Mémoires pour servir à l'Explication Toelichtende Verhandelingen des Cartes Géologiques et Minières voor de Geologische en Mijnkaarten de la Belgique van België Mémoire N° 29 Verhandeling N° 29
THE KNOKKE WELL (11E /138) with a description of the Den Haan (22W 1 276) and Oostduinkerke (35E /142) wells
by P. LAGA & N. VANDENBERGHE
MINISTERE DES AFFAIRES ECONOMIQUES MINISTERIE VAN ECONOMISCHE ZAKEN ADMINISTRATION DES MINES BESTUUR VAN HET MIJNWEZEN
Service Géologique de Belgique Belgische Geologische Dienst 13, rue Jenner 13, Jennerstraat 1040 BRUXELLES 1040 BRUSSEL
Mém. Exp!. Cartes Géologiques et Minières de la Belgique 38fig. 1990 N° 29 118 7 pl. Toelicht. Verhand. Geologische en Mijnkaarten van België ~lz. 5 tabl.
LITHOLOGICAL DESCRIPTION OEPTH (m) below STRATIGRAPHY gn>undl... l v•ry 112 at•4~9m tine - tight grey yeUow mm to fin~ sand with sh~llfrQ9'1'1tnts (0-6) Q u - fine oltemo.tion of day o.nd fi~ grey sand(!. e~ry cm) ( 6-12) A T - ~~~~t \~!~i%~ to 1/2 coarse sand (at theo bau) with Flemish valley - grey ·mm sand alternoted with S-10cm thick ctoyloyers {20-25) deposits betwem 22.80 - 23.45 : si~~ clay 1 : ~~~~:~~ ~n~~~~t\ fo -Y!~agments ( 25- 30) _Y_ : gr~~l'i~ ~~n~~~~v~dsrn~ ~d 3c~-37> _!L - greygreen clay ( 37-4&) az l!" - green f.ine clayey sand (48 -50) 5 ::€,::: 2l - veen grey heavy ctay with gkruconite at t~ base CS0-66} al "'3: !; ë - very sandy g-een clay wi,O {much) gtouconite (66 - 71. S) z 70 - - greygreen fine lo very fine ela~~ sand with glouconite. W.t~~{:~?j~QfJ:i? c san'11Jl&,~"~\\(a!l!lJ~3tsci n~li H • molusks (71,5- 74) BRUSSELS FM? 4 80 - KNESSELARE 90 - FORMATION (PZ) 100 - 110 -..o3: ,_,Oz 120 3: g~ Zij; 130 PJTTEM mbr m T ::MERElBEKE iilb'i':!:... 140 EGEM FORMATION E 150 R 160 T - greengrey he-Qvy <:lay (sometimes breccioted.} with siltspots, silt tametla and P}'fîet (144 -283) 170 180 A 190 R y 200 - 1 EPER 210 FORMATION 220 Y 230 - V"fine coorse sand sand 240 250 260 270 280 - siUy ctay {283 -288} - tîghtgrey to d.arkgrey- fine sandwith peatdebris {288 -297) 290 KNOKKE - silly clay with severo! $.heHfragmentzones {297 -303} 300 mbr : ~H':~~fo~o~rili lev~/o.(~l sand with sitty ctay (303 - 308) - pate clayey san~at t~e bas~ tamirlae of fine sand and ctay (308 - 311} 310 MAASTRICHT lAN 320 u -pure white chalk wHh fossils {tower half endurated) (311-428) p 330 p 340 E 350 R 360 ( CAMPAN lAN 370 R E 380 T 390 A ( 400 E 410 0 u 420 s 430 - ~ro"ëi~ w~\ht~~a1:ag~<>[f~~2~g~)tes with a "greensand" sand SANTëiNÏ)iN soft greengrey weo.thered shale {432,05-432,70) 440 soft greengrey state 444 phosphate LEGEND E2J nodules e coarse sand lominated to fine sand brea:iated ~ • Pers. comm. (1990} by Geert Van Gr~tet, based on the presence of Chitinozoa 1}.,;_""4 clayey sand -~ shelt fragments ~. sandy eloy -~ pea.tdebris ~ clay G gtO.uconite ITlTTTTT, chatk ~- nummulites KNOKKE 11 E 138 lïlllJ enduro.ted chatk ISD moll~o~scs -shah~ and sta.te 131 sandstone 2 TABLE OF CONTENT The Knokke Weil (11 /E/138) with a description of the Den Haan (22W/276) and Oostduinkerke (35E/142) wells by P. LAGA & N. VANDENBERGHE • . . . . . • ...... • ...... • . . . . • ...... 3 Chapter 1 : Lithological description of the Knokke Weil by N. VANDENBERGHE, P. LAGA. J. HERMAN & J. BACCAERT ...... • . 9 Chapter Il: Grain-size and heavy minerais of the Tertiary strata in the Knokke Weil by S. GEETS & G. DE GEYTER . • ...... • ...... • ...... 19 Chapter Ill : Etude de la sédimentation argileuse Tertiaire du sondage de Knokke by M. MERCIER & Ch. DUPUIS • ...... 27 Chapter IV : Biostratigraphic data - Ostracodes and organic walled microfossils - of the Landen formation and the base of the Ieper formation in the Knokke borehole by Ch. DUPUIS, J. DE CONINCK, C. GUERNET & E. ROCHE ...... •. 33 Chapter V: Calcareous nanno{II{Jnkton assemblages from the Tertiary in the Knokke borehole byE. STEURBAUT ...... •.....· ...... •...... •..... 47 Chapter VI : Upper Cretaceous nannoplankton in the Knokke Weil by S.G. BAL & J.W.VERBEEK ...... 63 Chapter VI/: Eocene Stratigraphy of the Knokke borehole (Belgium) by C. KING ...... •...... •..... 67 Chapter VIII: Top occurrence of selected Dinophyceae from the Cretaceous of the Den Haan Weil and correlation with the Knokke Weil by S. LOUWYE ...... • ...... 103 Chapter IX : The correlation of the Knokke, Den Haan and Oostduinkerke Wells by P. LAGA, N. VANDENBERGHE, J. HERMAN & J. BACCAERT ...... 107 Reference list of papers published in this volume ...... 11 7 3 THE KNOKKE WELL (11E/138) with a description of the Den Haan (22W/276) and Oostduinkerke (35E/142) wells by P. LAGA & N. VANDENBERGHE Therefore an emphasis was put on geophysical INTRODUCTION weil data. The geometrie and lithostratigraphic frame for Besides, geophysical weil data are a very power the Belgian coastal area is weil documented by full correlation tool and might even be more the excellent profiles drawn by HALET (1921) and economie than classical coring techniques. GULINCK (1970). Three weil sites were selected (fig. 1 ). At each Most of the data, their work was based upon, location drilling reached the Caledonian basement however, were provided by samples from aider of the Brabant Massif. water flush-wells. Hence precise and detailed The Knokke weil ( 11 E/ 138) has been en ti rely lithological descriptions were rare as were the cored, while bath other wells at Den Haan samples suitable for modern biostratigraphical (22/276) and at Oostduinkerke (35E/ 142) are analyses. flush-wells with a standard geophysical weil lncreasing geotechnical work off-shore and Jogging program. The cored Knokke weil had in the expected interest in exploration on the addition density and sanie transit time logs as an Belgian shelf wou Id also benefit from the modern a id to elucidate seismic investigations in the area. geological reference data- along the coast. The figures 2, 3, 4 gives a detailed location Techniques to link th~ known on-shore geo scheme of the three wells. The topographie levels logy to data obtained off-shore will certainly for a of the three wells are in TAW: Knokke+ 4,91 rn, large part be geophysical in nature. Den Haan+ 5,02 rn, Oostduinkerke+ 6,55 m. The ( ,~... • \ ""~-9 KNOKKE -HEIST~/., ' 4 "'os ,.....(' NORTH SEA . \ r..~"...... OE HAAN \. \ i 0 ''·"-'--·- Oostt>ndt> 0 Bruggc! • OOSTDUINKERKE F R 0 A Oiksmuidt> N c 0 5 10 km E Fig. 1.- Location of the three wells, Oostduinkerke, Den Haan and Knokke 4 . \ . i Bori~-- ~~ ~e~~~--~A~~: --- -_j Fig. 2.- Location of the Den Haan weil (22 W/276) .... . :-_: Boring 83 5 Note on the stratigraphie terminology terminology in the different chapters. As the stratigraphie terminology for the For the members we have therefore chosen to Tertiary is currently under review by the follow the recommendations of the Commission appropriate National Stratigraphie Commission although they were not yet published at the time the editors have chosen for a consistent of publishing this memoir. Kallo complex Different authors terminology Geological map (see footnote) (GULINCK, symbols 1969) Kallo Formation 1Buisputten member 52 1Zomergem member A2 1Qnderdale member 51 As d 1Ursel member As c (pp) Asse member Al As b, As c (pp) «bande noire» bed As a Wemmel member We Lede Formation Le Brussei Formation Br Knesselare Formation 2Aalter member P2 2Qedelem member 38eernem member Mont-Panisel Formation 4VJierzele member P1 d (and, Pl n) 5Pittem member Pl c BMerelbeke member Pl rn Egem Formation Yd (and Pl b) Ieper Formation Yc Landen Formation Upper Landen Formation 7Knokke member L2 Lower Landen Formation L1 1terms introduced and defined by JACOBS (1978), 2 by NOLF (1972), 3 by JACOBS & GEETS (1977), 4 by KAASSCHIETER (1961 ), 5 by GEETS (1979), 6 by DE MOOR & GEETS (1973); 7the Working Group of the Stratigraphie Commission has proposedto replace the term Oostende-ter-Streep member (KAASSCHlETER, 1961) by Knokke member because of the unappropriate geographie tdrm (Oostende-ter-Streep cannot be found on a map and Oostende has already been used for a Quaternary deposit). 6 WESTKAPELLE 11E-138(1Idl Boring 81 te KNOKKE. in m 0,13 cm r,=;pD.'-'F. _____ GAOUND LEVEL original description of cores and flush samples 20 are kept at the Geological Survey files: 11 E/138 • 210 mm Corini 249 mm (Knokke), 22\f\1/276 (Den Haan) and 35E/142 (Oostduinkerke). The geophysical logs are kept in the weil-log library of the Geological Survey. 80 Figure 5 shows a technical weil sketch of the Knokke weil (Smet DB, drilling company). 120 1 240 mm The Den Haan weil was drilled with a 240 mm rock bit till 202,44 m depth, with 7.7/8" till ..E 304,30m; the 304,30m till 321 m section was i Ill cored in 95 mm diameter. Ill Ill ~ 200 a. The Oostduinkerke weil was drilled with a 240 mm rock bit till 253,80 m; the 253,80 m till Ol 270, 30 section was cored in HO (96 mm). ·É 0 u 1 E 1 1 E 1 300 1 1 1 1 1 1 1 400 CONVENTIO AL ROTARY - lOOmm CORING 60 mm T.D. 444m CORING 100mm;l 460 Fig. 5.- Technical weil sketch of the Knokke weil 7 REFERENCES GULINCK, M., 1970. SW-NE profiel volgens de kustlijn. Archieven Belgische Geologische Dienst, MG/70/L295, (unpublished}. HALET, F.. 1921. Coupe géologique du littoral belge entre Bray-Dunes (France) et Knokke. (unpublished}. JACOBS, P., 1978. Lithostratigrafie van het Boven-Eoceen en van het DE MOOR, G.·& GEETS, S., 1973. Sedimentologie en lithostratigrafie Onder-Oiigoceen in noordwest België. Prof. Paper, 1978/3, nr. 151. van de Eocene afzettingen in het zuidoostelijk gedeelte van de Gentse JACOBS, P. & GEETS, S., 1977. Nieuwe ontwikkelingen in de kennis agglomeratie. Natuurwet. Tijdschr. 55 : 129-192. van het Boven-Paniseliaan. Natuurwet. Tijdschr., 59: 57-93. GEETS, S., 1979. De overgang leperiaan-Paniseliaan in de streek van KAASSCHIETER, J.P.H., 1961. Foraminifera of the Eocene of Belgium. Roeselare en Tielt. Natuurwet. · Tijdschr. 60 : 41-69. Kon. Belg. lnst. Natuurwet., Verh .. 147: 271 p. GULINCK, M., 1969. Le Sondage de Kallo. Mém. Cart. Géol. et Min. NOLF, D., 1972.- Stratigraphie des Formations du Panisel et de Den Belgique, Nr 11, 7p., 2 figs. Hoorn (Eocène belge). Bull. Belg. Ver. Geol. Pal. Hydrol.. 81: 75-94. 9 Chapter 1 LITHOLOGICAL DESCRIPTION OF THE KNOKKE WELL by N. VANDENBERGHE, P. LAGA, J. HERMAN & J. BACCAERT Belgische Geologische Dienst, Brussel For a detailed description the reaçler is transported, as shown by the two valves still referred to the Geological Survey files (11 E/138). sitting together. The 74-79 m interval is a fine A summary description is presented together sand with several layers of cemented calcareous with a lithostratigraphic column on figure 1. sandstone. The presence of Nummulites wem melensis in the upper sand unit identifies it as the Wemmel sands (Wemmel member of the Kallo 1.- THE QUATERNARY Formation). The lower sand unit. badly cored because of The top 30 m consist of mainly sandy, often stone layers, would in the tradition of the regional laminated deposits. They represent tidal and geological knowledge be interpreted as the Lede estuarine deposits of mainly Pleistocene age. sands. At 73 m however, the mollusc Ca/lista They belong to the Flemish Valley river system proxima (1) is commonly present; it is diagnostic deposits (TAVERNIER & DE MOOR. 1974; PAEPE for the Brussel sands. The presence at the same & VANHOORNE, 1967). level of numerous transported and rounded Nummulites laevigatus is also an indication for the former presence of the Brussel sands. ln 2.- THE KALLO FORMATION general, this type of concentration is typical for the base of the Lede sands although numerous A mainly heavy clay unit forms the top of the Nummulites laevigatus have been found in the Tertiary, from 30 m to 71,5 m. Two glauconitic Brussel sands at the Mont des Récollets and in fine clayey sand intervals exist at 33-36 m and the Woensdrecht weil as reported by GULINCK 48-50 m. The general lithological appearance and (op. cit.). the position in the stratigraphie sequence inden The idea of a widespread very thin Brussel tifies this unit as belonging to the Kallo complex sands shell and nummulite bed, almost comple (sensu GULINCK). The two sand units are s1 and tely removed before the deposition of Lede and s2. The glauconite rich and sandy nature of the a1 Wemmel sands to the west of the lenne valley, base is in accordance with the character of the was put forward by GULINCK and HACQUAERT Asse Clay. A formai lithostratigraphic nomen (1954, p. 485). clature for this sand, clay sequence was worked out by JACOBS (1978). The presence of Brussels sands at 73 m means that the 74-79m sand interval could also represents Brussel sands and hence the Lede 3.- THE SAND UNITS BETWEEN sands could be lacking. THE ASSE Similar conclusions were obtained by DEPRET AND THE IEPER CLAYS and WILLEMS (1983) for the nearby area around Zeebrugge (see also chapter VIl). a.- Two thin sand units below the Asse Clay have distinct lithological properties. The 71,5-74m interval is a fine clayey glauconitic sand with numerous nummulites and calcareous shells sorne not or only slightly (1) Determined by C. King, this volume. 10 b.- The whole section between 79 and 135 rn A striking feature is the occurrence of severa! can be attributed to the Panisel formation. lt is a horizons of a brecciated Ieper clay. Although typical glauconite rich sediment, in which clays sorne of the fragments have sorne rounding (Plate and almost pure sands alternate and in which the 2, photo 5), most of the breccia fragments are still occurrence of cemented sandstone layers is angular. and have barely moved (Plate 2, photo 4, corn mon. 5; Plate 3, photo 6, 3). Photo 6 shows that Severa! subunits can be recognized. The 79 to brecciation is associated at least in sorne instan 105 rn interval of fine clayey glauconitic sands ces with small faults, pointing to gliding phe with numerous shells, ditrupa's and calcareous nomena in the clay. Obviously a borehole is too sandstones corresponds to the typical Upper small to develop a detailed hypothesis for their Panisel Aalter sands facies. ln the terminology of origin. Nevertheless a few comments can be DEPRET and WILLEMS (op. cit.), this Upper made. The angular nature of the clay fragments Panisel facies is. described as the Den Hoorn and especially the tact that they have not been formation (2). Although severa! members can be compressed, suggests a brecciation at an already recognized in this formation these authors identi weil compacted stage; we suppose that the fied in the Zeebrugge area 35 rn of the Oedelem brecciation occurred at least at sorne tens of member, making up the whole Den Hoorn meters burial depth or even deeper. formation. Below 105 rn, five more subunits can The origin at depth could th en be related to the be recognized. observations of HENRI ET and MARECHAL (1982), The interval between 105 and 116 rn consists who have interpreted from sparker-seismic sur of fine glauconitic sands with clay laminae and veys diapirs and other deformations in the Ieper stone layers in its lower part (Pl. 1, photo 1, 2, 3). clay off-shore. lt is suggested that the common The interval between 116 and 124 rn is a occurrence of Ieper clay deformation in the coarsening upwards glauconitic medium to Belgian North Sea (HENRIET and MARECHAL, coarse grained sand. 1982) in contrast to almost undeformed Ieper Clay on land is due to unloading as the Channel The 124-132 rn interval is a silty clay with was eroded. This explanation is analogous to the severa( cemented sandstone layers. The 132- occurrence of clay diapirs in the Rupelian Boom 133 rn interval is aga in a fine glauconitic clayey clay along the tract of the eroded Scheldt valley sa nd horizon. The 1 33-135 rn is a heavy homo (WARTEL, 1978; SCHITTEKAT et al., 1983) in geneous grey clay horizon. contrast to undeformed clay on land. The latter unit is the basal Panisel clay Thin black pyrite linings surround the frag (Merelbeke clay) and the 124-132 rn silty clay ments in many cases. The faults shown in photo 7 with cemented sandstones fits the geometrical should not be confused with the slickensided position and the facies of the Pittem clay (Pl c map fissures, so common in the overconsolidated symbol). · Tertiary clays and also present in the Ieper clays The 105 to 124 rn part is more difficult to of the Knokke weil. associate with one of the known Panisel facies in At the base the clay is slightly brownish. the outcrop area to the south-southeast. Generally speaking however the same litho logy and depositional facies are involved as in the 5.- THE LANDEN FORMATION type area. The Landen Formation sediments occurring from 288 rn to 311 rn ca n be s ubdivided in three 4.- THE IEPER FORMATION AND main subunits. THE EGEM FORMATION The upper one between 288 and 297 rn consists of quartz sands with peat debris. The The Ieper Formation extends from 144 rn down 297 rn to 308 rn interval consists of silts, fine to 288 m. The overlying interval, 135-144 m. sands, heavy clay, shell fragments and a compact which is a laminated clay with fine sand horizons shell bed at 303 m. These fossils point to a and even cemented sandstones is now called the Egem formation. Except for the silty basal 5 rn (283-288 rn), the entire Ieper Formation consists of homogeneous (2) The Den Hoorn Formation is made up of the Oedelem, Beernem green grey heavy clay with sorne rare silty spots or and Aalter members (Nolf, 1972). lt is proposed now to use the term the thin silt laminae; pyrite is present as weil. Knesselare Formation instead of the Den Hoorn Formation. 11 brackish water lagoonar environment, with sali fragments had already suggested a resemblance nities lower th an 10 %o. The fossils represent a to the white chalk sequence in north east Belgium. typical Sparnacian-type fau na (see a Iso chapter IV). The 308-311 rn interval consists of pale 7.- THE CALEDONIAN BASEMENT coloured, also pink to purple sands. At the base the sediment becomes clayey and greenish. The top of the Brabant Massif consists of a jointed · slate dipping 30 to 40°, attributed to the lt is thought that, except for the very lowermost Lower Revinium (Oisquercq slates) by LEGRAND greenish clayey sediments, the whole section of (1968) in the nearby 11E/48 weil. the Landen Formation should be associated with the continental Upper Landen Formation, sedi ments deposited at the sea-continent transition. REFERENCES DEPRET, M. & WILLEMS, W., 1983. A record in situ of Nummulites laevigatus (BRUGNIERE, 1792) in sediments of Lutetian age in the area 6.- THE UP PLATE 1 1. Clay laminae with glauconitic sand layers (1 05.60-106 m) 2. Storm affected laminated glauconitic sands, with a thin transported clay fragment (106.35-106.60 m) 3. Bioturbation in glauconitic fine sands (112.50-112.80 m) 13 105,60 m- 106 m 106,35 m - 106,60 m 112,50 m-112,80 m 14 PLATE 2 4. Brecciation in the Ieper clay (153.20-153-40 rn) 5. Strong brecciation in the Ieper clay. Sorne of the breccia fragments are slightly rounded (154.20 rn) 15 153,20 m - 153,40 m 154,20 m 16 PLATE 3 6. Sliding in the clay, associated with brecciation in the Ieper clay (170-171 m). 7. Slight brecciation in the Ieper clays (180-180.90 m) 17 170m -171 m 180 m- 180,90 m 19 Chapter Il GRAIN-SIZE AND HEAVY MINERALS OF THE TERTIARY STRATA IN THE KNOKKE WELL by S. GEETS & G. DE GEYTER Geologisch lnstituut, Rijksuniversiteit Gent 1.- GRAI N-SIZE ANAL YSIS C. GRAIN-SIZE PARAMETERS AND ENVIRONMENTAL ANALYSIS A. METHOD OF INVESTIGATION Graphie parameters, according to f3.l. FOLK 20 g of each air-dried sample was divided in a and R.C. WARD (1957) were calculated for the coarse and a fine fraction by wet-sieving on a sandy and coarse-silty sediments, whereas the 50pm-sieve. The first part was mechanically moment measures were determined for ali subdivided on a sieve-series with a successive samples (table Il). difference in mesh-width of 0.5 cp. The fine A few methods, based on grain-size distribu fraction was analyzed by a CAHN-R.G.-sedimen tion, have been used to obtain sorne information tation-balance. The results are given in table 1 about the depositional environments of sorne (more detailed figures are available with the members in the Knokke weil. authors). The C/M-diagram (PASSEGA & BYRAMJEE, Samples containing shell fragments were 1969) distinguishes s·everal kinds of «suspen decalcified with 0,5 N HCI before the grain-size sions» and is used as an indicator of the hydraulic analysis. conditions under which sediments were depo sited. B. SEDIMENT-NOMENCLATURE AND GRAPHIC REPRESENTATION The analysis of the cumulative curves on log probability-paper in different populations and the Three fractions were calculated: the sand comparison with the examples published by fraction (2000-63pm), the silt-fraction (63-2pm) DOEGLAS (1946, 1947), SINDOWSKI (1957) and and the clay-fraction (< 2pm). The ir percentages VISHER ( 1969) gives information about the energy were plotted in a modified triangular diagram of the depositional agent and about the environ after SHEPARD (1954) (G.EETS, 1978). ment. With the classification of WENTWORTH (1922) as a base, a term has been addedtothe na me sand O. KALLO FORMATION (sandy) or silt (silty), which corresponds to the Buisputten Member, S2 interval with the highest percentage in each of (33-37 m, table 1 and Il, nrs. 3-6) these fractions, in order to give a more accurate determination of each sediment. The member consists of coarse-silty, very fine sands, very poorly to extremely poorly sorted; the The results of the grain-size analyses were base is formed by an extremely poorly sorted, very plotted as cumulative curves on log-probability fine-sandy, clayey, coarse silt. The sediments paper, wh.ich makes it more easy to read the coarsen towards the top: X 1 4 s 6 7891 0 4 5 6 7 8 910 2 4 5 6 7 8 910 4 5 6 7 8 910 1 i 3 1 i 1 1 1 1 ( J ~ 3 - IX 1 1 II 1 in 1 -· 2 / 2 pm - - 1 1 1 00 10 9 9 -~!-~~ v 8- --- ·- 8 7-r------·-· f----1-· 7 6 - v 6 12 5-1--- 15 6 121" 3 v s 4 .L v 4 ( "20 1 •22- J-1--- .. / 3 r 1~ J1 - ? - 2------.- v 2 4 - - 1 1 7. r• 100 1--- 10 9 '2 9 .. v 8 ---1-- 8 7- ---- 7 6-~-- 6 s- - __ _J~------=1. 0 14 v s .17 •g ... --- - - 1 v • 3 • 6 • 3------/ 3 - - VT 2- ---~- / 2 - / 1 r-- l 1 10 v - 1 i 1 ' l 1 2 1 3 4 s 6 7 8 910 1 2 1 3 5 6789•00 1 2 3 4 5 6 7 . 91000 1 2 1 3 4 s 6 7 8 910 ~ • __ LLL ______J _ __.____._ __ 1___Uj_L_ ------'----'--'----'--'----'--..._._-'-- ' M in ,um fig .. 1.c C/M diagram of the sediments frc;>m the Kallo Formation The cumulative curves show one saltation Ursel Member, a1 clay unit population and a smaller suspension population. (50-66 m, table 1 and Il, nrs. 13-19) The two lowest samples (5 and 6) contain a very This member starts with a clayey, coarse silt at small traction population (± 2 %) (fig. 2) (the the base, passing over a very-fine- to fine-silty numbers along the curves correspond with these clay, into a (clayey) fine to very fine silt. They ali of the samples on table 1 and 2). These sediments belong to the fi nest uniform suspension sediments seem to be deposited in a shallow water (fig. 1 ). environment near to the coast or along distri butary channels. Their cumulative curves show a very weil developed suspension population and a very high Zomergem Member, a2 break point (at 7 rp) with the saltation population (37-48 m, table 1 and Il, nrs. 7-12) (fig. 2): their form strongly resembles the ones of At the base a very poorly sorted coarse silt ( 11- the curves of crevass deposits in near-shore 12, X:cp= 6,5 rp) occurs, which passes into a very distributary systems (VISHER, 1969). poorly sorted clayey very fine silt (7-10, Xcp= 7.88 rp). The suspension population becomes Asse Member, a1 sandy unit more important towards the top of the member at (66-71.5 m, table 1 and Il, nrs. 20-21) the cost of the saltation population, whereas the The sediment consists of extremely-poorly small traction population disappears above 45.5 m sorted, medium-silty, clayey or clayey fine sands. (fig. 2). Below it belongs to the uniform suspension These silts, which gmw from uniform sus sediments, passing into a graded, moderate pension sediments at the base into finest uniform turbulent suspension sediment (fig. 1 ). Their suspension sediments (fig. 1), were probably cumulative curves show a saltation population of deposited in quiet, protected areas along the 60%, which at 3.7 rp (21) or 2.4 rp (20) changes coast. into a suspension population. 