Bull. Soc. belge Géol., Paléont., Hydrol. T. 78 fasc. 2 pp. 111-130 Bruxelles 1969 Bull. Belg. Ver. Geol., Paleont., Hydrol. V. 78 deel 2 blz. 111-130 Brussel 1969

THE TYPE-LOCALITY OF THE SANDS OF GRIMMERTINGEN AND CALCAREOUS NANNOPLANKTON FROM THE LOWER TONGRIAN

E. MARTINI 1 & T. MooRKENS 2

CONTENT

Summary 111 Zusammenfassung 111 Résumé 112 1. Introduction . 112 2. Historical review of some chronostratigraphical conceptions. 114 3. The Eocene-Oligocene transitional strata in Belgium 115 4. Locality details 122 5. The calcareous nannoplankton assemblages 124 6. Conclusions . 125 7. Acknowledgments . 127 8. References 127

SuMMARY. A. DUMONT (1839-1849) considered the Sands of Grimmertingen as the base of his Ton­ grian stage (Grimmertingen is at present a hamlet in the municipality of Vliermaal in the Eastern part of Belgium). Samples have been taken from the outcrop of the type-locality and from a new boring reaching a depth of 12,5 m, towards the base of this member. Sorne of these sa.mples from both outcrop and boring yielded fairly rich assemblages of calcareous nannoplankton of which a list is given: the assemblages belong to the Ellipsolithus subdistichus zone, the zone which was also recognised in the sand extracted from the molluscs of the type-Latdorfian (Lower Oligocene). The recent sampling of the Grimmertingen-locality also permitted to find fairly rich associations of Hystrichospheres and of planktonic and benthonic Foraminifera, which are under current study.

ZusAMMENFASSUNG. A. DUMONT (1839-1849) stellte die Sande von Grimmertingen an die Basis seines ,,Tongrien" (Grimmertingen befindet sich heute im Stadtbereich von Vliermaal im ostlichen Teil von Belgien). In der Typuslokalitat der Sande von Grimmertingen wurden horizontmaBig Proben genommen und eine Bohrung bis zu einer Tiefe von 12,5 m niedergebracht, um nach Moglichkeit die Basis der Sande zu erreichen. Verschiedene Proben aus dem AufschluB und besonders aus der Bohrung enthielten Nannoplankton, das listenmaBig erfaBt wurde und das eine Einstufung der Schichten in die Ellipsolithus subdistichus Zone erlaubt, in die ebenfalls das Nannoplankton aus Mollusken der Typuslokalitat des Latdorfs (Unter-Oligozan) zu stellen ist.

1 Geologisch-Palaeontologisches Institut der Universitat, 6 Frankfurt a.M. Senckenberg-Anlage 32 (Germany). 2 Geol. Instit. of tlle State Univ. Ghent, Rozier, 6, Ghent (Belgium).

111 In den neugewonnenen Proben von Grimmertingen wurden ferner verhaltnismiiBig reichhaltige Gemein­ schaften von Hystrichosphaeriden sowie von planktonischen und benthonischen Foraminiferen gefun­ den, die zur Zeit bearbeitet werden.

RÉSUMÉ. A. DUMONT (1839-1849) définissait la base de son étage Tongrien par les Sables de Grimmer­ tingen. (Grimmertingen est un hameau dans la commune de Vliermaal dans l'est de la Belgique). La localité-type a été échantillonnée dans son affieurement et par le moyen d'un sondage de 12,5 m vers la base de l'assise. Quelques échantillons de l'affieurement et du sondage ont montré une association assez riche en nanno­ plancton calcaires dont une liste est dressée: les associations appartiennent à la zone à Ellipsolithus subdistichus, zone qui fut également reconnue dans les sables extraits des coquilles de mollusques du Latdorfien-type (Oligocène inférieur). L'échantillonnage récent de la localité de Grimmertingen a également permis de découvrir des associa­ tions assez riches d'Hystrichosphères et de Foraminifères p\anctiques et benthiques, qui sont actuel­ lement à l'étude.

1. Introduction had been established in many areas: the zonations of the Nummulites, of the plank­ Sorne controversial viewpoints have been tonic Foraminifera and of the calcareous expressed recently in connection with the nannoplankton. stratigraphie situation of the Eocene-Oligo­ Although these three groups are represented cene boundary, and some of them have been in the basins bordering the North Sea, the discussed during the « Colloque sur ! 'Eo­ endemic character of most of the species of cène» (Paris, May 1968). the first group prevent wide correlations; the It appears that there is a fairly good agree­ scarcity and small dimensions of the plank­ ment between West-European geologists as tonic Foraminifera in the West-European area, to the correlation of the respective lithologie make their use dubious also, for the time units of the Eocene-Oligocene transitional being. strata in the English-, Paris-, Belgian-, and The third group has been studied recently North German basins. in the West-European basins, and it seems The exact situation of the Eocene-Oligocene that the calcareous nannoplankton give the boundary in the stratigraphy of the basins best results in wide correlations at present, bordering the North Sea hence becomes more as characteristic species of the zonation are a problem of convention than one of corre­ generally represented both in the basins lation difficulties within this area. bordering the North Sea and in more tropical However, correlations within the North Sea regions. area were based until recently only on paleon­ The importance of the West-European tological groups of a rather restricted geo­ basins lies in the fact that a great numbér of the graphical distribution: Molluscs, benthonic internationally recognized stratotypes of chro­ Foraminifera, Vertebrates, a.s.o. nostratigraphic units were established here. The first two groups are generally strongly The rather poor results of previous paleon­ faciesbound and a number of species seem to tological research have entailed that the be endemic for this area or even in one of its intensive study of these stratotypes had been basins; furthermore the third group seems not abandoned during some years in the West­ very useful in this area as the fossils are European countries; some recent positive rather scarce. results, however, justify a more thorough The paleontological discussions during the search in the classical localities, which also Colloquium were therefore concentrated on has been recommended by E. BRABB (in press) the microfossil groups for which a biozonation after his visit to the are~.

112 TABLE 1

cont.-delt. lag. Lit.-ner.

