese ash contents are gener- In the lowest interval, between 288 m and the deepest level ally higher than in the brown coal exploitation area of the of the borehole, the sediment describes a coarser cycle and Lower Rhine area. has relatively higher glauconite contents (Fig. 7). & e brown coals of the Maaseik borehole are weakly layered, pale to light coloured and preserving 10 to 35 & e depositional environment for the whole Breda sand volume % of plant remains. Generally the coals contain section in this well must have been marine seen the many abundant mineral matter, xylith, fusain and resins. marine fossils and the glauconite. Depositional depth was & e caloric value of the Maaseik brown coal varies be- probably deeper than about 10 to 20 meter because of tween 8830 to 11.250 J/gr and therefore can be classifi ed the abundance of glauconite. & e two gravelly horizons at as soft brown coal (German rank) or lignite B (ASTM 236.9 and 240 m, the abundance of shells and shell debris rank). An elemental analysis (Table 1 and Fig. 6a) plotted in several levels, common traces of bioturbation, and also on a Van Krevelen diagram (Fig. 6b) shows the Maaseik the presence of small wood fragments in several cores all brown coal to be intermediate between soft brown coal point to a rather shallow depositional environment, situ- from Lower Rhine exploitations and peats. ating the depositional depth around the minimal depth limit of 10-20 m given above.

3. The green glauconitic sands (198 – 302 m) 3.2. Dinoﬂ agellate analysis

3.1. The lithological description 3.2.1. Introduction

& e sands below 198 m and till 302 m are generally An analysis of marine organic-walled phytoplankton fi ne-grained, glauconitic, bioturbated and often contain- based on a low resolution sampling of the Breda Forma- ing abundant shell debris, as described for the Breda tion was carried out for the assessment of the stratigraphic Formation in this area (see also Westerhof et al., 2003, position of the sequence and the establishment of its p.300-303). relationship to other Miocene deposits in contiguous Based on the core description, geophysical well-log areas. Sixteen samples (Tab. 2) were prepared using characteristics, grain-size analysis and glauconite content, standard palynological maceration techniques involving several subunits can be approximately delineated (Figs. demineralisation with HCl and HF. No oxidation or 2 & 7). alkali treatments were applied in order to avoid damage Between 198 m and 225.5 m, the sands are slightly (loss of pigment, thinning of cyst walls) and selective loss coarser than below. At the base of this unit a coarse level of species. A better dispersion of fi ne organic debris was occurs, enriched in glauconite. & is upper interval is also obtained through a short ultrasound treatment for 15 s. characterized by higher glauconite contents than below A minimum of 250 marine palynomorphs was counted (Fig. 7). Within this interval, at about 212 m a further systematically in every sample. & e rest of the slide was subdivision can be made with an uppermost part that is then scanned for rare specimens. A total of 100 in situ fi ner-grained, clay-richer, less glauconitic and containing organic-walled marine palynomorphs, mainly dinofl agel- abundant fi ne shell debris. & e lower part has a very loose late cysts and acritarchs, were recorded. Preservation of packing and at its base occur some carbonate-cemented the palynomorphs is variable. & e basal three samples layers. & is further subdivision is also expressed on the (Tab. 2) yielded a poorly preserved assemblage of dino- gamma-ray log (Figs. 2 & 7). fl agellate cysts and abundant well preserved specimens 16 VANDENBERGHE, LAGA, LOUWYE, VANHOORNE, MARQUET, DE MEUTER, WOUTERS & HAGEMANN

rt -198m -212 -225,5 -234 -240 -249 -261 -273 -288 for the Breda Formation (198-300m) and the overlying unit X (198-300m) and the overlying for the Breda Formation ned as < 8 µm, glauconite is separated by an electromagnet and ﬁ meters below surface. Sample positions are indicated by the sho surface. meters below the lithological column is same as in Fig.2. fore de nest, clay and glauconite content, shell fragments abundance, nest, clay and glauconite content, shell fragments abundance, ﬁ ysis is carried out by laser diffraction; clay content is there ysis is carried out by laser diffraction; from the cores for sediment analysis. Depths are expressed in from the cores for sediment analysis. Depths are expressed . The subdivisions are discussed in the text and the legend of and the legend are discussed in the text The subdivisions . $$ MODE m) ( 90% finer percentilem)( CLAY % 0 50 100 150 200 250 0 50 100 150 200 250 300 350 400 0 5 10 20 30 40 0 5 10 20 30 0 + -200 -205 -210 -215 -220 -225 -230 -235 -240 -245 -250 -255 -260 -265 -270 -275 -280 -285 -290 -295 -300 -195m -200 -250 -300 Sediment analysis data: modal size, 90% percentile- Figure7. Figure7. (192.7-198m) of possibly Sylt stratigraphic position. Size anal shell debris content is estimated visually in the samples taken horizontal lines, left of the zero value line of each parameter horizontal lines, left of the zero value STRATIGRAPHIC INTERPRETATION OF THE NEOGENE MARINE Ð CONTINENTAL RECORD IN THE MAASEIK WELL 17 ,0 <1 <1 -191.5 +<1 <1 -201.5 +<1 +<1<1 <1 1,5 <1 -210.8 ,9 1,2 2,3 3,4 <1 <1 <1 -220.5 +<1<1 -234.5 1,1 + <1 <1 -245.5 <4, 111,1 <1<1 +<142,9 +<1<1 +<1 1,5 -256.3 + + <1 <1 <1 1,1 <1 2,3 1,1 <1 <1 <1 <1 <1 -265.8 -275.8 + + <1 <1 1,9 1,1 + 3,8 15,6 <1<1 1,3 + + <1 <1 + <1 + <1 1,5 <1 1,8 1,5 <1 1,1 <1 1,1 1,8 1,0 + <1 <1 ++ 1,9 1,5 <1 <1 + <1 <1 1,2 + <1 <1 <1 1,8 <1 + + <1 + 1,0 1,5 + <1 <1 2,3 + <1 1,2 2,2 <1 <1 <1 + 3,1 <1 <1 2,3 1,1 11,3 + 2,9 2,8 <1 <1 <1<1 <1<1 <1 <1 <1 <1 + <1 + + <1 + <1 + + 1,4 <1 5,0 <1 <1 <1 1,91,9 <1 1,1 4,9 26,9 + <1 2,3 <1 2,2 + <1 1,1 <1 1,1 + + 1,0 <1 <1 -285.8 + <1 <1 + <1 <1 <1 <1 + 1,1 + ++ 2,7 <1 + 1,9 2,3 + 1,5 3,0 3,1 2,3 1,9 1,9 5,8 2,5 1,5 1,5 2,1 1,8 1,9 8,4 1,5 7,3 1,1 1,9 1,9 3,8 <1 + <1<1++ +++ ++ <1<1<1 1,9 1,5 4,9 <1 1,9 <1 4,8 2,3 3,0 1,9 2,3 <1 1,3 3,3 11,2 <1 <1 1,1 <1 1,1 2,1 1,5 1,5 3,3 1,3 3,1 6,2 <1 5,2 2,6 5,0 <1 2,1 9,5 <1 1,2 15,6 <1 3,1 1,2 1,1 19,3 9,0 21,3 7,9 3,8 <1 + 1,5 4,4 + 5,4 <1 <1 -295.8 -292.4 -279.9 -270.9 -227.5 -215.6 Samples spp. 3,7 2,2 28,0 6<1 34,6 25,1 63,5 55,6 65,9 21,4 23,4 43,1 29,7 46,2 56,5 37 Achomosphaera eirikianum spp. ind. + <1 + + <1 <1 serratum spp.ind. 1,5 2,6 <1 + + sp. 1 Head et al. 1989 ? ? sp. 1 Louwye 2002 <1 + <1 1,5 2,3 + 1,1 <1 1,5 + + + <1 <1 1,5 <1 spp. ind. + + 3,8 <1 3,1 <1 <1 + <1 + + <1 spp. / Dinoflagellates (n=81) Bitectatodinium arborichiarum Dapsilidinium pseudocolligerum Labyrinthodinium truncatum Reticulosphaera actinocoronata Lingulodinium machaerophorum Lejeunecysta Operculodinium centrocarpum + O. israelianum Round brown protoperidiniacean cysts + + 2,3 <1 1,1 8,8 <1 1,5 + 1,7 <1 <1 4 Spiniferites Trinovantedinium Operculodinium Batiacasphaera minuta Selenopemphix quanta Selenopemphix dionaeacysta Habibacysta tectata Echinidinium euaxum Trinovantedinium glorianum Batiacasphaera Heteraulacacysta campanula Operculodinium borgerholtense Gramocysta verricula Pentadinium laticinctum Pyxidinopsis tuberculata Organic wall of calcareous cyst Amiculosphaera umbraculum Ataxiodinium zevenboomii Hystrichokolpoma rigaudiae Barssidinium pliocenicum Selenopemphix nephroides Tectatodinium pellitum Bitectatodinium Selenopemphix Operculodinium antwerpensis Lejeunecysta Selenopemphix brevispinosa Trinovantedinium ferrugnomatum Trinovantedinium variabile Achomosphaera andalousiensis Invertocysta lacrymosa Barssidinium graminosum Melitasphaeridium choanophorum Hystrichosphaeropsis obscura 18 VANDENBERGHE, LAGA, LOUWYE, VANHOORNE, MARQUET, DE MEUTER, WOUTERS & HAGEMANN -191.5 -201.5 + + <1 -210.8 <1 <1 +++ -220.5 -234.5 +<1 <1 ++ + + + <1 + -245.5 + <1 <1 <1 1,2 -256.3 <1 -265.8 + + +1,5 <1 <1 + <1 <1 + +<1 <1 + <1 <1 <1 <1 <1 -275.8 <1 <1 <1 <1 <1 <1 + <1 <1 + ++ +<1+ + -285.8 + + + <1 <1 <1 <1 <1 + <1 <1 +<1 + <1 2,2 1,1 3,9 + + + + <1<1 + 3,3 <1 3,4 3,0 5,3 4,4 1,1 <1 3,3 2,1 5,6 4,7 11,5 8,1 2,7 2,7 87,6 89,3 14,4 4,5 5,7 3,1 1,1 1,2 <1 4,6 2,2 11,7 18,5 1,2 3,8 1,9 -295.8 -292.4 -279.9 -270.9 -227.5 -215.6 Samples andalousiensis xylochophorum spp. ind. sp. A simplex ? cf. reticulata marieae sp. ind. + sp. ind. <1 + + sp. 3 de Verteuil & Norris 1996 <1 <1 sp. A cf. cf. ? sp. 1 Louwye 2002 trematophora sp. A cf. sp. ind. sp. ind. ? Paralecaniella indentata Trinovantedinium harpagonium Dinopterygium cladoides Barssidinium olymposum Palaeocystodinium Pyxidiniopsis brabantiana Scaldecysta Selenopemphix Operculodinium Bitectatodinium tepikiense Apteodinium tectatum Cerebrocysta Pyxidiniopsis Cerebrocysta poulsenii Sumatradinium druggii Achomosphaera Cannosphaeropsis passio Selenopemphix Operculodinium Lejeunecysta Filisphaera microornata Marine algae incertae sedis (n=16) Cyclopsiella Selenopemphix armageddonensis Lejeunecysta Systematophora placacantha Spiniferites pseudofurcatus Barssidinium taxandrianum Capisocysta wallii Operculodinium giganteum Trinovantedinium Palaeocystodinium golzowense Operculodinium piaseckii Sumatradinium soucouyantiae Lingulodinium multivirgatum Tuberculodinium vancampoae Pyxidiniopsis Geonettia clineae Batiacasphaera deheinzelinii Trinovantedinium Selenopemphix conspicua Tectatodinium STRATIGRAPHIC INTERPRETATION OF THE NEOGENE MARINE Ð CONTINENTAL RECORD IN THE MAASEIK WELL 19 -191.5 + <1 -201.5 <1 1,2 -210.8 + eworking, +: recorded outside eworking, ++ + 1,2 <1 <1 -220.5 +<1 + <1 <1 -234.5 <1 -245.5 -256.3 ++ + + <1 -265.8 + + <1 <1 <1 <1 <1 + <1 + <1 -275.8 rcentages are given for each sample. *: reworked or suspected r for each sample. *: reworked rcentages are given 1,1 + <1 4,5 <1 + + <1 + + -285.8 + 6,7 1,1 + <1 + 1,8 5,9 + 1,1 3,8 + + 241 270 264 266 263 227 266 259 270 238 269 274 286 260 262 262 -295.8 -292.4 -279.9 -270.9 -227.5 -215.6 Samples sp. ind. sp. ind. Total number of palynomorphs sp. ind. <1 + <1 spp. ind. <1 + <1 <1 sp. ind. <1 + + + spp. ind. spp. ind. spp. ind. 3,0 <1 6,8 <1 49,8 4,6 sp. ind. sp. ind. spp. ind. <1 <1 + sp. ind. sp. ind. sp. ind. sp. ind. Distribution of marine palynomorphs in the Maaseik borehole: pe Distribution Waaslandia gemina Incertae sedis 2 Acritarch sp. 2 Head et al. 1989 Small spiny acritarchsCyclopsiella elliptica/granosa Algal cluster Nannobarbophora gedlii Comasphaeridium + 1,1 <1 <1 <1 <1 <1 Incertae sedis 1Palaeostomocystis globosa <1 <1 + <1 <1 <1 Chiropteridium Enneadocysta Incertae sedis 3 Acritarch sp. 1 Louwye 2002Cyclopsiella Quadrina condita Green algae (n=3) Tasmanites Pterospermella Pediastrum boryanum Reworked palynomorphs (n=15) Cerebrocysta <1 1,5 Wetzeliella Homotryblium Areoligera Cribroperidinium Areosphaeridium dictyoplokus Perisseiasphaeridium Raetidinium Gonyaulacacysta Deflandrea Gorgonisphaeridium ambiguum Oligosphaeridium complex Scriniodinium the count, n: number of recorded species. Table 2. Table 20 VANDENBERGHE, LAGA, LOUWYE, VANHOORNE, MARQUET, DE MEUTER, WOUTERS & HAGEMANN