21 0-1 4t 1-2 4t 2-3 4t 3-4 41 4-5 41 5-6 41 6-7 4t 7-8 $ 8-9 4t < 9 (l Table 1.- Results of the grain-size analysis 4. 255.6 m 3.45 3.10 11.15 9.80 12.00 60.50 5. 259.7 rn 4.60 4.70 13.10 8.20 9.40 60.00 6. 263.7 rn 3.60 5.60 13.30 8.60 9.40 59.50 7. 267.6 rn 3.25 4.05 12.25 9.50 10.95 60.00 8. 270.7 m 0-1 $ 1-2 Q 2-3 $. 3-4 $ 4-5 $ 5-6 $ 6-7 $ 7-8 $ B-9 $ < 9 ~ 4.35 2.60 9.80 9.70 10.55 63.00 9. 275.7 m 3. 25 2.85 11.40 8.65 9.85 64.00 ~1 ~- 30.9 rn o.so o.so J.oo 12.00 1a.Js 10.9~ 1J.oo 11.10 9.60 21.od ~o. 280.65 rn 4.85 3.90 9.55 4.50 4.20 73.00 31 .0 rn 35.35 4.00 10.00 16.65 5.70 4.80 6.15 lt.90 3.95 8.5~ 17. ~1. 283.8m 2.80 3.40 11.55 5.95 5.30 71.00 3. 33.8 rn 1.00 11.00 55.00 9.15 2.05 3.15 1.80 2.05 14,8{~ ia2. 287.7 rn 0.05 0.05 0.30 31.40 26.30 5.75 4.90 3.35 4.40 23.50 4. 3-4 .B rn 5.50 47.00 20.20 3.6 6.65 4.35 3.15 9.5q ~3. 290,7 m 3.30 83.15 11.10 0.30 0.20 0.40 0.25 0.20 1.10 5. 35.35 rn la•· 294.3 rn 0.05 57.30 41.00 0.55 0.15 0.20 0.15 0.10 0.50 6. 36.8 rn ~:~~ ~::~ ~:~~-~~:~~ ::::~ ::~~ :::~ ~::~ ::~~ :~:~~ ~5. 297.35 m 0.05 0.10 10.80 75.70 2.70 0.95 1.55 1.10 0.95 6.10 38.9 rn 11.00 ,8,7 18.60 14.00 13.20 34.5 ~6. 299,7 m 0.05 0.15 1.15 5.20 4.95 6.95 6.40 7.15 68.00 ~- 40.5 rn 5.50 16.45 22.75 14.10 13.70 27.5 ~7. 304.4 m 0.05 1.40 71.15 6.90 2.55 3.90 2.35 2.20 9.50 9. 41.5 rn 9 25 27 85 23.25 12.10 9.55 18.0 ~8. 306.4 m 0.05 0.10 0.60 12.70 9.00 13.-45' 6.60 6.50 51.00 10. 43.5 m 6.70 20:95 20.85 11.85 11.15 28.5 ~9. 307.9 rn 0.10 0.20 '1.20 20.20 3.70 5.90 7.40 3.75 4.55 47.ooll ·11. 4::~. 5 rn o.5o o sol o.5o 1.so 25:95 24.60 17.50 9.8o 1.1s 12.0Q 1 f.Jo. 308.5 rn 0.05 23.30 55.70 2.45 0.80 0.90 0.65 0.95 15.20 12. 47.5 rn 1.50 o:so 0.501 2.50j 23.90 16.75 17.65 13.55 8.65 12.5~ jg1. 309.5 rn 0.10 0.05 5.15 47.75 25.05 2. 30 1. 90 1. 25 1.25 15.20 13. 50.5m 0.30 10.15 33.55 26.05 17.45 12.5~ 14. 52.3 rn j 1 15.30 22.90 24.45 13.80 10.55 13.od 15. 54.5 rn 1.00 o.so o.soj 2.ooj12,35 19.35 21.45 6.4o 5.9sl3o.sn 1 16. 58.5 rn 1 1 1.45 10.80135.85125.10 16.50110.3~ Wemmel Member 17. 60.5 rn t ! 1 3.55 4.70 13.30 5.80 4.65168.00: (71-74 m, table 1 and Il, nr. 22) 18. 62.5 rn ' : 3.95 6.50112.501.11.30' 12.751153.00 19. 65.5 rn 1.00 1.ool1 9.solz8.eo 6.20 6.7o! 3.Boj 4.oo, 39.0~ 20. 67.5 rn 21.50 24.~o] 13.oo; s.95 2.2oi 2.65: 2.851 2.1s; 2s.2o_ The member consists of a poorly-sorted, very 21. 70.5 rn 1.so 11.50 26.soj 8.so 7.75 9.sol 6.4o,1 2.ss! 2.5Di23.oo· fine sand. lt is a uniform suspension sediment 22. 72.0 rn 0.50 1.00 26.0Dj61.00: 3.25 0.90. 1.10) 0.45! 0.90! 4.90 3. 79.5 rn 1.00 12.50] 74.00! 4.30 0.60: o.oo: 0.45! C! .• 25 6.10' (fig. 1 ); the cumulative curve shows a traction 24. 82,5 rn o.soj53.oo] 38.so; 2.20 o.4o~ o.5o~ o.,.a; o.4o· 4.10 population, 2 saltation populations and a small 25. 84,5 rn 1.00126.50!41.00 3.6011.55] 2.30 1.60 1.45 21.00 26. 87.5 m o. soi 4.soj 73.so~ s.1o o.95! 1.40 1.05, 1.oo: 12.oo suspension population (fig. 2). lt seems to be 27. 90.75 rn 1.oo: 1.oo' 36.50: 18.6DJ 'i.55j 5.3s: 2.45~ 2.o5: 25.50 deposited on a beach foreshore. 28. 96.50 rn o.soj. 31.5oj42.oo;.. 1.401 o.9sj 2.5o: 1.75 1.40 18.oo. 29. 98.85 rn o. 5o: 4o.no: 3o.oo, 3.10 o.8s1 1.4o. 0.85· 0.80 14.50 30. 110.5 rn 1.00 o. 5o: o.soJ14.oo; 6.05 6.6o; 18.50~ 8.45' 8.30 36.oo; E. MONT-PANISEL FORMATION 1 31. 113.75 rn 1.50 0. 5o) O.SDI42.DOj 14.30' 3.G5 5.40 6.15 5.50 20.501 32. 115.1 rn 1.5o' a.so\ 6.5o; 27.oo1 ·J8.35 4.35 4.30 4.05' 2.45 :?J.od 1 79-99 m (table 1 and Il, nrs. 23-29) 33. 119.8 rn 1.50 35.50,49.501' 6.0 1 7.5 1 34. 120.'J~· m 23.00150.00 9.50 5.25 2 95 2.25! 1.1Qi 1.45 4.?0] 35. 124.2 m 1o.oo!32.5o 15.5o\ 8.oo 4:7o 5.8ol 3.5a·l =.no 1G.ool The sediment consists of fine (24, 29), very 1.oo 1 36. 126.5 rn 1.so 2.so 21.soj12.50i 4.15 5.8oj6.00j 3.75, .},3oj33.ool 1 fine (23, 26) and clayey, very fine sand (25, 28), with an intercalation of clayey, coarse-silty sand 0-1 • at 90.75 m. The sorting is extremely poor at the 1 37. 130.0 m 0.50 1.00 13.50 22.ooj 7.45 5.4ol! 8.ooj 5.65 6.sot3o.oo_ base, but grows better towards the top of the 38. 132.5 m 1.00 2.oo 24.50 39.5o! 7.30 3.25 1 3.251 3.HJ 2.6DI13.'W 39. 135.8 rn o. 50 1.oo 46.oo 3o.oo! 1.85 1.20~ 1.1si 1.4o o.3o!1o.ol complex. 40. 139.5 m 1.00 1.00 50.50111.40 3.90] 4.BO~ 2.95 2.45!22.0! 41. 141,5 rn o. 50 1.oo/ 0.50 74.00113.7011.301 1.051 o.no 0.3517.00 According to PASSEGA and BYRAMJEE, most 1 1 42. 144.5 m o. 50 0.50 0.50 0.50 18.95 14.851 15.75! 9.2~] 8.20 31.00 of the sands are deposited from a uniform 43. 149.1 m 5.45118.90 18.40\10.50 20.75 26.00 44. 150 rn , 8.95111.50111.60~6.35 5.60j5G.OO suspension, which are graded, moderate-turbu 45. 15l, rn . 4.40110.451 6.00 7.15,72.00 lent suspension sediments (fig. 3). The cumu 46. 154.65 m 0.75! 8.10i 15.50i10.30 20.35]4~.001 1 47. 158 m 1 9.451 16.75,16.20i 7.65 "7,951l,2,fl01 lative curves of the very fine sands (23, 26) 48. 162 m 8 • .30 12.90l11.00Î G.OD 4.80 57.00, comprise two saltation and one suspension 49. 163.5 m 1.35111.45;17.15! 9.60 9.4 Table 11.- Grain~size parameters Mz cri 4. 255.6 m 9. 76 -0.80 -0.89 Md$ Hz 5. 259.7 rn 9.63 -o. 74 -1.06 6. 263~? rn 9.62 2.41 -0.70 -1.13 1. 30.9 rn 6.35 6.76 6.84 2.84 2.89 0.25 0.42 0.90 -0.94 7. 267.6 m 9.71 2.33 -0.75 -1.01 2. 31.0 rn 3.05 3.?0 3.67 3.08 3.38 0.38 0.98 0.82 0.01 B. 270.7 rn 9.85 2.30 -0.91 -0.67 3. 33,8 rn 3.75 5.08 4.95 2.51 2.97 0.68 1.48 2.00 0.68 f79. 275.7 rn 9.89 2.27 -0.92 -0.71 4. 34,8 rn 4.10 4.95 5.01 2.05 2.51 0.67 1.63 1.47 1.56 10.14 2.33 -1.30 0.03 ""· 280.65 rn 5. 35,35 rn 3.95 5.30 5.42 2.24 2.89 0.81 1.25 0.98 0.15 ~1. 283.8 rn 10.13 2.24 -1.18 -o·.z5 6. 36,8 m 4.70 6.10 6.18 2.93 3.23 0.66 0.74 0,75 -0.99 ~2. 287.7 m 4.70 6.15 6.25 2.86 3.17 0.70 0.82 0.75 -1.00 7. 38,9 m 7.80 8.32 2.55 0.11 -1.43 ~3. 290.7 rn 2.60 2.62 2.73 0.40 1.10 0.18 6.25 1.41 44~52 8. 40,5 rn 7.40 8.02 2.38 0.43 -1.22 ~4. 294.3 rn 3.00 3.07 2.99 0.31 0.85 0.30 5.79 1.23 52.17 9. 41.5 rn 6.55 7.26 7.25 2.27 2.26 0.49 0.92 1.13 -0.42 ·~5. 297.35 m 3.55 3.53 4.06 1.30 2.08 0.37 2.00 5.37 7.35 10. 43,5 rn 7.15 7.92 2.48 .0.45 -1.3(] "6. 299.7 rn 9.91 2.47 -1.16 -0.17 11. 45.5 rn 5.9(] 6.33 6.46 1.80 2.28 0.38 0,98 0.97 0~52 87. 304.4 rn 3.80 4.52 4.69 1.?? 2.40 0.78 2.02 3.48 2.66 12. 47.5 m s.10 6.43 6.56 1.91 2.39 o.2e o.s2 o.a8 o.29 BB. 306.4 rn 8.88 2.85 -0.36 -1.55 13. 50.5 m 7.20 7.38 7.63 1.32 1.?1 0.23 1.16 1.02 0.63 9. 307.9 rn 8.35 7.94 3.63 -0.24 -1.67 14. 52.3 rn 6.50 6.75 6.96 1.?2 2.11 0.26 1.02 0.89 0.1? 90. 308.5 rn 3.50 4.82 4.62 2.35 3.03 0.80 1.70 3.65 1.13 15. 54.5 m 6.70 7.90 7.60 3.24 2.85 0.50 0.24 0.91 -1.08 91. 309.5m 3.95 5.28 5.13 2.34 2.86 0.76 1.50 2.21 0.88 16. 58.5 rn 7.10 7.30 7.46 1.28 1.65 0.27 1.21 1.08 1.11 17. 60,5 m 9.93 2.38 -1.01 -0.68 18. 62.5 m 9.37 2.42 -o. so -1.30 19. 65.5 rn 6.50 ? . 56 3.36 0.14 -1. ?0 20. 67.5 rn 3.30 5.75 5.25 4.38 3.95 0.73 0.74 0.65 -1.16 21. 70.5 rn 4.20 5.45 5.50 3.55 3.70 0.48 0.66 0.76 -1.07 22. 72.0 rn 3.35 3.35 3.74 1.28 1.97 0.34 3.08 3.61 9.25 23. 79.5 m 3.50 3.50 3.95 1.35 2.03 0.38 3.12 5.05 8.74 24. 82.5 rn 2.95 3.08 3.37 0.93 1.84 0.56 3.62 2.38 12.89 25. 84.5 rn 3.60 5.4? 5.17 3.25 3.45 0.76 1.14 1.09 -0.46 26. 87.5 rn 3.70 4.12 4.61 1.60 2.67 0.69 2.02 5.22 2.41 2?. 90.75 rn 4.60 6.73 6.21 3.74 3.30 0.75 0.79 0.71 -1.08 28. 96.5 m 3.45 5.42 4.86 3.25 3.30 0.81 1.34 2.12 0.07 29. 98.85 rn 3.05 4.33 4.33 2.31 3.10 0.83 1.72 2.83 1.24 30. 110.5 rn 7. 40 7.84 3.12 -0.11 -1.26 31. 113.75 rn 4. 40 5.97 5.98 2.9? 3.20 0.721 0.78 0.82 -0.86 32. 115.1 rn 4.35 s. 77 5. 74 3.34 3.50 o. 54 o. 71 0.90 -0.94 •t • ..------, 33. 119.8 rn 2~20 2.23 2.33 0.92 0.86 0.30 0.90 1.80 0.83 34. 120.95 rn 2.55 2.90 3.20 1.63 2.26 0.59 2.49 2.46 5.97 99+------~ 35. 124.2 rn 3.40 4.88 4.86 2.95 3.36 0.62 1.05 0.82 -0.30 36. 126.5 rn 5.25 6.62 6.42 4.15 3.92 0.45 0.29 0.69 -1.60 cri 37. 130.0 rn 6.00 7.02 6.70 3.99 3.56 0.36 0.28 0.73 -1.50 38. 132.5 m 3.60 5.43 4.75 3.31 3.02 0.73 1.40 1.87 0.60 39. 135.8 m 3.10 4.88 4.45 2.79 3.23 0.81 1.57 2.65 0.75 40. 139.5 rn 3.95 5.82 5.81 2.96 3.26 0.85 0.97 0.87 -0.76 41. 141.5 rn 3.70 3.85 4.26 1.33 2.11 0.61 2.80 6.28 6.87 42. 144.5 rn 6.90 7.93 7.69 3.24 2.84 0.45 0.22 0.85 -1.25 43. 149.1 m 7.70 8.02 2.35 0.38 -1.20 44. 150.0 rn 9.18 2. 75 -0.50 -1.49 45~ 154.0 rn 10.26 2.06 -1.20 -o. 2a 46. 154.65 rn 9.16 2.28 -o. 21 -1.50 47. 158.0 m 8.00 B. 48 2. 74 -0.01 -1 .69 48. 162.0 rn 9, 21 2. 76 -0.52 -1.49 49. 1'63.5 rn 9.19 2. 48 -0.31 -1.62 50. 164.25 7. 45 8.19 2.63 0.21 -1.55 51~ 17'2.5 rn 7. 65 B. 29 2. 55 o. 20 -1.53 52. 1?4.0 rn B. 75 8.89 2.68 -o. 23 -1.66 53. 176.9 rn 7. 55 8.34 2. 64 0.17 t-1.66 54. 178.0 rn 7. 95 B. 22 1. 95 o. 46 -o. 52 1 55. 178.5 rn 9. 79 2.15 -0.62 l -1.31 56. 182.0 rn 9. 00 9. 56 2.07 -0.42 I-1 .17 57. 186.0 rn 9. 91 2.31 -0.93 58. 190.0 111 9. 35 2. 58 -0.52 1 =~:~~ 59. 194.0 m 10.06 2. 22 -1 .11 60. 198.0 m 9. 86 2. 42 -0.99 !=~:~: 61. 202.0 rn 9. 76 2. 42 -0.84 1-1. DO 62. 210.0 rn 9.87 2.38 -o. 95 j-0. 77 i63. 214.0 m 9.99 2. 36 -1.09 1-o. 48 164. 218.0 rn 9.59 2. 43 -0.63 !-1.36 i 65. 222.0 rn 9. 53 2. 38 -0.54 i -1.41 166. 224.4 rn 8.60 B. 99 2. 41 i -0.12 l-1.63 !67. 226 rn 9. 42 2. 45 j -0.51 !-1.44 j68. 228.7 l'l 9. 77 2. 33 . J-0. 78 ! -1.03 69. 232.5 rn 9. 45 2. 50 j-O. 59 r -1.30 70. 235.8 rn 9. 43 2. 51 -o. 59 l-1. 30 1 239.7 rn 9. ?6 2. 24 -0.73 :-1 .04 1 Fig. 2.- Cumulative curves of the sediments ~:: 243.4 rn l 9. 07 2. 70 1-0.39 ! -1.55 73. 247.7 m from the Kallo Formation 1 ;,o. 26 2.10 J -1.37 1 o. 47 23 --.-,---, • 5 6 7 8 910 i 3 r-- 2 1-- 10 9 8 7 6 5 • 3 ~ 2 r-- 10 9 8 7 6 5 • 3 r-- 2 1- i 1 5 6 7 8 910 ~1 • _1 M in )Jm Fig. 3.- C/M diagram of the sediments from the Mont-Panisel Formation •t • .,------, 99+------~ 119-121 m (table 1 and Il, nrs. 33, 34) The fine sands are very poorly (34) or moderately sorted (33), and were deposited from a graded, moderate- (34) or high-turbulent sus pension (33) (fig. 3). Their cumulative curves show one saltation population (85-90 %), going at 3.2 cp over into a suspension population. The sediments were probably formed in shallow water along the coast under a unidi rectional current. 124-133 m (table 1 and Il, nrs. 35-38) Between coarse-silty, fine (35) and very fine sand (38), occur very-fine-silty, clayey, fine (36) or very fine sands (37). These sediments are ali extremely poorly sorted and were formed from a uniform suspension (fig. 3). They are composed of two saltation popula tions and a suspension population (fig. 4). The -2 -1 o .1 .2 .3 .4 .s .6 .7 .a sediments originated in a very-low-energy en Fig. 4.- Cumulative curves of the sediments from the Mont-Panisel Formation vironment, under influence of tidal currents. 24 ~ 4 5 6 7 8 910 1 2 1 3 ~ 5 6 7 8 910 2 1 3 5 6 7 8 910 2 1 3 2 1 3 4 5 6 7 8 910 1 1 1 ( 3 3 ·m - IX I I II 1-- 2 v 2 )lffi - 1- 1' 000 10 9 9 ~-'LH!_ v v v a- 8 7 ·- ·-- ·- ... 7 6 6 5 ---· / 5 4 v 4 1 •39 3 ·- C7 3 - ~ p ro· f-- 89 2-f--- 7 2 !!! • - 91. ,_... ,_ 82. ~J lOO l:/ 10 9 9 8-l-- 8 7- •86 88 7 6 v 6 5-1------v 5 1--;:i 43 sç ~ --- v 4 0 52 54. ~~~ 3-c----- 1/ 3 - f-- VI 2 - 1/ ~ •55 - 1- 1 1// 10 1 1 1 2 1 3 4 5 6 7 8 910 1 1 4 1 1 1 r 2 3 56789!00 2 3 4 5 6 7 9!000 2 1 3 ~ 5 6 7 8 9 10 M in )Jm Fig. 5.- C/M diagram of the sediments from the Egem, Ieper and Landen Formations F. EGEM FORMATION (133-144 m, table 1 and Il, nrs. 39-41) This member consists of very poorly sorted, 95+------+------~ very fine sand (41) at the base, passing into extremely-poorly sorted, coarse-silty, clayey, very fine sand (40) or fine sand (39). The sediments are deposited from a uniform suspension (fig. 5) and contain one traction, one saltation and one suspension population (fig. 6). The fine sand at the top originated from a graded, moderate turbulent suspension, with tw.o saltation popu lations and a suspension population. They seem to have formed along a low energy coast, with tidal influence during the deposition of the top of the member. G. IEPER FORMATION (144-284 m) 144-178 m (table 1 and li, nrs. 42-54) Most of these sediments consist of clayey, medium, fine or very fine silt, with some intercalation of very fine silty clay. They were ali formed from finest, uniform suspensions (fig. 5). Their cumulative curves show a saltation popula Fig. 6.- Cumulative curves of the sediments from the Egem, tion (40-1 0 %), which passes at 5-6 qJ in a Ieper and Landen Formations suspension population (fig. 6). 25 178-284 rn (table 1 and Il; nrs. 55-81) 2.- HEAVY-MINERAL DISTRIBUTION The sediments consist mostly on very-fine-to fine-silty clays, with a layer of clayey, very fine silt A. KAllO FORMATION (table Ill, nrs. 3-21) near 244 m. They were ali formed from finest The upper, sandy member S2 contains 56 % uniform suspensions (fig. 5). Their cumulative ubiquists on an average, with nearly 40 %zircon, curves contain a saltation population, which as the most important mineral, followed by rutile occupies less than 20 % of the whole curve and and tourmaline. Garnet accounts for 34 %, which passes, between 5 and 6 cp, into a whereas the content in parametamorphic mi suspension population (fig. 6). nerais and epîdote gets 5 %. The sediments of this clayey member were The percentage of the ubiquists reaches up to probably deposited on a flat part of the shelf, 71 % in the clayey members a 2 and a 1 of the under very quiet conditions. Kallo Formation : this is especially due to the Mont-Héribu Member increase of zircon, at the expense of garnet, (284-288 m, table 1 and Il, nr. 82) whose content drops to 17 %. 1;, The sediment is an extremely-poorly sorted, The Wemmel Member (table Ill, nr. 22) very-fine-sandy, clayey, coarse silt, originated contains very much ubiquists (91 %), with plenty from a graded, law-turbulent suspension (fig. 5). zircon; the remainder of the heavy-mineral The cumulative curve shows a saltation popula distribution is formed by parametamorphic mi tion (55 %), which passes at 4.2 cp into a nerais and garnet. suspension population (fig. 6). lt was probably formed in a low energy, protected environment B. MONT-PANISEL FORMATION near the coast. (table Ill, nr. 23-38) H. LANDEN FORMATION The heavy-mineral distribution is rather cons (288-311 m, table 1 and Il, nrs. 83-91) tant throughout the whole formation. ft is characterised by a preponderance of ubiquists, Knokke Member The base is formed by extremely-poorly sorted, Table Ill.- Heavy-mineral distribution sand or coarse-silty, very fine sand, very fine w w ~ w 2 w w w w m z ~ ~ deposited from a graded, law-turbulent suspen- ~ 210 ~ 2 m ~ w 0 ~ ~ 0 ~ U H w ~ 0 ~ z 2 0 ~ ~ ~ I ~ ~ ~ ~ ~ H ~ ~ ~ ~ ~ and 91 ). These sands ~ ~ "~ > ~ sion (fig. 5, samples 90 " ~ 0 ~ N ~ 2 m 0 ~ ~ ~ w 0 2 ~ "' conta in one saltation population and a suspension ·- ~ "' "' population (fig. 6) and might have been formed in '- 33.8 rn 48 3 40 13 3 33 8 distributary channels on a broad coastal plain. ... 34.8 m 50 3 45 10 4 32 5. .35 .35 rn 75 10 32 1 42 They pass into very-fine-sandy, very-fine-silty o. 36.8 rn 56 46 16 3 28 12. 47.5 rn 1 54 10 3 22 8 calcareous clay (sample 89 : 14.3 % CaC03 ) and 19. 65.5 rn 8 48 10 6 16 fine-silty clay (sample 88) covered by a shell bed. ~0. 67 .S rn 60 4 57 18 2 9 21. 70.5 rn 53 5 57 1 21 At 304.4 m a very-poorly sorted, coarse-silty, very ??. 72.0 rn 49 7 79 occurs, containing fragments of mol- ?.3. 79, ~ rn 56 4 73 11 1 7 fine sand ?4. 8::>.5 m 69 14 44 12 12 4 12 ?rJ. fuses ( 10.2% CaC03 ). This sandy unit (303-305 m) 84.5 rn 59 20 41 8 16 <'6. 87.5 rn 49 58 14 4 16 is aga in covered by very-fi ne-silty clay(sa mple 86). !'1, 90.75 m 45 2 72 8 1 12 The ela ys be long to the fin est uniform suspension ;.>CL 96.5 rn 61 15 24 14 1 15 18 ;.>'). 'J0.13~ rn 50 11 46 11 2 6 7 15 sediments (fig. 5); the fauna of the fossiliferous .HJ. 110.'1 rn n h 4fo 12 14 14 beds is brackish (see part Il) suggesting deposition 31. 11 J. 75 rn 4 61 13 5 10 32. 11 ?,1 m 3 53 13 4 18 in large shallow bays or lagoons. 33. 11'3. B rn 57 32 31 8 2 1 15 3 34. 120,95 m 39 26 32 11 1 14 5 The top of the Formation consists of poorly- 35. 124.2 rn 46 13 43 13 2 5 4 16 sorted, very fine to moderately-sorted, fine sand. 36. 12fi. 5 m 61 17 42 8 3 12 1 4 10 ~7. 130.0 rn 53 17 37 8 3 4 13 They are deposited from graded, low- or modera te- rn 3tl. 132.5 •• 11 38 10 2 6 18 turbulent suspension (fig. 5, samples 83, 84 and 59. 135.13 rn 58 36 38 11 6 40. 139.5 rn 72 6 36 12 5 31 85). Their cumulative curves show an important 41. 141.5 m 61 2 46 1U 6 28 saltation population, which at 3.3-4 cp passes into B?. 267.7 m n 13 20 7 5 20 4 12 fU. 290.7 rn 41 33 21 10 1 20 3 a suspension population (fig. 6). These sands seem l\4, 291.. 3 rn 63 20 26 1 12 11 to be formed in a more energetic littoral environ- 1\'). 2'J7, 35 m 60 21 26 2 1 10 16 10 ll'J. 304.4 rn 58 8 40 4 22 ment. 1111 •.Hlfl.4 m 93 6 51 8 1 6 12 I! which attain 70 % : zircon is the most important E. LANDEN FORMATION (table Ill, nrs. 83-90) mineral in this group, mostly followed by rutile and tourmaline. The ubiquists obtain 64 %, with a preponde rance of zircon, except for the top and the base of The parametamorphic mineFals fetch 14 %, the formation, where tourmaline dominates : with a domination of kyanite over staurolite. The rutile, anatase, brookite and sphene occur in gamet-content obtains 13 %, whereas epidote smaller quantities. The content in metamorphic accounts for the remaining part. minerais is 20 %, with more kyanite than ln the sandy part of this formation, at about staurolite. 120 m, the percentage of the parametamorphic Gamet is absent or nearly absent in the base minerais increases till 23 %, at the expense of and top-sample, but obtains 14% on an average gamet (4 %). in the other samples of the Landen Formation. There is still 3 % epidote and 2% amphibole in C. EGEM FORMATION (table Ill, nrs. 39-41) this lithostratigraphic unit, whereas chlorite only sporadically occurs. The heavy minerais of this sand contain 63 % The very high percentage of opaque grains in ubiquists, mostly zircon, with smaller quantities sample 88 is due to the presence of pyrite and of rutile and tourmaline, except for the top even larger amounts of iron sulphides are found sample, wherein equal quantities of zircon and in the samples 86 (299.7 m) and 91 (309.5 m). tourmaline occur. ln that last sample, gamet obtains only 6 %, in contrast with the 30% in the lower part of the sediments. The percentage of REFERENCES the parametamorphic minerais and of epidote stays constant, at respectively 13 and 2 %. DOEGLAS, D.J., 1946. Interpretation of the results of mechanical analyses. Jou rn. Sed. Petrol., 16 ( 1) : 19-40. DOEGLAS, D.J., 1947. De interpretatie van korrelgrootte-analysen. Verh.: Kon. Nederl. Geol Mijnbouw. Gen .. Geol. serie, XV : 247-328. O. IEPER FORMATION FOLK, R.L. & WARD, W.C., 1957. Brazos River Bar : a study in the significance of grain-size parameters. Journ. Sed. Petrol, 27 : 3-26. Mont-Héribu Member (table Ill, nr. 82) GEETS, S., 1978. De overgang leperiaan-Paniseliaan in de streek van The heavy-mineral distribution of this sedi Roeselare en Tielt. Natuurwet. Tijdschr .. 60 : 41-49. ment has the lowest amount of ubiquists in the PASSEGA, R. & BYRAMJEE, R., 1969. Grain-size image of clastic whole series of Tertiary deposits in this weil : deposits. Sedimentology, 13 : 233-252. 45%. Zircon re mains the most important mineral, SHEPARD, F.P., 1954. Nomenclature based on sand-silt-clay ratios. Journ. Sed. Petrol, 24 : 151-158. followed by tourmaline, rutile and anatase. ln the SINDOWSKI, K.H., 1957. Die synoptische Methode des Kornkurven group of parametamorphic minerais (14 %), Vergleiches zur Ausdeutung fossiler Sedimentationsraüme. Geol. Jb., staurolite dominates over kyanite. 73 : 235-275. Besides gamet (20 %) a nd epi dote (5 %), there is VISHER, G.S., 1969. Grain-size distributions and depositional pro cesses. Journ. Sed. Petrol.. 39: 1074-1106. a remarkable 4% of amphibole and an even more WENTWORTH, C.K., 1922. A scale of grade and class term for clastic remarkable 12 % of chlorite. sediments. Journ. Geol.. 30 : 377-392. 27 Chapitre Ill ETUDE DE LA SEDIMENTATION ARGILEUSE TERTIAIRE DU SONDAGE DE KNOKKE par M. MERCIER & Ch. DUPUIS Institut Jules Cornet - Faculté Polytechnique, Mons Les mineraux primaires (chlorite, illite), des semble-t-il, avec une augmentation progressive, traces d' édifices interstratifiés irréguliers (illite de bas en haut, de la taille du grain moyen des smectite [1 0-14s], chlorite-smectite [ 14c-14s]), la sédiments. smectite et la kaolinite, constituent la fraction Dans la zone 1, la somme des minéraux argileuse des sédiments tertiaires du sondage de primaires et de la kaolinite domine, et aux Knokke. poussées des premiers correspondent des pous sées de la seconde. Parmi ces maxima, deux sont 1. DESCRIPTIONS DES RESULTATS nettement plus accusés, l'un à la base de la {fig. 1) Formation, l'autre au sommet. Les états de la chlorite et de l'illite sont très bons. A. FORMATION DE LANDEN. La zone Il, plus silteuse, enregistre le déclin des La base sableuse de la formation est marquée minéraux primaires et de la kaolinite dont les par une arrivée brutale de kaolinite qui passe de teneurs varient peu. Les interstratifiés ont 37% (-310m) à 94% (-308m). A -310m, les disparus. La cristallinité de l'illite est inchangée autres minéraux de la fraction argileuse sont la par rapport à la zone 1 (même valeur moyenne chlorite (3 %), l'illite (25 %) et la smectite (35 %). A 4,2 mm) en revanche l'état cristallin de la smectite -308 m, seules quelques traces d'illite et de s'améliore (9° en moyenne au lieu de 21 °). smectite accompagnent la kaolinite. La zone Ill, avec la disparition quasi-totale du Dès que l'on aborde les niveaux argileux sus couple chlorite-kaolinite et la faible représentation jacents, la smectite (55%) domine la kaolinite qui de l'illite, est surtout smectitique. chute, sur une dizaine de centimètres, de 94 à 7%. La chlorite (C) apparaît en quantité notable (12 %) avec l'illite (1 = 26 %). Le reste de la Formation est C. LA FORMATION DU MONT-PANISEL, dominé par les minéraux primaires (C = 14%,1 = LES SABLES DE BRUXELLES ET DE 28 %) qui précèdent la smectite (44 %) et la WEMMEL ET LA FORMATION DE KALLO kaolinite (11 %); des traces de minéraux interstra tifiés irréguliers [1 0-14s] et [14c-14s] font leur Les sédiments sableux compris entre -116 et apparition. -124m ressemblent aux Sables de Bruxelles reconnus dans d'autres sondages, à Mol par L'état cristallin des minéraux, chlorite, illite et exemple. Ils~ se singularisent par une légère smectite est bon en général. Quartz et feldspaths poussée des minéraux primaires sans a~menta sont présents. tion significative de la kaolinite ni présence d'i nteq>tratifiés. B. LES FORMATIONS D'EGEM ET D'YPRES Le reste de la Formation du Mont-Panisel (-80 à Les Formations d'Egem et d'Ypres se sub -105 m) est essentiellement smectitite et illitique. divisent en trois zones minéralogiques caractéri La chlorite ne fait sa réapparition que vers le sées par la diminution des minéraux primaires et passage à la Formation de Lede. Au même niveau, de la kaolinite au profit de la smectite. La figure 2, une légère progression de l'illite amorce l'impor reprenant par zones les teneurs moyennes des tante modification qui va affecter la base de la différentes espèces minérales, schématise le formation de Kallo. En effet, dès l'Argile d'Asse (a), caractère saccadé de l'évolution. Celle-ci coïncide, les minéraux primaires augmentent rapidement 28 jusqu'à 40% en même temps que la kaolinite frôle saccadé des apports de chlorite et d'illite les 20%. Le sédiment est très glauconieux, suggèrent une certaine instabilité tectonique des cependant, le rapport 1002/1 001 de l'illite oscillant zones continentales amont. Par ailleurs, on autour de 4 indique l'absence d'illite glauconitique remarque la qualité de la corrélation qui relie les dans la fraction fine. Chlorite, illite et smectite sont pourcentages de chlorite et de kaolinite (fig. 3). bien cristallisées. Connaissar.