Upp. Jl Cl. of Boom î (sandy layers) X ~------1------~1------~7'----I Cl. of Klein Spouwen X Low. ------1-----1---+----- [ 1 S. of Berg -X

S. & M. of Oude Biezen Upp. [ X..::._? ~ ~ Clay of Henis i . ffi (hiatus) ~ l S. of Neerrepen '\. S. of Grimmertingen 1---X i!:J unconformity ~ X-----

TABLE 2

Cont.-delt. Lag. lit.-ner. X

--'-1---+-----x *

S. Kerkom

~ Upp. -~:__& M~_Bouters~~- _ ~ ll Hoogbutsel horizon X-- ? - ---;------~-1- ----·------

low. 11 \:~~~:on-~------~--- X-?-X

~ unconformity ~ X

113 2. Historical review of some chronostratigra­ The later defined Stampian s.l. ( = definition phical conceptions by A. d'ORBIGNY, 1852) in the Paris Basin, of which the lower part was later separated, The division of the Tertiary in three periods to form the Sannoisian (A. de LAPPARENT, (or sub-epochs) established in 1833 by Ch. 1893) and of which the remaining part was LYELL was based mainly on the percentages of defined again as Stampian s.s. fall in synonymy recent living mollusc species in the respective with part of the earlier created Tongrian and fossil assemblages. Rupelian stages. This scheme of LYELL was followed by As the transitional Eocene-Oligocene layers A. DUMONT (1839, 1849) when defining some in the Paris basin are mainly reflecting fresh­ of his stages and placing them in the strati­ water and brackish to lagoonal conditions, graphie column. G. DENIZOT (1968) concludes that the succes­ The Tongrian s.l. ( = definition by A. Du­ sion of the Paris basin better should not be MONT, 1839) was thus placed tentatively at the chosen to establish the stratotype of the basal base of the Miocene; later A. DUMONT ob­ Oligocene, thus controversing C. CAVELIER served that the succession of lithologie units (1968) who proposes to consider the ,,Argile of his Tongrian s.l. reflected at least two verte de Romainville" of this area as the basal consecutive transgressions (cf. tables 1 and 2). stratum of the Oligocene. The succession of the second transgression The Oligocene conception was defined by was therefore defined as Rupelian (A. Du­ E. BEYRICH (1854, 1856) who observed that the MONT, 1849) with the «sable jaunâtre » (later mollusc-assemblages found in a number of called the Sands of Berg) at the base. The outcrops in Germany could be correlated Rupelian was thus separated from the Ton­ with those of the classical Tongrian deposits grian s.l., while the remaining basal part of described by A. DUMONT. this conception was redefined as Tongrian s.s. He had noticed that these mollusc assem­ ( = definition by A. DUMONT, 1849). blages could be distinguished from the typical The basal stratum of the Tongrian s.l. and Eocene associations as well as from those of the Tongrian s.s. are the same layers from the the typical Miocene: the layers containing this same locality, already cited in 1839: Grim­ assemblage therefore characterized a certain mertingen (see also the following chapter). period which he called the Oligocene, and The Sands of Berg (in their type-locality), which was defined on a number of localities the full-marine sediment deposited at the in Germany. beginning of the second transgression was The basal part for this German Oligocene considered as the base of the Rupelian stage, succession was tentatively parallelised with the while the type-locality of the Clay of Boom, "Tongrien inférieur" of A. DUMONT which is near the Rupel river (the type-Rupelian) defined by the Grimmertingen-locality. shows sediments deposited during the upper Unfortunately the cited outcrops for the part of this Rupelian stage. lower Oligocene in Germany belong to differ­ As all the localities, and the members of ent ages, as could be deduced from the cal­ these two transgressive cycles can easily be careous nannoplankton (E. MARTINI & recognised and as the region shows a simple S. RITZKOWSKI, 1968). stratigraphy, the definitions of A. DUMONT The Latdorfian stage defined by MAYER­ (1849) can unambiguously be followed; both EYMAR (1893) and equated with BEYRICH's the basal and the top-sediments of the lower Oligocene, however refers to one Tongrian and the Rupelian cycles are defined locality, which unfortunately is not to be seen by marine deposits; only part of the Upper anymore. The calcareous nannoplankton Tongrian consists of continental sediments 1, shows planktonic and benthonic Foraminifera 1 The Upper part of the Oude Biezen member and also some calcareous nannoplankton and is ( = Vieux Joncs), considered as Upper Tongrian, thus to be considered as an open marine facies.

114 extracted from the mollusc-shells found at this the mollusc assemblages and probably also locality belong to a zone which is younger in the Vertebrates association, which would lie than those found in the classical outcrops of approximately at the base of the Upper the Bartonian and of the Priabonian (E. MAR­ Tongrian (Hoogbutsel horizon) in Belgium, TINI & S. RITZKOWSKI, 1968). the base of the "Sannoisian" (Argile verte de Traditionally the base of the Oligocene has Romainville) in the Paris Basin, and the base been situated at the base of the Latdorfian or of the "Neuengammer Gassande" and of the Tongrian by the majotity of the authors "Magdeburger Sande" in Germany. (this new in the stratigraphie literature. definition was suggested by W. KRuTZSCH & Sorne authors however (A. WRIGLEY, 1929; D. LOTSCH, 1957, 1963, 1964 and by c. CAVE­ A.M. DAVIEs, 1934; AI. KoROBKOV, 1964; LIER, 1968). W. KRUTZSCH & D. LOTSCH, 1957, 1963, c) To consider another faunal break as the 1964; C. CAVELIER, 1968) suggested that the most important of this period, which would definition of the basal Oligoc~ne should be take into consideration the extinction of some altered, as it does not (according to their groups of larger Foraminifera (the Disco­ opinion) coïncide with the major faunal break cyclines and some Nummulites) in the more of this period: for some groups of macro­ northern basins of Russia; according to some fossils, like the molluscs (C. CAVELIER, 1968) Russian authors this limit would have to be and the vertebrates, the major faunal break situated at the base of the traditional Middle would lie higher in the succession. Oligocene (sensu E. BEYRICH, 1856), or at the Different viewpoints for redefining the base of the Rupelian stage, or at the base of Oligocene conception by situating its base the Stampian stage s.s. (this new definition higher in the biostratigraphy than the base of was suggested by A. WRIGLEY, 1929; AM. the Latdorfian and the Tongrian have how­ DAvœs, 1934; AI. KoROBKov, 1964, pp. 747- ever been emitted, as these authors do not 760 and pp. 911-913). agree with each other where to situate the The fact that two different propositions (b, c) most important faunal break. of redefining the Oligocene are both refering It appears now that three different main to "a major faunal break" suggests that this viewpoints exist concerning the situation of phenomenon is not so easy to localize as has the Eocene-Oligocene boundary: been declared by these different authors. a) To follow as much as possible the original None of the new propositions (b, c) refer definition of the conception given by E. BEY­ clearly to any biozonation of planktonic RICH (1854, 1856), and to see which groups organisms, which, however seem for the permit to situate this limit in the biostrati­ moment to be the only tool for world-wide graphy. Except for a number of mollusc correlations. species, some species of planktonic Foramini­ fera and of calcareous nannoplankton have been cited. F. GRAMANN (1968) further sub­ stantiates a lineage in the benthonic Fora­ 3. The Eocene-Oligocene transitional strata in minifera ( Asterigerina) and some Ostracods. Belgium E. MARTINI & S. RITZKOWSKI (1968) have restricted the classical Lower Oligocene out­ The Tongeren and Rupel Formations - crops of E. BEYRICH and of A. v. KoENEN to taken together with the Voort Formation they those which are equated to the type-Lat­ are traditionaly called the Oligocene deposits dorfian (belonging to the E. subdistichus zone) of Belgium - are to be found in Belgium while older sediments are equated with the below the Quaternary in a WNW-ESE Bartonian or the Priabonian. This calcareous oriented area, reaching from Stekene to nannoplankton zonation shows the advantage Tongeren (see fig. 1). to lead to world-wide correlations. South of this region they have been almost b) To consider an important faunal break in completely eroded; to the north they are