of Paralecaniella indentata. Other samples, e.g. 201.5 m, However, both de Verteuil & Norris (1996) and Strauss yielded a very good preserved assemblage with a high et al. (2001) stress the abrupt last common, and well species diversity. Reworking of pre-Neogene is moder- dated, occurrence of this species in the base of calcareous ate, except for sample 227.5 m where high numbers of nannoplankton Zone NN6, an event not recorded in our Homotryblium spp. are recorded (Tab. 2). All species of the study material. & is implies that the whole studied interval genus Spiniferites are grouped together because of their is younger than early Serravallian. & e DN6 Zone of de limited biostratigraphical value, except for Spiniferites Verteuil & Norris (1996) is defi ned as the interval from pseudofurcatus subsp. pseudofurcatus, which is a marker the highest occurrence (HO) of S. placacantha to the lowest species in the northern German Miocene biozonation occurrence (LO) of Cannosphaeropsis passio. & e LO of Se- of Strauss et al. (2001). & e nomenclature used is after lenopemphix dionaeacysta is a diagnostic event for this zone. Williams et al. (1998), Louwye (1999, 2001) and De & is zone is recognised in samples 285.8 m and 279.9 m. Schepper et al. (in press). & e DN6 Zone is considered equivalent with part of cal- & e assemblage of marine organic-walled palynomorphs careous nannoplankton Zone NN6 and is thus of middle from the Breda Formation in the Maaseik borehole Serravallian age. C. passio is recorded in sample 275.8 m compares well to the Middle and Upper Miocene as- and this points to the presence of the DN7 Zone, defi ned as semblages recovered by de Verteuil & Norris (1996) from the interval from the LO to the HO of the aforementioned the Salisbury Embayment (Atlantic Margin, USA) and species. Based on ODP data, de Verteuil & Norris (1996) by Strauss et al. (2001) from the Nieder Ochtenhausen propose a chronostratigraphic position of upper Middle Research Well in Northern Germany. & e dinofl agel- Miocene to uppermost Middle Miocene for their C. passio late cyst biozonations constructed in both latter areas DN7 Zone, i.e., equivalent to the upper part of calcareous can readily be applied to our study material, and are nannoplankton Zone NN6 to NN8 (late Serravallian). discussed below. An overview of the biostratigraphical Hardenbol et al. (1998) and Williams et al. (2004) place useful species for correlation and relative dating are given the HO of C. passio at 11.3 Ma (latest Serravallian), just in fi gures 1 and 2. below the Middle - Late Miocene boundary. Strauss et al. (2001) stress the very restricted range of C. passio of only a 3.2.2. Salisbury Embayment, Atlantic Margin, USA - de couple of meters in the upper Middle Miocene sequences Verteuil & Norris (1996) in the North Sea Basin and the North Atlantic realm (a.o. Brown & Downie, 1985; Lund & Lund-Christensen, Samples 295.8 m and 292.4 m are strongly dominated 1992; Engel, 1992), which underlines the stratigraphic (87.6% and 89.3%) by the acritarch Paralecaniella inden- potential of this species. However, the chronostratigraphic tata (Tab. 2, Fig. 8). & is species is a common element in calibration of this event remains uncertain because of the Mesozoic and Cenozoic organic-walled palynomorphs lack of a parallel record of calibration data from other fos- assemblages. P. indentata apparently has a broad eco- sil groups. Strauss et al. (2001) furthermore speculate that logical tolerance since it thrives in marine to marginal the short lasting occurrence of C. passio might be situated marine environments (Elsik, 1977). Noteworthy is that just before the important sea level drop associated with dinofl agellate cysts diversity in these samples is very low sequence boundary 10.5 Ma sensu Haq et al. (1987) or - only 19 species were recorded - and the preservation of the major sequence boundary Ser4/Tor1 at 11.7 Ma sensu the cysts is poor. & e high abundance of P. indentata in Hardenbol et al. (1998). & e single record of C. passio, as C. this interval indicates a depositional environment highly utinensis, in the Mazzapiedi section (Italy) by Zevenboom unfavourable for dinofl agellates, maybe very marginal (1995) in the earliest Tortonian is dissonant vis-à-vis other marine or even brackish. & e decrease of P. indentata in regions (North Sea Basin and the North Atlantic realm), the above-lying samples (14.4% in 285.8 m and 4.5% in and thus needs further research. 279.9 m) points to a gradual return to more favourable & e interval from 270.9 m to 227.5 m holds the DN8 marine depositional environments for dinofl agellates. Zone, which is defi ned as the interval from the HO of C. Although the dinofl agellate cyst diversity in the two latter passio to the HO of S. soucouyantiae. Additional diagnostic samples is higher, the preservation of the cysts remains events are the HO of C. poulsenii (sample 265.8 m) within poor. & e increase of the relative abundance of P. indentata the zone and the HO of Palaeocystodinium spp. (sample in a higher interval (234.5 m to 215.6 m) to a maximum 227.5 m) near the upper boundary of the zone. Neoglo- of 18.5% testifi es of a return to more unfavourable condi- boquadrina acostaensis is recorded in the basal beds of the tions for dinofl agellates (Fig. 8). & is is underscored by DN8 Zone in the type area. Its appearance, at 10.9 Ma the relative increase of Cyclopsiella species. & is interval according to Berggren et al. (1995), defi nes the lower is furthermore characterised by a pronounced infl ux of boundary of planktonic foraminifer Zone N16. & e upper reworked dinofl agellate cysts (Tab. 2). boundary of the DN8 Zone is close to the calcareous nan- Poorly preserved specimens of Systematophora placacantha noplankton Zone NN10/NN11 boundary. De Verteuil are sporadically present in low numbers in some samples. & Norris (1996) estimate that this DN8 Zone spans the Whether the specimens are reworked or not is unclear time from the beginning of the Late Miocene to the early and cannot be judged solely from the state of preservation. part of Chron C4r. & e HO of Hystrichosphaeropsis obscura STRATIGRAPHIC INTERPRETATION OF THE NEOGENE MARINE Ð CONTINENTAL RECORD IN THE MAASEIK WELL 21