~t la plus grande vulnérabilité du Au dessus, minéraux primaires et kaolinite premier minéral par rapport au second, on est retrouvent des pourcentages faibles (25 et 5% amené à imaginer un enchaînement très rapide, respective ment). de l'érosion qui les libère des roches et des sols, de leur transit et de leur enfouissement. Les deux poussées du couple minéraux 2.- INTERPRETATION primaires-kaolinite à la base et au sommet de la Formation peuvent être considérés comme deux La diversité et la permanence de la composition phases d'érosion continentale plus importantes. minéralogique, dans une large mesure indépen La première se retrouve dans les deux sondages de dante de la lithplogie ou de la profondeur, Mol et de Kallo. La seconde trouve probablement indiquent l'origine détritique du cortège argileux. un écho à Kallo, mais n'est pas décelable à Mol situé plus à l'Est (MERCIER, en préparation). Cette A. LA FORMATION DE LANDEN. diminution progressive d'Ouest en Est, des quantités de minéraux primaires et de kaolinite La Formation de Landen, probablement in implique d'une part, un approvrs10nnement complète, est très réduite en épaisseur (23 m). Ses occidental et d'autre part, l'intervention d'une caractères lithologiques traduisent un milieu floculation sélective par rapport à la smectite littoral. Sa partie supérieur, de type lagunaire est à (GIBBS, 1977).11 est remarquable de constater que rapprocher de certains faciès du sparnacien du de tels phénomènes ne se manifestent pas lors de Bassin de Paris (DU PUIS et al., ce mémoire). la première poussée. En effet, les pourcentages de La fraction fine, riche en minéraux primaires minéraux primaires et de kaolinite restent voisins (C=13 %,1=27 %) corrobore ce caractère littoral. La sur l'ensemble du Bassin belge. La cause de la fraction smectitique proviendrait de l'érosion des première reprise d'érosion semble donc avoir un sols formés dans les régions aval mal drainées et caractère plus général. Elle peut être mise en peu accidentées. La kaolinite exprimerait la relation avec l'histoire géodynamique de l'Atlan contribution des amonts au relief plus accusé et tique Nord. Vers la base de I'Eocène a lieu la bien drainé. Si elle n'est pas héritée de séparation du Groenland et du Plateau de Rockall. pédogenèses plus anciennes, sa présence témoi De nombreuses éruptions volcaniques qui mon gnerait de l'établissement d'un climat chaud à trent que ces mouvements affectent nos régions, humidité constante. se produisent alors en Grande-Bretagne et en Mer du Nord (JACQUE & THOUVENIN, 1975; KNOX & Remarque: ELLISON, 1979). L'anomalie en kaolinite du niveau sableux de la L'arrivée de détritiques provenant probable base de la formation de Landen ne peut pas être ment de l'Ouest ne se conçoit que si aucune interprétée en terme de paléoenvironnement en barrière s'oppose à leur passage. Or, il est raison de son lien étroit avec un changement traditionnel de considérer que I'«Axe de l'Artois» lithologique. est émergé à I'Yprésien inférieur. Les données de la minéralogie des argiles tendent ainsi à B. LES FORMATIONS D'EGEM ET D'YPRES confirmer les résultats récents qui minimisent le Dans la Formation d'Ypres, les changements rôle du horst de l'Artois (DUPUIS et al., 1984). Le de la minéralogie des argiles se moulent sur les Sud du Bassin de la Mer du Nord aurait été en évolutions de la lithologie (fig. 2).Dans la zone 1, communication avec le Bassin du Hampshire, l'abondance de minéraux primaires et de kaolinite, relais possible dans le transit des minéraux la coïncidence de leurs maxima et le caractère primaires et de la kaolinite (MERCIER. 1986). Fig. 1.- Minéralogie des argiles du sondage de Knokke. De gauche à droite, colonne lithostratigraphique, composition estimée de la fraction argileuse(< 2pm), rapport 1002-1 001 et cristallinité de l'illite, cristallinité de la smectite. Clay mineralogy of the Knokke borehole. From left to right, lithostratigraphic column, estimated composition of the clay fraction(< 2pm), 1002-1001 ratio and cristallinity of the illite, smectite cristallinity. 29 Ch lori te Kaolinite Illite Smectite QUATERNARY -~-- KALLO 50 Fm. 1iasëa1 Wirü"niel sands? BRUSSEL Fm. ___ PA NI SEL 100 - Fm. ? -Pim- EGEM Fm. ZONE III . . 150 - ZONE II 200- IEPER Fm. ZONE I 250 - 300 - LANDEN Fm. 320- CRETACEOUS M. MERCIER et Ch. OUPUIS (1984 J 30 % Chlorite 20 z 0 i= • Chlorite <( L: a:: 0Illite 0 0 • IL D lnterst. mins. 10 . . Sm edite • a:: ITIIlJ w •• a.. ~ Kaolinite w- R = 0,86 0 10 20% Kaolinite Fig. 2.- Composition minéralogique moyenne des Fig. 3.- Diagramme kaolinite-chlorite pour la zone 1 trois zones de la Formation d'Ypres. de la Formation d'Ypres. Mean mineralogical composition of the three Kaolinite-chlorite diagram for the zone 1 zones of the Ieper Formation. of the Ieper Formation. Dans les zones Il et Ill, le cortège argileux qui C. lA FORMATION DE KAllO. s'appauvrit graduellement en minéraux primaires et en kaolinite et devient plus homogène, fai~ Dans l'Argile d'Asse (a), la composition des d'abord songer au rétablissement d'une certaine argiles change à nouveau. La kaolinite réapparaît stabilité tectonique. Une telle intervention paraît avec les minéraux primaires et les interstratifiés peu conciliable avec la nature de plus en plus qui prennent le pas sur la smectite. Ce sableuse des sédiments. En revanche, l'augmen changement qui se retrouve avec la même tation de la teneur en smectite dont la cristallinité ampleur à Kallo et à Mol, résulterait d'un s'améliore, s'expliquerait bien par une migration phénomène d'ordre tectonique. La présence de de l'instabilité tectonique vers les zones littorales. kaolinite reflète la participation des zones Ce sont alors des sols riches en smectite bien continentales amont, probablement l'Ardenne cristallisée qui sont érodés. En outre, la présencè (MERCIER, en préparation). de minéraux fibreux (± 5 %) dans la Formation Au dessus de l'Argile d'Asse, la nature des d'Ypres du sondage de Mol est en accord avec argiles, indique le retour à un certain calme cette interprétation. Les bassins semi-clos et tectonique. La smectite bien cristallisée y témoi confinés où est susceptible de se former ce type de gne d'un climat chaud à humidité saisonnière minéraux argileux, occupenttoujours une position contrastée. L'absence des terrains sus-jacents ne bordière par rapport aux terres émergées. Une permet pas de saisir l'évolution du cortège argileux telle instabilité des marges ardenno-rhénanes qui marque la dégradation climatique du début de préfigure celle, qui à I'Eocène moyen, va conduire l'Oligocène (QUINIF et al., 1983). à l'émersion du horst de l'Artois (POMEROL, D'une façon générale, la sédimentation ar 1973). On ne trouve pourtant qu'un écho très gileuse du sondage de Knokke paraît plus marquée assourdi de ces mouvements dans le cortège par les événements d'ordre tectonique que .par les argileux sous la forme d'une légère progression de phénomènes d'origine climatique. L'abondance de la chlorite et de l'illite à la base de la formation du la smectite bien cristallisée suggère la prépon Panisel. L'abondance de la glauconie et le dérance d'un climat chaud à humidité contrastée. caractère très grossier de ces dépôts sableux Cependant, des périodes à humidité plus cons soulignent aussi leur caractère littoral et peu tante, favorables à la formation de la kaolinite, ont profond. dû exister à la fin de I'Eocène inférieur et à I'Eocène moyen (QUINIF et al., 1983). 31 REFERENCES Europe. Vol. 1, Geology, Applied Scit3nce Publishers Ltd, The lnstitute of Petroleum, Great Britain : 455-465. KNOX, R.W. O'B.& ELU SON, R.A., 1979. A lower eocene ash sequence DU PUIS, Ch., DE CONINCK, J. & ROCHE, E., 1984. Remise en cause du in SE England.Journa/Geol. Soc. of London, 136:251-253. rôle paléogéographique du horst de l'Artois à I'Yprésien inférieur. Mise MERCIER, M., 1986. Etude de la sédimentation argileuse tertiaire dans en évidence de l'intervention du Môle transverse Bray-Artois. C.R. Acad. le Bassin belge, le Nord de la France et le Bassin du Hampshire. Sc. Paris, 288, Il (2) : 53-56. Comparaison avec le domaine atlantique Nord. Doctorat de 3è cycle, DUPUIS, Ch. (coord.), DE CONINCK, J., GUERNET, C. & ROCHE, E., Lille. 1985.- Biostratigraphic data - Ostracods and organic walled micro POMEROL, C., 1973. Stratigraphie et Paléogéographie - Ere Céno fossils of the Landen Formation and the base of Ieper Formation in the zoïque. Do in, Paris, 267 p. Knokke borehole (this issue). QUINIF, Y., MERCIER, M., ROCHE, E. & DUPUIS, Ch. (coord.), 1983. GIBBS, R.J., 1977. Clay mineral segregation in the marine environ Essai de reconstitution géodynamique du Paléogène du Bassin belge à ment. J. Sedim. Petr., 47 (1): 237-243. partir des données de la minéralogie des argiles, de la géochimie des JACQUE, M. & THOUVENIN, J., 1975. Lower tertiary tuffs and volcanic radioéléments (U, Th, K20) et de la palynologie. C.R. Ac ad. Sc. Paris, 296, activity in the North Sea. Petroleum and the continental shelf of NW Il: 1621-1624. 33 Chapter IV BIOSTRATIGRAPHIC DATA - OSTRACODS AND ORGANIC WALLED MICROFOSSILS - OF THE LANDEN FORMATION AND THE BASE OF THE IEPER FORMATION IN THE KNOKKE BOREHOLE by Ch. DUPUIS Faculté Polytechnique de Mons J. DE CONINCK Geologisch lnstituut, Rijksuniversiteit Gent C. GUERNET Laboratoire de Géologie des Bassins Sédimentaires Université Pierre et Marie Curie, Paris VI E. ROCHE Musée Royal d'Afrique Centrale, Tervuren INTRODUCTION boreholes (DE CONINCK, 1975). They belong in part to the W. astra zone at Newhaven (DUPUIS Sorne strata attributed to the «upper Lan and GRUAS-CAVAGNETTO, 1985) and at St. denian» show a strikking similaritywiththe«upper Josse-St Aubin (DUPUIS et al., 1984). They are Sparnacian» of the Paris basin. The diagnostic probably situated in the W. meckelfeldensis zone facies is an alternation of grey clays, silts and/or at Lihons towards the Paris Basin heart (1 ). sands associated with brackish coquina con The today Cyrena brackisp layers distribution taining among others, Cyrena, Tympanotonos, is partly the expression of the existence of two Unio (LERICHE, 1899, 1929; FEUGUEUR, 1 055) basins separated by an Artois-Brabant high which and with sorne oysters limestones. vanished afterwards at the transgression maxi These layers are comparable, for instance, to mum (fig. 2). From the lithologie point of view, the the Woolwich Shell Beds (DUPUIS & GRUAS upper Landen Formation and the base of the Ieper CAVAGNETTO, 1985), the Argile de Saint Aubin Formation are readily related to the transgressive (DUPUIS et al., 1984), the Sables et Argiles à sequence elsewhere identified. Mollusques et Ostracodes (BIGNOT, 1973). They ln the Knokke borehole the silty clays with are transgressive on the underlying arenaceous several shell fragment zones (-297 m to -303 m) regressive complex (BROECKMAN, 1978; DU PUIS and a compact fossillevel- an oysters limestone et al., 1982) usually attributed to the «middle and (-303 m) are indentical in many aspects with the lower Landenian», to the «Thanetian» or to the brackish deposits of the «Upper Sparnacian». The Woolwich Marine Beds and the Thanet Beds. similarity is confirmed by a cursory examination Higher up the transgressive sequence comprises of the malacologie fau na which gave for instance: coastal sands and/or pebbles (Sables à Galets du Cyrena cuneiformis FER. and Planorbis cf sub Mont-Hulin, DUPUIS in ROBASZYNSKI et al., ovatus DESH. between -299.28 m and -299.31 m 1981, for instance) and then marine clays, silts · Ostrea bellovacensis LAMK. and Tympanotonos and sands such as the Ieper Formation and the London Clay. South of the North Sea Basin, the dinoflagellate zonation allows to establish the (1) At Lihons, the Cyrena cuneiformis-bearing brackish slight diachronism of the transgression (fig. 1 ). layers lie on lacustrine limestones and maris concealing a ln fact, the Cyrena brackish layers belong to charophyta flora of the Peckichara piveteaui zone which is correlated with the W. meckelfeldensis zone in the Lower the A. hyperacanthum zone in the London Basin Ypresian (DU PUIS in ROBASZYNSKI et al., 1981; RIVEL! NE, {KING, 1981 ), in Knokke (this work) a nd Ka llo 1984 and DU PUIS et al., 1986). 34 Dinof lage l. Zonation 1 WOOLWICH OLDHAVEN OJ 0 LONDON CLAY- Div. A )> BEDS FORMATION (/) z 0 z 0 z ) ) ) ) )l A (/) ) ) ) ) l) z: )l ) ) 0 oz ; ; ) ) ) l ) l A ) ) co ) ) ; ) ) ) A 1 m -i:::O 1 w N' I-i C> oo: :::r: C> LT1 1 ·~"1 1 OJ(/) 1 1 rn A Cl )> )> :::r: 1 1 -i 0 ' w 1 CXl C> ::,·~ :lll ,' ""'\J -... ' , 1 ::;:,.. ' 1 • ' ' , , . .lb z: ' ;::, m :::r: ~ )> :::r: :::. )> 3: < -u ,, ~ m (/) 1 ~· z: , , , lb :::r: ,, :::0 1 rn V1...... Vl...... l ) ) l l ) ) ...._ l ) l ', )> .·.·. l ) l ) -u ) l J ., c 0 ) l l ) l CD Vl )> ) ) l ) ) l ) Vl ) ) l ) ) z: m :::0 1 (/) OJ )> 1 (/) :::r: - 0 :z: z: V1 1 1 1 (Il ::r 0 ro -(Il Charophyt. ~ Peckichara Peckichara (Il (Il 0 disermas piveteaui Zonation !iï Fig. 1.- Relations between the regressive (arenaceous camp/ex= «Thanétien», Woolwich Marine Beds, ... ) and the transgressive facies (brackish facies= «upper Sparnacian», «upper Landenian», Woolwich Beds; coastal and then marine facies: London Clay, Ieper Clay, ... )a round the Paleocene-Eocene limit in the southern North Sea, the Hampshire and NW Paris Basin. 35 Woolw. Beds, ' .... -·'' 1 ,~ and upper NORTH SEA "Sparnacian., ~ Reading Beds ---and assimilated Ypresian Form. SOUTH limits. BIGHT .,.?/- / 0 150Km Fig. 2.- Extensions of brackish («upper Sparnacian», «Upper Landenian», Woolwich Beds) and marine facies (Ypresian formations: London Clay, Ieper Clay, ... ) of the Landenian transgressive facies. Related and presumably related continental deposits ' are indicated (Reading Beds and assimilated Formations) funatus MANTEL at -300.15 m; T. funatus var. 1.- OSTRACODS FAUNA. cossmani M. CH. between -307.4 m and -307.5 m COMPARISON WITH THE (determination of M. PERREAU, Paris). The PARIS BASIN following study of the Ostracods extracted from the «Upper Landenian» in the Knokke and Kallo The «Upper Landenian» from the wells of boreholes, supports such an equivalence. Knokke and Kallo has delivered Ostracods The fine weil sorted sands (median = 114 to assemblages (Plate 1 and fig. 3) more or less rich in 145pm ; sorting coefficient, Qdcp = .13 to .33) specimens but poorly diversified, as usual in fou nd in the Knokke borehole between -288 and- brackish environments. They are nevertheless 297 m represent the coastal deposit which pre typical, in the Paris Basin of the «Upper cedes the marine facies appearance of the Ieper Sparnacian» sands and ligneous clays with Formation. The chronostratigraphic situation of oysters, Cyrena, Tympanotonos and so on, of this appearance has been specified by the study Epernay («Mont Bernon», ... ), Reims, Soissons, of the dinoflagellates and sporomorphs contained Mantes,... (APOSTOLESCU, 1956; GUER NET, in eleven palynologie samples. 1981 ). They are indeed composed of the following species: 36 fluctuations (the influence of other environ mental UJ N 0 ~ _J "' Ln parameters such as depth, turbulency and tem ~ Table 1.- The Phytoplankton in the Knokke borehole e e e e e e e e e 0 0) 0 r;:; 0 0 0 0 0 ~ "! "'~ "!. q_ '": "!. 0 0 0) ,... 0 0 0) 0) 0) r;:; "'M M "' "' "" "'1 1 1 1 1 "'1 "'1 "' "' '1' "' e e e 0 0"' 0"' 0"' 0"' 0)"' 0 0"' 0"' 0"' 0"' \0 ~ Phytoplancton "'! a;. ~ "':. \0 "':. ~ q_ 0 "' ,... è r--"' r-- ..; "' 0 0 0 0) 0) 0) 0) r;:; M"' "'M M M"' "' "' 1 1 1 1 "'1 "'1 "'1 "'1 1 1 1 1 - Bacillariophyceae "' "' "' "' "' "' "' pyritised centric diatans ------'------F - Chlorophyceae Paralecaniella indentata (DEFLI\NDRE & axJKSJN 1955) ------s ff FF F f s Pediastrum sp. ------s f - Dinophyceae Achanosphaera alcicornu (EISENACK 1954) ------ s s s Achanosphaera spp. indet. ------ff f s ff ff ff .1\dnatosphaeridium multispinosum (WILLil\MS & in'INIE 1966) ------ s s Alisocysta margarita (HARLIIND 19.79) --,------ s f Apectodinium haocm:>rphum (DEFLIINDRE & axJKSJN 1955) ------ x F s ff F FF F ff A. hyperacanthum (axlKSJN & EISENACK 1965) ------ ? ? s s A. paniculatum (COSTA & DOWNIE 1976) ------? s A. parvum (ALBERTI 1961 ) ------x x F ff f f f s A. quinquelatum (WILLil\MS & DOWNIE 1966) ------ s f ? s s A. sumisuum (HARLIIND 1979) ------ ? Apteodinium granulatum (EISENACK 1958) ------~------s Apteodinium sp. indet. ------s s s s Areoligera coronata (O. WETZEL 1933) ------ s A. Coronata ? (O. WETZEL 1933) ------ s A. senonensis (LEJEUNE-cARPENI'IER 1938) ------ s s Areoligeraceae sp. 1 in Gruas (CAVAGNETTO 1976) ------ x f Ceratiopsis depressa (MJRGENROI'II 1966) ------s s Cordosphaeridium exilimurum (DAVEY & WILLil\MS 1966) ------ s c. firbrospinosum (DAVEY & WILLil\MS 1966) ------ s C. gracile (EISENACK 1954) ------ s s s f C. inodes (KL\JiolPP 1953) ------ f f f f f ff f s C. ? minimum (MJRGENROI'II 1966) ------ i s Cribaperidinium giuseppei (MORGENROI'II 1966) ------ ' s Cyclonephelium hystrix (EISENACK 1958) ------ s ? Dapsilidinium ? langii (WALL 1965) ------·------ f Deflandrea denticulata (ALBERTI 1959) ------s s s 0. cf. denticulata (ALBERTI 1959) ------'------f s 0. oebisfeldensis (?) (ALBERTI 1959) ------ s s f f f s Dinopterygium cladoides (DEFIJINDRE 1935) ------ s s s s Diphyes colligerum (DEFLANDRE & axlKSON 1955) ------ f s s f s s Eocladopyxis hispida (DE CDNINCK 1969) ------ s s s E. peniculata (MORGENROI'II 1966) ------ s ff s s E. aff. peniculata (MJRGENROI'II 1966) ------ x f f ff Exochosphaeridium phragmites (DAVEY, DOWNIE, SARJEANT, WILLil\MS 1966)--- s Fibrocysta aff. axialis fEISENACK 1965) ------ f F. bipolaris (axlKSON & EISENACK 1965) ------ ? s ? ? Gerdiocysta cassicula (DRUGG 1970) ------ s Glaphyrocysta divariacata (WILLil\MS & DOWNIE 1966) ------ s s f f s G. exuberans (DEFLANDRE & axlKSON 1955) ------ s G. ordinata (WILLil\MS & DOWNIE 1966) ------ s f s G. pastielsii (DEFLIINDRE & axlKSJN 1955) ------s 38 e e e e e e e e e 0 co 0 0 0 0 0 3. "! ": "2. "''-';. M ":. 0 '": N 0 0 co r-- 0 0 co co !X) ;;; "'M M "'N "'N N N N "'N 1 1 "'1 "'1 "'1 1 1 1 e e e 0 0"' 0"' 0"' 0"' co"' 0 0"' 0"' 0"' 0"' \0 M ~ ": "':. '-';. ":. '": "! ~ ":. 0 "'r-- 0 "'r-- r-- ..; N 0 0 0 G\ G\ G\ co !X) co !X) ;;; "'M "'M M "'M "'N N N N N N N 1 1 1 1 1 1 "'1 1 1 1 1 1 G. aff. reticulosa (GERLACH 1961 ) _------ s s ff s G. ? sp. cf. Eatonicysta ursulae (MJRGENRarH 1966) ------ s G. sp. aff. G. ordinata (WILLIAMS & IXJWNIE 1966) G. Divaricata ------ Glyphancdinium facetum (DRUGG 1964) ------ s s f s Gonyaulacysta jurassica (DEFLANDRE 1938) ------ s Gonyaulacystaceae spp. indet. ------f s s s f Hanotryblium sp. indet. ------x F F F FF f f Hystrichokolpana unispinum (WILLIAMS & IXJWNIE 1966) ------ s ? Hystrichosphaeridium latirictum (DAVEY & WILLIAMS 1966) ------ s H. tubiferum (EHRENBERG 1838) ------ s s f ff s ? Hystichosphaerina schindewolfii (ALBERT 1961 ) ------ s Impagidinium victorianum (OOOKSON & EISENACK 1965) ------ s s Impagidinium sp. indet. ------ s Irnpletosphaeridium implicatum (MJRGENRal'H 1966) ------ s f Kallosphaeridium orchiesense (DE CONINCK 1976) ------ s ? Kenleyia lophophora (OOOKSON & EISENACK 1965) ------ x f K. pachycerata (OOOKSON & EISENACK 1965) ------ s Lejeunecysta hyalina (GERLACH 1961 ) ------ s ? Lejeunecysta ? sp. indet. ------ s Lentinia wetzelii (MJRGENRarH 1966) ------ s f s Leptcdinium subtile (KLEMENT 1960) ------ s Lingulcdinium machaerophorum (DEFLANDRE & OOOKSON 1955) ------ f f ff ff f f s s Melitasphaeridium pseudorecurvatum (MJRGENRal'H 1966) ------ s s Membranilarnacia minuta (DE CONINCK 1969) ------~---- s Micrcdinium ornatum ? ( OOOKSON & EISENACK 1960) ------s ~1. aff. reticulatum (VOZZHENNIKOVA 1967) ------ f f Muratcdinium fimbriatum (OOOKSON .& EISENACK 1-967) ------ f f f Nematosphaeropsis reticulensis (PASTIELS 1948) ------ s f s Odontochitinopsis , sp. A in DE Wetzeliella meckelfeldensis (GOC!fl' 1969) ------7 ------s - Prasinophyceae Cymatiosphaera aff. punctifera (DEFLANDRE & OOOKSON 1955) ------ s Pterospermella hartii (SARJEANT 1960) ------s - Acritarcha Baltisphaeridium ligospinosum (DE working paper of the I.G.C.P. project 124, COSTA Knokke -297.4 m (1981) points out the presence of the first H. One slide. About fifteen species. A. homo tenuispinosum DAVEY & WILLIAMS, 1966 in the morphum is very abundant, reaching nearly40%. A. hyperacanthum zone. ln the Newhaven out Para/ecaniel/a indentata and Spiniferites spp. crop, a form intermediary between H. tenui reach between 15 and 20%. A. parvum and spinosum and H. tasmaniense COOKSON & Lingulodinium machaerophorum appear regu E!SENACK, 1967, is known in the Woolwich Beds larly, é'ttaining about 5%. (DUPUIS & GRUAS-CAVAGNETIO, 1985). H. tasmaniense itself was described in Upper Pa Knokke -290.1 to -290,2 m leocene deposits in Tasmania (Australia). One slide. Few fossils and a very poor Knokke -305.8 to 305.88 m. assemblage in which only Spiniferites spp. and Para/ecaniella lndentata, have been observed. Two slides. About twenty five species of Apart from these phytoplankton species, we find phytoplankton.Homotryblium sp. and Apectodi sorne pyritized frustules and valve fragments of nium homorphum dominate. Spiniferites spp. and centric diatoms. Achomosphaera spp. appear frequently. Poly sphaeridium zoharyii, 'Eocladopyxis aff. peniculata Knokke -287.9 to 288 m and Areoligeraceae sp. 1 (GRUAS CAVAGNETIO, Two slides. The number of phytoplankton 1976) are found regularly. A few specimens of species attains about thirty. P. indentata (20%), Muratodinium tibriatum, Phthanoperidinium cre Spiniferites spp. (20 %), A. homomorphum (20 %) nulatum (Ginginodinium crenulatum in table 1) are the most frequent ones. Cordosphaeridium and Apectodinium quinquelatum have been inodes, Eocladopyxis peniculatum, L. machaero e~countered together with one form which phorum and Operculodinium centrocarpum are resembles Eatonicysta ursulae (which appears less weil represented (between 5 and 10 %). A. higher in the Ieper Formation) and which can be parvum and Homotryblium sp. are rare. Five compared with «Cyclonephe/ium conopium» reco forms seem reworked from the Mezosoic. vered in the < Remark : A. quinque/atum ressembles to Wetze One slide. About forty species. The assem liella astra but is smaller and its endophragm blage is dominated by Spiniferites spp. (about remains in contact with the ectophragm except 25 %), followed by lmpletosphaeridium ligospi under the processes and weakly developed horns. nosum (Baltisphaeridium /igospinosum in table 1 ) These characteristics allow to distinguish A. (about 15 %), and Achomosphaera spp. (about quinque/atum from W. astra. 10 %), A. homomorphum has disappeared. De f/andrea oebisfeldensis (?) remains rather fre Knokke -299.28 to -299.31 m quent as at 287 m. One specimen of Pseudomasia Four slides. The assemblage counts about trinema, index species of the lower Ypresian, has fifteen species. ln decreasing abundance arder, been found. Five individuals are tentatively we find : Homotryblium sp. followed by A. classified as Achomosphaera, three as A. parvum homomorphum, Tha/assiphora patu/a-pe/agica and one as A. quinquelatum. and Lingulodinium machaerophorum; finally A. Remark : A. paniculatum shows characteristics parvum, Spiniferites spp. and Polysphaeridium tending towards those of the genus Wetzel/iella zoharyii. which is nevertheless not yet present. 