115 .,, 1 ...... ~ {• O'I " f " • ~ .. 1.' J.",,.... -r_..._""~"""~)' ,. ~ ~" .... THE NETHERLANDS '"i ~,~ ,.~ ... ,. ~ ,." .. '( \'...... '" '1 '-4.-..>" t~

~, \" ~ -ci."' ... "" ~ 4 ...... l ..... -"( 'i. v ~ (fi... i\.

CVOORT

AS~~' ~WEiME A1 -_µ ';§w~ BRUSSEL~-'~'.\.\. .. ~..... \..,"'). ... .,..'P..,.., ...... of'"' B R

f22.2J Neogene and Quaternary Extension of the Tongeren­ amnand Rupel formations f·'•····lolder sediments T.M. Fig. 1. Classical localities and extension of the Tongeren and Rupel formations (Oligocene) in Belgium. dipping gently and are covered by younger stage was, however, characterised by the same (Neogene) deposits. stratum: the Sands of Grimmertingen, called The members distinguished within thesetwo after the first cited locality by A. DUMONT Formations change from region to region: in (1839). The Grimmertingen-locality may thus the Tongeren region and in the Leuven-Diest be considered as the stratotype of the base of region two transgressive cycles clearly can be the Tongrian stage. observed, while in N.W. and North-Central In DuMONT's mind however the conceptions Belgium the Tongeren Formation passes "Tongrian system" and "Rupelian system" gradually to the underlying Eocene sediments not only represented chronostratigraphic downwards, and upwards to the Rupel forma­ terms, but, as he correlated mainly on litho­ tion: a possibly continuous marine series of logical facts, also litho-stratigraphical concep­ alternating clay and sandlayers has been tions for which we now would prefer the term observed. "formation". The different members and their super­ In the Tongeren region the following mem­ position thus will be treated for each region bers can be observed within the Tongeren and separately. Rupel formations (table 1), overlying uncon­ Unless stipulated otherwise the denomina­ formably Upper Cretaceous and Paleocene tions and historical details of the members, deposits. formations and chronostratigraphic concep­ The environmental characteristics of the tions were explained by J. DE HEINZELIN & deposition of each of the members are given M. GuBERT (1957, in: Lex. Strat. int.). at the right of the table, showing the two transgressive cycles.

3.1. The Tongeren region

A hilly landscape characterised by relatively 3.2. The Leuven-Diest region deep valleys and a thin late Quaternary cover favours the geological field work, as the The series of members which is observed in Tertiary can be observed in shallow outcrops this region reflects two similar transgressive and in hollow roads. cycles, here overlying unconformably Lower The Oligocene members are lying nearly and Middle Eocene deposits. horizontal in this region and their thickness is Sorne of the members, however show here fairly constant over large distances. a completely different facies as to their lateral A. DUMONT (1839), observing these facts, equivalents in the Tongeren region. first incorporated in the original description The superposition of these members is given of his "Tongrian system" the two formations in table 2. of Tongeren and of the Rupel (and some The Sands of Kerkom show a fluvial facies, younger deposits as well) both showing a while the Sands and Marls of Boutersem were transgressive cycle in this region, and which apparently deposited in brackish-lagoonal 1 conditions; some marine Mollusc species have he placed at the base of the Miocene • Later (1849) he restricted his Tongrian stage to however also been recorded. deposits belonging to the first transgressive The Horizon of Hoogbutsel was defined by cycle only, while the following transgression M. ÜLIBERT & J. DE HEINZELIN (1952, 1954a). was equated with his Rupelian stage (establish­ At Hoogbutsel and later at Hoeleden import­ ed in 1849). ant continental vertebrate remains have been For both definitions (the Tongrian s.l., 1839 discovered in this member by J. DE HEINZELIN and the Tongrian s.s., 1849) the base of the in 1952, which were studied partly by S. Mr­ SONNE (1957), S. MISONNE & G.E. QUINET (1967), G.E. QUINET & S. MISONNE (1965, 1 At that time the Oligocene conception of 1967), G.E. QUINET (1965a, 1965b) and by E. BEYRICH (1854-1856) was not created as yet. M. RECHT & R. HOFFSTETTER (1962).