Salisbury Embayment us East Coast U.S.A.

de Verteuil & Norris (1996) s

s andalousiensis

ata

late cyst

us pseudofurcat

ulum

usiensi

uyantiae

gnomat

spp.

a indent

ula

nctum laticinctum

dofurcat

psis passio

um feru

um glorianum

Age

Biozones

Epoch

aera andalo

a poulsenii

um souco

a tectata

a verric

mphix dionaeacyst

um latici

phaera umbrac

phaero

pemphix armageddonensis

hosphaeropsis obscu

Reworked dinoflagel

antedini 6 Paralecaniell

vantedini

omosph

Habibacyst

Ach

Amiculos

Palaeocystodini

Pentadini

Hystric

Cannos

Depth in m Selenope Sumatradini

Samples

Seleno

Spiniferites pseu

Cerebrocyst

DN10

Trinov

Gramocyst

Trino 7 Messini 0 100%

ne 191.5

8 DN9 201.5 200

9 210.8 215.6 220.5

Tortonian

DN8

10 Late Mioce 227.5 234.5 11

245.5 12 250

DN7 256.3

llian

13 6 265.8 270.9 275.8 14 279.9 Serrava ?

DN5 285.8 ? 15 292.4 295.8

Middle Miocene 300 16

DN4 Langhian Maaseik borehole 49W220

Figure 8. Distribution of selected dinofl agellate cysts in the Maaseik borehole (49W0220) and correlation with the biozonation of de Verteuil & Norris (1996). Depth of samples is given in m below topographic surface. defi nes the upper boundary of the DN9 Zone, while its 3.2.3. Nieder Ochtenhausen Research Well, Northern base is defi ned by the upper boundary of the DN8 Zone. Germany - Strauss et al. (2001) & e fi ve uppermost samples of the Maaseik borehole can be accommodated within the DN9 Zone. Labyrinthod- & e low species diversity and poor preservation in samples inium truncatum occurs in the uppermost sample of our 295.8 m and 292.4 m hinder the recognition of a biozone. studied section and has its HO at the upper boundary of Samples 285.8 m and 279.9 m might hold the Naq Zone, the DN9 Zone in the Salisbury Embayment. & e DN9 defi ned as the strata between the LO of Unipontedinium Zone is equivalent to the lower part of calcareous nan- aquaeductum to the LO of Cannosphaeropsis passio (Fig. 9). noplankton Zone NN11 and has a late Tortonian age. According to Strauss et al. (2001), the last common oc- Selenopemphix armageddonensis has in our study material currence of Systematophora placacantha and the HO of U. an early entry already in the DN9 Zone, while in the type aquaeductum are situated high in this zone. U. aquaeductum area it only appears in the superjacent latest Tortonian to is absent in the Maaseik well and S. placacantha occurs Messinian DN10 Zone. Hardenbol et al. (1998) place the only in low numbers (see above). & us, it is probable LO of S. armageddonensis at 9.0 Ma, which is before the that only the uppermost part of the Naq Zone is present HO of H. obscura at 7.34 Ma. in the Maaseik well. Since this zone is correlated with 22 VANDENBERGHE, LAGA, LOUWYE, VANHOORNE, MARQUET, DE MEUTER, WOUTERS & HAGEMANN

the middle and upper part of calcareous nannoplankton Achomosphaera andalousiensis andalousiensis, is thus present Zone NN5 (lower to middle Serravallian), samples in samples 270.9 m and 265.8 m. & is zone is interpreted by 285.8 m and 275.8 m could have a middle Serravallian Strauss et al. (2001) to be equivalent to the upper part of NN6 age. Sample 275.8 m holds the Cpa Zone, defi ned as the and the lower part of NN7, and to be of (middle to) late Ser- interval from the LO to the HO of C. passio. Contrary ravallian age. & e Gve Zone, defi ned as the interval from the to the fi ndings of de Verteuil & Norris (1996) in the US LO of Gramocysta verricula to just below the LO of Amicu- Atlantic Margin, Cerebrocysta poulsenii has a HO within losphaera umbraculum, is recorded in samples 256.3 m and this zone at Nieder Ochtenhausen. Strauss et al. (2001) 245.5 m. & e Gve Zone is interpreted to straddle the Middle suggest a correlation with calcareous nannoplankton Zone - Upper Miocene boundary (Strauss et al. 2001). However, NN6 (middle to late Serravallian) based on an indirect this interpretation should be considered tentative since it is correlation by means of bolboforms. based on an indirect correlation, namely the occurrence of G. & e upper boundary of the superjacent San Zone lies just verricula in an interval of the Gross Pampau borehole which below the LO of Gramocysta verricula, recorded in sample is indirectly calibrated with calcareous nannoplankton Zones 256.3 m. & e San Zone, also characterised by the LO of NN8 and NN9 by means of bolboforms.

Nieder Ochtenhausen Northern Germany Strausset al . (2001)

andalousiensis

pseudofurcatus

atum

Age

Dzones

Subzones

“Stufe”

sio

anum

spp.

sis obscura

andalousiensis

umbraculum

sis pas

Sylt

x dionaeacyst

x armageddonensis

um ferugnom

um glori

laticinctum laticinctum

a poulsenii

um soucouyantiae

Unnamed

pseudofurcatus

atectat

a verricula

Depth in m

Habibacyst

Achomosphaera

Amiculosphaera

Palaeocystodinium

Pentadinium

Hystrichosphaerop

Cannosphaerop Selenopemphi Sumatradini

Selenopemphi

Spiniferites

Cerebrocyst

Trinovantedini

Samples

Gramocyst Pla Trinovantedini

Aum 191.5

201.5 200

Late Miocene

Gram 210.8 Sps 215.6 220.5 227.5

Ncr 234.5 Pal ? Gve 245.5 250 de San Cpa 256.3

265.8 270.9 Langenfel ? Naq 275.8 279.9 ? 285.8

Middle Miocene 292.4 Cpl 295.8

Reinbeck 300

Oxl. Pmc Maaseik borehole 49W220

Figure 9. Distribution of selected dinoﬂ agellate cysts in the Maaseik borehole (49W0220) and correlation with the biozonation of Strauss et al. (2001). Depth of samples is given in m below topographic surface. STRATIGRAPHIC INTERPRETATION OF THE NEOGENE MARINE Ð CONTINENTAL RECORD IN THE MAASEIK WELL 23