40 DINOFLAG. ZONES heavy clay 28~01 ~ __tl! ______------~ - a..wu 1 UJ 1 silty clay ...... 1 • 1 290 ·. ·. ·. • -·.·. ·.·:.- A. hyperac. fine sand ' ~ ' 0::: '' 0 .' silty clay with, LL shellfrag.zones 7 7 7 "Cyrena clay, 7 - fine clayey sand . with ' s1lty clay '' '1 '1 ' 1 1 1 1 1 1 claye y sand 310 V) W. astra E forerunners? '- chalk 1 1 1 1 1 .E f\.. ~~~~nf~~~- ·~ frequent ~ enougt freq. ~ sporadic -o present ~ '- ~ 0 ~ QJ 0:: Fig. 4. Distribution and abundance of sorne phytoplankton species, diatoms and reworked mesozoic forms. lnferred Dinoflagellate zonation Knokke -282.18 to -282.26 rn Knokke boreale as follows: Apectodinium parvum Two slides. About forty five species. Spini and A. homomorphum dominate the lower ar ferites spp. are the most abundant with approxi gillaceous part of the Landen Formation. ln the mately 40%. Achomosphaera spp., Baltisphaeri upper part of this unit (top of the «Cyr ena Clay») A. dium ligospinosum, lmp/etosphaeridium ligospi homomorphum supplants A. parvum. ln the nosum and Comasphaeridium cometes reach sandy, uppermost part of the Landen Formation, 10%. One specimen of Kallosphaeridium archie microfossils are very scarce, but the presence of sense has been observed. Apectodinium spp. are sorne valves and nu merous fragments of pyritized absent, except one specimen being close to A. centric diatoms suggests a correlation with the hyperacanthum. Two specimens of Wetzelie/la volcanic ash layers observed in the North Sea have been found; the first belongs to W. meckel Basin, and of which the lower levels are situated feldensis, the second ressembles it but differs by in the A. hypercanthum zone (KING, 1981, the two antapical horns which are of more or less p. 131 ). equal length. Five forms are probably reworked ln -287.9 to 288 m, at the base of the Ieper from Mesozoic. Formation, the number of species increases considerably and the Spiniferites spp. come to the 2) Comments (J. DE CONINCK & Ch. DUPUIS) foreground. Nevertheless, sorne of the main We can outline the assemblages evolution of species which characterize the «Landenian>> beds, the «Landenian» and «Ypresian» levels in the namely Paralecaniella indentata and A. homo- 41 morphum remain weil represented in this lower - Subtriporopol/enites magnoporatus tectopsi/a- most «Ypresian» assemblage in which Homotry tus (37), blium sp. appears a last time. - Subtriporopollenites spissoexinus (38), Between -287 to 287.1 and -282.26 m P. - lntratriporopo/lenites microinstructus (43), indentata and A. homomorphum seem to dis - Striatriopollenites longostriatus (62). appear butA. hyperacanthum and A. paniculatum are present. Since -287 m, characteristic forms of the Yc appear: At -282.26 m Wetzeliel/a meckelfeldensis arrives for the first time in the assemblage which - Caryapollenites circulus (41 ), has now a pronounced «Ypresian» character. - Triatriopollenites myricoides (28), - Triatriopol/enites plicatus (29), ln none of the slides we have found true W. - Clavatrico/porites iliacus (63), astra, but forms very close to it are present such - Retitricolporites o/eides (59). as A. paniculatum, A. quinquelatum and A. hyperacanthum. These three species are found The Normapolles which normally continue together between -287 and -282 ril. ln this part of above the L are a Iso present: the traject they a;e accompanied by a slight 2 increase of the frequency of Deflandrea oebis - Plicapollis pseudoexce/sus (22), fe/densis (?) which can probably be correlated - Pompeckjoidaepol/enites subhercynicus (19) with the acme zone of this species at the top of - lnterpol/is supplingensis (21) the A. hyperacanthum zone and just below the W. - Nudopollis endangÙ/atus (20) astra zone (KNOX & HARLAND, 1979; HEIL MANN-CLAUSEN, 1982). The LrYc boundary is underlined both by the disappearance of lntratriporopollenites micro Ali these data indicate that in the Knokke instructus and by the appearance of Caryapolle borehole the base of the Ieper Clay can (just as in nites circulus. the Kallo borehole) be situated in the summit of the A. hyperacanthum zone, what is a Iso the case for the base of the London Clay in the London Briefly we can notice that the main pollinic Basin. The delimitation of the W. astra zone in the break is located in the lower part of the Knokke borehole is conjectural just as in sorne Deflandrea oebisfeldensis acme zone, a few areas within the London and Hampshire Basins meters above the chronostratigraphic base of the (KNOX & HARLAND, 1979; KING, 1981 ). lt can Ypresian (sensu HARDENBOL & BERGGREN, either be restricted to the -284 to -286 m interval 1978) here delimited by the conjectural Wetze approximately (hypothesis adopted in figures 1 liella astra zone (fig. 5). and 4) or should be considered as missing. CONCLUSIONS B. SPORES AND POLLENS (fig. 5) The study of the Landenian Ostracods of the Thirteen samples, covering the Landen For Knokke and Kallo boreholes shows the similarity of the facies of the Cyrena cuneiformis- bearing mation (L2) and the lower part of the Ieper Formation (Yc) between -310.3 m and -282.2 m, beds on the southern Belgian Basin and on the have been examinated. north-western Paris Basin. From the palynolo Three levels are barren: -310.3 m, -310 m and gical point of view, these deposits are probably 290.1 m. more or Jess contemporary in the London-Belgian and Dieppe Hampshire Basins. But they seem to The sporopollinic analysis of the others sam be markedly diachronous in the Paris Basin heart. pies allows to establish the distribution of the The. Sparnacian facies appear to be of Thanetian figure 5. Examination of this distribution shows age in the Southern North Sea Basin and of that the main floristic break coïncides more or Ypresian age in the Paris Basin. Such data point Jess with the lithologie L2-Yc discontinuity (bet out again the ambiguity of the chronostratigra ween -288 and -287 m). phic utilization of the «Sparnacian» term. Under -288 m we fi nd the L2 markers: The analysis of the phytoplankton in the lower - Basopollis basalis (18), part of Knokke borehole confirms the synchro - Triporopol/enites betuloides (24), nous sedimentation of the lowermost Ieper - Subtriporo/lenites magnoporatus magnopora- London Clay facies in the southern North Sea tus (36), Basin (on top of the Apectodinium hyperacan- DISTRIBUTION OF THE SPOROMORPHS IN THE LANDEN FORM. AND IN THE BASE OF THE IEPER CLAY. ,o DINOFLAG. t t t + • t • t + t t 1 + t t t t t • t + + ZONES • ++ ••••• 1 r H .,~, !------1 1 1 1 1 1 1 H 212.31• 1 1 1 1 1 1 • • 1 1 1 1 1 W. meckelf. 1 1 1 ~ 1 1 1 LJ 214.1 1 1 1 1 1 I : 1 : 1 1 1 1 Wastra? ·-·-· 1 1 1 1 1 ,___ 1 oëfianëlrëa -·-·-·-·-· 1 1 1 '- oebisfeld -·-·- 217 1 1 1 1 1 1 1 1 1 1 0 : r r r 1 1 1 1 1 1 1 acme zone ... 211 1 1 1 1 1 1 1 1 1 1'- 1":" 1 1 1 1 1 1":" 1 1 ---- 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 0 1 1 1 1 1 1 1 1 1 Q_ 290.11 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 .. 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 A.hyperac. 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 .. 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 .... 1 1 1 1 1 297.4 1 0 1 1 1 1 1 1 1 1 1 1 1 1 r 1 1 1 1 1 1 1 1 1 1 0 299.3 1 '1 '1 1 1 1 ' ' 0 1 1 299.61 1 1 1 " 1 1 1 1 1 1 1 1 1 1 1 : 1 1 1 0 :1 1 1 1 c::: •u1.51 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 • 1 1 1 1 1 1 1 1 1 ·... ·.· 30s.ll 1 1 1! 1 1 1 r 1 1 11 1 1 1 1 1 1 1 1 1 1 1 1 1 1 L 310 .. ... 1 ..... 1 l' 1 Sporo ~ 11 3 5 7 9 11 12 15 17 19 21 23 25 27 29 31 33 35 37 39 41 43 45 47 49 51 53 55 57 59 61 63 65 67 morphs 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 32 34 36 38 40 42 44 46 48 50 52 54 56 58 60 62 64 66 68 0 'gnJzea sp. Fig. 5.- Distribution of the sporomorphs. The extensions of the main stratigraphical markers are surrounded. The adopted Dinoflagellate zonation is indicated for comparison. List of the species: 1. Leiotriletes adriennis; 2. Stereisporites stereoides; 3. Trilites Multival/atus; 4. Cicatricosisporites dorogensis; 5. lschyosporites tertiarus; 6. Polypodiaceoisporites potoniei; 7. Camarozonosporites sp.; 8. Laevigatosporites haardti; 9. Laevigatosporites discordatus; 1O. Disaccates div.; 11. lnaperturopollenites hiatus; 12. lnaperturopollenites dubius; 13. Sparganiaceaepollenites reticulatus; 14. Sparganiaceaepol/enites cuvillieri; 15. Milfordia hungarica; 16. Graminidites sp.; 17. Diporites iszkaszentgyorgii; 18. Basopollis ba salis; 19. Pompeckjoidaepollenites subhercynicus; 20. Nudopollis endangulatus; 21. lnterpollis supplingensis; 22. Plicapol/is pseudoexcelsus; 23. Triporopollenites robustus; 24. Triporopollenites betuloides; 25. Triatriopollenites platycaryoides; 26. Triatripollenites engelhardtioides; 27. Triatriopollenites belgicus; 28. Triatriopollenites inyricoides; 29. Triatriopollenites plicatus; 30. Triatriopollenites sibiricus; 31. Triatriopollenites rurensis; 32. Triatriopollenites roboratus; 33. Triatriopollen(J.es aroboratus; 34. Subtriporopollenites anulatus; 35. Subtriporopollenites constans; · 36. Subtriporopollenites magnoporatus magnoporatus; 37. Subtriporopollenites magnoporatus tectopsilatus; 38. Subtriporopollenites spissoexinus; 39. Subtriporopollenites subporatus; 40. Caryapollenites triangulus; 41. Caryapollenites circulus; 42. Caryapollenites praesimplex; 43. fntratriporopollenites microinstructus; 44. lntratriporopollenites microreticulatus; 45. lntratriporopollenites pseudinstructus; 46. Pistillipollenites macgregorii; 47. Polyporopollenites undu/osus; 48. Polyvestibulopol/enites verus; 49. Monocolpopollenites tranquillus; 50. Monocolpopollenites parareolatus; 51. Dico/popollis luteticus; 52. Psilatrocolpites liblarensis fa/fax; 53. Scabratricolpites deconinckit;· 54. Scabratricolpites moorkensii; 55. Psilatrico/porites cingu/um fusus; 56. Psilatrico/porites cingulum oviformis; 57. Psilatricolporites kruschi; 58. Retitricolporites marcodurensis; 59. Retitricolporites oleoides; 60. Verrutricolporites antwerpenensis; 61. Striatricolporite sittleri; 62. Striatricolporites longostriatus; 63. N Clavatricolporites iliacus; 64. Bombacacidites europaeus; 65. Psilastephanoco/porites dsp.;_ 66. Tetradopollenites ericius; 67. ""' Tetradopollenites callidus; 68. Ovoidites ligneo/us. 43 thum zone). From a more general point of view DUPUIS, C., GAUDANT, J., PERREAU, M., RIVEUNE, J. & WILLEMS, the more or lèss close juxtaposition of severa! W., 1986. Sables thanétiens et faciès sparnaciens duN. du Bassin de Paris à Uhons (Somme). Données paléontologiques, interprétations sporomorphs disappearances and appearances stratigraphiques et paléogéographiques. Bull. /nf. Géol. Bass. 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P., PERREAU, M., RIVEUNE, J. & THIRY, M., 1983. Les sondages et la Bull /nf. Géo/. Bass. Paris, 18/4: 3-19. coupe du Mont-Bernon à Epernay (Marne). Etude sédimentologique et paléontologique du stratotype du Sparnacien et de la série éocène. BROECKMAN, J.A., 1978. Le Paléogène inférieur de l'lie-de-France Bull B.R.G.M. Géol. France, 2 (3): 235-254. septentrionale. Essai de reconstruction paléogéographique et strati graphique. Proceed. Koninkl. Nederl. Akad. Wetensch., Ser. B, 81:389- LERICHE, M., 1899. Notice sur les fossiles sparnaciens de la Belgique 415. et en particulier sur ceux rencontrés dans un récent forage à Ostende. Ann. Soc. géol. Nord. 38: 280-283. COSTA, L., 1981. A standard dinoflagellate zonal notation for the Tertia"ry of NW Europe- Preliminary draft. Document de travail distribué LERICHE, M., 1929. Sur la répartition des facies lagunaire et fluviatiles aux membres du Palynology Subgroup Dinoflagellates dans le cadre du du Landénien dans les bassins belges et parisiens. Bull Soc. belge projet I.G.C.P. 124: The NW-European Tertiary Basin. Géol., 38: 69-91. DE CONINCK, J., 1975. Microfossiles à paroi organique de I'Yprésien RIVELINE, J. 1984. Les Charophytes du Cénozoïque (Danien à du Bassin belge. Prof. Paper, 1975, n• 12. Burdigalien) d'Europe occidentale. Implications stratigraphiques. Thèse de Doctorat d'Etat, Univ. Piere et Marie Curie, Paris 6. DENISON, C.N.O., 1977. The microplankton ofthe Thanetian/Ypresian boundary in SE England and their stratigraphie and paleoecological ROBASZYNSKI, F., DUPUIS, Ch. & COLBEAUX. J.P., 1981. De la significance. Thesis, Ph. 0., Univ. of Sheffield (Unpubl.). Picardie au Boulonnais. Aspects de la couverture céno et mésozoïque. Front varisque et soubassement paléozoïque. Excursion de I'A.G.P.B. DUCREUX, J.L., MICHOUX, D. & WYNS, R., 1984. Contrôle climatique du 9 au 11 octobre 1981. Bull /nf. Géol. Bass. Paris, mars 1982, 19, de la sédimentation yprésienne (Eocène inférieur) en Brie et en (1): 9-62. Champagne (Est du Bassin de Paris, France). Conséquences strati graphiques. C.R. Acad. Sc. Paris, 299, Il (18): 1283-1286. ROCHE, E., 1973. Marqueurs stratigraphiques (Pollen et spores) du Paléocène et de I'Eocène inférieur de Belgique. Acad. Roy. Belg., Bull OUPUIS, Ch., DE CONINCK, J. & ROCHE, E., 1984. Remise en cause Classe des Sc., 5è s. UX, 1973-9: 956-969. du rôle paléogéographique du horst de l'Artois à I'Yprésien inférieur. Mise en évidence de l'intervention du Môle Bray-Artois. C.R. Acad. Sc. ROCHE, E., 1983. Les Normapolles du Paléocène et de I'Eocène de Paris, 298, Il (2): 53-56. Belgique. Stratigraphie et paléoécologie. Physio-Géo, 6: 13-26. DUPUIS, Ch. & GRUAS-CAVAGNETTO, C., 1985. Données nouvelles SCHUMACKER-LAMBRY, 1978. Palynologie du Landénien inférieur sur les Woolwich Beds et le London Clay du gisement Tertiaire de (Paléocène) à Gélinden-Overbrock (Belgique). Relations entre les Newhaven (Sussex). Bull. /nf. Géol Bass. Paris,22 (2): 19-33. microfossiles et le sédiment. Lab. Paléobot. Pa/ynol. (éd.), Univ. Uège, 157 p. 44 PLATE 1 OSTRACODA OF THE UPPER LANDENIAN Figs 1 & 10.- Cytheromorpha aillyensis Big not. 1.- Right valve, Kallo -385 m, x 100, stereosc. view. 10.- Sieve of the sa me valve; the sieves are without central pores, x 2500. Fig. 2.- Eocytheropteron cf thiliensis Apostolescu Left valve, Kallo -384,5 m, x 70, stereo. Fig. 3.- C!itherocytheridea hieroglyphica Apostolescu R.V., Kallo -384,5 m., x 90, stereo. Figs 4, 5, 7 & 11.- Cladarocythere obesa Guernet. 4. R.V., ~, with strong phenotypic nades. and ribs 5. L.V., ~, int. view. 7. L.V., rf. without nades. Ali these valves from Knokke, -298,2 m., x 60, stereo. Fig. 6.- Vetustocytheridea lignitarum Dollfus. R.V., ,Kallo -385 m., x 55, stereo. Figs 8-9.- Neocyprideis durocortoriensis Apostolescu R.V., , ext. view and L.V., int. view (stereo), Knokke, -298,2 m., x 60. 45 47 Chapter V CALCAREOUS NANNOPLANKTON ASSEMBLAGES FROM THE TERTIARY IN THE KNOKKE BOREHOLE by E. STEURBAUT Geo/ogisch lnstituut, Rijksuniversiteit Gent The upper part of the Knokke weil sequence The calcareous nannoflora of the Knokke weil (from 0 to 33 rn) consists of Ouaternary sandy is characterized by the relative abundance of the deposits with interbedded thin claylayers. These genera Pontosphaera, Reticulofenestra, Ericsonia, overlie 278 rn of Palaeogene sediments resting on Braarudosphaera and Chiasmolithus, throughout the Cretaceous at 311 m. The Palaeocene is the sequence, and by Micrantholithus and represented by a sandy-clayey complex overlai n by Rhabdosphaera at certain levels. Many of these a 10 rn thick fine sand with peat debris. The Eocene genera are represented in nearshore, shaflow comprises a lower rather thick clayey part, known water environments, and suggest sublittoral as the Flanders Clay or Ieper Clay, a sandy middle deposition (see ROTH, 1974: 982, 989, 990; part with severa! sandstone bands and finally an PERCH-NIELSEN, 1977:744 and MOSHKOVITZ& alternation of clays and thin sandy layers, known EHRLICH, 1982: 44 for comments on the ecology as the Meetjesland Formation (see JACOBS, of braarudosphaerids; see also MUELLER, 1979: 1978) or Kallo complex (see GULINCK, 1969 a and 614-616 and TAPPAN, 1980: 769-771). The b). The top of the Palaeozoic is at a depth of 432 m. scarcity of discoasters and helicosphaerids as weil Core-recovery was nearly complete, except for as the absence of scyphosphaerids, groups which the interval from 74 to 79 m. Tertiary calcareous are weil represented in the bathyal deposits of the nannoplankton has been studied through very Aquitanian Palaeogene (see STEURBAUT, 1983 close spaced sa mpl es. 190 sa mp les were selected, and unpublished data), would also seem to of which 124 were tully examinated with the a id of indicate a sublittoral environment. the light microscope. For the methods, preparation of the samples 2. BIOZONATION and investigation tech niques the rea der is referred to the excellent work of ROMEIN (1979). During the last decades severa! Cenozoic nanna-zonations have been proposed. For a review of these the reader is referred to the 1. GENERAL CHARACTERISTICS OF excellent work by AUBRY (1983: 273-317). The THE CALCAREOUS NANNOPLANKTON zonations of MARTINI (1971) and BUKRY (1973, 1975 and 1978), later refined by OKADA& BUKRY Of the 124 studied samples only 60 yielded (1980) and BUKRY ( 1981 ), have been successfully interpretable nanna-assemblages. 8oth the basal applied on a nearly worldwide scale. Both (Landen Formation a nd the major part of the Ieper zonations are interva 1 zonations wherein the zonal Formation) and the uppermost part of the section boundaries are defined by the entry or exit of a are devoid of nannoplankton. The remainder single species. BUKRY's zonation is based on data contains low diversity, poorly to moderately derived from deep-sea boreholes and covers low preserved assemblages, except for the interval latitude open-ocean assemblages. MARTINI's 62.50 to 71.95 m. Table 1 shows the species «Standard nannoplankton zonation» is based on recognized and their distribution through the middle to high latitude near-shore assemblages cored weil. .p. CX> ~- ~HANETIAN y p R E. s 1 A N LUTETIAN ·+BARTONIAN AGE -o m "111D r ::::0 n 1 E P E R F 0 R MA T 1 0 N PANISEL FORMATION JO"' MEETJESLAND FORMATION )> -1 ;:tl LANDEN -~ DEN HOORN ê LITHOSTRATIGR- -~v; --,--- r------~- -~--- -,--- FORMATION -:------;------f ~- =:------:, -- -- - FORMATION APHY . m ,~g; ~:%~: .E :-P: ~ : :f ~ =E z )> ~ ...... m ëjl )> c ::::0 :J -· :::Q, m -1 0" C') Ul oUI 5:z o." z r -< i» m trC c: c lOO "0 -c ::;:g üï "':J )> r (") 0 -:;·ii'' z&. ;· z !2: :J :J z 0 n ~!tl ;:tl z ., o. 0 ..., "'00 s -u&.g ..., NANNO-ZONE c ·-> \' ~ 0 0 "'S. )> ~~ -1 (J) :::~~ ' ..... Ul ~:t "' -< - ·(!) ~:J- z~ z (MARTI Nl,1971 l z , -fi~ E~. ~ ' .,_ r Ul !Il ' Ul !Il -os· -o ::::0(") ~ ' iii .§0 =E iiï e~: 0 )> -< CD (") WWWWNNNNNNNN NNNNN NN-- _. _ _._._._._. 3: ::::0 Cl ';:! WWNNNN_._._.O U)(QCJ)Q)(OQ)CJOQ)-.,J....:J -ooo .j:>. CD 50 Table 11.- Eocene calcareous nannofossil zonation A FIRST CALCAREOUS NANNOFOSSIL ZONATION LAST G OCCURRENCES OCCURRENCES E CP OKADA & BUKRY 1980 MARTINI 1971 NP Sphenoli th us pseudoradians pseUdoradians L- 20 s. b Isthmolithus recurvus o. barbadiensis·, o. Discoaster Isthmolithus recurvus 19 saipanensis I. recurvus '--- 15 Cb barbadiensis 0 Q Chiasmolithus oamaruensis Chiasmolithus oamaruensis . 18 ...J c. oamariensis L c. grandis Discoaster saipanensis b P.eticulofenestr Discoaster saipanensis 17 w r-- 14 o. bifax, c. soli tus umbilica Q Discoaster bifax Discoaster tanj nodifer 16 o. bi fax, R. R. gladius umbilica z c Birkelundia staurion Nannotetrina r--. c. gigas ~ 13 b Chiasmolith,us gigas 'Jannotetrina fulgcns 15 fulgens 1J c. '9'Îqù.S '--- w 1J Q Discoaster striclus ~ t!. fulgens R. inflata u b Rhabdosphaera ir,flata Dis coas ter Discoaster sublodoensis p.. inflatu. ,,c__ 12 14 sublodoensis Q Oiscoaster kuepperi r-- o. sublodocnsis 0 Discoaster lodoensis 13 11 Discoaster lodoensis T. orthostylus c. crassus 12 w 10 'l'rib rach iatus ortho.stvlus Tribrachiatus orthostylus ...» o . loclocnsis 0 b Discoastcr binodosus Discoaster binodosus w Discoaster 11 9 T. contortus diastypus Q Tribrachiatus con tortus Tribrachiatus contortus 10 o. diastypus, 'l'- contortus from outcrop sections and appears to be applicable Bou nd aries to the present study. These zonations and their The lower and upper boundaries cou Id not be established as respective boundary-species are shawn in table 2 the :underlying and overlying strata are devoid of nanno plankton. As Tribrachiatus orthostylus is common and T. (slightly modified after PERCH-NIELSEN in BECK contortus and D. lodoensis are absent, the interval from 245.50 MANN et al., 1981 ). to 220.60 has to be assigned to MARTINI's Discoaster binodosus Zone. The zonation used in this paper is the standard Tertiary nannoplankton zonation of MARTINI, Common species (1971 ). The original definition of each zone is Pontosphaera exilis, Toweius occultatus, Toweius pertu given, together with its occurrence, its most sus, Discoaster kuepperi. Ericsonia eopelagica and Tribrachia tus orthostylus. common species and its boundaries in the Knokke weil. lt should be emphasized that some of MARTINI's boundary-species, such as Discoaster Tribrachiatus orthostylus Zone lodoensis BRAM LETTE& RIE DEL 1954, Discoaster (NP 12) sublodoensis BRAMLETIE& SULLIVAN 1961 and Rhabdosphaera gladius LOCKER 1967 are rather Definition rare and often disco ntinuously distributed through lnterval from the first occurrence of Discoaster lodoensis BRAMLETTE & RIEDEL 1954 to the last occurrence of the Knokke weil which hinders stratigraphie Tribrachiatus orthostylus SHAMRA! 1963. interpretations. Additionally some Discoaster species, such as D. Jodoensis, D. strictus and D. Occurrence sublodoensis sometimes show a s,light to mode Not encountered in the Knokke weil. rate etching or overgrowth masking specifie features, making indentification difficult. Discoaster Jodoensis Zone (NP 13) Definition Discoaster binodosus Zone lnterval from the last occurrence of Tribrachiatus (NP 11) orthosty/us SHAMRA! 1963 to the first occurrence of Discoaster sublodoensis BRAMLETTE & RIEDEL 1961. Definition Occurrence lnterval from the last occurrence of Tribrachiatus co nt artus (STRADNER 1958) to the first occurrence of Discoaster From 132.50 to ? 