117 3.3. North West and Central Belgium has been observed in this area between the Sands of Wemmel and the Clay of Boom; it In the region ofBrussels (Province of Brabant) consists of alternating clay and sandlayers, Middle and Upper Eocene deposits can be which make a lithologie interpretation very observed in outcrops e.g. the type-localities of difficult, as gaps in the sedimentation could the Sands of Wemmel and of the Clay of exist in this succession. Assel which have also been considered by Similar difficulties of lithologie correlation some authors as the stratotypes of the Wem­ for this interval occur also in the borings melian and Assian stages (chronostratigraphic between Antwerp and Leuven (M. GuuNCK, terms which have now generally been aban­ 1965). doned). ln the Eastern Flanders province the most These two stages (taken together) have long cotnplete succession has been observed in the been considered as the Belgian equivalent of Kallo well, for which M. GuLINCK (in press) the Bartonian in England; recent studies, and refeired to the sand- and clay layers by the mainly the calcareous nannoplankton zona­ symbols al, a2, a3 (clay) and Sl, S2, S3 (sand), tion however, would suggest that the Sands as correlations with known members of East of Wemmel in their type-locality (according to Belgium are still hasardous. This complete E. MARTINI & S. RITZKOWSKI, 1968) would be section of alternating clay and sand !ayers was older than the type-Bartonian and would be called the "Clay and Sand complex of Kallo" the Iateral equivalent of the Upper Brackles­ by M. GULINCK (in press). ham beds; probably they may also be correlat­ M. GuLINCK also created the name "Sands ed with the "Uppermost Lutetian" (Falun de of Bassevelde" to indicate the (lower?) part Foulangues) layers in the Paris Basin, and of the S3 member, characterised by Nummu­ with the "Biarritzian-stratotype" in Southern lites and by Ostrea ventilabrum in the boring France (according to C. CAVELIER, 1968). of Bassevelde some km W of Kallo. The base of the Asse formation (the Table 3 shows the layers which have been "Bande-noire" horizon) sampled in Oedelem observed in the Kallo well and of which (according to E. MARTINI & S. RITZKOWSKI, some parts have also been recognized in 1968) and a sample at -174 m of the Kallo other (older) borings. well yielded nannoplankton assemblages of The Foraminifera and Ostracoda of the the Chiphragmalithus alatus zone, the same -80 m to -176 m interval of this boring in nannoplakton zone in which the nanno­ Kallo have been studied by C.W. DROOGER plankton assemblage of the type Wemmelian (in press) and compared with the lists of the has to be placed. Eocene (J.P.H. KAASSCHIETER, 1961) and of the The younger layers of the Asse Formation Oligocene (D.A.J. BATJES, 1958) Foraminifera, could not be placed as yet in the planktonic and the Ostracoda of both Eocene and zonations, except in the Kallo well (-167 m) Oligocene (A.J. KEY, 1957). where C.W. DROOGER (in press) observed one The localisation of the boring of Kallo is specimen of Globorotalia cerroazulensis. given in fig. 1. Towards the north in the Antwerp region the Asse-, the Tongeren- and the Rupel 3.3.1. Possible ENE-WSW correlations by Formations are burried under thick layers of M. Gulinck (in press) Neogene deposits, whereas in Eastern Flanders However the boring of Kallo shows a the Asse and/or Tongeren Formations lie possibly continuous series of marine sediments under a continuous cover of Pleistocene near the Eocene-Oligocene transition, a deposits: the Eocene-Oligocene transitional possible gap in the sedimentation could exist, strata have here to be studied in borings. at the -125,5 m level, where an indurated An obviously continuous marine succession layer (with some "perforations") was ob­ served. M. GuuNcK (in press) believes that 1 Also spelled "Assche" by some authors. this Ievel could be correlated with the regres-

118 TABLE 3.

members in 1 Kallo Depth Environment Formation 1 well inm. of deposition outcrops older borings 1 1 1 1

CL of B. Clay of Boom Boom a probably Rupel Fm. (transition) - 80 continuous [ j Sands of Berg ( ?) marine ? (alternation clay & sand) se ries "Clay and Sand '~Sands ·-of. Bassev~lde': Sa· a:pparefl.tly Complex of Kallo" (M. GULINCK, i.p.) completely (M. GuuNCK, in press) - 125 neritic; however, clay layer a3 sedimentation -- 137 gaps could be sand layer S2 expected in - 150 this succession 1 clay layer a2 ? - 162 S. of Asse Sand of Asse ( ?) S1 Asse Fm. - 168 CL of Asse Clay of Asse "bande noire" ai ll - 176 Wemmel Fm. S. of W. Sands of Wemmel Wemm. ' c

-\0 sion observed in the Tongeren-, Leuven- and It is in this interval (at -131 m) below the Diest regions which is there characterised by crucial -125,5 m level that C.W. DROOGER the Hoogbutsel horizon, and the paleosoils at observed an individual of Cassigerinella chipo­ the top of the Sands of Neerrepen. lensis, suggesting an Oligocene age. Thus: ai = Clay of Asse, as the "bande A correlation with Grimmertingen might noire" occurs at its base, overlying the Sands proove valuable when the association of the of Wemmel facies. type-locality will be described (under current Si = Sands of Asse overlying the Clay. study by Mr. WILLEMS, Ghent). a2 = a silty memb~r, maybe the equivalent of C.W. DROOGER's, third interpretation (c) the Grimmertingen sand. thus differs from the one given by M. GULINCK S2 and aa = possibly a lateral equivalent of (as the 124-131 m interval falls partly in the Sands of Neerrepen M. GULINCK's aa layer, partly in his S2) and Sa = possibly a lateral equivalent of the apparently denies the stratigraphie importance continental layers of the Upper Tongeren of the possible discontinuity at -125,5 m. formation. Also to be correlated with part of A schematic correlation scheme of the the boring of Bassevelde (The Sands of Basse­ Eocene-Oligocene transitional strata of Bel­ velde, M. GuLINCK, in press). gium is given in Fig. 2. The alternation of thinner clay and sand layers above the Sa could then be the transition 3.3.3. Possible correlations indicated by the to the Sands of Berg and the Nucula clay calcareous nannop/anton. ( = Clay of Klein Spouwen). On top the Clay The results of the analysis of the calcareous of Boom shows here the same facies as in nannoplankton of some samples of the Kallo outcrops along the Rupel river and is easy to well were given, together with the description recognise. and analysis in a "Mémoire" on this boring (to be communicated by M. GuuNcK and others). 3.3.2. Possible ENE-WSW correlation given 19 samples from the Kallo well between by c. W. DROOGER (in press). -82,70 m and -174,00 m have been studied The results of his micropaleontological inves­ for calcareous nannoplankton. Unfortunately tigations show a superposition of three only 4 samples contained calcareous nanno­ different assemblages of Foraminifera which plankton, of which the sample -82,70 m can be distinguished in the intervals (17 6-167 yielded only a few specimens without strati­ m), (131-124 m) and (80-100 m). The intervals graphie value. in between seem nearly barren in Foramini­ The calcareous nannoplankton from a fera. sample at -85,90 m contained among others a) In the interval (176-167 m) (or ai, Si) an Dictyococcites dictyodus (DEFLANDRE & FERT), assemblage was found showing much affinity Isthmolithus recurvus DEFLANDRE, Reticulo­ with the one found in the. Wemmel- and Asse fenestra insignita ROTH & HAY, R. umbilica Formations by J.P.H. KAASSCIDETER (1961) (LEVIN), and some unidentified Cyclococco­ thus confirming the lithological correlation. lithus spp., El/ipsolithus subdistichus ROTH & b) In the interval (80-100 m) an assemblage HAY as well as Cyclococcolithus formosus was found showing much affinity with the one KAMPTNER have not been found. This assem­ found by D.A.J. BATJES (1958) in the Berg­ blage is comparable best with that of some Boom Formations. This correlation also fits samples from the Sands and Maris of Oude with the lithology. Biezen ( = Vieux-Joncs) at Galgenberg near c) The interval in betwe~n (124-131 m) has Tongeren, and probably belongs into the shown an assemblage which indicates most Cyclococco/ithus margaritae zone or Reticulo­ affinity with the one found in the Lower fenestra laevis zone. Tongeren Fm. (in the Hendrik IV mineshaft) A sample at -124,60 m shows an intriguing by D.A.J. BATJES (1958). nannoplankton assembla~e. Besides well pre-