& e above lying Aum Zone covers the greater part of correlation is mainly based on the recognition of the DN6 the Upper Miocene and is defi ned by the LO of A. Zone and DN7 Zone of de Verteuil & Norris (1996). umbraculum (sample 234.5 m) to the LO of Spiniferites Louwye (2002) recorded a well-preserved and rich dino- cf. pseudofurcatus sensu Harland (not recorded). & e up- fl agellate cyst assemblage from the Deurne Sands, a local per part of the studied section from samples 234.5 m member of the Upper Miocene Diest Formation. & e to 191.5 m thus holds the Aum Zone. & e Aum Zone investigated sequence is located in the Antwerp area and is subdivided into four subzones and an uppermost un- has a thickness of only a few meters. & e dinofl agellate named interval (Fig. 9). Recognising these subzones of cyst assemblage recorded in the Deurne Sands is com- Strauss et al. (2001) in the interval 234.5 m to 191.5 m parable to the assemblages recorded in samples 234.5 m is much more diffi cult. to 220.5 m of the Maaseik borehole. & e comparison is & e lowermost Pal Subzone is defi ned as the interval from based on the occurrence of species such as Amiculosphaera the base of the regular occurrence of A. umbraculum to the umbraculum, Lejeunecysta sp. 1, Sumatradinium soucouy- HO of Palaeocystodinium spp. However, the latter species antiae, Spiniferites pseudofurcatus and Trinovantedinium has its highest common occurence in sample 245.5 m. glorianum. & e Deurne Sands were correlated with dino- Whether the two single specimens of Palaeocystodinium fl agellate cyst zone DN8 of de Verteuil & Norris (1996) spp. in samples 234.5 m and 227.5 m, recorded outside and the Aum biozone of Strauss et al. (2001), and, more the counting, are reworked or in situ if diffi cult to assess, tentatively, with their Sps Subzone. As stressed by Louwye and renders the formal recognition of the Pal Subzone (2002), neither the lower nor upper boundaries of the diffi cult (Fig. 9). & is interval is furthermore typifi ed by above mentioned zones were recognised in the unit. & e the substantial presence of reworked cysts (see above). & e presence of Impagidinium species in the Deurne Sands Pal subzone is calibrated against NN8/NN10 and has a is noteworthy. According to Dale (1996), the presence supposedly early to middle Tortonian age. of this species (and also Nematosphaeropsis species), even Sample 220.5 m possibly holds the Sps Subzone whose in very low numbers, is an indication of the infl uence of upper boundary is defi ned by the top of the regular oceanic water masses, a phenomenon not recorded in the occurrence of Spiniferites pseudofurcatus. However, the Maaseik borehole. Striking is the absence of Gramocysta occurrence of this species is sporadic in the Maaseik verricula in the Deurne Sands, which might be environ- borehole and never regular. & e Sps Subzone is probably mentally controlled. equivalent to calcareous nannoplankton Zones NN10 and & e Dessel Sands and Diest Sands are the two other NN11 (pars) (middle Tortonian to ?earliest Messinian). members of the Diest Formation and are found in the & e underlying thin Ncr Subzone, defi ned by the LO and Campine area. Both members are diachronous (Louwye HO of Nematosphaeropsis crassimuratus, was most prob- et al.. 1999). & e fi ne-grained Dessel Sands and coarse- ably not recognised in the Maaseik well because of the grained Diest Sands are genetically related to the forma- low sampling resolution. Furthermore, this Ncr Subzone tion and infi lling of a large gully in the eastern Campine is diffi cult to calibrate since N. crassimuratus was never area, which presumably formed at the end of Middle recorded outside the type locality Nieder Ochtenhausen. Miocene times or during early Late Miocene times. & e Samples 215.6 m to 201.5 m can possibly be placed Dessel Sands in the vicinity of the gully in the eastern within the Pla Subzone, whose upper boundary is defi ned Campine area hold the DN8 Zone of de Verteuil & Nor- by the HO of Pentadinium laticinctum laticinctum. & is ris (1996), while the same sands hold the DN9 Zone in species, however, also has a very sporadic occurrence and the western Campine area. & e above-lying Diest Sands is never abundant. According to Strauss et al. (2001), this holds, in respectively the same areas, the DN9 and DN10 subzone is most probably equivalent to the upper part of Zones. & e recognition of these biozones in both units calcareous nannoplankton Zone NN11, and they suggest allows a correlation with the Maaseik sequence (Fig. 8). a ?latest Tortonian - early Messinian age. The uppermost “unnamed” Subzone in the Nieder 3.2.5. Conclusions Ochtenhausen well is characterised by common occur- rences of, a.o., Hystrichosphaeropsis obscura and Reticulat- At Maaseik, the deposition of the Breda Formation opshaera actinocoronata, a phenomenon also observed in started in a marginal marine environment unfavourable sample 191.5 m. for dinofl agellate cysts, testifi ed by high numbers of Paralecaniella indentata in the very base of the sequence. 3.2.4. Comparison with Miocene deposits in northern Decreasing numbers of this species higher up in the Belgium sequence indicate that deposition took place in increas- ingly more marine conditions during middle Serravallian & e dinofl agellate cyst assemblages recorded from sam- times. An age for the basal section cannot be proposed. ples 285.8 m to 275.8 m are comparable to those found in According to the biozonation of de Verteuil & Norris the upper part of the Antwerpen Sands, a member from (1996), the Middle - Upper Miocene boundary is located the Berchem Formation, in the “Borgerhout Rivierenhof ” between samples 275.8 m and 270.9 m, while according outcrop in the Antwerp area by Louwye et al. (2000). & is to Strauss et al. (2001) the boundary lies somewhere in 24 VANDENBERGHE, LAGA, LOUWYE, VANHOORNE, MARQUET, DE MEUTER, WOUTERS & HAGEMANN

the interval 256.3 m to 245.5 m. & e upper Miocene the boundary between Middle and Upper Miocene zones sequence in the Maaseik well was deposited sometime between 228.5 and 237.5 m represented by a hiatus of during Tortonian times. & e Messinian biozone DN10 more than 2 Ma. of de Verteuil & Norris (1996) was not recognised in the Maaseik borehole, while according to the Strauss et 3.4. Molluscan fauna al. (2001) biozonation the uppermost sample could hold their Messinian “unnamed” biozone. & e low-resolution 3.4.1. Material and methods sampling does not allow us to draw conclusions regarding changes of the depositional rate. An increase of P. A number of cores, taken between 200 and 298 m depth, indentata and Cyclopsiella species in the upper part of were sieved on a 0.5 mm mesh and all identifi able frag- the sequence from samples 234.5 m to 215.6 m, and a ments of mollusca were collected (deposited in the IR- pronounced infl ux of reworked species in sample 227.5 m ScNB/KBIN collection, Department of Palaeontology, indicate a return to less favourable conditions for dino- section Invertebrate Palaeontology). & e cores sorted out fl agellate cysts, i.e. much shallower conditions during a consisted of half of tubes of 1 m long, with a cross section period of low sea level or uplift. of 10 cm, taken in the intervals 297-298 m, 285-286 m, 279-267 m, 258-248 m, 242-228 m and 218-200 m. & is 3.3. Calcareous microfossils yielded a collection of more than 3000 shells and shell fragments. & e highest density was reached between 242 3.3.1. Benthic foraminifera and 228 m, in which several lenses or beds mainly consisting of single valves of the bivalve subspecies Glycymeris & e section between 196.50 m and 232.50 m was exam- obovata baldii Glibert & Van de Poel, 1965 occurred. ined. Below 203.50 m abundant Florilus boueanus and & e remaining material was distributed randomly in some Elphidium antoninum are present. In addition, in the cores. some samples with abundant foraminifera, also Uvigerina & is material was identifi ed using the works of Gürs hosiusi deurnensis is present. & e planktonic forams, the so (2001, 2002), Gürs & Weinbrecht (2001), Janssen (1984), called Globigerina pachyderma, in the samples are generally Heering (1950), Hinsch (2000), Menzel et al. (1994), dextrally coiling (see De Meuter & Laga, 1970 and also Moths (1989), Van Voorthuysen (1944) and Wienrich Hooyberghs et al., 2004). (2002). & e data are represented in Table 3. & is section between 196.50 and 232.50 m can therefore be correlated biostratigraphically to the Uvigerina hosiusi 3.4.2. Previous research about the Miocene Mollusca deurnensis – Elphidium antoninum assemblage zone (De from Belgium Meuter & Laga, 1976) or the BFN3 (Belgium Benthic Foraminifera) – FC2 (biozone in the Netherlands) of Although already Nyst (1845) described molluscan Doppert et al.(1979). & is biozone corresponds in Bel- species from the Miocene of the Antwerp area, the fi rst gium to the Deurne and Dessel Sands of the Diest Forma- systematic studies were these of Glibert (1945, 1952, tion; in addition, characteristic foraminifera associations 1954) and Glibert & de Heinzelin de Braucourt (1955). of known over- and underlying lithostratigraphic units & e fi rst three works mentioned treated respectively the are missing in this interval. bivalves, gastropods (minus Turridae) and Turridae of the Early and Middle Miocene, the last the whole fauna of 3.3.2. & e Ostracods the Late Miocene Deurne Sand Member. All Glibert’s studies however were based on material collected in In the approximately same interval between 201.50 m the nineteenth century, by Nyst and other amateur col- and 235.50 m ostracods are determined. Especially the lectors. A systematic fi eld survey was never attempted, presence of A aerocythere sp.1, Sagmatocythere variolata because of lack of exposures before and at the time of and Propontocypris propinqua are typical for the Sands of the studies of this fauna by Glibert and de Heinzelin. Deurne. None of these three species were ever found in & is had however several drawbacks. First of all, a lot other Miocene or Pliocene stratigraphic units in the area. of material was collected ex situ, so that a number of & e other species present point to a Miocene rather than Pliocene species were included in Middle Miocene Pliocene deposit. fauna lists. & is was emphasized by Janssen & Van Der & e presence of Callistocythere sp.1 and 2 and Leptocythere Mark (1969) and confi rmed by Marquet (1995, 1997a, sp. is interesting as these species were never recorded in b, 2002, in press) regarding the Pliocene malacofauna. the Deurne Sands of their classical Antwerp Campine Secondly, only part of the Belgian Miocene was known occurrence area. It could point to a diff erent palaeoenvi- to Glibert: the Early Miocene Houthalen and Edegem ronment as the species of both genera preferentially live Sand Members, the Middle Miocene Antwerpen Sand in shallow environments in association with algae. Member, the Late Miocene Deurne Sand Member and Hooyberghs et al. (2004) have recently described the the reworked silicifi ed Bolderberg fauna. & irdly, in the Bolboforma zones in the borehole Maaseik and identifi ed collection of the IRScNB/KBIN, the material of the STRATIGRAPHIC INTERPRETATION OF THE NEOGENE MARINE Ð CONTINENTAL RECORD IN THE MAASEIK WELL 25