1 03.50 m. lodoensis BRAMLETTE & RIEDEL 1954. Boundaries Occurrence The lower boundary ofthiszone cou Id not be detected as the From 245.50 to 220.60 m. underlying strata did not yield nannofossils. The upper 51 boundary is situated between 109.40 and 99.25 m depth. The Discoaster tanii nodifer Zone presence of D. lodoensis and the absence of T. orthostylus and D. sublodoensis justify the assignment of the above mentioned (NP 16) interval to the Discoaster lodoensis zone. Definition Common species lnterval from the last occurrence of Rhabdosphaera gladius LOC KER 1967 to the last occurrence of Chiasmolithus solitus Ericsonia eopelagica, Pontosphaera pulchra, Nannoturba (BRAMLETTE & SULLIVAN 1961). spinosa, Nannoturba robusta, Discoaster lodoensis and lmperiaster sp. Occurrence From 65.50 to 62.50 m. Discoaster sublodoensis Zone Bou nd aries (NP 14) The lower bound.ary is situated between 67.50 and 66.50 m. The upper boundary could not be fixed as no nannofossils were Definition recognized in the interval from 61.50 to 33.00 m. ln the lnterval from the first occurrence of Discoaster sub/o uppermost part of the weil (from the surface to 33.00 m) no doensis BRAM LETTE & SULLIVAN 1961 to the first occurrence autochthonous nannofossils were observed. of Nannotetrina fu/gens I?TRADNER, 1960). Common species Remarks Ericsonia eopelagica, Ericsonia formosa, Ponto~phaera Nannotetrina fu/gens cannot be used to define the top of multipora, Reticulofenestra umbilica, Nannotetrina fu/gens zone NP 14 and consequently the base of zone NP 15 in and Discoaster bifax. sequences of infralittoral origin. According to MUELLER ( 1978:48) this species seems to be restricted to offshore, circalittoral to bathyal deposits. This explains why it appears in The present investigation shows that most of the Knokke weil only at a depth of 67.50 m, at the top of the the above mentioned standard nannoplankton Nannotetrina fu/gens zone (=NP 15). The boundary between zones can be further subdivided into one or more zones NP 14 and NP 15 can be determined approximately with the entry of Rhabdosphaera gladius LOCKER 1967. This assemblage-units. Each unit is charaterized by the species is known only from near-shore deposits. dominance, the presence, the paucity or absence of certain nannospecies, or by a certain combi Occurrence nation of species. They seem predominantly From? 106.40 to 71.95 m. determined by local paleoecological conditions Bou nd aries and hence have local significance only. They are The lower boundary is situated between 109.40 and expected to allow short-distance correlations {in 99.25m, the upper one between 71.95 and 71,65 m. the order of sorne hundreds of kilometres) and are Common species suitable for the refinement of the North Sea Basin, Tertiary biostratigraphy. Ericsonia eopelagica, Pontosphaera pulchra, Chiasmolithus solitus, Cruciplacolithus mutatus, Discoaster sublodoensis, Reticulofenestra umbilica, Cyclococcolithus sp., Rhabdo sphaera crebra and Chiasmolithus expansus. Assemblage - unit 1 This unit is characterized by the dominance of Ponto Nannotetrina fu/gens Zone sphaera exilis, Toweius occultatus and Discoaster kuepperi (NP 15) and by the presence of Neococcolithes protenus and Tribrachiatus orthostylus. Definition lt covers the interval from 245.50 to 220.60 m and lnterval from the first occurrence of Nannotetrina fu/gens corresponds to MARTINJ's Discoaster binodosus Zone. (STRADNER 1960) to the last occurrence of Rhabdosphaera · gladius LOCKER 1967. Assemblage - unit 2 Occurrence From 71,65 to 67.50 m. ln unit 2 Pontosphaera pulchra, Nannoturba robusta and Discoaster kuepperi are common, while Micrantholithus flos Boundaries and Micrantholithus inaequalis are rare. lhe lower boundary was taken at the entry of Rhabdo lts lower limit is uncertain as itoverlies a totally barren non sphaera gladius, instead of N. fu/gens (for comments: see calcareous interval. lts upper boundary is situated between above), and is situated between 71.95 and 71.65 m. The upper 130.00 and 128.50 rn Unit 2 corresponds to the basal part of boundary coïncides with the exit of R. gladius and lies between MARTINJ's Discoaster /odoensis Zone. 67.50 and 65.50 m. Common species Assemblage - unit 3 Ericsonia eopelagica, Reticulofenestra umbilica, Rhabdo sphaera crebra, Ericsonia fenestrata, Reticulofenestra cal/ida, Unit 3 is characterized by the dominance of Micrantholithus Rhabdosphaera gladius, Lanternithus minutus, Nannotetrina flos and Micrantholithus inaequalis; Braarudosphaera bige fu/gens and Sphenolithus furcatolithoides. lowii and Zygrhablitus bijugatus are rather common. Such 52 assemblages are due to special.environmental conditions (e.g. Assemblage - unit 10 very shallow waters). This unit is characterized bythe abundance of Zygrhablitus Unit 3 covers the interval from 128.50 to 121.90 rn and can crassus, by the first appearance of Rhabdosphaera gladius, be correlated with the lower middle part of MARTINI's Rhabdosphaera scrabrosa and Lanternithus minutus and by Discoaster lodoensis Zone. the presence of sorne Zygrhab/itus bijugatus. lts lower limit is placed at 71.90 rn, its upper between 71.65 Assemblage - unit 4 and 69.50 m. Unit 10 is correlated with the lower part of MARTINI's Nannotetrina fu/gens Zone. This unit is dominated by Reticulofenestra cf. onusta, whereas Micrantholithus flos and M. inaequa/is are absent. The lower boundary lies between 121.90and 117.75 rn, the Assemblage - unit 11 upper one between 109.40 and 106.40 m. Unit 4 corresponds This unit yields Zygrhablitus bijugatus, Rhabdosphaera to the upper middle part of MARTINI's D. lodoensis Zone. crebra, Reticulofenestra umbilica in great number and, to a lesser degree, Rhabdosphaera g/adius and Sphenolithus furcatolithoides. Zygrhab/itus crassus is no longer present. Assemblage - unit 5 Unit 11 corresponds to the upper part of MARTINI's Unit 5 is charactl:lrized by the final occurrence of Nannotetrina fu/gens Zone. lts lower li mit is situated between Nannoturba spinosa and by the first Chiasmolithus mutatus. 71.65 and 69.50 rn, the upper between 67.50 and 65.60 m. Zygrhablitus bijugatus seems to be missing. Moreover, in comparison with the under- and overlying units, it contains a greater number of Discoasters. Assemblage - unit 12 Unit 5 is difficult to correlate with MARTINI's nanna Unit 12 is characterized by the first appearance and zonation. lt covers the interval from 106.40 to 103.50 m. abundance of Discoaster bifax and by fairly abundant Nannotetrina fu/gens, Reticulofenestra umbilica and Reticulo fenestra cal/ida. Assemblage - unit 6 lts lower limit coïncides with the exit of Rhabdosphaera ·unit 6 shows few diagnostic characters. lt contains the first g/adius, and is situated between 67.50 and 65.50m.lts upper Chiasmolithus expansus, Reticulofenestra umbilica and limit has not been enceuntered as the overlying strata are Discoaster sublodoensis. barren of nannofossils. Unit 12 can be correlated with lts upper limit is situated between 97.50 and 90.75m, its MARTINI's Discoaster tanii nodifer Zone (NP16). lower li mit between 103.50 and 99.25 m. Unit 6 can be correlated with the lower part of MARTINI's Discoaster sublodoensis Zone. 3.- THE SPECIES RECOGNIZED WITH SOME REMARKS ON THEIR Assemblage - unit 7 STRATIGRAPHie IMPORTANCE Unit 7 contain many Discoaster species, among which the final Discoaster lodoensis and Discoaster kuepperi. The first Ali species encountered in the Tertiary of the Rhabdosphaera crebra, Discoaster barbadiensis and Discoas Knokke weil are listed in alphabetical arder ter stradneri appear in this unit. according to their generic name. Each species lt corresponds to the lower middle part of MARTINI's D. name is followed by the original author(s) and by sublodoensis Zone. lts upper limit lies approximately at its date of publication and by possible subsequent 89.00m, its lower limit issituatedbetween 97.50and 90.75 m. author(s) who proposedthe preferred combination. References to the illustrations in this paper (plates Assemblage - unit 8 1, 2 and 3) are added. This unit is characterized by the presence of Cruciplaco Most of the species are weil documented lithus staurion and by the last Chiasmolithus expansus and elsewhere and need no further discussion. The Nannoturba robusta. comments concern only stratigraphically impor lt covers the interval from approximately 89.00 to 73.00 rn tant species, species rarely found in the Tertiary and corresponds to the upper part of MARTINI's D. assemblages of Northwestern Europe or species sublodoensis Zone. being taxonomically modified in the present study. No synonymy lists are given. Assemblage - unit 9 Birkelundia arenosa PERCH-NIELSEN 1971 (pl. 1, fig. 1 a-b). Unit 9 is essentially characterized by the abundance of Originally described from the Nannotetrina fu/gens Zone Zygrhablitus crassus, by the first appearance of Reticulo (NP 15) from Den mark (see PERCH-NIELSEN, 1971 :1 0). fenestra cal/ida, Discoaster wemmefensis and Pontosphaera punctosa and by the last Chiasmolithus mutatus and Braarudosphaera bigelowii (GRAN & BRAARUD 1935) Discoa.ster sublodoensis. DEFLANDRE 1947. lt comprises the interval from 73.00 to 71.90 m and is correlated with the uppermost part of MARTINI's D. Cepekiel/a lumina (SULLIVAN 1965) BYBELL 1975. sublodoensis Zone. The lower limit could not be established, as Known throughout the Eo-Oiigocene (see BYBELL, 1975:236). no cores were recovered from the interval from 79 to 74 m. Chiasmolithus californicus (SULLIVAN 1964) HAY & MOHLER 1967. 53 Chiasmolithus consuetus (BRAM LETTE & SULLIVAN 1961) these three for ms it is difficult to decide whether the Knokke HAY & MOHLER 1967. material represents a new species or not. Chiasmolithus expansus (BRAM LETTE & SULLIVAN 1961) Discoaster barbadiensis TAN SIN HOK 1927 (pl. 1, fig. 16-17). GARTNER 1970 (pl. 1, fig. 2-3). Discoaster bifax BUKRY 1971 (pl. 1 , fig. 21 ). Chiasmolithus grandis (BRAMLETTE & RIEDEL 1954) RA A species easily recognizable by its rather short broad distal DOMSKI 1968. stem and its more elongate, slender proximal stem. Originally described from the Middle Eocene from the Atlantic Ocean (see Chiasmolithus medius PERCH-NIELSEN 1971. BUKRY 1971 :314-315). This species is known from MARTINI's NP 15 and NP 16 and disappears at the top of the D. bifax Chiasmolithus solitus (BRAMLETTE & SULLIVAN 1961) subzone sensu BUKRY (see BUKRY 1978:57; text-Fig. 13). LOCKER 1968 (pl. 1, fig. 4). Originally described from the Lodo Formation (Early & Middle Discoaster binodosus MARTINI 1958. Eocene of California) (see BRAMLETTE & SULLIVAN, 1961 :140). One of the most common species in the Belgian Discoaster deflandrei BRAM LETTE & RIE DEL 1954. Eocene. Discoaster diastypus BRAMLETTE & SULLIVAN 1961. Chiasmolithus sp. Discoaster distinctus MARTINI 1959 (pl. 1, fig. 18). Small Chiasmolithus spefies, close to Chiasmolithus minimus PERCH-NIELSEN 1971 (see PERCH-NIELSEN, 1971:19, pl. 14, Discoaster gemmeus STRADNER 1959. fig. 2, 5 and 3?). Discoaster germanicus MARTINI 1958. Chiphragmalithus ca/athus BRAMLETTE & SULLIVAN 1961 Discoaster kuepperi STRADNER 1959 (pl. 1, fig. 20). Cruciplacolithus de/us (BRAMLETTE & SULLIVAN 1961) Very common in the Discoaster binodosus Zone of the Knokke PERCH-NIELSEN 1971. weil. Also encountered in the Discoaster lodoensis Zone. Cruciplacolithus mutatus PERCH-NIELSEN 1971 (pl. 1, fig. 5- Discoaster lodoensis BRAMLETTE & RIE DEL 1954 (pl. 1, fig. 6). 14-15). Only a few specimens of D.lodoensis are present in the Knokke Cruciplaco/ithus staurion (BRAMLETTE & SULLIVAN 1961) weil. GARTNER 1971. Discoaster mirus DEFLANDRE 1952. Cruciplaco/ithus sp. 1 . This species is characterized by sm ali elliptical coccoliths (L = 4 Discoaster nodifer BRAM LETTE & RIEDEL 1954. to 6 pm) with an elliptical central opening bridged by a thin Discoaster stradneri MARTINI 1961 (pl. 1, fig. 19). central cross-structure, parall~l to the axes of the ellipse. Unfortunately, the specimens are too poorly preserved to allow lt would seem th at Discoaster bou/angeri LEZAUD 1968 (see specifie identification. LEZAUD, 1968:23, pl. 1, fig. 9-12; pl. 2, fig. 14), known from the Discoaster lodoensis Zone of Aquitany, is a junior synonym of Cruciplacolithus sp. 2 (pl. 1, fig. 7). Discoaster stradneri from the same zone (see MARTINI, This species has a small central opening, almost closed by a 1961:10, pl. 2, fig. 22 and pl. 5, fig. 52). broad and short, cruciform structure. The bars of the cross make a sm ali angle with the axes ofthe ellipse. The wall, which Discoaster strictus STRAD NER 1961 (pl. 1, fig. 1 2-13). is very bright in cross-polarized light, is as wide as the distal These asteroliths are characterized by six to seven straight shield. Up to now only a single moderately preserved specimen rather blunt rays and by a marked central knob with radial has been fou nd. lt might representa new species, but, as the sutures on the distal side (see STRADNER& PAPP, 1961:65, pl. variability of this form is still unknown and no scanning 3, fig. 1-6 and text-fig. 8-3). photomicrographs are available, a specifie name cannot be Discoaster sublodoensis BRAMLETTE & SULLIVAN 1961 (pl. 2, proposed. fig. 14-16). Cyclolithella sp. This species is regularly distributed throughout the D. Sm ali circular coccolith (6pm) with raised inn er margina round sublodoensis Zone (NP14) from the Knokke weil. lt is mostly the central opening, somewhat similar to Cyclolithella aprica represented by its six-rayed form.· ROTH 1973 (see ROTH, 1973:730, pl. 11,fig. 4-6; pl. 12, fig. 1-4). Discoaster tanii BRAMLETTE & RIEDEL 1954. Cyclococcolithus bramlettei HAY & TOWE 1962. Discoaster wemmelensis ACHUTHAN & STRADNER 1967. Cyclococcolithus kingi ROTH 1970. Discoaster woodringii BRAMLETTE & RIEDEL 1954. Cyclococcolithus sp. (pl. 1, fig. 8-11 ). Circular coccoliths consisting of an outer cycle composed of 30 Ellipsolithus mace/lus (BRAM LETTE & SULLIVAN 1961) to 35 elements with anti-clockwise oblique sutures and a SULLIVAN 1964. central area closed by radial elements. ln cross-polarized light, the outer cycle is very bright, whereas the central a rea is only Ericsonia eopelagica (BRAMl:ETTE & RIEDEL 1954) ROMEIN faintly illuminated and shows a central fairly broad extinction 1979. cross. The diameter ranges from 7 to 9 pm. This form is related This is the most common species in the Belgian Eocene. to Cyclococcolithus hirsutus MUELLER 1970 and Cyclococco lithus hoerstgensis MUELLER 1970 known respectively from Ericsonia fenestrata (DEFLANDRE & FERT 1954) STRADNER & the Middle Oligocene of Belgium and the Upper Oligocene of EDWARDS 1968 (pl. 2, fig. 5). Germ any (see MUELLER, 1970:93, pl. 9, fig. 1-4 and 94; pl. 9, A species of Ericsonia with many pores arranged parallel to the fig. 5-8). However, si nee no SEM photos are available of any of long and the short axis of the ellipse. For the definition and 54 description of this species and its relation with ether Ericsonia Nannoturba spinos a M UELLER 1979 {pl. 3, fig. 1 ). species the rea der is referred to ROTH (1970:841, pl. 1, fig. 6). This species was originally described from MARTINI's D. lodoensis Zone {NP 13){see MUELLER 1979:617, pl. 8, fig. 1-3). Ericsonia formosa (KAMPTNER 1963) ROMEJN 1979 (pl. 2, fig. lt is corn mon in the NP 13 of the Knokke weil. 4). Neococcolithus dubius {DEFLANDRE 1954) BLACK 1967 (pl. 3, Ericsonia subdisticha (ROTH & HAY 1967) ROTH 1969 (pl. 2, fig. 3). fig. 6-7). This species has a worldwide distribution and occurs According to MUELLER (1978:table 1) this species is restricted throughout the Eocene. lt is particularly abundant in the to the zones NP20, 21 and 22. This studyshows its presence in Nannotetrina fu/gens Zone {NP 15) (see ROMEIN, 1979:138 for NP 15 of the Belgian Tertiary. the synonymy; see BYBELL, 1975:236 and SHERWOOD, 1974:70-71 for its distribution). Helicosphaera lophota BRAMLETTE & SULLIVAN 1961. Neococcolithus protenus {BRAMLETTE & SULLIVAN 1961) Helicosphaera seminulum BRAMLETTE & SULLIVAN 1961. HAY& MOHLER 1967. lmperiaster obscurus (MARTINI 1958) MARTINI 1970. Pemma sp. This species is characterized by a central cone on which six Only poorly preserved specimens occur, not identifiable on the arms are attached, ali of the same length. These arms are specifie level. arranged in two sets at different heights on the cone, so that each arm makes an angle of 60° with the adjacent one in the Pontosphaera exilis {BRAM LETTE& SULLIVAN 1961) ROMEIN ether set. According to MARTINI (1970:385) this species is 1979. restricted to the upper part of NP 11 and lower part of NP 12. This species is very common in the assemblage-unit 1 of the However, MUELLER (1979:612) cites it also from the Knokke weil. For an excellent illustration the reader should Discoaster lodoensis Zone (NP 13). An excellent illustration is consult PERCH-NIELSEN {1971 :38, pl. 27, fig. 3, 5 and 6; pl. 31, given in PERCH-NIELSEN (1968:253, pl. 1, fig. 7-8; pl. 2, fig. 1- fig. 4). 6). Pontosphaera frimbriata {BRAM LETTE & SULLIVAN 1961) lmperiaster sp. (pl. 2, fig. 1-3). ROMEIN 1979. This form differs from/. obscurus by the presence of one set of three short, pointed triangular arms as weil as a set of elon gate Pontosphaera labrosa (BUKRY & BRAMLETTE 1969) PERCH arms instead of the normally developed double set of equally NIELSEN 1977. elongate ar ms. lt might representa new species or an aberrant form of lmperiaster obscur us. Pontosphaera multipora (KAMPTNER 1948) ROTH 1970. Lanternithus minutus STRADNER 1962. Pontosphaera obliquipons (DEFLANDRE 1954) ROMEIN 1979 (pl. 3, fig. 6). Lithostromation operosum (DEFLANDRE 1954) BYBELL 1975. Pontosphaera ocellata (BRAM LETTE & SULLIVAN 1961) Lophodolithus acutus BUKRY & PERCIVAL 1971. PERCH-NIELSEN 1984. Markalius inversus (DEFLANDRE 1954) EDWARDS 1966. Pontosphaera prava (LOCKER 1967) ROMEIN 1979. Micrantholithus crenulatus BRAMLETTE & SULLIVAN 1961. Pontosphaera pulchra (DEFLANDRE 1954) ROMEIN 1979 (pl. 3, fig. 5). Micrantholithus flos DEFLANDRE 1950 (pl. 2, fig. 13). Pontosphaera punctosa (BRAM LETTE & SULLIVAN 1961) Micrantholithus inaequalis MARTINI 1961 (pl. 2, fig. 1 0-12). PERCH-NIELSEN 1984. This species is very abundant in assemblage-unit 3 of the Knokke weil (interval from 128.50 to 121.90 rn; lower middle Pontosphaera sc issu ra (PERCH-NIELSEN 1971) ROMEIN part of MARTINI's Discoaster lodoensis Zone (NP 13)). lt has 1979. originally been described from the NP 13 of the Aquitanian Basin (see MARTINI 1961:7) and is here considered to be a Pontosphaera wechesensis (BUKRY & PERCIVAL 1971) senior synonym of Micrantholithus attenuatus BRAM LETTE & AUBRY 1983 (pl. 3, fig. 1 0). SULLIVAN 1961, known from the NP 12 from the Lodo section Originally described from the Weches and Cook Mountain ofCalifornia (see BRAM LETTE& SULLIVAN 1961:154, pl.8, fig. Formation of the Gulf Coastal Plain (zones NP 14 and NP 15) 8-11 ). The pentaliths of this species show a considerable (see BUKRY & PERCIVAL 1971:142, pl. 7, fig. 7-10). lt is variability {see pl. 2, fig. 1 0 and 11). suggested here that P. wechesensis is a senior synonym of Pontosphaera excelsa (PERCH-NIELSEN 1971) PERCH-NIEL Micrantholithus vesper DEFLANDRE 1954. SEN 1977, known from NP 12 to NP 15 (see PERCH-NIELSEN, 1977:789, pl. 27, fig. 2-3). ln the Knokke weil it has beenfound Naninfula deflandrei PERCH-NIELSEN 1968. only in the assemblage-unit 11, corresponding with the upper part of MARTINI's Nannotetrina fu/gens Zone (NP 15). Nannotetrina fu/gens {STRADNER 1 960) ACHUTHAN & STRADNER 1969 {pl. 2, fig. 8-9). Pseudotriquetrorhabdulus inversus {BUKRY & BRAMLETTE 1969) WISE & CONSTANS 1976. Nannotetrina pappi {STRADNER 1959) PERCH-NIELSEN 1971 {pl. 3, fig. 15). Reticulofenestra cal/ida (PERCH-NIELSEN 1971) BYBELL This species was weil illustrated by PERCH-NIELSEN {1971 :67, 1975. pl. 54, fig. 1-6; pl. 57, fig. 9). Reticulofenestra foveolata (REl NHARDT 1966) ROTH 1970. Nannoturba robusta MUELLER 1979 {pl. 3, fig. 2). This species is characterized by its relatively small rim and its This species has been regularly encountered in the zones central grille consisting of an outer ring of numerous elongated NP 13 and NP 14 of the Knokke weil. lt is known from many pores and a central area with fewer rounded smaller pores. ln Early Eocene deposits of Europe {see MUELLER 1979:617). the Knokke weil it is known from the assemblage-unit 11 55 corresponding with the uppermost part of MARTINI's· Toweius gammation (BRAMLETTE & SULLIVAN 1961) Nannotetrina fu/gens Zone (NP 15). ROMEIN 1979. Reticulofenestra cf. onusta (PERCH-NIELSEN 1971) nov. comb. Toweius magnicrassus (BUKRY '1971) ROMEIN 1979. These relatively sm ali coccoliths (0 =± 5 pm) are characterized by a central grille with many small pores and a median furrow Toweius occultatus (LOCKER 1967) PERCH-NIELSEN 1971. as weil as a rather small rim, which is very bright in cross Toweius pertusus (SULLIVAN 1965) ROMEIN 1979. polarized light. These coccoliths closely resemble PERCH NIELSEN's Dictyococcites onustus (see PERCH-NIELSEN, Toweius sp. (pl. 3, fig. 11). 1971 :29, pl. 20, fig. 3-4; pl. !)1, fig. 28-29), which is transferred This form is composed of a composite rim and a rather large into the genus Reticulofenestra (sensu BACKMAN) because of grille with many minute pores. ln cross-polarized light the its open central area (see BACKMAN, 1980:48 and 58). central a rea is only faintly illuminated and shows an extinction However, using only the light microscope it is difficultto prove cross. The proximal shield is very bright and more conspicuous whether both forms belong to the sa me species or not. than the distal o.ne. This species resembles Toweius magnicrassus (BUKRY 1971) (see BUKRY 1971:309. pl. 2, fig. Reticulofenestra umbi/ica (LEVIN 1965) MARTINI & RITZ 1-5) but can be distinguished by its larger central area and KOWSKI 1968. might therefore represent a new species. Reticulofenestra sp. t · Tribrachiatus orthostylus SHAMRA! 1963 (pl. 3, fig. 4). Numerous small coccoliths with a small central opening are present in the Knokke weil. They can be assigned to the genus Zygrhablitus bijugatus DEFLANDRE 1959. Reticulofenestra as they may be related to Reticulofenestra An excellent description and illustration of this species isgiven prebisecta AUBRY 1963. by GARTNER & BUKRY (1969:1218, pl. 140, fig. 3-6 and pl. 142, fig. 1-2). Rhabdosphaera crebra (DEFLANDRE 1954) BRAMLETTE & Zygrhablitus crassus LOCKER 1967 (pl. 3, fig. 13-14). SULLIVAN 1961. This species is no longer placed in synonymy with Z. bijugatus, because of its clearly different holococcoliths, having a stem Rhabdosphaera g/adius LOCKER 1967 (pl. 3, fig. 7). which is as wide as or wider than the base of the coccolith (see Rhabdosphaera pseudomorionum LOCKER 1967. LOC KER, 1967b:764, pl. 1, fig. 7; pl. 2, fig. 7-S).In the author's opinion such differences should not be regarded as mere Rhabdosphaera scabrosa (DEFLANDRE 1954) BRAMLETTE & intraspecific variations. SULLIVAN 1961. incertae sedis sp. 1 (pl. 3, fig. 9). Rhabdosphaera solus (PERCH-NIELSEN 1971) AUBRY 1983. A single large specimen (33 pm) is known from the Knokke weil. lt is composed of a central cone to· which eight arms are Rhabdosphaera tenuis BRAMLETTE & SULLIVAN 1961. attached forming two crosslike structures lying in different parallel planes and covering aach other when viewed from Rhabdosphaera vitrea (DEFLANDRE 1954) BRAMLETTE & above. Each cross-bar shows short transverse protrusions at SULLIVAN 1961. the end, pointing in the same direction, but so that the protrusions of superposed cross-bars point in opposite Sphenolithus furcatoh"thoides LOCKER 1967 (pl. 3, fig. 1 7). directions. This specimen may represent a new species but, This species shows a considerable variability (see LOCKER having found no other1Tlaterial anEI lacking SEM photos, it is 1967a:363, fig. 7 and 8, pl. 1, fig. 14-16). lt has been kept in open nomenclature. encountered in zones NP 15 and NP 16 of the Knokke weil. incertae sedis sp. 2 (pl. 3, fig. 8). Sphenolithus moriformis (BROENNIMANN & STRADNER Small globular enigmatic object (5 pm) showing in cross 1960) BRAMLETTE & WILCOXON 1967. polarized light a rather faintly illuminated central area and two Sphenolithus radians DEFLANDRE 1952. small bright segments which are diametrically opposed. Sphenolithus sp. 1 This species is common in assemblage-unit 1 of the Knokke weil. lt is characterized by a triangular column with rather broad base and a sm ali elongate spine. ln cross•polarized light, ACKNOWLEDGEMENTS parallel to the polarization directions, only the column and the basal cycles of the cone are illuminated and show extinction The autor wishes to thank Dr. K. PERCH lines parallel to the polarization directions. Viewed at 45° the spine also becomes bright. while the extinction li nes occupy a NIELSEN (ETH-Zentrum, Zürich) and Dr." T. diagonal position. ROMEIN (Rijksuniversiteit Utrecht) for valuable discussions on the taxonomy of certain nanno Sphenolithus sp. 2 (pl. 3, fig. 1 6). fossil-species. This species consists of a relatively high column; a cycle of lateral elements and four long spin es. The extinction li nes are He is also grateful to T. TEMMERMAN for parallel to the polarization directions when the specimens are reproducing the photos and to N. REYNAERT for aligned parallel to these directions. Viewed at 45° the typing the manuscript. extinction tines become diagonal, while the spines are no longer conspicuous (see pl. 3, fig. 16). These sphenoliths are The National Fund for Scientific Research similar to PERCH-NIELSEN's Sphenolithus quadrispinatus(see (Brussels) is gratefully acknowledged for the PERCH-NIELSEN, 1980:3, pl. 1, fig. 11-13; pl. 2, fig. 1-4) known financial support. from the Uppe(-Miocene of the South Atlantic. 