120 WESTERN EASTERN 1 KALLORControversed LEUVEN &. DIEST TONGEREN DUTCH BRABANT FLANDERS FLANDERS WELL I' correlations) REGIONS REGION LIMBURG

Ci) ~ en LLI...., ~------!;:( Cil Clay of Boom 1 1 Clay of Boom Clay of Boom C.B 1 .§ '§ ûl ~ GULINCK(i.p.) d cCl 80 _,)~ ___ o_Rgo_G~RiLp.J (san 1y layers) ------(sandy la.yers) .Ë ------r-- - "' ~ "'E Clay of KI. Spouwen Clay of KI. Spouwen ~ clays and sands "t:Ic Cl> lOOl fl!~~~lll!ll Sands of Berg .-,... 1 Sands of Berg 1 ::i:: 0: (fluv.) Sands of Kerkom 1 llag) S.&M.ofOude Biezen l.1.1 Alter- recently ? t ~ I .tian eroded · 8 ? 0 & (co~t.) 0: Of (l ag.) S. M. of Boutersem Clay of Henis Cl clay ~ and Ci)' cj Il'> ~ 0) u ~ "t:I -(/) c z ::J l.1.1 "'>. "'~ ::::> ..'!! ü (!) u ~ Cl :i olsand 4i .?:' unconformfty L.,_ _; ~E 14i~ / / recently "' Cl> 0 Jr;,~;- l., 0 E :::: u ____ !;:lL ___ 1s2 / l. Eocene //Paleocene e3oded 1u / ------"'-- T.M. Sands of Asse Sands of Asse Fig 2 Lithostratigraphical unit of the Wemmel-, Asse-, Tonge­ ren-and Rupel-Formations in Belgium, and correlations. S. "-"'''Lt.. -Clay--- of-i- Asse--- Clay of Asse tentative correlations of M. GULINCK(inpress),mainly based on lithologyi .... --~~é!.f"!..d!_ '!~i:.tL' = = = Clay of Asse 1 ____ -- == E tentative correlations M. GU BERT & J. de HElNZELIN(1954b),molluscs. _.. ~ -- Sands of Wemmel ----s.;;;.;,m. lllll Sands of Wemmel --=--"-=="- =·.:::1<------1;. _, tentative correlations C. W. OROOGER(inpress~O.A. J. BAT JES(1958), mIIII1Il Foram. served but rare Ellipsolithus subdistichus ROTH the basal stratum of bis Tongrian "system" & HAY, Rhabdosphaera tenuis BRAMLETTE & (= stage). SULLIVAN, Reticulofenestra umbilica (LEVIN) Grimmertingen lies at about 6 km NW of and others, specimens of Zygolithus aff. Tongeren in the Eastern part of Belgium (see Z. minutus PERCH-NIELSEN, which are present fig. 1). The localisation of the hollow road only in the uppermost Discoaster tani nodifer outcrop in this hamlet is given in fig. 3. zone, are quite common, indicating that The top of the bill at the crossing of the nannoplankton from certain layers of the hollow road, lies approximately at + 70 m Upper Eocene have been reworked into the above Ostende 0.D. sealevel. Ellipsolithus subdistichus zone of the Lower Recently a small quarry which now bas been Oligocene. The sample can be correlated abandoned was opened next to the crossing of approximately with the type-Grimmertingen. the hollow road. It belongs to Mr. A. PoEs­ This correlation fits with DROOGER's inter­ MANS, Guighoven, who benevolently gave us pretation for this interval in the boring. the permission to study the section of this The lowest sample which yielded calcareous outcrop, and to carry out a boring in the nannoplankton bas been obtained from quarry. -174,00 m. Chiphragmalithus alatus (MAR­ When D.A.J. BATJES (1958) visited the TINI), Discoaster barbadiensis TAN SIN HoK, region, this quarry apparently did not exist, Discoaster distinctus MARTINI, and Zygolithus which explains that bis sampling was less dubius DEFLANDRE, and others are present, an succesful; all of BATJEs's samples appeared assemblage which belongs like that of the almost barren. However, we recently found a Clay of Asse and the type Wemmelian into the fairly rich association of benthonic and Chiphragmalithus alatus zone of the Middle planktonic Foraminifera at the base of this Eocene. quarry, whereas BATJES had taken most of his samples at higher levels. The section in this outcrop (approx. 7 m) 4. Locality Detai/s was described (see fig. 4) and sampled every 50 cm, on Sept. 10, 1968. 4.1. The Grimmertingen locality 'As reference level (0 m) we took the bottom According to J. DE HEINZELIN & M. GLIBERT of the way next to the quarry and the measure­ (1957) the hollow-roadside outcrop at Grim­ ments of the boring (see fig. 4) carried out on mertingen (cf. also GLIBERT & DE HEINZELIN, Oct. 2, 1968, are refering to a zero level which 1954, point 101, p. 295) is to be considered as approximately 30 cm higher. the type-locality of the Sands of Grimmer­ tingen, DUMONT1, synonymous with the Sands of Vliermaal, d'OMALIUS d'HALLOY1, 4.2. Lithology and with the Sands of Lethen, DuMONT2• This The lithologie description of the section is member is indicated by the symbol Tglc on given in fig. 4. the Geological map of Belgium. This section has earlier been described by A. DUMONT (1849) established the name of M. GLIBERT & J. DE HEINZELIN (1954b; point this member after a fossiliferous locality of 101, and section fig. 10, p. 305) and by A. DUMONT (1839) then considered to show