Kattendijk Formation (Early Pliocene) is included in dii Glibert & Van de Poel, 1965, Modiolula phaseolina that of the Late Miocene Deurne Sand, (pers. obs.), so (Philippi, 1844), Scacchia degrangei (Cossmann & Peyrot, that the age of this Member could be underestimated. 1911); Goodalia waeli waeli (Glibert, 1945), Digitaria Lastly, only large shell species were collected, minute beyschlageri (Kautsky, 1925), Ervilia pusilla (Philippi, ones are underrepresented. So this pre-1960 material is 1836), Parvicardium scabrum (Philippi, 1844), Spani- for a large part unsuited for stratigraphic comparisons. odontella nitida (Reuss, 1867), Gouldia minima (Montagu, 1803) (Bivalvia), Hyalia laevigata (von Koenen, 1882), From the 1960’s onward, large scale works allowed the Fusiturris duchasteli fl exiplicata (Kautsky, 1925), Retusa collection of a large amount of material from the Belgian subangystoma (d’Orbigny, 1852) and Cylichna cylindracea Miocene. & is material was collected better, including (Pennant, 1777) (Gastropoda). All these however are the smaller species, but it has not yet been published species with a long stratigraphic range, encompassing completely. & e Ring Motorway and Kennedy Tunnel the whole Miocene and some even reaching till now. A around Antwerp and the Antwerp Metro works con- notable exception is E. pusilla, an extremely rare species tained abundant material from the Edegem, Antwerpen in other Belgian Miocene sediments: it is very common and Deurne Sand Members. In Doel, Oost-Vlaanderen in the upper part of the Maaseik boring, but also occurs (Deurganckdok) a Miocene fauna preserved in sandstone, rarely in the lower part; before, it has been found in the of yet unknown age, was discovered. In Deurne (Antwerp, Early Miocene Edegem Sand Member. Middelares Hospital), the Deurne Sand Member could be Only a rather low number of taxa - 24 - seem to have sampled. Furthermore, in Heist-Op-Den-Berg the rich stratigraphic signifi cance. First of all, some characterize Zonderschot Sand Member was discovered and sampled only part of the section investigated and are well enough extensively during several large scale diggings, organized represented in the samples. & ey allow the distinction mainly by the “Werkgroep voor Tertiaire en Kwartaire Ge- of two diff erent parts in the section, although there is ologie”. Smaller exposures also proved to contain unknown a considerable overlapping part in their ranges. & ey molluscan faunae, especially a clay pit in Ramsel (Antwerp are listed in Tables 4a and 4b. & e overlapping part is province) with an internal mould fauna and building between 239 and 227 m, with one species characteristic works in Putte, near Lier (Antwerp province). Last of all, of this part by its great abundance, but reaching above as a fauna, preserved in phosphorite nodules, could be studied well as below: Anodontia benoisti (Cossmann & Peyrot, in Broechem (same province), which seems to represent a 1912) found between 268 and 214 m depth. Secondly, Miocene-Pliocene boundary assemblage. Material of all other species only were found in one or few samples, but these exposures is conserved in the collection Marquet (to characterize part of the Neogene in other parts of the be transferred to the IRScNB/KBIN in Brussels) and the North Sea Basin. NNM Naturalis in Leiden, & e Netherlands, as well as in Of the 14 species characterizing the upper part of the numerous private collections. Publications however about section, only two have been found before in the Belgian this new material are scarce: Janssen & Müller (1984) dis- Miocene, while of the 10 species in the lower part, only cussed the Ramsel fauna, Marquet (1980) the Broechem one is new (A. benoisti). & e upper part of the section ap- fauna and Marquet in Bosselaers et al. (2004) that of the parently contains molluscs new to the Belgian Miocene; Deurne (Middelares Hospital) section. & e bulk of the only two species in this part are known from earlier newly collected material remains however to be described; research, namely from the Deurne Sand Member, one the doctoral thesis by Ringelé (1974) about the Neogene of which is also found in Pliocene deposits. & e lower Bivalvia, unfortunately was never published. A systematic part of the section contains species found in both the revision of the whole Belgian Miocene molluscan fauna is Zonderschot and the Antwerpen Sand Members, so it consequently needed and this would considerably enhance could be corresponding to both; their general molluscan its stratigraphic utility. content only diff ers slightly.

3.4.3. Results 3.4.4. Notes on systematics

Even taking the unpublished material collected after 1960 Glossus lunulatus lunulatus (Nyst, 1835) was found in frag- into account, the Maaseik boring yielded 32 taxa new to mentary condition in the whole section, but the lack of the Belgian Miocene fauna, probably representing a part shell sculpture and the shape of the umbo are recognizable of the Miocene which was not found before in Belgium in the material collected. & is subspecies is only present in and therefore not to be correlated with any of the known the middle part of the Belgian Miocene: the Antwerp and Members (see Table 3). Zonderschot Sand Members. & e Deurne Sand Member A total number of 187 species was found, composed of contains another species, Glossus (Glossus) forchhammeri 75 bivalve, 2 scaphopod and 107 gastropod taxa. Table (Beck in Ravn, 1907; Marquet, in press), diﬀ ering by its 3 gives a list of the distribution of these species. Most lower shell and much less protruding umbo. were represented by few specimens in each core part Aequipecten opercularis (Linnaeus, 1758) s.l. makes part only. Exceptions are mainly Glycymeris obovata bal- of a group of very similar species and the specimens 26 VANDENBERGHE, LAGA, LOUWYE, VANHOORNE, MARQUET, DE MEUTER, WOUTERS & HAGEMANN

297 285 278

277 x 276 275 274 273 272 271 270 269 268 267 257 256 255 254 253 252 251 250 249 248 241 240 239 238 237 236 235 234 233 232 231 230 229 228 227 226 225 217 216 215 214 213 212 211 210 209 208 207 206 205 204 203

xxx 202 xx xxx xxxxxxxxx xxxxxxxxxxxxxxx xx x xxx x xx x x xxxxxx x x xx x xxxxxxxxxxxxxxxx xxxxx x xxxx xxxxxx x xxx xxxxx x xx xxx xxxxxx xxxxxx x x xxxxxx xxx xxx x x x xx xxxxxxxxxx xxxx x x xxx x xxx x x x xx xxx xxx x x x xx x x xxx x x x xxxx x xxx x xx x

201 xx xx x xxxxx xxxxxxxxxxxxx xxxxxxx x xx xxxxxxx xx x xxxx x xxxxx xx xxxxxxxxx x xxx xxxx x x xxxx xx x xxxx x xx xxxxxxx xxxxx xxxxxx x x xx xxx xx x xxxxxx xxx x xx x xxx x x x x x xxxx x x xxxxxxxxxxxxxxx xxx xx xxxxxxx xxxxxxxxxx x x xxx x xxx x x x x xxx x x x x x x x x x x x xxx x x xxxx x x xx xx xxxx xx xxxxx x xxxx xx x xxx x x x xx ? xx xx x xx x x x x xxxx x xx x x x x x x x xx xx xx x xxx x x x x x x x x x

200 x x xx x xx xxx x x x x x xx xx x x x xx xx x xx x N xN x xN x xxx x x x

New xxx x xx xx x xxxxxx x Marquet, 2004 (Nyst, 1835) Marquet, 2005 (Linnaeus, 1758) s.l. (Kautsky, 1925) (De Serres, 1819) (Beyr. in v. K., 1868) (Linnaeus, 1758) (Philippi, 1844) (Kautsky, 1925) (Philippi, 1844) (Reuss, 1867) (Cossm. & Peyr., 1914) auct. (Sowerby, 1818) Glibert & V.d.Poel, 1966 (Olivi, 1792) (Cossm. & Peyr., 1911) Gl. & V.d. Poel, 1965 (Linnaeus, 1758) (Linnaeus, 1758) (Lehmann, 1885) Glibert, 1945 (Wood, 1850) (Linnaeus, 1758) (von Münster, 1817) (Lamarck, 1805) Wood, 1851 Bellardi, 1875 Gürs, 1996 (Linnaeus, 1758) (Linnaeus, 1758) lupinus cf. sp. nov. ? Name: Bivalvia Isocrassina f. ariejansseni Lentidium turonensis Arcopagia cf. ventricosa Callista chione Digitaria beyschlageri Glossus lunulatus Scacchia degrangei Dosinia Spaniodontella nitida Aequipecten opercularis Mactra Yoldia glaberrima Goodallia angulata Nucula jeffreysi Leionucula laevigata Lucinoma borealis Parvicardium scabrum Abra antwerpiensis Corbula gibba Thracia (T.) i. microgranosa Glycymeris o. baldii Angulus benedeni fallax Periploma ariei Turneria cylindrica Nucula trigonula Panopea kazakovae Ensis Pododesmus squamula Modiolula phaseolina Hiatella arctica Scapharca diluvii Spisula "subtruncata" Acanthocardia hanseata Angulus donacinus STRATIGRAPHIC INTERPRETATION OF THE NEOGENE MARINE Ð CONTINENTAL RECORD IN THE MAASEIK WELL 27

297 285 278 277 276 275 274 273 272 271 270 269 268 267 257 256 255 254 253 252 251 250 249 248 241 240 239 238 237 236 235 234