56 PLATE 1 Bar scale on each figure represents 5 pm 1. Birke/undia arenosa PERCH-NIELSEN 1971 distal view, sample Knokke 71.65m; a. cross-polarized light; b. transmitted light. 2-3. Chiasmolithus expansus (BRAMLETIE & SULLIVAN 1961) GARTNER 1970 2. distal view, sample Knokke 89.50 rn; a. transmitted light; b. cross polarized light; 3. distal view, sample Knokke 89.50 rn; cross-polarized light. 4. Chiasmolithus so/itus (BRAM LETTE & SULLIVAN 1961) LOCKER 1968 distal view, sample Knokke 69.50 rn, transmitted light. 5-6" Cruciplacolithus mutatus PERCH-NIELSEN 1971 5. distal view, sample Knokke 73.00 rn, cross-polarized light; 6. proximal view, sam pie Knokke 106.40 rn, cross-polarized light. 7. Crucip/aco/ithus sp. 2 distal view, sample Knokke 71.65 rn, cross-polarized light. 8-1 1. Cyc/ococco/ithus sp. 8. distal view, sample Knokke 97.50 rn; a. cross-polarized light; b. b. transmitted light; 9. distal view, sam pie Knokke 71.95 rn; a. transmitted light; b. cross polarized light; 1 O. distal view, sample Knokke 73.00 rn; cross-polarized light; 11. proximal view, sample Knokke 90.75 rn; cross-polarized light. 1 2-1 3. Discoaster strictus STRADN ER 1961 1 2. proximal view, sample Knokke 89.50 rn, transmitted light; 13. proximal view, sample Knokke 80.75 rn, transmitted light; 14-1 5. Discoaster lodoensis BRAM LETTE & RI EDEL 1954 14. distal view, sample Knokke 97.50 rn, transmitted light; 1 5. proximal view, sample Knokke 132.50 rn, transmitted light. 1 6-1 7. Discoaster barbadiensis TAN SIN HO K 1 927 16. distal view, sample Knokke 71.95 rn, transmitted light; 17. proximal view, sample Knokke 71.65 rn, transmitted light. 18. Discoaster distinctus MARTINI 1959 proximal view, sample Knokke 89.50 rn, transmitted light. 1 9. Discoaster stradneri MARTINI 1961 proximal view, sample Knokke 90.75 rn, transmitted light. 20. Discoaster kuepperi STRADN ER 1959 side view, sample Knokke 89.50 rn, a. transmitted light; b. cross polarized light. 21 . Discoaster bifax BUKRY 1971 side view, sample Knokke 62.50 rn, cross-polarized light. 57 58 PLATE 2 Bar scale on each figure represents 5 pm 1-3. lmperiaster sp. 1. sample Knokke 1 32.50 m, transmitted light; a. high focus, b. middle focus, c. low focus; 2. "sample Knokke 132.50 m, transmitted light; a. high focus, b.low focus; 3. sample Knokke 132.50 m, transmitted light. 4. Ericsonia formosa (KAMPTNER 1963) ROMEIN 1979 distal view, sample Knokke 69.50 m, transmitted light. 5. Ericsonia fenestrata (DEFLANDRE & FERT 1954) STRADNER & EDWARDS 1968 distal view, sample Knokke 69.50 m, transmitted light. 6-7. Ericsonia subdisticha (ROTH & HAY 1967) ROTH 1969 6. proximal view, sample Knokke 69.50 m, transmitted light; 7. distal view, sample Knokke 69.50 m, transmitt~ light. 8-9. Nannotetrina fu/gens (STRADNER 1959) PERCH-NIELSEN 1971 8. distal view, sample Knokke 67.50 m, transmitted light; 9. proximal view, sample Knokke 65.50 m, transmitted light. 10-1 2. Micrantholithus inaequalis MARTINI 1961 1 O. proximal view, sample Knokke 124.70 m, cross-polarized light; 11. distal view, sample Knokke 122.50 m, cross-polarized light; 1 2. distal view, sample Knokke 128.50 m, cross-polarized lig ht. 1 3. Micrantholithus flos DEFLANDRE 1950 distal view, sample Knokke 128.50 m, cross-polarized light. 14-16. Discoaster sublodoensis BRAMLETTE & SULLIVAN 1961 14. distal view, sample Knokke 73.00 m, transmitted light; 1 5. proximal view, sample Knokke 89.50 m, transmitted light; 16. proximal view, sample Knokke 73.00 m, transmitted light. 60 PLATE 3 Bar scale on each figure represents 5 pm 1. Nannoturba spinosa MUELLER 1979 sample Knokke 132.50 m, transmitted light, a. high focus, b. middle focus, c. low focus. 2. Nannoturba robusta MUELLER 1979 sample Knokke 132,50 m, cross-polarized light. 3. Neococcolithes dubius (DEFLANDRE 1954) BLACK 1967 distal view, sample Knokke 69.50 m, transmitted light. 4. Tribrachiatus orthosty/us SHAMRAI 1963 sample Knokke 235.50 m, transmitted light. 5. Pontosphaera pulchra (DEFLANDRE 1954} ROMEIN 1979 distal view, sample Knokke 97.50 m, cross-polarized light. 6. Pontosphaera obliquipons (DEFLANDRE 1954) ROMEIN 1979 distal view, sample Knokke 71.65 m, cross-polarized light. 7. Rhabdosphaera gladius LOCKER 1967 side view, sample Knokke 69.50 m, transmitted light. 8. incertae sedis sp. 2 sample Knokke 106.40 m, cross-polarized light. 9. incertae sedis sp. 1 sample Knokke 106.40 m, a. high focus, b. low focus, transmitted light, c. middle focus, cross-polarized light. 1O. Pontosphaera wechesensis (BUKRY & PERCIVAL 1971) AUBRY 1983 proximal view, sample Knokke 67.50 m, cross-polarized light. 11 . Toweius sp. distal view, sample Knokke 71.95 m, cross-polarized light. 12. Reticulofenestra foveo/ata (REINHARDT 1966) ROTH 1970 proximal view, sample Knokke 67.50 m, a. and b. cross-polarized light, c. transmitted light. 13-14. Zygrhablithus crassus LOCKER 1967 13. side view, sample Knokke 71.65 m, cross-polarized light; 14. side view, sample Knokke 73.00 m, cross-polarized light. 15. Nannotetrina pappi (STRADNER 1959) PERCH-NIELSEN 1971 sample Knokke 65.60 m, transmitted light. 16. Sphenolitus sp. 2 side view, sample Knokke 71.65 m, cross-polarized light, viewed at 45° to the polarization directions. 17. Sphenolitus furcatolithoides LOCKER 1967 side view, sample Knokke Knokke 69.50 m, cross-polarized light, parallel to the polarization directions. 61 62 REFERENCES MOSHKOVITZ, S. & EHRLICH, A., 1982. Biostratigraphical problems of the Middel Miocene calcarecius nannofossils and the peleoecological significance of the Braarudosphaerids in the Coestai-·Piain and offshore AUBRY, M.-P., 19B3. Biostratigraphie du Paléogène épicontinental de of Israel. Geol Survey Israel. Currant Research 1981 (1982): 43-47. l'Europe du Nord-Ouest. Etude fondée sur les Nannofossiles calcaires. Docum. Lab. Gtlol. Lyon, B9: 1-317. MUELLER, C., 1970. NanRoplankton aus dem Mittei-Oiigoziin von Norddeutschland und Belgien. N. Jb. Geol Pa/sont. Abh. 135 (1): 82- BACKMAN, J., 19BO. 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Calcareous Nannofossil Systematics, Paleo Kallo-Halle. ln: Le sondage de Kallo (Au Nord-Ouest d'Anvers). ecology, and Biostratigraphy of the Middle Eocene Weches Formation of Toelichtende Verhandelingen voor de Geologische keart en Mijnkaart Texas. Tulane Stud. Geol. Paleont., 11 (1): 1-79. van België, 11: 3-7. STEURBAUT, E., 1983. The stratigraphie position of the Lower JACOBS, P., 1978. Litostratigrafie van hat Boven-Eoceen en van hat Oligocene Yrieu Sands (Southwestern France), basad on calcareous Onder-Oiigoceen in Noordwest ·selgië. Mijnwezen-Aardkund. Dienst nannofossils and a new Helicosphaera species. Eclogae geol He/v., 76 België, professions/ paper 178/3, l-VI: 1-92. (2): 327-331. LEZAUD, L., 1968. Espèces nouvelles de nannofossiles calcaires STRADNER, H. & PAPP, A., 1961. Tertiiire Discoastariden aus (Coccolithophoridés) d'Aquitaine sud-ouest. Rev. Micropal., 11 (1 l: 22- Oesterreich und deren stratigraphische Bedeutung, mit Hinweisen auf 28. Mexico, Rumiinien und Italien. Jahrb. Geol. Bundesanst., Sonderb•• 7: LOCKER, S., 1967a. Neue Coccolithophoriden (Fiagellata) aus dem 1-160. Alttertiiir Norddeutschlands. Geologie, 16 : 361-365. TAPPAN, H., 1980. Haptophyta, Coccolithophores, and other Cal LOCKER, S., 1967b. Neue, stratigraphisch wichtige Coccolithophoriden careous Nannoplankton. ln: The Paleobiology of Plant Protists. 9 : 678- (Fiagellata) aus dam norddeutschen Alttertiiir. Monatsber. Deutsche 803 (Freeman & Comp.• San Francisco). Akad. Wissenshaft., 9: 758-768. MARTINI, E., 1961. Nannoplankton aus dam Tertiiir und der obersten Kreide von SW-Frankreich. Sanckenb. Lethaea, 42 (1 /2): 1-41. POSTCRIPT MARTINI, E., 1970. lmperiaster n.g. aus dam europiiischen Unter Eoziin (Nannoplankton, incel'fi.e sedis). Senckenb. Lethaaa, 51 (4): 383- The manuscript of this paper wes submitted for publication in the 386. middle of 1984, before the publication of the author's revisions of the MARTINI, E., 1971. Standard Tertiary and Quaternary Calcereous Tertiary stratigraphy of Belgium (several·papers in 1986 and 1988). The Nannoplankton Zonation. Proc.ll Planktonic Conference (R~ma 1970), litho- and biostratigraphic subdivisions proposed here to do not Il: 739-785. correspond to these in the author's 1986 and 1988 papers. 63 Chapter VI UPPER CRETACEOUS NANNOPLANKTON IN THE KNOKKE WELL by S.G. BAL & J.W. VERBEEK lnstitute of Earth Science, Free University, Amsterdam Geological Survey of the Netherlands, Haarlem Sample 7 (Early Campanian) INTRODUCTION Sample 7, taken 1.85 m above sample 8, is Eight core samples taken from the Knokke weil assigned to the 8roinsonia parca Zone of in Belgium between 430.5 m and 311 m, were VERBEEK (1977), indicating an Early Campanian analysed to determine their depositional age from age. This conclusion is based on the joint their calcareous nannoplankton content. The occurrence of 8roinsonia parca, Reinhardtites exact location of the weil and its geologie and brooksii (BUKRY), 8roinsonia lacunosa FORCH technical data are given in the introduction to this HEIMER, and Podorhabdus coronadventis (REIN volume. The relative position of the samples is HARDT), and on the absence of Lithastrinus shown in figures 1 and 2. floralis in sample 7 and higher samples. The authors are grateful to the Director of the According to SISSINGH's (1977) zonation, Geological Survey of Belgium and The Nether sample 7 belongs to the Aspidolithus parcus s.l. lands for permission to publish this study. . Zone (18), which is defined as the interval from the first occurrence of Aspidolithus ex. gr. parcus (STRADNER) (= 8. parca) to the last occurrence of 1.- BIOSTRATIGRAPHY Marthasterites furcates (DEFLANDRE). The ap proximate age of this zone is Early Campanian Ali of the sam pies under studyyielded a diverse (early part). Below the A. parcus s.l. Zone, but moderately weil preserved nannoflora gene SISSINGH recognizes another zone, the Calculi rally overgrown with secondary calcite. ln ali, 62 thus obscurus Zone ( 17) placed in the earliest part species were recorded (Fig. 1 ). of the Early Campanian, which is defined as the The zonations of SISSINGH (1977) and interval from the first (regular) occurrence of VERBEEK (1977) were used for chronostratigra Calculithus obscurus (= Phanulithus obscurus) to phical correlation. The results are discussed in the first occurrence of A. ex. gr. parcus. Both P. stratigraphical order. obscurus and 8. parca are absent in sample 8, but they occur in sample 7. Thus, according to Sample 8 (late Santonian) SISSINGH's zonation there could be a hiatus between samples 8 and 7. Sample 8 can be assigned to VERBEEK's (1977) Z. spiralis Zone on the basis of the presence of According to VERBEEK (1977), the first Zygodiscus spiralis, Lithastrinus floralis STRAD occurrence of 8. parca correlates with the NER, Lucianorhabdus cayeuxii as weil as the Santonian-Campanian boundary. Due to his absence of 8roinsonia parca (STRADNER), and to different species concept,. SISSINGH places the SISSINGH's (1977) Lucitmorhabdus cayeuxiiZone first occurrence somewhat higher. on the basis of the pr~sence of Lucianorhabdus cayeuxii and the absencle of Phanulithus obscurus Sample 6 (Early Campanian) (DEFLANDRE). Both zones can be correlated with Sample 6 too is assigned to the 8roinsonia the Late Santonian. . parca Zone (VERBEEK, 1977), because of the 64 occurrence of Broinsonia parca, Podorhabdus " ""'' "' "', VI lA " coronadventis and Reinhardtites brooksii. Ac -< -- "'z ,.,..,_"'cm "' OOO»N " ~ ::0:: cording to SISSINGH's (1977) zonation it is not t>;j 1 .., ... z M~MM z l' >O certain whether sample 6 should be placed in his oo;r:: t-< 0 Aspidolithus parcus s.l. Zone (18) or the Calculi "' "'-< t-< ::0:: "' ::0:: tes ovalis Zone (19), because the zonal marker "' -- t>;j "' ttl Marthasterites furcatus, which marks the bound zen .... C> ary between these two zones, was not en .,,r::r:: ...... countered in this or the other samples. Other "'"' species that could help to distinguish between HMUELLERELLA REGULARIS these zones are not indicated by SISSINGH's RKHANGELSKIELLA SPECILLATA (1977) zonation. ISCUTUM CONSTANS B 1 GELOW 1 1 ~~~~f!RAARUDOSPHAERAIOISCUS IGNOTUS ROINSONIA PARCA HIASTOZYGUS AMPHJPONS Sample 5 (Early Campanian) ETARHABOUS CONICUS RETARHABDUS CRENULATUS RIBROSPHAERELLA EHRENBERGI 1 Since Broinsonia lacunosa, Broinsonia parca, HIASTOZYGUS LITTERARIUS ! RJBROSPHAERELLA PELTA Podorhabdus coronadventis and Reinhardtites RETARHABDUS SURIRELLUS IIIIIYLIFFELLITHUS 1 N'ÔRAL 1 THUS TURRISEIFFELI SERR"ATUS brooksii are still present, sample 5 has been placed ARTNERAGO OBLJQUUU AMPTNERIUS MAGNIFICUS in the Broinsonia parca Zone of VERBEEK (1977). ITHRAPHIDITES CARNIOLENSIS UCIA~ORHABOUS CAYEUX! 1 ICRORHABOULUS BELGICUS For the sa me reason as mentioned for sample :~ICRORHABDULUS DECORATUS 6, it is not clear whether sample 5 should be ~~À~~~~T~~~~S~~~~ATOIDEA assigned to the Aspidolithus parcus s.l. Zone (18) I ARHABDOLITHUS1 SCOSPHAERA EMBERGERICRETACEA iii!~IPREO HANULITHUS OBS€URUS or the Ca/culites ovalis Zone (19) of SISSINGH REDISCOSPHAERA SPINOSA HAGOOISCUS ANGUSTUS (1977). i EINHARDTITES LEVIS ~~~~~~~V~~~~:ATZNAUERIA ~~~~~ BARNESAE~~~~OTN 1 CAE Sample 4 (Early Campanian) IZYGOOISCUSYGODISCUS COMPACTUSACANTHUS I I~YGOOISCUS OIPLOGRAMMUS lt is not certain whether sample 4 belongs to IFFELLITHUS EXIMIUS the Broinsonia parca Zone, the Cerato/ithoides lll~il~~~gg:KKOLJTHUS ~~~~ ~~AUSTRALIS ~ ~~~~ s EJNHAR~TITES ANTHOPHORUS aculeus Zone, or the Quadrum gothicum Zone of RANOLITHUS ORIONATUS YGODISCUS ELEGANS VERBEEK (1977). Podorhabdus coronadventis is jBROINSONIA ENORMIS ROINSONIA LACUNOSA absent from this sample. Reinhardtites brooksii, EINHARDTITES BROOKS! 1 YGOOISCUS THETA Rucinolithus hayii STOVER, and Eiffellithus ~~~~~l~UCIANORHABDUS MALEFORMIS ! HANULITHUS OVALIS eximius (STOVER) are still present, but the marker ~ UCINOLITHUS HAYII ai=E~l~ROROINSONJA 1 NSO.N 1 A FURTSIGNAlA 1 VA species Ceratolithoides acu/eus (STRADNER) and ~ UCIANO.RHABOUS QUADRIFIDUS Quadrum gothicum (DEFLANDRE) were not S CORONADVENT 1 S a~=E~l~ODORHABOUCAPHOLITHUS FOSSILIS ~ UCIANORHABOUS ARCUATUS encountered, in either this or the other samples. lt nE=E~l;HARUS s 1 MULACRUM. ITHASTRINUS FLORALIS is quite possible that their geographical distribu ~ !CULA CONCAVA ~E=ES:E~HAGoo 1 scus REN 1 ro-RM 1 s tion was restricted (see also under Conclusions). F TEPHANOLITHION LAFFITTE! 1 jmj<>i'-'i''i'"i-il"' PERCENT AGE INDETERMINABLE On the basis of the presence of Luciano rhabdus maleformis RHEINHARDS and Phanu/itus ova/is (STRADNER), and the absence of these two species in higher samples, sample 4 might be placed in SISSINGH's (1977) Cerato/ithpides aculeus Zone (20). The approximate age of this zone is the last part of the Early Campanian. j? ~ N ~· 0 ~ z ~ S. 1"' Sample 3 (Late Campanian) ~ i ::: Reinhardtites brooksii and Broinsonia enormis (SHUMENLO) appear last between samples 2 and ~ 1 r 3. ln the zonation proposed by VERBEEK (1977) this occurs in the lower part of the Quadrum trifidum Zone, which can be correlated with the Late Campanian. However, the zonal marker Quadrum trifidum (STRADNER) is absent. Fig. 1.- Stratigraphical distribution of Senonian calcareous Sample 3 can be assigned to subzone bof the nannofossils in the Knokke weil in relation to the nannofossil Tetralithus trifidus Zone (22) of SISSINGH (1977). zonation of SISSINGH (1877) and VERBEEK (1977). SISSINGH used the first appearance of Rein- 65 KNOKKE 81 SOUTHERN LI MBURG Sample 1 (Early Maastrichtian) -,., Sample 1 is arbitrarily assigned to the ~ "' z Maastrichtian part of the Quadrum trifidum Zone "'0 Vl ;:: V) "".. of VERBEEK (1977). Lithraphidites quadratus, ~ .... .0 ~ cC z "... 1- 0 .._0 whose first appearance denotes the base of the Vl N >" "' l=l==t====F=i------_J=~~:-':::::::_.::d next higher Lithraphidites quadratus Zone(Middle 1 (312,5ml Maastrichtian), was not found. ROTH (1978) 1------..,1' characterized L. quadratus as a species of !;:1-----_, / 2. (324,5m) relatively cold water. On the other hand, PERCH "'ce "' Nephrolithus ~ 1----- frequens "' J 1 NIELSEN (1979) remarked that this species occurs ~ ~ / , Jess consistently in higher latitudes than in the i ~ l:=::1' / 3 (340,5m) Tethyan rea lm, where it is a fairly reliable marker. ~ f------1' 1 1 ~~~--~~~~ 1 1 The nannoplankton assemblages of sample 1 :.:. Lithraphiditus ? 1 quadratus 4 1 ~ fits in with SISSINGH's (1977) definition of the ~ 4 (356,5ml _. J\rkhange 1 skie 11 a z 1 L; Reinhardtites levis Zone (24), as ranging from the cymbiformis L&J 1 ., / ~ lt --~ last occurrence of Tranolithus phacelosus STO ~~"'-+~Q~ua~dr~u~m----~ g ~ VER to the last occurrence of Reinhardtites levis. T. trifidum 6 ,., l/Uadrum L-, orionatus occurs last between samples 2 and 1 ~~·g•o~th~i~cu~m----4-~L' 5 (376,5ml and R. levis is present in sample 1. The approximate age of the R. levis Zone is Early Maastrichtian (early part). Since SISSINGH's ~z ~ _. Broinsonia Tranolitus phacelosus Zone (23) was not reco 5 pareil vered, a hiatus might be present between samples 6 (400,5m) 2 and 1. · ...... , barren Conclusions ' .... , v! (428,5m) ? __ --- - _... vB (430,35m) Calcareous nannofossil analyses have shown that the sediments between 430.5 m and 311 m Fig. 2.- Proposed correlation of Knokke weil with the results of a calcareous nannofossil study of the Senonian in southern were deposited between Late Santonian and Early Limburg (VERBEEK, 1983). Maastrichtian times. hardtites levis PRINS & SISSINGH to define the Due to the absence of many zonal markers, lower boundary of subzone b of the Tetralithus zonal assignment is mainly based on other species trifidus Zone (22) and the last occurrence of considered to be of biostratigraphical importance. Reinhardtites anthophorus (DEFLAN ORE) to de Why these marker species are absent is not clear. fine the upper boundary of this subzone. The first SISSINGH (1977) suggested that Ceratolithoides appearance of R. levis occurs between samples 4 aculeus, Quadrum trifidum and Tetralithus nitidus and 3, and R. anthophorus is still present in sample MARTINI are geographically confined to, or are 3. The approximate age of the T. trifidus Zone is most common in, the tropical belt. PERCH Late Campanian (late part). Since SISSINGH's NIELSEN (1979) noted that Marthasterites furca Tetralithus nitidus Zone (21) and subzone a of the tus is a reliable marker species in high latitudes T. trifidus Zone were not found, a hiatus may be and that C. aculeus, Q. trifidum and Q. gothicum present between samples 3 and 4. might be restricted to tropical areas, because she had not found them in the North Sea area. ROTH Sample 2 (Late Campanian) (1978) stated that the distribution of Q. trifidum was latitudinally controlled. He did not find this Sample 2 is referable to the Late Campanian species in Early Maastrichtian sediments at DSDP part of the Quadrum trifidum Zone of VERBEEK site 390A (Blake Plateau; paleolatitude 25-30°N). (1977), because Eiffellithus eximius has its last CRUX (1982), however, has found C. aculeus, M. occurrence between this sample and sample 1. furcatus and W. trifidum in northern North Sea The extinction of E. eximiut; marks the Cam material. FINCH (pers. comm. 1981, in CRUX panian/Maastrichtian boundary. 1 982) has reported Q. gothicum from the southern The co-occurrence of Reinhardtites levis and part of thè North Sea. VERBEEK (1983) found Q. Reinhardtites anthophorus indicates that sample trifidum in the Gulpen Formation (below the 2 belongs to subzone bof SISSINGH's TetralithLis Maastrichtian stratotype) deposited in the south trifidus Zone (22) (see also under Sample 3). eastern part of The Netherlands. According to 66 CRUX (1982), it seems probable that sorne of the correlates with the Earl y Maastrichtian part of the species that are Jess corrimon or absent have Gulpen Formation. distribution patterns determined by factors other The Late Santonian Aachen Formation and the than water temperature alone. Early Campan·ian Vaals Formation of southern According to SISSINGH's(1977) zonation three Limburg consist predominantly of sandstone hiatuses may be present : one between samples 8 sequences deposited in a marginal marine and 7 (Early Campanian (earliest part)), one environment (ALBERS & FELDER, 1979). Based between samples 4 and 3 (late Campanian (early on the results of the present study, we postulate part)), and one between samples 2 and 1 (Late that during the same interval open marine Campanian (latest part) to Early Maastrichtian carbonates accumulated at the Knokke locality (early part)). But according to VERBEEK's (1977) approximately 180 km W of southern Limburg. zonation, we must also take into account the From the Late Campanian through the Early possibility of a hiatus in the Late Campanian (early Maastrichtian, carbonates were deposited under part). Because of the low resolution of sampling, it open marine conditions in both areas. ln contrast is impossible to delimit the stratigraphie gaps with southern Limburg, no Middle and Late precisely and the, possibility of condensed Maastrichtian deposits were found at the Knokke sequences between the samples cannot be ruled site. out. 2.- CORRELATION BETWEEN THE KNOKKE WELL AND SOUTHERN REFERENCES LIMBURG ALBERS, H.J. & FELDER, W.M., 1979. Litho-, Bistratigraphie und Palôkologie der Oberkreide und des Alttertiiirs (Priiobersanton VER BEEK ( 1983) performed a calcareous Dan/Paliioziin) von Aachen-Sudlimburg (Niederlande, Deutschland, nannoplankton study in Senonian rocks in the Belgien). ln: WIEDEMANN, J. (ed.), Aspekte der Kreide Europas./UGS, southern part of Limburg. ln the study area there Ser. A. 6 : 47-84. are four formations (see fig. 2). Except the Aachen BUKRY, D., 1969. Upper Cretaceous coccoliths from Texas and Europe. Univ. Kansas Paleont. Contrib., art. 1 (Protista 2): 1-79.d. Formation and the top of the Maastricht Forma CRUX, J.A., 1982. Upper Creta~eous (Cenomanian to Campanian) tion, the upper Cretaceous deposits of Limburg calcareous nannofossils./n: LORD, A.R. (ed.), A Stratigraphicallndexof contain well-preserved nannofloras. The zonal Calcareous Nannofossils. Ellis Horwood Limitee/, Chicester, England: assignment of these deposits is after VERBEEK 81-136. (1983), i.e., a slightly modified version of his earlier PERCH-NIELSEN, K., 1979. Calcareoils Nannofossils between the North Sea and the Mediterranean./n: WIEDMANN, J. (ed.), Aspekte der zonation (VERBEEK, 1977). This version has only Kreide Europas. E. Schweizerbart'sche Verlagsbuchhand/ung, Stutt local value and therefore should not be applied to gart: 223-272. other areas without qualification. VERBEEK fou nd ROTH, P.H .• 1978. Cre~aceous nannoplankton biostratigraphy and a fairly complete sequence of zones in the rocks of oceanography of the Northwestern Atlantic Ocean, Deep Sea Drilling Project.ln: BEN SON. W.E. etal., /nit. Rep. DeepSeaDri/1. Proj., 44:31- southern Limburg. Only the Ceratolithoides 759. acu/eus Zone could not be defined. SISSINGH. W.. 1977. Biostratigraphy of Cretaceous calcareous nannoplankton. Geol. en Mijnbouw, 56 (1): 37-65. · Correlation between the upper Cretaceous VERBEEK, J.W.