1 Grimmertingen, sometimes spelled Grimit­ lithologie unit, and probably also to the same tingen (1839), later Grimmersingen (1849) by outcrop. Following J. DE HEINZELIN & M. GLIBERT A. DUMONT; however erroneously spelled, there (1957) we will only use the term Sands of Grimmer­ exists no confusion with other localities. Grimmer­ tingen. tingen is actually a hamlet of the municipality 2 The village of Lethen (sometimes spelled Vliermaal: apparently the term Sands of Vliermaal Leeten, or Leten by some authors) lies approxi­ of d'OMALIUS d'HALLOY (1853) refers to the same mately 6 km. NE of Vliermaal.

122 • GUIGOVEN

• •• •• ..•• •• ••••• • •• • •

Fig. 3. Type locality of the Sands of Grimmertingen

M. GuuNCK (1968: Vliermaal-Grimmertin­ & J. DE HEINZELIN, 1954b, point 108). This gen). member is indicated by the symbol Tgld on Under approximately 1 m of late Quater­ the Geological map of Belgium. nary loam, one observes some 3 m of gray­ The Sands of Neerrepen in the Grimmer­ green coarse sands, showing the facies of the tingen locality show some cross-bedding, Sands of Neerrepen ÜRTLIEB & DoLLFUS, mudballs, and some bifid and trifid tubular 1873. Neerrepen is a village SE of Grimmer­ structures of unknown origin. The Sands of tingen (cf. fig. 3), the type locality is a Sand-pit Neerrepen appear to be almost completely near the Castle of Neerrepen (see M. GLIBERT barren in Foraminifera (D.A.J. BATJES, 1958).

123 The contact of the Sands of Neerrepen with - Astarte bosqueti NYST the underlying Sands of Grimmertingen is - Murex brevicauda HEBERT formed by an indurated layer of red colour - Turritella crenulata NYST (iron-oxyde) and a concentration of rolled b) Fish teeth: Sorne 8 species were recovered mollusc shells and fish teeth. The latter are in the Lower Tongeren Formation at Grim­ probably partly reworked from Eocene mertingen, Neerrepen and Lethen by M. LE­ deposits. (M. LERICHE, 1910). RICHE (1910). The facies of the underlying Sands of Grim­ The fish teeth found at the contact of the mertingen is a fine glauconiferous and mica­ Sands of Grimmertingen and the Sands of ceous green-brown sand containing many Neerrepen are, according to LERICHE, mainly mollusc shell, ( Ostrea ventilabrum and reworked Eocene forms. Turritella crenulata appear to be quite fre­ quent). This same facies with rusty stains persists in the boring as deep as -9 m, where 4.5. Micropaleontology apparently the sediment becomes richer in clay, and shows (abruptly) a blue-gray colour a) Calcareous nannoplankton: 34 samples from (probably reduction of iron). Shell-fragments the zero level on downwards were analysed; have been observed throughout the section a list of the species is given in the following of the Sands of Grimmertingen in the outcrop chapter. and boring. b) Bryozoans: F. CANU & R.S. BASSLER (1931) The level of the groundwater was at the time described a number of species derived from of the boring at - 3 m. The base of the the Lower Tongeren Formation in this region. Grimmertingen member was not reached in c) Foraminifera: D.A.J. BATJES (1958) record­ this boring. ed 4 species in a sample approximately 2 m above our zero level of the outcrop ; his other samples of this locality appeared to be barren. 4.3. Sedimentology At present Mr. W. WILLEMS (Ghent) studies a fairly rich association from samples near the A. KONING (1945) and R. TA VERNIER (1946) zero level of the outcrop section. have analysed the heavy minerais of the Lower d) Hystrichospheres: This group is studied at Tongeren Formation and some results are present by Mr. W. WEYNS (Ghent). given by M. GLIBERT & J. DE HEINZELIN e) Radio/aria: These organisms seem quite (1954b, pp. 308, 309). frequent in most of the samples of the outcrop A more extensive sedimentpetrological and the boring. analysis of the samples which are now at hand f) Ostracoda: They seem to be qui te rare, as is presently carried out by Mr. A. RUMES only two single specimens as yet have been (Ghent). recorded by Mr. W. WILLEMS. Earlier A. KEY (1957) determined one specimen of Legumino­ cythereis striatopunctata (RoEMER). 4.4. Paleontology a) Molluscs: In this outcrop some 214 species (84 Pelecypods, 130 Gastropods) have been 5. The calcareous nannoplankton assemblages recovered by M. GLIBERT & J. DE HEINZELIN (cf. Table 4) (1954b). According to these authors, the following From the 34 samples between 0 and -12, 70 m species seem to have some stratigraphie value: of the boring at the sandpit of Grimmertingen - Pycnodonta queteleti (NYST) only 9 samples yielded calcareous nanno­ - Ostrea ventilabrum GOLDFUSS plankton. These samples are listed in table 4. - Venericardia latisulcata NYST ( = V. lati- The calcareous nannoplankton is poorly pre­ sulca NYST served, and only more robust forms are present

124 TABLE 4. Distribution of calcareous nannoplankton at the type-locality of the Sands of Grimmertingen ( Vliermaal).

s E -- samples 0 s ~---- s E s E s N' 0 0 0 ~ "' N spec1es. ------~ 8 "' N N"' OO q ô E ô -ô ô ô ô "' N (f = few; r = rare) -~ 0 1 1 1 1 1 1 ï