233 x

232 xx xx x 231

230 xx x x

229 x x xxxx

228 x x xx xxx xxx x x

227 xxx

226 xxx xxxxx x xxxx xx x xxxx x

225 xxxxxx xxx x x xxx x x x 217 216 215

214 xx xxxxx x x

213 xxxxxxxx x xxxxx xx xx xx 212

211 xxxxx xxxxxxx x xxxxx xxx x x xxx

210 xxx

209 x 208

207 x xx xxx xxxxx xx xxxxxx xxx x x x x x xx x 206 205

204 x x x xxxxxx x 203

202 x x xxx x xxxxx x xx xx x xx x x 201 200 ?x x New Nxxxxx N xNxx xxxxx x x x x (Poli, 1795) (Scacchi, 1844) (Payraudeau, 1826) Marquet, 2002 (Nyst, 1839) (Glibert, 1945) (Olivi, 1792) (Deshayes, 1835) (Wood, 1859) A.W. Janssen, 1972 Anderson, 1967 (Leathes in Sow., 1825) (Pusch, 1837) (Lamarck, 1818) (Laskey, 1822) (Cossm. & Peyr., 1912) (Bronn, 1811) auct. (Montagu, 1803) (Philippi, 1843) (Montagu, 1803) Sorgenfrei, 1958 (Brown, 1827) (Montagu, 1803) (Montagu, 1803) (Pennant, 1777) (Philippi, 1836) sp. Name: Bivalvia Goodallia waeli Similipecten similis Lyonsia Erycinidae Teredinidae Ervilia pusilla Timoclea ovata Aligena Lajonkairea lajonkairei ? Arcoperna sericea Mioerycina coarctata Pandora copiosa Limopsis anomala Pitar rudis Pseudamussium lilli Lepton Anodontia benoisti Bathyarca pectunculoides Cyclocardia scalaris Gouldia minima Pseudamussium clavatum Yoldiella p. wesselinghi Thyasira flexuosa Musculus sorgenfreii Axinulus germanicus Limatula sulcata Pteria phalaenacea Atrina Carinastarte anus Nuculana westendorpi Cuspidaria cuspidata Mysella bidentata Cardiomya costellata Ostreidae indet. 28 VANDENBERGHE, LAGA, LOUWYE, VANHOORNE, MARQUET, DE MEUTER, WOUTERS & HAGEMANN

297

285 x 278

277 x

276 x

275 xxxx 274 273 272

271 xx x 270 269 268 267 257 256 255 254 253 252 251 250 249 248

241 xx 240 239 238 237 236 235 234

233 x xxx xx 232 231 230 229 228 227

226 xxxx xx x x x x x x x

225 xxxxxx x 217 216 215 214 213 212 211 210 209 208 207 206 205 204 203

202 xxx xxx xx xxxxx xxx x xx x x xxxxx xxxx x xx x xx xxxxxx x xxxxxxxx xxxx xxx xxxxx x xxx x xx xx xxx xx x x xx xx x x x xxx xx x x xx x x x x x x

201 xxxxxxxx xxx xxx x xxxx x x x x x xx x x xx xxxxxx x x x xxxx 200

New N xN xx x xNxxx x xx xxx x xx xNx xx x xxxx x xNxxx xxxxxxx N xNx xx x x x x xx x xx (Lamarck, 1818) Hinsch, 1972 (Nordsieck, 1972) (d'Orbigny, 1852) Sorgenfrei, 1958 (Eichwald, 1830) (Peyrot, 1927) (von Koenen, 1872) Gürs, 2003 (Bronn, 1831) (Beyrich, 1856) (De St. & P., 1880) (Brocchi, 1814) (Beyrich, 1854) (Brocchi, 1814) (Mayer, 1874) (Wood, 1848) (Kautsky, 1925) (Sowerby, 1824) (Cossm. & Peyr., 1916) (Bronn, 1831) (Nyst, 1844) auct. (Dujardin, 1837) (Brocchi, 1814) d'Orbigny, 1852 (Brongniart, 1823) (Da Costa, 1778) sp. nov. ? Name: Bivalvia Spaniorinus cimbricus Limea strigillata Ventricoloidea multilamella Clausinella scalaris Laevicardium subturgidum Mimachlamys angelonii ? Callista chionides Name: Scaphopoda Dentalium Laevidentalium Name: Gastropoda Sveltia var. paucicostata Ringicula ventricosa Ficus conditus Turritella eryna Semicassis bicoronata Turbonilla Coralliophila bracteata Calliostoma laureatum Circulus subcirculus Alvania curta nieheimensis Eulima glabra Turbonilla gastaldi Epitonium frondiculum Hadriania coelata Brocchinia mitr. parvula Turbicauda spinicostata Nassarius prysmaticus Asthenotoma pannoides Sorgenfreispira sorgenfreii Xenophora Euspira helicina protracta Chrysallida semireticulata Daphnobela miocaenica STRATIGRAPHIC INTERPRETATION OF THE NEOGENE MARINE Ð CONTINENTAL RECORD IN THE MAASEIK WELL 29

297 285

278 x 277 276 275 274 273 272 271 270 269 268 267 257 256 255 254 253 252 251 250 249 248 241 240 239 238 237 236 235 234 233 232 231 230 229 228 227 226 225 217 216 215 214 213 212

211 x

210 x xx xx

209 xx

208 xx xxxxx xxxxxxxxxxxxx xxx xxx x x xxx xx x x xx x

207 x xxx xxxxxxxxx xxxxx x x xxxxxx x xxxx x xxx xxx x x xxx xx x xx x x x x x xxxx xx 206 205 204

203 x x xxx xxxxxxxx x xx xxxxxxx x x xxx xxxx

202 xxx xxxxx xxx x x xx xxx xxxx x xxx xxxxxxx xx xx xxxx x xx xx x xxx xxx x x x xxx x x x x xxx xx xx xx x xxxx x xx xx xx xxx x x xx x x x x x x x xx x xxx xx x x x xxxx x x xx xxx xx x x

201 x x 200

New N xx x xx N x xxNxxxx Nxx xxx xxxx x xxN x x x x x xx xxx xxx x x ., 2002 et al (Brocchi, 1814) (Philippi, 1843) (Sacco, 1890) (Nordsieck, 1972) (von Koenen, 1871) Marquet (Kautsky, 1925) (Beyrich, 1854) (Kautsky, 1925) (d'Orbigny, 1852) (Cantraine, 1835) (Michelotti, 1847) (Brocchi, 1814) (Grateloup, 1838) (Linnaeus, 1758) (Pennant, 1777) auct. (Brocchi, 1814) Sorgenfrei, 1958 (Brocchi, 1814) (Brocchi, 1814) (Jeffreys, 1867) (Etheridge & Bell, 1898) (Grateloup, 1827) (Brocchi, 1814) (von Eichwald, 1830) (von Koenen, 1882) (Benoist, 1872) Glibert, 1952 Deshayes, 1845 (Récluz, 1850) Van Der Linden & A.W. Janssen, 1996 (Van Voorthuyzen, 1942) Name: Gastropda Fusiturris d. flexiplicata Retusa subangystoma Calyptraea chinensis Babylonella fusiformis Pleurotomella mioweberi Roxania utriculus Cylichna cylindracea Ringicula buccinea Hyalia laevigata Asthenotoma obtusangula Turritella subangulata Mitrella nana Aporrhais dingdenensis Semicassis miolaevigata Philine aquila Hyaloscala Hermiaclis walleri Caecum banoni Calcarata calcarata Nassarius tenuistriatus Odostomia conoidea Retusa elongata Scaphander grateloupi Circulus hennei Evalea basistriata Crenilabium terebelloides Acteon arnumensis Tectonatica miopusilla Conus dujardini Acteon laevigatus Baryspira obsoleta Orthosurcula steinworthi Chrysallida pygmaea Sinum aquense 30 VANDENBERGHE, LAGA, LOUWYE, VANHOORNE, MARQUET, DE MEUTER, WOUTERS & HAGEMANN

297 285 278 277 276 275 274 273 272 271 270 269 268 267 257 256 255 254 253 252 251 250 249 248 241 240 239 238 237 236 235 234

233 x

232 x x xx xx xx xxx xxxx xxxx xxx xxx x xx x xxxxxxxx x x xx x x x x x xxx x x xxxx 231 230