• 1977. Calcaraous nannoplankton biostratigraphy of deposits of southern Li mburg and those of Knokke, Middle and Upper Cretaceous deposits in Tunisie. Southern Spain and give the following results (see Fig. 2). Sample 8 France. Utrecht Micropal. Bull., 16: 1-57. • correlates with the Aachen Formation, and VERBEEK. J.W.. 1983. The calcareous nannofossils from the samples 7-4 correlate with the Vaals Formation. Campenian and Maastrichtian rocks of southern Limburg (The Netherlands) and the adjacent Belgian area./n: abstracts- Symposium Samples 3 and 2 correlate with the Campanian on Cretaceous Stage Boundaries. Geologisk Centra/institut. Univerity of part of the Gulpen Formation, and sample 1 Copenhagen K, Denmark: 197-200. 67 Chapter VIl EOCENE -STRATIGRAPHY OF THE KNOKKE BOREHOLE (BELGIUM) by C. KING Pa/eoservices Ltd, England INTRODUCTION B. SAMPLES STUDIED A. GENERAL FEATURES The borehole cores were studied and sampled at the Belgian Geological Survey office in 1982, The Knokke borehole penetrated the Eocene and additional samples were supplied by the BGS sediments between 30 m and 288 m, beneath the in 1984. Sampres were collected, as far as Pleistocene and overlying the Landen Formation possible, at 1 -meter intervals, and were about (chapter 1). The base ofthe Eocene is here ta ken for 10cm in length. convenience to equate with the base of the Ieper The samples were processed by sieving on a Formation, although this is not strictly correct. 120 micron sieve, in order to concentrate the The Eocene sequence comprises represen microfossils. Each sample was dried, soaked in hot tatives of the Ieper Formation, the Egem water until disaggregated, and sieved. The Formation, the Mont-Panisel Formation, the resulting residue was soaked in a 10% solution of Knesselare Formation, a very thin representative Ca Igon (sodium hexametaphosphate) for one hour of the Brussels Formation, and the lower part of and then sieved again. the Kallo Formation (including a thin development This technique produced clean residues in of the Wemmel Member). The Lede Formation is most cases, but sorne of the clays in the upper part absent. Core recovery was almost complete, with of the Ieper Formation did not respond weil to this the exception of the section between 74 m-79 m, method, and after the first sieving were treated · where little core was recovered due to drilling with a 20% solution of cold hydrogen peroxide and problems associated with the presence of hard resieved. sandstone beds. The sa mples processed weighed between 200 The Knokke section is important for the studyof and 500 grams. lnitially samples were processed Eocene stratigraphy, as it is situated in the a rea of at 2 -metre intervals, with intermediate samples maximum thickness of the Early Eocene in being processed if ·necessary, in order to define Belgium (see KAASSCHIETER 1961, Map 1 0). ln faunal changes more closely. 152 samples were particular, it provides a continuously co red section processed. through the Ieper to Knesselare Formations. lts geographicaJ.. location is also import~nt for C. FOSSIL GROUPS STUDIED correlation with sequences in the southern North Sea and in southern England.lt th us provides a key The main fossil groups studied are the section for this part of Belgium. benthonic foraminiferids and the ostracods. This paper deals with the lithostratigraphy, microfaunas and macrofaunas of the Eocene succession, and discusses its correlation with N.B. This paper was submitted in 1985, and only other sections in Belgium, the southern Nether minor revisions have been made subsequently. lands, the southern North Sea and southern Lithostratigraphic terminology on the figures may England. therefore differ from that in the text. 68 Planktonic foraminiferids·were identified generi 1.- «PRESERVATIONAL FACIES» cally, but have not been studied in detail. -ITS EFFECT ON BIOSTRATIGRAPHIC Molluscs were collected from the core samples AND ECOLOGICAL INTERPRETATIONS before disaggregation, and also picked from the washed residues. Particular attention has been The distribution and preservation of calcareous paid to the planktonic molluscs (pteropods). and siliceous Eocene fossils in the Knokke borehole has been significantly influenced by Bryozoa, solitary corals and annelids (ser differentiai post-depositional diagenesis, related pulids) are also recorded at sorne levels. to the differing skeletal mine.ralogy ofthesefossils Other groups encountered include diatoms, (fig. 1). Similar processes have affected ali fossil radiolaria, sponge spicules, calcareous and phos assemblages, but their influence in altering the phatic microproblematica (including Pseudarcel/a original composition of the assemblage has often and similar taxa), fish debris, and seeds, and these been ignored or under-estimated. Their reco have also been included in this study. gnition is critically important for interpreting fossil Identifications o1 species are based mainly on distributions and fossil assemblages, and for the following references: reconstructing depositional environments. As the sequence at Knokke is below the modern zone of Foraminiferids: SH ER BORN & CHAPMAN (1886), weathering, the geochemical changes can be KAASSCHIETER (1961), MURRAY & WRIGHT assumed to be due to diagenetic processes rather (1974), WILLEMS (1980; 1983).. th.an to recent weathering processes-: 'Problematica': KEIJ (1969,1970), WILLEMS (1972,1975). A. SILICEOUS FOSSILS Serpulids: WRIGLEY (1949, 1954). Diatoms, radiolaria and siliceous sponges have Benthonic molluscs: COSSMANN (1886-1913), skeletons of opaline silica. Their diagenesis in the COSSMANN & PISSARRO (1904-1913), GU BERT Knokke sequence involves the dissolution ofthese (1933). skeletons and their replacement or infilling by Pteropods: CURRY (1965). pyrite. Ostracods: JONES (1857), JONES & SHERBORN ln the Eocene of the Knokke borehole, siliceous ( 1889), KEIJ (1957), HASKINS (1968-1971 ), KEEN microfossils are preserved only in two intervals: (1978). between 145 m-1 04 rn (from the top of the Ieper Formation to the lower Mt.-Panisel Formation) and Comparative material in the author's collection between 41.5 m-35 rn (within the Kallo For from various English and Belgian localities has mation). Throughout the rest of the section, also been utilised as far as possible. diatoms, radiolaria and sponge spicules are The distribution and abundance ofthefossils is represented only by pyrite casts and moulds. There plotted on a semi-qualitative basis on range charts is no obvious correlation between the lithology and (figs.3, 5, 8, 9, 10, 12, 13). the type of preservation, but the levels with siliceous skeletons preserved may reflect rela D. LITHOLOGICAL LOGGING tively high levels of original biogenic silica in the sediment. Basic lithologicallogging, including qualitative Different groups of siliceous organisms have estimates of grainsize and sorting, has been different relative susceptibilities to dissolution. carried out using macroscopic study and law The order of increasing susceptibility is: sponge power stereo microscope examination. spicules-radiolaria-diatoms (HEIN et al, 1978). The presence and relative abundance of pyrite, This may explain the often observed occurrence in glauconite, mica, woody debris, and other the same sample of pyritised radiolaria with components of the sediments in residues of the siliceous sponge spicules. washed samples, has been estimated semi q uantitatively. B. CALCITIC FOSSILS The lithostratigraphic interpretation and no Most foraminiferids, ostracods, severa! groups menclature used is taken mainly from VANDEN of bivalve molluscs (chiefly ostreids and pectidids), BERGHE et a/.,(cha~tter 1), JACOBS, (1978) and and serpulid annelids have entirely or partly WILLEMS et a/.,(198 1). calcitic skeletons. Calcite is a relatively stable form 69 of calcium carbonate, and in impermeable sediments it is often stable over very long periods c "'0 c ..... c "'0 of ti me. ln more permeable sediments, it is subject QJ 0"' ...... QJ Qi QJ to dissolution by acidic groundwater solutions. -"' Qi QJ Qi -"' "'s.. "' -"' ln the Eocene of the Knokke borehole, calcitic ..... u "' QJ :z: ·~ til 0 ..... "'u :::> fossils are preserved in the intervals between ~ ·~ ·~ 0 ~ c ..... QJ 248 m-217.5 m (middle Ieper Formation), and cc 0 ·~ u =..... ::E u o. a! "' between 133 m-63 m (lower Mt.-Panisel For QJ 0 "'s.. ·~ 0 LI.. cc Vl mation to lower Kallo Formation),but are largelyor entirely absent at other levels. ln the Mt.-Panisel Formation and the Knesselare Formation, the 50 foraminiferids and ostracods are often slightly corroded and partly encrusted by reprecipitated calcite, indicating sorne diagenetic redistribution of calcite. The distribution of calcitic fossils is partially related to permeability, as the coarser grained parts of the Mt.-Panisel Formation are preferen tially decalcified, but sorne of the silty clays of the Ieper Formation and the Kallo Formation are also devoid of calcareous microfossils. This is a regional feature, seen at similar levels in other sections in Belgium, and is discussed in more P'7'7/l Ori gina1 detail below. lt is probably due to an originally low ~ skeleton abundance of biogenic calcite, combined with the 1-~±:ttf;::±~;:;~ preserved presence of acidic porewaters. Pyrite moulds of formerly calcitic fossils occur consistentlythrough :}::::}:} ::::::::::=::::: !::::::::::::::::1 by the upper part of the Ieper Formation and in the 150 ~~~~~;~~=~~s ...... ::::::::::::::::·.:::::::::::::::· Kallo Formation ...... {))))(f(~ C::J not preserved C. ARAGONITIC FOSSILS Ittt l!lf!lil!l!lil !lil!!!Ili!t Aragonite skeletons are prevalent in most groups of molluscs. Aragonite is a relatively unstable form of calcium carbonate, and so occurs in generally decreasing abundance in rocks of increasing geological age. ln the Knokke borehole aragonitic 200 molluscs are preserved only within the intervals 104 m-68 m and 133 m-122 m (in the Mt.-Panisel Formation, the Knesselare Formation and the basal Kallo Formation). They are often partly corroded and porous ('chalky'), indicating sorne Joss of carbonate. At other levels they are represented by pyrite moulds. 250 D. CONCLUSIONS The fossil distributions observed in the Knokke borehole only imperfectly reflect the original assemblages, due to significant modification at most levels by diagenetic geochemical processes. Reconstruction of the original assemblage can be :::::::::::::::· partially achieved by careful observation of the presence of pyrite casts or moulds, often rare and poorly preserved, giving sorne indication of the Fig. 1 .- «Preservational biofacies• of the Eocene section nature of the original fau na. Selective dissolution in the Knokke borehole of calcareous foraminiferids and calcareous- 70 cemented agglutinants in an original mixed ::iE: :.::::..:.:·~.:.:1 LLJ ;..:: calcareous/agglutinating assemblage (e.g. in 140- CD ·-·-·-··· LLJ 1- ·-·- ---· 1 parts of the Ieper Formation) can produce 1--- ~---:...-.:..:r misleading environmental implications unless - - r- - - recognised. Sections which appear at first sight to - - ' be virtually unfossiliferous (e.g. parts of the upper 1-- - - - • Flanders Member) can reveal the presence of 160- 1-_ ~- =--) traces of what was originally probably a relatively - - - diverse fauna. r-- - - - 1 -1 1------) 1 -- - 2.- IEPER FORMATION 180- - - 1-- - AND EGEM FORMATION - -,rj 1 1------1 A. LITHOSTRATIGRAPHY. - - - - - The Ieper formation in the Knokke borehole can --- - 1-- - be subdivided into three Members (Fig. 2). The 200- - - lowest Member has not been recorded elsewhere 1-- - - - in Belgium, but the other units (Fianders Member 1-- - (/) and Egem Formation) can be recognised regionally 0::: -- -J LLJ (see WILLEMS et al., 1981, WILLEMS, 1982). Cl - - - ' 1-- - r z ce - - «Member X» (288.0 m-283.4 m) .....1 1- - - 220- u.. - - - 1-- - Sandy clayey silt, heavily bioturbated and - -- r-- - «streaky», with irregular pockets and lenses of very - -- fine silty sand. Fine-grain~d mica, woody debris - ---- and glauconite are present throughout. The basal ------contact with the sands of the Landen Formation is - --- - sharp and even. 240------Fine to coarse-grained angular to subangular ------grey < subangular pebbles of fl·int. This bed passes up interval 278.5 m-217. Om, small pyritised diatoms gradationally into bioturbated very silty clay (chiefly small biconvex and biconcave Coscino (283.4 m-c.282.6 m) which is overlain by homo discus spp.) are recorded fairly consistently; at genous silty clay. 253.5 m-251.5 m Coscinodiscus sp.1 is common. lt is possible that this basal part of the Flanders Between 212 m and 206 m no diatoms are Member (283.4 m-282.6 m) correspondstothe Mt. recorded. From 206 m to the top of the Flanders Heribu Member, as defined elsewhere, but it is so Member, small pyritised diatoms again occur thin that it is not separated here. The biostrati commonly and consistently. These are mainly graphic data (see below) indicate th at microfaunas small biconcave and biconvex Coscinodiscus spp.; and microfloras typical of the Mt. Heribu Member Triceratium sp. is also recorded. A similar at outcrop are here fou nd in the lower part of the assemblage occurs in the Egem Formation, but Flanders Member. specimens are less common. Above these basal beds, the lower half of the Radiolaria Flanders Member (282.6 m-c.213.5 m) is an Occasional large pyritised spherical reticulate extremely homogeqous silty clay. Rare partings of radiolaria, similar to the forms referred to very fine sand occur near the base at 271.5 m and 'Cenosphaera' in the North Sea (KING, 1983)occur 275.26 m, but otherwise no bedding is visible. Thin through the interval189 m-145 m. Large lenticular horizontal branching pyrite «Sticks» are common. radiolaria, accompanied by occasional spherical These clays are probably intensely bioturbated, but radiolaria, occur between 145 m-139 m. due to their very homogenous texture they appear «massive». 'Problematica' At c.213.5 m there is a change to siltier clays Problematic calcareous microfossils are re with a few silt streaks and partings. The upper hait corded rarely in two samples: at 231.5 ma single of the Flanders Member (c.213.5 m-c.144. Om) specimen of Pseudarcella trapeziformis, and at consists of alter nations of homogenous silty clays, 221. Om single specimens of P. trapeziformis and and very silty clays/clayey silts with silt streaks Voorthuyseniel/a graci/is. Both these species are and partings, in units c.5-1 0 m thick. The recorded by WILLEMS, (1972) from the middle of boundaries between these units are generally the Flanders Member in the Kallo borehole. transitional, and no sharp lithological junctions A problematic phosphatic microfossil (recorded were observed. Bioturbation is expressed mainly as 'phosphatic microproblematicum' in WILLEMS, by the «Streaky>> texture of sorne of the siltier beds, 1982, Table 1 and as organism ·x· in KING, 1984) but discrete burrows are rarely visible, except for occurs fairly consistently but in low numbers Chondrites burrow systems at sorne levels (e.g. at (rarely more than one specimen per sample) 146 m-148 m). Pyrite «Sticks» and lumpy pyrite through the interval 183.0-271. Om, and occa nodules are common. Small glauconitised faecal sionally at other levels. This form is widespread in pellets occur consistently through the interval the London Clay Formation in England and 213.5 m-156 m; they are particularly corn mon elsewhere in the Ieper Formation, but has not yet between 199m and 191 m. been recorded elsewhere. Egem Formation (Yd) (c. 144.0m-135.0m) Ben tho nic fora miniferids The Egem Formation is represented mainly by a Benthonic foraminiferids occur consistently bioturbated very sandy silt/very silty sand, with through the lower and middle parts of the Ieper argillaceous streaks. The basal junction is Formation. Above 181 m the section is entirely transitional. lt contains corn mon very fine grained barren except for occasional pyrite casts of glauconite, and less common very fine grained foraminiferids (see comments above on preser woody debris and mica. The top 1-1 ,5 metres is vation). coarser grained; comprising a very fine to fine silty sand, with fine and medium grained glauconite. As noted by WILLEMS, (1983), two distinct associations of agglutinating foraminiferids are B. BIOSTRATIGRAPHY present in the Ieper Formation- and similar associations can be recognised widely in Cainozoic Diatoms sediments of the North Sea Basin. The first Pyritised moulds of the large diatoms Coscino assoc_iation (AA-1 of WILLEMS) includes the discus sp.1.and C. sp.2. (see KING, 1983, Pl. 1, genera Ammodiscus, Haplophragmoides, Mili Figs. 1-3) are corn mon in the basal Ieper Formation ammina, Recurvoides, Rhabdammina and Tro (Member «X» and the basal Flanders Member) chammina; and certain species of Textularia and between 284.5 m and 278.5 m, associated at Spiroplectammina (T. p/ummerae and S. specta 281.5 m with common Triceratium sp. ln the bi/is). The second association (AA-11 of WILLEMS) 72 ~ ~ "'0> "' "'... "' "'0 0> :;;: Depth (metres) 0 "'0 0 0"' 0 0 0"' 0 Il Ill llllllllllllllll lill lllllllll lill 11111 llllllllllllllllllllllll lllllllllllllllllllllllll SAMPLE POSITIONS ~ HapZophragmoides/Troahammina spp. indet. • Verneuil-ina subeocena • HapZophragmoides sp • n. aff. walteri 1--.J Trochamminoides subtrullisatus - 1- -- - - Rhabdammina sp. f- -- Ammodiscus cretaceus - • TPoahammina af. infZata 1• - 1- ~ 1- 1-t - - - • Spiroplectammina adamsi - -- - .- Recurvoides gr . lùalteri ... - -· - - Bathysiphon sp. ------Spiroplectarnrn1.-ua spectabilis - ~-~ - - -- Lenticulina spp. CibiaideslAnoma Zinoides spp. indet. •1 GZanduZina sp. ------11-- 1 Karrerie lla ?conversa - Lagena sp. 1 ~ .. Pulsisiphonina prim~ r- - - - - HapZophragmoides liJaZteri - - AnomaZinoides spp. - Te:x:tularia plummerae ------Haplophroagmoides burroliJBi Miliammina paleocenica - Vaginulinopsis. wetherellii 1- - - - Nodosaria Zatejugata f- f- ~ Uvigerina batj esi ... A Zabamina obtusa - == - DentaZina megaZopoZitana ·- -1 Stilostomella midwayensis -----"' 1 1 Cibiaidoides crassus .... Cibiaidoides sp. nov. - • Eponides sp. .... - PuZZenia quinqueZoba - --1 ill- Karreriella oveyi •- - - - Praeg Zobobu Zimina ovata - -- Pseudoclavulina anglica - -- 1+- "'- Gyroidinoides angustiumbilic~tus - - Anomalina grosserugosa --- Lagena striata Nodosaria longiscata --- Lagena hystri:r: Cibicidoides pz:opriùs Anomalinoides acutus - - Brizalina anglica ••- Loxostomoides applinae - GZoboaassiduZina subgZobosa - Textularia smithvillensis 1- 1-- Lenticulina megalopoZitana -- Uvigerine ZZa abbreviata 1 Textularia agglutinans - - Flori lus commune - 1• Ano_malinoides gr. nobilis - _,_ Oridorsalis umbonatus 1 Cibicides ungerianus Nodbsaria sp. af. natchitochensis - ~onioneZZa spissa - StiZostomeZZa aauZeata OsanguZaria pZummerae - Lagena axiformis -- Nodosaria so luta Ammodisaus af. septatus - - - - - ~ - Reophax sp. - KarrerieZZa sp. - -- - Cibiaidoides af. proprius - - Spirop Zeatammina/Textu Zaria sp. b c d e f -- - FZoriZus cf. commune KN KN KN KN-4 1 2 3 KN-5 KN-6 KN-7 BENTHONIC FORAMINIFERID ASSEMBLAGES Fig. 3.- Distribution of benthonic foraminiferids in the Ieper Formation of the Knokke borehole 73 includes the genera Karreriel/a (except K. conver within the Ieper Formation of the Knokke section, sa) and Pseudoclavulina and most species of with boundaries ta ken at significant changes in the Textularia and Spiroplectammina. total benthonic foraminiferid assemblage (Fig. 3, Fig. 4). The first association generally occurs either as a «pure» agglutinating assemblages, or associated Assemblage KN-1 {288. Om-283.4 rn) with rare and often corroded calcareous foramini ln the basal «Member X» only very rare and ferids. lndividuals are often partially collapsed and poorly preserved indeterminate agglutinating deformed (see WILLEMS, 1983, Fig. 4). The second foraminiferids have been recorded (Haplophrag association usually occurs together with a diverse moides/Trochammina spp. indet). Although this and well-preserved calcareous benthonic forami hardly qualifies as a well-defined assemblage, it niferid assemblage, and specimens are normally can be defined negatively by the absence of taxa well-preserved and uncrushed. occurring in the overlying unit, including Ammo These two associations clearly reflect differing discus and Rhabdammina. environmental contexts. As WILLEMS notes, the first group often odeurs as one of the «exclusively agglutinating» faunas discussed by MOORKENS, Assemblage KN-2 (283.5 m-278.4 rn) (1975) and GRADSTEIN & BERGGREN, (1981 ). These are regarded as adapted to oxygen-poor and A limited and poorly assemblage of AG1 alkaline seafloor environments, probably origi agglutinating foraminiferids (AG 1 index 1 00%), nating in conditions of reduced circulation, and partly crushed and distorted and often rather their tests are non-calcareous or with a low coarsely agglutinated, including Ammodiscus cre carbonate content. The second group generally taceus (= A. siliceus of WILLEMS), Trochammi- have a significant proportion of calcareous cement noides subtrullisatus and Verneui/ina subeocaena in their tests, and occur in contexts indicating a The two latter species are restricted to this well-oxygenated marine environment. interval. The distinction between these two associations Assemblage KN-3 (277.5 m-274.5 rn) is often enhanced by early post-mortem disso lution of calcium carbonate in the first association, The base of this assemblage is defined by the due to the acidity of the sediment pore-waters. This first appearance of calcareous benthic foramini leads to the corrosion or dissolution of calcareous ferids. These include Cibicides/Anomalinoides foraminiferids. ln the Knokke borehole, and in spp. indet., Pulisiphonina prima and Lenticulina similar contexts in the London Clay in England, it is sp., and are rather poorly preserved and recrystal noticeable that as the abundance of calcareous lised. This event is associated with an increase in foraminiferids decreases, in passing vertically diversity of the AG 1 agglutinating foraminiferids, from dominantly calcareous to dominantly ag including the first appearance of Spirop/ectam glutinating faunas, they become corroded and mina spectabilis and Haplophragmoides walteri. partly crushed before disappearing entirely. Ammodiscus cretaceus is the commonest ag glutinant. The AG1 index varies from c.15% toc. Here WILLEMS' terminology for these asso 70%. ciations is modified for simplicity; the first association (AA-1 of WILLEMS) is designated the Assemblage KN-4 (273.5 m-248.5 rn) AG1 association and the second (AA-11) the AG2 The base of this assemblage is defined by the association. · disappearance of calcareous foraminiferids and a The ratio between the numbers of individuals of return to an agglutinating assemblage of AG1 calcareous and agglutinating foraminiferids in a type (AG1 index 100 %); characterised by the sample is sometimes used as an environmental association of Ammodiscus cretaceus, Bathy index, but it is considered that a much more siphon sp., Spirop/ectammina spectabi/is, Haplo sensitive index is provided by the ratio between the phragmoides burrowsi and H. wa/teri. Miliam nurribers of AG 1 agglutinants and the remainder of mina paleocenica is restricted · to this interval, the benthonic foraminiferids (AG2 agglutinants occurring consistenly between 270.5 m and and calcareous benthonic taxa). This ratio (ex 255.5 m. Very rare pyrite moulds of calcareous pressed as the percentage of speciments of AG 1 taxa (e.g. Lenticulina sp.) are recorded in the upper agglutinants in the sample) has been calculated for part of this interval. the Knokke section, and is referred to here as the 'AG1 index' (see Fig. 4). Assemblage KN-5 (247.5 m-218. Om) Seven successive benthonic foraminiferid The base of this assemblage is defined by the assembla€JeS (KN-1 to KN-7) are here defined incoming of a diverse assemblage of calcareous 74 foraminiferids and AG2 agglutinating foramini species are Lenticulina spp.,Pulisiphonina prima, ferids.At the base they form less th an 10% of the Anomalinoides acutus, Vaginulinopsis wetherellii foraminiferid fauna (AG1 index c.90%), but ( = Marginulinopsis enbornensis of WILLEMS), through most of this interval they constitue at least Nodosaria /atejugata, Alabamina obtusa, Stilos 50% of the fau na (AG~ . index 0-50 %). The tomella midwayensis ( = 'Nodosaria spinulosa' of calcareous benthonic asemblage is rather consis SHERBORN & CHAPMAN), Uvigerina·batjesi( = U. tent throughout this interval; the most common garzaensis of WILLEMS). The AG2 agglutinants include common Karreriella oveyi, Pseudoclavu lina anglica and Spiroplectammina adamsi. The '+-U AG1 component includes common Ammodiscus c:: a.. ,...., o·~ C::Vl x o~'i>lt cretaceus, Recurvoides sp., and Karreriella con QJ +' N S..OQJ ...... "C Q) .r;: · <.oc: ~~v .Q.j..