Coccolithus pelagicus (WALLICH) f f f r r r r r f Coccolithus sp. f r r r Cyclococcolithus formosus KAMPTNER r r f r r r r r Dictyococcites dictyodus (DEFLANDRE & FERT) r r r Discolithina distincta BRAMLETTE & SULLIVAN r r r r Discolithina pulcheroides (SULLIVAN) r Discolithina sp. r Ellipsolithus subdistichus ROTH & HAY r Helicopontosphaera sp. r Isthmolithus recurvus DEFLANDRE f f f r f r f r f Micrantholithus vesper DEFLANDRE r r r r r Reticulofenestra insignita RoTH & HAY r Reticulofenestra umbilica (LEVIN) f f f f f f f r f Rhabdosphaera tenuis BRAMLETTE & SULLIVAN r r Sphenolitlrns pacificus MARTINI r r Transversopontis obliquipons (DErLANDRE) r r

except for samples at -0,25 m and -10,20 m. Reworked calcareous nannoplankton is The calcareous nannoplankton of the extremely rare, and has been observed only in samples between 0 and - 2,5 m represent the a few specimens derived from the Upper Ellipsolithus subdistichus zone. The guide­ Cretaceous like Eijfellithus turriseijfeli (DE­ fossil Ellipsolithus subdistichus ROTH & HAY FLANDRE) and Micula staurophora (GARDET) has been found in the better preserved cal­ in samples at 0 m, -0,20 m and -10,20 m. careous nannoplankton assemblage of sample -0,25 m. Of interest is the presence of Cyclococcolithus formosus KAMPTNER in all samples, indicating that they belong below the 6. Conclusions (cfr. Table 5) Cyclococcolithus formosus extinction line (MARTINI, 1969) and are equivalent to the 6.1. The Sands of Grimmertingen yielded at type-Latdorfian (Lower Oligocene). their type-locality a calcareous nannoplankton Somewhat questionable is the status of assemblage belonging to the Ellipsolithus sub­ sample -10,20 m, because Ellipsolithus sub­ distichus zone ROTH & HAY, 1967. distichus ROTH & HAY has not been found. A boring in this locality shows that the same The lack of rosette-shaped discoasters like assemblage is probably present towards the Discoaster barbadiensis TAN SIN HoK and base of this member in this locality. Discoaster saipanensis BRAMLETTE & RIEDEL 6.2. This Grimmertingen locality was origin­ indicates that the calcareous nannoplankton ally and in later publications mentioned by represents more likely the Ellipsolithus sub­ A. DUMONT (1839-49) as the fossiliferous out­ distichus zone of the Lower Oligocene than the crop showing the base of his "Tongrian underlying Isthmolithus recurvus zone of the system" ( = stage). Upper Eocene. 6.3. When E. BEYRICH (1854-,56) established

125 N -0\ TABLE 5.

ZONATIONS BELGIUM STRATOTYPES of some EUROPEAN STAGES

Ca/car. Western ~ Plankton . North Central Be/gium Eastern Be/gium Eng/and •s;: Nannopl. and Central German y Italy ... Foram. zones (Kallo well) (Tongeren) (Hampshire B) ~ zones Belgium

Cassigerinella E. subdisti- Sands of (Type) Lower (Type) "Lower ...... r:5 ....1 chipolensis/ chus zone Bassevelde TONGRIAN (at LATDORFIAN Oligocene" 0 Hastigerina Sa -124 Grimmertingen) micra zone -125,5 aa ~ 131? Globorotalia · T. recurvus -137 Brockenhurst cerroazulensis zone S2 ? some other Bed -150 ~ German (=Middle PRIABONIAN ?~ a2 ?~ localities Headon) at ~- ,....__ -162- mentioned Possagno D. tani Sands of S1 Sands of by E. (Type) u.l nodifer zone Asse? -168 Asse'? BEYRICH BARTONIAN z (Upper u.l Clay of ai Clay of ü Barton Beds) 0 Asse Asse u.l -and "bande "bande V. Upper ''BIARRITZIAN'' , Ch. alatus ::::---~ ~== = -176 ------A. (= quadra- noire" noire" KOENEN Bracklesham or "Uppermost tus) zone (at Oedelem) Beds LUTETIAN" (also (Type) Sands'of in South. France WEMMELIAN s.w. Wemmel and Paris B.)

1 the Oligocene conception he already correlat­ ciation of the Lower Tongeren Formation in ed, on basis of the mollusc assemblages, the eastern Belgium. An individual of Cassigeri­ basal strata of the then established Oligocene nella chipolensis was recorded by this author in Germany with the "Lower Tongrian" of at -131 m; both the Foraminiferal association A. DUMONT. and the calcareous nannoplankton assemblage 6.4. According to the calcareous nanno­ found near the -174 m level can be correlated plankton zonation the base of the type with the Asse Clay formation as recovered in Tongrian can be correlated with the type­ Oedelem (Western Flanders). The situation Latdorfian (MAYER-EYMAR, 1893) and with a of the Eocene-Oligocene transitional strata of number of the classical localities of the Belgium and that of some stratotypes of "Lower Oligocene" mentioned by E. BEYRICH European stages in the biozonations of plank­ (1854-56) and later A. v. KoENEN (1863-94), tonic Foraminifera and of calcareous nanno­ while some other localities mentioned by these plankton is given in Table 5. authors are older than both stratotypes, The interval -131 m to -162 m of the Kallo (according to MARTINI & RITZKOWSKI, 1968). well being nearly devoid of microfossils cannot 6.5. The calcareous nannoplankton zonation be situated in the biozonations as yet, but it further substantiates that the base of both, probably corresponds (at least partly) to the the type Tongrian and the Latdorfian, is missing zones (the D. tani nodifer zone and younger than the top of the Priabonian the /. recurvus zone) as this succession (belonging to the Isthmolithus recurvus zone, apparently reflects a continuous marine according to PRorn DECIMA & TonEsco, 1968) sedimentation for this interval. and. much younger than the top of the type­ Bartonian (belonging to the Discoaster tani nodifer zone, according to MARTINI & RITz­ 7. Acknowledgements KOWSKI, 1968). In Belgium, the type Wem­ melian and the lower part of the Asse forma­ Many thanks are due to Drs. C.W. DROOGER tion even belong to an older zone (both (Utrecht) and J. DE HEINZELIN (Ghent), and showing assemblages of the Chiphragmalithus to Ir. M. GuuNCK (Brussels) for their discus­ alatus zone according to MARTINI, 1969). sions and critical comments. 6.6. In the Kallo boring where the Eocene­ We wish also to express our gratitude to Oligocene transitional strata show a probably Dr. E.E. BRABB (U.S.A.) for his valuable continuous marine succession the E. subdisti­ hints during part of the field work. chus zone (with its guide fossil) was recorded Further thanks are due to Dr. G. DEMOOR from the -124 m level; this level falls in the (Ghent) for bis readiness to execute a boring -124 m to -131 m interval in which C.W. at Grimmertingen and to the licentiate­ DROOGER recognized the Foraminiferal asso- students for their help during this work.