229 x xxx

228 xx

227 x xxx xx x x x 226

225 xxxxxx xx x x x 217 216 215

214 xxx xxxxxx x xxxx xx x x x xxx 213 212

211 xx x xxx x xx xx xx x xx x x x x x 210 209 208 207 206 205 204 203

202 xxxx 201 200

Nx xxx New Nxxxxxx Nx Nx Nx Nx Nxx Nxxxx (Kautsky, 1925) Schilder, 1929 Gürs, 2001 (Mayer, 1861) (Boettger, 1906) Cossm. & Peyr., 1917 (Cossm. & Peyr., 1921) (Csepreghy-Mezn., 1954) Glibert, 1952 (von Koenen, 1882) (Bruguière, 1792) (Beyrich, 1856) (Bruguière, 1792) (Semper, 1861) (Kautsky, 1925) (Philippi, 1847) (von Koenen, 1882) (Grateloup, 1832) (Wienrich, 2001) (von Koenen, 1882) (von Koenen, 1882) (von Koenen, 1882) (De Serres, 1829) (Basterot, 1825) Basterot, 1825 (von Eichwald, 1830) (von Koenen, 1872) (Beyrich, 1854) (d'Orbigny, 1852) (Beyrich, 1856) (Da Costa, 1778) truncatula cf. Name: Gastropda Tornatina bellardii Terebridae Syrnola neumayri Balcis alba Retusa Amyclina facki Volvulella acuminata Pyramidella elata Actaeopyramis elatus Trigonostoma umb. pluricostata Turbonilla undulata Lyrotyphis sejunctus Euspira nysti Crassispira borealis Mitrella nassoides Nassarius karinae Natica Oliva dufresnei Raphitoma spinoreticulatum Pyramidella grateloupi Semibittium duvergieri Cerithiopsidae Erato exmaug. hemmoorensis Latirus rothi Trigonostoma extractrix Neverita jos. olla Acamptogenotia escheri Agatothoma hontensis Ficus simplex Bathytoma c. jugleri Nassarius holsaticus Teretia anceps Genota ramosa Alvania antwerpiensis STRATIGRAPHIC INTERPRETATION OF THE NEOGENE MARINE Ð CONTINENTAL RECORD IN THE MAASEIK WELL 31

297 285 278

277 x

276 xx

275 x 274 273

272 column. rst ﬁ 271 270 269 268

267 x 257 256 255 254

253 The depths rst occurrence in the borehole. ﬁ 252 251 250 249

248 x x

241 x x x 240 239

238 x 237 236 rst time in the area are indicated with N

235 ﬁ 234 233 232 231 230 229 228 227 226 225 217 216 215 214 213 212 arranged according to their depth of ed in the Breda Formation 211 ﬁ 210 209 208 identi 207 206 205 204 203 in meter below surface. The molluscs described for the surface. in meter below

202 x 201 200

N xxx New Nxx NN Nx Nx xxxxx N C. & P., 1912) in (Van Voorthuyzen, 1944) (Grateloup, 1832) (Beyrich, 1856) (von Koenen, 1878) R. Janssen, 1993 (Brocchi, 1814) (von Koenen, 1882) (Bellardi, 1882) (Brocchi, 1814) (de Boury (d'Orbigny, 1852) (Nyst, 1871) (Hörnes, 1855) Gürs, 2001 Distribution of molluscs (Bivalvia, Scaphopoda and Gastropoda) of molluscs (Bivalvia, Distribution Name: Gastropoda Bela ankae Nassarius cavatus Actaeocina spirata Putilla gottscheana Brachystomia Acirsa duvergieri Hydrobiide Opalia pertusa ? Dorsanum semiplicata Trigonostoma apertum Tornus quadrifasciatus Vexillum plicatulum Bittium spina Mitra grateloupi Spirotropis gramensis Pleurotomoides luisae Table 3. Table given in the top of table are tops core interval given 32 VANDENBERGHE, LAGA, LOUWYE, VANHOORNE, MARQUET, DE MEUTER, WOUTERS & HAGEMANN

Species Minimum depth Maximum depth

Mactra sp. nov. ? 201-202 211-212 Arcopagia cf. ventricosa (De Serres, 1819) 201-202 232-233 Callista chione (Linnaeus, 1758) 201-202 233-234 Lentidium turonensis (Cossm. & Peyr., 1914) 202-203 207-208 Turbonilla sp. nov. ? 202-203 229-230 Turneria cylindrica (Wood, 1850) 202-203 233-234 Caecum banoni (Benoist, 1872) 207-208 237-238 Alvania curta nieheimensis Hinsch, 1972 202-203 238-239 Calcarata calcarata (Brocchi, 1814) 207-208 238-239 Evalea basistriata (Etheridge & Bell, 1898) 207-208 238-239 Lajonkairea lajonkairei ? (Payraudeau, 1826) 209-210 230-231 Anodontia benoisti (Cossm. & Peyr., 1912) 214-215 267-268 Pseudamussium clavatum (Poli, 1795) 226-227 228-229 Turbonilla undulata (von Koenen, 1882) 227-228 276-277 Carinastarte anus (Philippi, 1843) 229-230 230-231 Nuculana westendorpi (Nyst, 1839) 229-230 278-279 Acamptogenotia escheri (Mayer, 1861) 232-233 255-256 Bathytoma c. jugleri (Philippi, 1847) 232-233 276-277 Nassarius holsaticus (Beyrich, 1856) 232-233 278-279 Teretia anceps (von Eichwald, 1830) 232-233 278-279 Genota ramosa (Basterot, 1825) 232-233 278-279 Nassarius cavatus (Bellardi, 1882) 233-234 277-278 Clausinella scalaris (Bronn, 1831) 271-272 276-277 Laevicardium subturgidum (d'Orbigny, 1852) 275-276 278-279

Table 4a. List of the stratigraphic important molluscs in the Breda Formation arranged according to depth of occurrence in the borehole, expressed as the highest (minimum depth) and lowest (maximum depth) core intervals of occurrence, in meter below surface. encountered belong to a type, slightly deviating from stratigraphic distribution. In a number of characteristics, Pliocene to Recent material, described in Marquet & it comes closer to the Pliocene Mitrella scaldensis (Van Dijkstra (2000). Further study is needed to ascertain this Regteren Altena), with which it could form an endemic identifi cation. evolutionary series. Spisula “subtruncata” auct. does probably belong to another & e material from Amyclina facki (von Koenen, 1872) is species, as do Belgian Pliocene specimens, formerly re- in general badly preserved; fragments from the upper part ferred to by the same name, which belong to the extinct of the boring are larger than ordinary specimens from taxon Spisula (S.) obtruncata (Wood, 1857) (Marquet, in the Antwerpen Sand Member and appear to be relatively press). Mactra sp. probably is a new species, from which broader. & ese could belong to Amyclina badensis (Partsch unfortunately only fragmentary material was found. in Hörnes, 1856); this is a species probably typical of Mitrella nana (Van Voorthuysen, 1944) was originally Miocene deposits younger than sediments with A. facki (especially Badenian of the Paratethys), but also found by described as a variety of Mitrella nassoides (Grateloup, Van Voorthuysen (1944) in the North Sea Basin. 1832), with which it can coexist. & e diff erences between From Dorsanum semiplicata (Van Voorthuysen, 1944) only both however are clear enough to distinguish both on the one specimen was found, which is, however, much less species level. M. nana remains half as small as M. nassoides, slender than the type material and completely lacks spiral for adult specimens with completely developed apertural ornament. & is identifi cation is clearly only provisional. denticles. Its siphonal canal is shorter and the suture is more distinct. An important diff erence is the much 3.4.5. Comparison with other Miocene molluscan faunas lower, but broader aperture. It is furthermore only found from the North Sea Basin together with M. nassoides in a limited part of its Miocene range and seems to be endemic to the North Sea Basin, First, the fauna of the boring can be compared to that of while M. nassoides has an extremely wide geographic and the known Belgian Miocene Formations and Members. STRATIGRAPHIC INTERPRETATION OF THE NEOGENE MARINE Ð CONTINENTAL RECORD IN THE MAASEIK WELL 33

Species Depth range (m)

Characteristic of upper part Pseudamussium clavatum (Poli, 1795) 226-229 Anodontia benoisti (Cossmann & Peyrot, 1912) 214-268 Carinastarte anus (Philippi, 1843) 229-231 Mactra sp. nov.? 201-212 Lajonkairea lajonkairei ? (Payraudeau, 1826) 209-231 Arcopagia cf. ventricosa (De Serres, 1819) 201-233 Callista chione (Linnaeus, 1758) 201-234 Turneria cylindrica (Wood, 1850) 202-234 Lentidium turonensis (Cossmann & Peyrot, 1914) 202-208 Alvania curta nieheimensis Hinsch, 1972 202-239 Caecum banoni (Benoist, 1872) 207-238 Calcarata calcarata (Brocchi, 1814) 207-239 Evalea basistriata (Etheridge & Bell, 1898) 207-239 Turbonilla sp. nov.? 202-230 Characteristic of lower part Nuculana westendorpi (Nust, 1839) 229-279 Laevicardium subturgidum (d'Orbigny, 1852) 275-279 Clausinella scalaris (Bronn, 1831) 271-277 Nassarius holsaticus (Beyrich, 1856) 232-279 Nassarius cavatus (Bellardi, 1882) 233-278 Bathytoma cataphracta jugleri (Philippi, 1847) 232-277 Teretia anceps (von Eichwald, 1830) 232-279 Genota ramosa (Basterot, 1825) 232-279 Acamptogenotia escheri (Mayer, 1861) 232-256 Turbonilla undulata (von Koenen, 1882) 227-277

Table 4b. List of the molluscs characteristic for the upper and lower part of the Breda Formation with the indication of their depth range in meter below surface.

& e upper part (above 239 m) of the Maaseik Miocene below 239 m. Anodontia benoisti (Cossmann & Peyrot, deposits cannot be directly correlated with any of the 1912) also is a species unknown from the Antwerpen/ deposits, known from the Antwerp Basin. & e mollus- Zonderschot Members, reaching below this limit. It has can fauna from the Deurne Sand Member in borehole not been found in Ramsel, but recognizing this species in Maaseik diff ers considerable from the assemblages in the internal mould material would be very diffi cult. It could same member in the Antwerp region, especially by the be concluded that the lower Miocene part of the boring absence of species that are characteristic for the latest could be correlated with the Ramsel fauna, younger than Miocene (Langenfeldian and Gramian) such as Glossus the Antwerpen/Zonderschot Members. forchhammeri (Beck in Ravn, 1907) and the scaphopod Fissidentalium fl oratum R. Janssen, 1987. However, eco- & e best match for the boring Maaseik can be found in logical diff erences could also explain diff erences in mol- boreholes from adjacent regions in & e Netherlands. Van lusc content between time-equivalent units. Rooijen et al (1984) described borings from Broekhui- & e lower part of the boring examined diff ers only slightly zenvorst and Geldern in the Peel-Venlo area, which from the Antwerpen/Zonderschot Sand Members, all they divided into zones using diff erent stratigraphic species indicated in Table 4b as lacking in the upper marker groups: foraminifera, calcareous nanoplankton part of the boring being present in these Members. One and molluscs, besides heavy minerals. & ey introduced species, Turbicauda spinicostata (Bronn, 1831), has been a molluscan zone F (see further), which they correlated found until now in Belgium only in the Ramsel internal with the latest part of the German “Reinbek Stufe”. mould material. Its range in Maaseik does not include Sliggers & van Leeuwen (1987), working with material the lowest part of the Miocene, but it reaches well from the same and other borings, including material 34 VANDENBERGHE, LAGA, LOUWYE, VANHOORNE, MARQUET, DE MEUTER, WOUTERS & HAGEMANN

from Dutch Limburg, published a more detailed mol- Formation), with a thin cover of Pleni-Weichselian luscan and foraminiferal division of the Miocene of the fl uviolacustrine to eolian loam deposits (Molenbeersel southeastern part of & e Netherlands. Several of the Member). & e base of these Pleistocene deposits occurs species, not encountered in the Miocene of Belgium at 22 m depth. previously, and found mostly/exclusively in the upper part of the Maaseik boring, seem to be characteristic of & e main mass of quartzic pale grey sands below, with base their molluscan ecozones. Astarte fusca “incrassata” (= A. f. at 193 m depth, is known as the Kieseloolith Formation. ariejansseni Marquet, 1995) is found from Mol F5 to F3, It contains four lignite and clay-rich lignite horizons. Caecum banoni (Benoist, 1872) characterises Mol F4 only, Palynological associations divide this Kieseloolith Forma- Ervilia pusilla (Philippi, 1836), Lentidium donaciformis tion in two parts at 57.6 m. & e upper association shows (Cossmann & Peyrot, 1914) and Actaeocina lajonkai- a wooded landscape with extensive enclosed mires, open reana (= A. spirata (Brocchi, 1814) here) occur in F4 and enough to allow light demanding plants to grow. & e reappear in Mol H. & is Mol H, however, also contains lower association shows a denser forest landscape with species, characteristic of older Miocene deposits, such as less extensive mires. Patinopecten brummeli (Nyst, 1864), Lembulus emarginatus Clear increase of Sequioa deeper than 87.5 m could be (Lamarck, 1819) and Conus clavatulus d’Orbigny, 1852. linked to the Brunssumian (Pliocene, Zanclean) as charac- & ese species are absent from our material. So a correla- terized by Zagwijn (1960), although according to the paly- tion with Mol F4 seems most appropriate. & eir zone Mol nology also this part of the section is preferably interpreted G contains two species, Eudolium dingdense Anderson, as Reuverian. & e association in the top of palynozone A 1964 and Aquilofusus festivus (Beyrich, 1856), (both also between 87.5 and 57.6 m is similar to the palynology of marker species for the early Middle Miocene “Reinbek the lignites in the Mol Sand lignite to the west. Stufe), which are absent in borehole Maaseik. For this & e upper association A can be correlated with the latest reason a correlation with Mol F4 seems most appropriate. Reuver C (Pliocene, Piacenzian). Mol F4 corresponds with the foraminiferal zone FC2B, Based on the occurrence of the lignite horizons and the which according to Doppert et al. (1979) characterizes grain-size properties of the sands, the Waubach, Pey, the Upper Miocene Diest Formation by the presence of Schinveld/Jagersborg units have been identifi ed as well as Uvigerina hosiusi deurnensis. the Brunssum and Reuver Clays. & is traditional lithos- Gürs (2002) divided the German Miocene by means tratigraphic subdivision of the Kieseloolith Formation in of the occurrence of members of the Gastropod family the area, is not entirely corresponding to the palynological Nassariidae. All species of the genus Nassarius present in interpretation in this study. & e palynology suggests a the Maaseik boring are according to this paper typical of Reuver-Pliocene age for the whole section whilst in the the Reinbekian, Early as well as Late. & e Turridae, found Dutch stratigraphic nomenclature the Waubach Sand in Maaseik and new to the Miocene of Belgium, were unit is considered as Susterian of Upper Miocene age; however described by Gürs (2001) from the Pinneberger only the moderate increase in Sequioa below 90 m depth is Schichten, which have a Gramian-Syltian or Late Mi- supporting a possible Brunssumian age for this lower part ocene age. Also Alvania curta nieheimensis Hinsch, 1972 of the Kieseloolith Formation, an interpretation in line (Rissoidae) is a Reinbekian species. with the lithostratigraphic interpretation of Brunssum Bela ankae (Gürs, 2001) is the fi rst species of its genus clays and intercalated Pey Sands in the borehole. to appear in the North Sea Basin, in which it will have a marked evolutionary diversifi cation during the Pliocene & e thin pale yellowish gray mica-rich marine sand unit (see Marquet, 1997c). X between 193 m and 198 m, could not unequivocally be linked to any known lithostratigraphic unit in the 3.4.6. Conclusion area. Based on dinofl agellate content comparison with the Nieder Ochtenhausen borehole a Syltian uppermost & e best match for the upper part (200-239 m) of the Miocene age is proposed. Maaseik boring according to its molluscan fauna is the Mol F4 zone in & e Netherlands. & e lower part, slightly & e marine Breda Formation below extends till the overlapping with the upper part (232-298 m), could total depth of the borehole at 302 m. Biostratigraphi- correspond to the Ramsel fauna, which is Reinbekian- cally an upper part, approximately above 235 m, can be Hemmoorian in composition and comes close to the distinguished in this formation which based on molluscs, Antwerpen-Zonderschot Members. dinofl agellates and calcareous microfossils, ressembles the biostratigraphic content of the Deurne Sand (Diest Formation, Upper Miocene, Tortonian). Similarly a low- 4. General Conclusions est part below approximately 275 m, can be distinguished which based on molluscs and dinofl agellates corresponds At the very top of the Maaseik borehole, the Saalian to to the Berchem Formation, best comparable to the Ant- Pleni-Weichselian Meuse river gravels occur (Lanklaar werp, Zonderschot Members; the dinofl agellate zones STRATIGRAPHIC INTERPRETATION OF THE NEOGENE MARINE Ð CONTINENTAL RECORD IN THE MAASEIK WELL 35 ds, are illustrating the regional correlation of the ds, are illustrating the regional ed in the text. fi Valley Graben in northeast Belgium and the southeast Netherlan Valley the different lithostratigraphic names are explained and justi lithostratigraphic names are explained the different Resistivity and gamma-ray logs in selected boreholes the Rur and gamma-ray Resistivity Figure 10. Figure detailed study in the Maaseik borehole (49W0220). The origin of detailed study in the Maaseik borehole (49W0220). 36 VANDENBERGHE, LAGA, LOUWYE, VANHOORNE, MARQUET, DE MEUTER, WOUTERS & HAGEMANN

recognized in this interval in the Maaseik borehole East of Belgium). Internal report Belgian Geological correspond to a Middle Serravalian age. & e interval Survey, 3 p., 2 tables, 27 photogr. in between these upper and lower parts in the borehole de HEINZELIN, J., 1955. Considérations nouvelles sur contains dinofl agellates and molluscs which have not been le Néogène de l’Ouest de l’Europe. Bulletin Société Belge identifi ed before in the Belgian Campine area. de Géologie, 64 : 463-474. de HEINZELIN, J., 1963. Carte et coupe d’ensemble de Acknowledgements la région anversoise. Mémoire Soc. Belg. Géol. Symposium sur la stratigraphie du Néogène nordique, série IN-8, 6: & e authors sincerely thank Frans Moorkens for the help 247-249. with the core handling over all the years between the drill- DE MEUTER, F. & LAGA, P., 1970. Coiling ratios ing of the well and this comprehensive publication. Simi- and other variations of Globigerina pachyderma and the larly, we thank Greet Willems and Hilda Van Horebeek stratigraphical signifi cance in the Neogene deposits of for keeping track of all the provisional fi gures and texts that the Antwerpen area (Belgium). Bulletin de la Société belge have been produced over the years related to the Maaseik de Géologie, 79 (2): 175-184. borehole. Astrid Verheyen is thanked for help with the log DE MEUTER, F. & LAGA, P., 1976. Lithostratigraphy correlations in the area. Wim Westerhoff is thanked for and biostratigraphy based on benthonic foraminifera of the very useful reviewing of an earlier version of the paper the Neogene deposits of northern Belgium. Bulletin de which resulted in signifi cant improvements. la Société belge de Géologie, 85 (4): 133-152. DE SCHEPPER, S., HEAD, M.A & LOUWYE, S., in press. New dinofl agellate cysts and other palynomorphs 5. References from the Pliocene of Northern Belgium, southern North Sea Basin. 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