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128 hoheren Eoziins und des tieferen und mittleren de la Société malacologique de Belgique dans le Oligoziins in West- und Mitteleuropa und die Limbourg belge les 18 et 19 mai 1873 ». Ann. Lage der Eoziin/Oligoziin-Grenze in diesem Soc. Roy. Ma/ac. Belg., 8, pp. 38-57 (Brussels). Gebiet". Geologie, 12, Beiheft 39, pp. 63 PROTO DECIMA, F. & TooEsco, L. (1968). « Obser­ (Berlin). vations sur le Nannoplancton de la coupe de KRUTZSCH, W. & LOTSCH, D. (1964). « Proposi­ Possagno ». In: M.B. CITA «Guide de l'excur­ tions à l'appui d'une tentative en vue de sub­ sion en Italie (Coll. sur !'Eocène)», pp. 73-75 diviser les dépôts de l'Eocène supérieur et ceux (Milano). de l'Oligocène inférieur et moyen et de mettre RoosE, B. (1965). «Contribution à l'étude des en parallèle ces dépôts d'Europe occidentale Hystrichosphères et Dinoflagellates du Barto­ entre eux et avec ceux d'Europe centrale, et nien belge ». Bull. Soc. belge Géol. Paléont. étude de la position a assigner à la limite entre Hydrol., 73 (3), 1964, pp. 1-32 (Brussels). l'Eocène et !'Oligocène dans ces régions». In: QUINET, G.E. (1965a). « Un Condylarthre de Coll. sur le Paléogène, Bordeaux, 1962, Mém. Hoogbutsel ». Bull. Inst. Roy. Sei. nat. Belg., B. R.G.M., 28 (2), pp. 949-963 (Paris). 41 (15), pp. 5 (Brussels). LERICHE, M. (1910). «Les poissons oligocènes de QUINET, G.E. (l965b). « Myotis misonnei n. sp. la Belgique». Mém. Mus. Roy. hist. nat. Belg., Chiroptère de l'Oligocène de Hoogbutsel ». 5 (20), pp. 233-363 (Brussels). Bull. Inst. Roy. Sei. nat. Belg., 41 (20), pp. 11 LYELL, CH. (1833). "Principles of Geology". (Brussels). (3 Vol.) Murray (London). QUINET, G.E. & MISONNE, X. (1965). «Les Insec­ LYELL, CH. (1852). "On the Tertiary strata of tivores zalambdodontes de l'Oligocène inférieur Belgium and French Flanders". Quart. Journ. belge». Bull. Inst. Roy. Sei. nat. Belg., 41 (19), Geol. Soc. London, 8, pp. 277-370 (London). pp. 15 (Brussels). MAYER-EYMAR, CH. (1893). «Le Ligurien et le QUINET, G.E. & MISONNE, X. (1967). «Les Marsu­ Tongrien en Egypte». Bull. Soc. Géol. Fr., 3 (21), piaux de Hoogbutsel et de Hoeleden ». Bull. pp. 7-43 (Paris). Inst. Roy. Sei. nat. Belg., 43 (2), pp. 26 (Brussels). MARTINI, E. (1969). "Nannoplankton aus dem TAVERNIER, R. (1947). «Aperçu sur la pétrologie Latdorf (loc. typ.) und weltweite Parallelisie­ des terrains postpaléozoiques de la Belgique». rungen im oberen Eoziin und unteren Oligoziin. In: La géologie des terrains récents dans l'ouest Senck. !eth., 50, pp. 117-159, pls. 1-4 (Frankfort de l'Europe. Sess. extraord. Soc. Belge Géol. am Main). 1946, pp. 69-91 (Brussels). MARTINI, E. & RITZKOWSKI, S. (1968). "Was ist WruGLEY, A. (1929). "Ueber die Molluskenfauna das "Unter-Oligociin"? Eine Analyse der BEv­ eines Eoziingeschiebes von Cothen (Anhalt)". rucH'schen und v. KoENEN'schen Fassung der Zeitschr. f Geschiebeforschung, 5, pp. 102-110 Stufe mit Hilfe des fossilen Nannoplanktons". (Berlin). Nachr. Akad. Wiss. Gottingen, Il. Math-phys-Kl., 1968 (13), pp. 231-250 (Gottingen). MISONNE, X. (1957). «Mammifères Oligocènes de ANONYMOUS: COLLOQUE SUR L'EOCENE, PARIS, Hoogbutsel et de Hoeleden, 1. Rongeurs et MAI. 1968 «Propositions». Compte rendu somm. Ongulés ». Bull. Inst. Roy. Sei. nat. Belg., 33 séances, Soc. Géol. Fr., 1968 (7), pp. 248-251 (51), pp. 1-16 (Brussels). (Paris). MUNIER-CHALMAS, E. & DE LAPPARENT, A. (1893). ToPOGRAPHIC MAPS OF BELGIUM. 1 : 20.000, Inst. « Note sur la nomenclature des terrains sédi­ Geogr. Mil. (Brussels). mentaires ». Bull. Soc. Géol. Fr., 3 (21), pp. sheets: 33/4 - Kortessem 438-488 (Paris). 34/1 - Bilzen OMALIUS o'HALLOY, J. o' (1862). «Abrégé de 33/8 - Borgloon Géologie». A. Schnée (Brussels, Leipzig). 34/5 -Tongeren ORBIGNY, A. o' (1852). «Cours élémentaire de GEOLOGICAL MAPS OF BELGIUM. 1 : 40.000, lnst. paléontologie stratigraphique ». 2, pp. 764 Geogr. Mil. (Brussels) (same sheets as topo­ (Paris). graphie maps). 0RTLIEB, J. & DOLLFUS, G. (1873). «Compte rendu de Géologie stratigraphique de! 'excursion Communication presented April 4th, 1969.

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