>U versa . c( ·~ "'"C Il E<=QJ ~c:: :::IQJC. c.. •r- L.-1 Z.CVl There are weil defined vertical changes in the 0 0 0 AG 1 index (see Fig. 4) which en able six «SUb 0 N M assemblages» to be defined. They are essentially alternations of < Assemblage KN- 6 (217.0 m-181.9m) 270 Between 217.0 rn and 218.0 rn is the most abrupt microfaunal break in the Ieper Formation; from an assemblage at 218.0m comprising 99% calcareous benthonics + AG2 agglutinants (AG1 index c1 %) to a totally agglutinating foraminiferid 280 (No assemblage with an AG 1 index of ± 100% (see p"lanktonics Figs. 3, 4). This faw1al change is certainly to sorne KN-1 extent enhanced by decalcification of the interval above 218.0 rn, but it nevertheless reflects a major event in the sequence of benthonic microfaunas. Fig. 4.- Planktonic and benthonic foraminiferid assemblages in the Ieper Formation of the Knokke borehole The KN-6 assemblage consists almost entirely of AG1 agglutinating foraminiferids, dominated by N N N N N ...... 00 01 N 0 00 01 ..,. 0 0 0""" 0 0 0 cr' 0 Depth (metres) 111111 111111111 Il 1 1 1 1 Il 1 llllllllll 111111111111 111111 1111 1 1 1 1 11111 1 111111111111 11111111111 11111111111 1 1 SAMPLE POSITIONS "T1 . Coscinodiscus sp. 1 .p· .. • Coscinodiscus sp. 2 DIA TOMS -~- + + - r- ~ Coscinodiscus spp. 0 1 . - . Triceratium sp. ~· - --- . Scirpus lakensis SEED ë' -- c: .. • . . . 'Cenosphaera' sp. ....o· • :::l -1- Lenticular radiolaria RADIOLARIA a ?-? Radiolaria (undifferentiated) 3 . . . .. - . . .. . 'Organism X' (King 1983) rï - - 0 . . Pseudarcella trapeziformis PROBLEMATICA ë' . Voorthuyseniella gracilis "' "' 1--- . . Sponge spicules ijj - - _(D Geodia sp. SPONGES ë' x ... !2. . . r- . . . Lingula sp. LINGULA • c: ):.C. ------Scolecodonts ANNELIDS IQ -· -· ~cÈ - - Echinoderm debris ECHINODERMS ëS.., ...0' . Astarte sp • '<: Q) :;.3 . cf. Nuculana sp. Cb :; . Turritella gr. imbricataria i ~ . 1 Gastropods indet. a; s: .. Venericardia ?sp. Q)c.- "' . . MOLLUSCS 0 :;· . Bivalves indet • Cb .... ~::r . 'Corbula' cf. globosa :::-CD -coCb"- - Nuculana cf. prisca Qi""C -!!l . . Adeorbis sp. ;r ...... - Spiratella mercinensis 3 . - Spiratella cf. tuteU.na a PTEROPODS ë" . .. - Spiratella sp. nov. A• :::l . .. Camptoceratops prisca a . .. 5- Cytheretta sp. cf. nerva CD .. --: Pterygocythereis fimbriata taminosa :::l Cytherella londinensis 0"' - - Trachyleberidea pres~ichiana ~ HazeU.na aranea 8" •• OSTRACODS al - Pterygocythereis sp. nov. A ::r 0 - Agrenocythere ?bowerbankiana en 1 Cytheretta scrobiculoplicata . Cytheridea cf. newburyensis . . Echinocythereis cf. reticulatissima . ?Crustacean gastrolith CRUSTACEA -..J 01 -- • --. -- • - • - Fish debris FISH 76 Ammodiscus cf.septatus; Hap/ophragmoides/ Flanders Member (above 147 rn), and in the Egem Trochammina sp. indet. and Recurvoides gr. Member. The spicules appear to be predominantly wa/teri. The former existence of a significantfauna monaxons, tri axons, and tetraxons, but sterrasters of AG2 agglutinants and calcareous benthonic (< Only rare pteropods ·are recorded between Formation into five successive associations (BF 199.0 rn and 182.0 m. Between 182.0 rn and ass.l to BF-ass.VI), based mainly on the detailed 154.5 rn pteropods occur fairly consistently, study of the Kallo and Tielt boreholes. The vertical including Camptoceratops prisca, Spiratella mer ranges of the foraminiferid taxa and the faunal cinensis and S. sp. nov. A. This interval is referred associations in the Knokke borehole are not to pteropod Zone GP9 (Camptoceratops prisca exactly comparable with those recorded by Zone of KING 1981 ). WILLEMS, due to lateral biofacies changes, and to Above 154.5 rn no pteropods have been the extensive decalcification of the Knokke se recorded. quence, but equivalents of WILLEMS' associa tions 1 to IV can be identified. Ostracods WILLEMS' '8F-I association', comprising ex A single fragmentary specimen identified as clusively agglutinating foraminiferids of AA-1 Cytheretta cf. nerva is recorded from Member 'X' at (AG 1) type, recorded at the base of the Ieper 286.5 m. This may indicate the presence of the Formation, corresponds to the KN-2 assemblage. Cytheretta venable5;J ostracod Zohe (KEEN, 1978). The occurrence of Coscinodiscus sp.1 and C. sp.2 ln the lower part of the Flanders Member, no in the sa me interval as this assemblage at Knokke ostracods are recorded. ln the middle of the is consistent with their occurrence elsewhere in Flanders Member ostracods occur only in a few Belgium. WILLEMS ( 1982:9) notes the presence samples, asociated with foraminiferid assemblage of these diatoms at the base of the Ieper KN-5. lsolated valves of Pterygocythereis fimbriata Formation but gives no further details of their laminosa are recorded at 235.5 rn and 233.5 rn, but occurrence. ln washed residues supplied to the ostracods occur consistently only between author by WILLY WILLEMS, they occur commonly 222.5 rn and 219 m. The assemblage comprises between 368 m-372 rn at Kallo and 146.5 m- Hazelina aranea, P. f. laminosa, P. sp. nov. A (an 148.5 rn at Tielt, within the interval with the BF undescribed species which is widespread in the ass.l microfauna (see Fig. 6). middle London Clay Formation of the central and The base of WILLEMS' association BF-11, eastern London basin), Cytheretta scrobiculo marked by the appearance of calcareous foramini plicata, Cytherella londinensis, Trachyleberidea ferids, is rather ill-defined at Tielt, but well prestwichiana and Oertliella [Trachyleberis] defined at Kallo. lt corresponds to the base of bowerbankiana. This assemblage is referrable to assemblage KN-3. The first appearance of plank the Cytheretta scrobiculop/icata ostracod zone tonic foraminiferids at this level at Knokke (KEEN, 1978) which is recognised within the correlates with their first appearance at Kallo middle London Clay Formation (KING, 1981 ). A (WILLEMS 1980); they are considerably more very similar assemblage (but more diverse) is common at Knokke than at other localities recorded at a similar level at Kallo (WILLEMS, studied. 1973; KEEN, 1978) and Tielt (WILLEMS, 1978). ln the Knokke borehole there is a well-defined ln the decalcified interval of the Flanders change in the agglutinating foraminiferid assem Member above 219.0 rn, occasional pyritised blage at the base of assemblage KN-3. At this moulds of ostracods are recognisable, including level there is the replacement of a 'Trochammi Cytheridea cf. newburyensis (at 183.0 rn) and noides subtrullisatus-Verneuilina subeocaena' Echinocythereis cf. reticulatissima (at 178.8 rn association (assemblage KN-2) by a more diverse and 156.0 rn). This limited assemblage indicates assemblage which includes Spiroplectammina correlation with the E. reticulatissima ostracod spectabilis and Haplophragmoides walteri. A Zone (WILLEMS, 1973; KEEN, 1978; KING, 1981 ). similar change can be identified at Kallo at the base of BF-ass.2, but at Tielt it occurs at C. CORRELATION c.145.5 rn, within BF-ass.l. (WILLEMS 1980). As Belgium (fig. 6) this change is well-defined in ali three wells, and corresponds approximately to the top of the The basal unit of the Ieper Formation at interval with Coscinodiscus sp.1 and C. sp.2. lt is Knokke («Member X») has no equivalent in other believed to be synchronous event (see Fig. 6). sections studied in Belgium, and is represented elsewhere by a hiatus between the Ieper For ln the exposures of the Mt.-Heribu Member in mation and the Landen Formation. This is the Tournai-Mons area described by DE CONINCK confirmed by the dinoflagellate evidence (see et al. (1983), the 'T. subtrullisatus-V. subeocaena' DUPUIS et al. (chapter IV) and text below). association corresponding to KN-2 can be reco gnised at the base of the Member at Ghlin and WILLEMS (1980, 1982) subdivided the ben Mt.-Heribu. At St. Maur, at c. 7 rn above the base thonic foraminiferid microfaunas of the Ieper of the Member, the absence of these taxa, and the EASTERN LONDON BASI~ KNOKKE B.H. ----TIELT B.H. KALLO B.H. WOENSDRECHT B.H. basal Panisel Formation ~.::: (IJ ~) Efk j;J ,_ J111- ';::: ~ ,,,,.,"'''' EGEM HEMBER ?:,,,,,,{': -::}}t; a; :fj]_ ------Ï60_J::;;::::;:::: ------...... z 480 .::: t ~ -5 ::l E ~ Cl) .s:: 500 ~ .5 ·- .:::~"' -- .g c: D --- (IJ 0 / z: ...E" .::: "azoic interval" / Echinocythezoeis 0 0 0 ~ _E:_ zoeticuZatissima (F) ..... zoeticul.atissima u....J g g v - -- ..... / >.::: g g g / ---- (IJ ... 1 / - Cl) z: iLI.. urn .::: (IJ 1-s ffi 0 Cl) "- "0 Cl) ~1 c ------~ .::.s:; 0 .3 ... LI.. T. -;;mithviZZensis-- .," >- .::: 1ii <..... ------u co E .::: ::l z: .S! · 8 ...co Cl z: E Cl) .....0 ._al 0 .::: LL .._ ... Cl) Cl).s:: c.t:: Cl) 0 -.::: Cl) 580 .s::... 0 .::: .S! ...co ~ 8 1 Coscinodiscus <Ô 201 ci> ü: ~ Decalcified j9 9 9j Glauconite common 1*****1 "Siliceous" biofacies [:;:;:;:;:>;·:.1 Sands rLLLI intervals 99 1] Metres L - Last occurrence F - First occurrence I"KN-1" to "KN-7", ' 1 I~Vl'' = BENTHONIC FORAM ASSEMBLAGES! co ...... 79 occurrence of Miliammina paleocenica, indicates nodosariids are rarer, the top occurrence of correlation with association KN-4. These records Nodosaria /atejugata and Vaginulinopsis wethe demonstrate the wide extent of these successive rellit), and the top of the planktonic foraminiferid agglutinating assemblages, and indicate that the acme. boundary between the Mt.-Heribu Member and These two events are approximately coïncident the FI anders Member is significantly diachronous, in the three boreholes concerned. At Knokke they as at Knokke both as~emblages occur within the probably coïncide with the top of assemblage KN- Flanders Member. 5. At Kallo they coïncide with the main glauconite Association BF-111 has no recognisable equi horizon (304.6 rn); at Tielt they are probably at valent at Knokke, probably due to decalcification, 95.5 rn (see Fig. 6). The ··osangu/aria datum' but is likely to correspond to the upper part of KN- (KING 1981 ), (defined by the first occurrence of O. 4 (it is absent also at Tielt). plummerae), although now recognised at Knokke The base of assemblage KN-5, marked by the and important regionally in the southern North entry of nodosariids and the AG2 agglutinants Sea Basin (see below), has not been ldentified in Karreriella oveyi an'd Spiroplectammina adamsi, other Belgian sections. corresponds to the base of BF-IV. The reappea Assemblage KN-6 has no equivalent in the rance of planktonic foraminiferids just above this sections studied by WILLEMS. lt marks the return level compares with a similar event at Kallo and of an agglutinating assemblage of AG1 type, Tielt (WILLEMS 1982:6), but this event is ill restricted elsewhere to the lower parts of the defined, due to the rarity of planktonics in this part Ieper Formation. of the succession. The 'azoic' (decalcified) interval present above The subdivisions recognised within assem assemblage BF-IV in the Kallo and Tielt wells is blage KN-5 at Knokke (Fig. 4) may prove identi probably essentially a post-depositional feature, fiable elsewhere. Textularia smithvillensis is one due to secondary decalcification of the sediments. species which may be useful for detailed correla The approximately equivalent sequences at tion. lt has a short but well-defined vertical range Knokke (above 219 rn) and at outcrop (e.g. in the at Knokke, and occurs at a similar level at Kallo Kortemark quarry) contain pyrite moulds and and Tielt (Fig. 6). Other microfaunal events casts of formerly calcareous planktonic and recognisd in BF-IV in the Kallo and Tielt boreholes benthonic organisms. lts limits are probably (WILLEMS 1980) cannat be identified at Knokke, diachronous, as at Knokke it has expanded to probably due to lateral faunal changes. The include most of the upper Ieper Formation. planktonic foraminiferid abundance-level, which Assemblage BF-V is probably represented within is sharply defined at Knokke at 222.5 m-219. 7 rn this interval at Knokke, but is now entirely (Fig.6), probably correlates with the 'G/obigerina decalcified. Similarly, an equivalent to assem patagonica acme zone' (WILLEMS 1982). At blage BF-VI cannat be recognised at Knokke, due Knokke G. patagonica is not so abundant as in the to the decalcification of the Egem Member. other boreholes, but is the dominant planktonic at 219 m-218. Om, just above the abundance-level. The occurrence of pyrite casts of Pseudohasti The glauconite-rich horizons present at other gerina wilcoxensis and other planktonic foramini localities in the middle of the Flanders Member ferids near the top of the Flanders Member at ('lit glauconifère de Tielt' of DE CONINCK 1975) Knokke can probably be approximately correlated have not been recognised at Knokke, where the with similar records at Kallo and Tielt (see Fig. 6). lithology is very homogenous through this part of The 'siliceous' biofacies of the upper Flanders the succession. Although it has been suggested Member and the Egem Formation seen at Knokke, that the main glauconite level is a lithostrati characterised by the presence of common sponge graphic marker horizon, the data of WILLEMS spicules, including Geodia, which are associated ( 1980) show that two key biostratigraphic events, with spherical radiolaria, is widespread at this the 'Asterigerina bartoniana kaaschiteri acme' level. Samples studied by the author from the and the 'G. patagonica acme' occur be/ow the Kallo and Tielt boreholes, and from outcrops at main glauconitic level at Kallo and above it at Tielt Kortemark and Meulebeke, ali have a similar (Fig. 6). Mor.e detailed investigation of this interval siliceous spicule and radiolarian assemblage in is needed (see KING, in press). the upper part of the Ieper Formation (see Fig. 6). The most significant microfaunal datum levels in this part of the Flanders Member are believed to Southern England be the highest occurrence of common nodosariids The biostratigraphic sequence within the Ieper (or in the Kallo and Tielt boreholes, where Formation of the Knokke borehole can be corn- 80 pared with the London Clay sequence in the at Knokke, but, as in the eastern London Basin, Hampshire Basin. The data obtained from Knokke can be identified approximately by the corres permits the correlations between England and ponding faunal changes. Belgium proposed previously (KING 1981) to be ln the London Basin, the entry of the nodo refined and updated. sariid-rich benthonic foraminiferid assemblage The basal sandy unit of the Ieper Formation ('NRA'), and the associated 'planktonic datum' are (Member «X»), with ash debris, a restricted both just above the base of division B (KING 1981, agglutinating microfauna and common Coscino Text-fig. 8). The base of the NRA in England is discus spp., can be correlated lithologically and marked by the first appearance of Nodosaria micropaleontologically with the (ash-bearing) di latejugata and Vaginulinopsis wetherellii. At vision A 1 of the London Clay Formation (which Knokke these both appear at the base of assem includes Harwich Member of Essex and Suffolk). blage KN-5, together with other characteristic The dinoflagellate assemblage in this unit (DU elements of the NRA including Pseudoclavulina PUIS et al., this volume) confirms this correlat[on. anglica, Cibicidoides crassus and Stilostomella This is the first re<;brd of the North Sea ~asin midwayensis ('Nodosaria spinulosa'). The 'plank 'main tuff zone' (subphase 2b of KNOX & tonic datum' is not as weil defined in Belgium as it MORTON 1983) in Belgium. The limited cal is in the London Basin, as planktonic foramini careous microfauna recorded at 286.5 rn, al ferids are generally rare at equivalent levels. At though too poorly preserved for definite identifi Knokke, they occur very rarely from 245.5 rn, 2 rn cation, is very similar in aspect to division Al above the base of benthonic assemblage KN-5. microfaunas from the Swanscombe Member in Assemblage KN-5 is significantly richer in the London Basin (KING 1981 :24). Elsewhere in nodosariids than its equivalent BF-IV at other Belgium beds of this age are apparently absent localities in Belgium, and is similar to the and there is a significant hiatus between the Ieper nodosariid-rich assemblage of the eastern London Formation and the Landen Formation (DE CO Basin, which occurs through division B and the NINCK et al., 1983). Their occurrence at Knokke lower part of division C. The base of division C (even though represented only by a thin rem nant) corresponds in the London Basin to the first reflects the geographical location of the borehole appearance of Osangularia plummerae (='Osan relative to the margin of the North Sea Basin. gularia sp.' of KING 1981 ), the 'Osangularia The glauconitic level at the base of the datum'. This species has not previously been Flanders Member at 283.7 rn probably can be recorded in Belgium, but in the Knokke weil it equated with the sedimentary discontinuity de occurs commonly in the highest part of assem fining the base of division A2 in England. The blage KN-5 between 222.5 m-219 .Om. The Osan restricted agglutinating assemblage (KN-2) in the gularia-datum can thus be identified here, and lower part of the Flanders Member (283.7 m- enables the base of division C to be correlated 278.5 rn), and the continuing presence of Cosci with a depth of 222.5 rn in the Knokke weil. nodiscus sp. 1 and C. sp.2 in this interval, The abundance-level of planktonic foramini indicates correlation with division A2. ferids at 220 m-222 rn can be correlated with the The approximately simultaneous appearance similar abundance-peak in the top of division B of calcareous benthic foraminiferids (at the base and the lower part of division C in the eastern of assemblage KN-3), and of planktic foramini London Basin (KING 1981, Text fig. 46). ferids (at the same level) can be correlated with The abrupt faunal break at the top of assem the corresponding faunal change which occurs at blage KN-5 probably correlates with the top of the the base of division A3 in the London Basin. NRA in the London Basin, which occurs within the Division A3 has a restricted calcareous micro middle of division C. fauna in the central London Basin, but this becomes progressively attenuated and largely The higher parts of the Flanders Member and replaced by an AG 1 agglutinating assemblage in the Egem Member at Knokke cannot be accurately the east of the London Basin. Although in England correlated with sequences in the eastern London this assemblage is not as abundant or diverse as Basin due to the sparse faunas and sorne the agglutinating assemblage in assemblages KN- differences in facies. The occurence of Spiratel/a 3 and KN-4 at Knokke, it includes sorne of their sp. A from 199. Om upwards indicates probable most characteristic taxa such as Spiroplectam correlation of this part of the succession with mina spectabilis, Haplophragmoides burrowsi and division O. The presence of Camptoceratops Miliammina paleocenica. The lithological junc prisca at 182. Om and higher levels indicates tions used to define the limits of A3 and higher correlation with the C. prisca pteropod zone, divisions in England are not clearly recognisable which in the London Basin begins within the 81 lower part of division E. The limited benthonic 3. MONT-PANISEL FORMATION mollusc assemblage recorded between 1 69 m- 156 m is consistent with division E assemblages A. LITHOSTRATIGRAPHY recorded at Sheppey and in Essex (KING 1983). The limits of divisions D andE cannat be identified The sequence is here divided into seven on the basis of the_ fauna at Knokke, and no lithostratigraphic units (Fig. 7). Detailed corre dinoflagellate data is available for Knokke. lation with the units of the Mt.-Panisel Formation seen at outcrop is difficult, except for the basal There is hope that more detailed study of the unit (Unit 1) wich corresponds to the Merelbeke relevant sections will eventually enable lithostra Clay (P1m). tigraphic correlations to be made between the sequence of alternating clays and silty/sandy Unit 1. (135. Om-133. Om). Silty clay, homo units which forms the upper part of the London genous, probably intensely bioturbated. Small Clay Formation in the eastern London Basin (KING pyrite 'sticks' and burrow fills are common. 1983), and the ratt'ier similar sequence in the upper Flanders Member at Knokke. The Egem Unit 2 (133.0m-c.124.75m). Silty sand to Formation is probably a shallow marine sand unit sandy clayey silt; divided into two sub-Linits with similar to the Virginia Water Formation of the transitional boundaries : London Basin, but direct correlation is stiJl not Sub-Unit 2a (133. Om-c.129.5 m). Silty clayey certain. sand, argillaceous; very fine grained, glauconitic, (the glauconite is very fine grained), highly bioturbated, poorly sorted, with scattered medium North Sea to coarse sand grains and chips of flint; common fine woody debris; partly cemented (? by silica) to Correlations can be made with the zonal form sandstone at sorne levels. schemes based on benthonic and planktonic microfossils recently established (KING 1983) Sub-Unit 2b (c. 129.5 m-c.124.75 m). Sandy (see Fig. 14). The North Sea planktonic zone clayey silt, glauconitic, highly bioturbated (very NSP4, defined by the occurrence of Coscinodiscus 'streaky'), rather poorly sorted, with fine grained sp. 1 and C. sp. 2, can be correlated (at least in sand content; common fine woody debris; partly part) with the interval containing these species at cemented (?by silica) to form sandstone. the base of the Ieper Formation (284.5 m-278.5 m). Unit 3 (c.124.75 m-c. 124.2 m). Sandy clayey The base of planktonic zone NSP5 ('Giobigerina' silt, highly glauconitic (fine to coarse grained gr. linaperta zone) is correlated with the first glauconite), highly bioturbated, poorly sorted, with appearance of planktonics at Knokke at 275 m. medium sand content and occasional chips of This zone extends up to the top of the planktonic flint. Glauconite is very abundant and very coarse abundance levet at 220 m. Planktonic zone NSP6, at the base ( 124.6 m-124. 75 m). characterised by a siliceous microflora with abundant large spherical reticulate radiolaria Unit 4 (c. 1 24.2 m-122. Om). Silty sand, very ('Cenosphaera' sp.) can be correlated with the fine grained, glauconitic, highly bioturbated, with siliceous radolarian and sponge spicule assem argillaceous streaks and patches. blage occurring in the upper part of the Ieper Formation and the lower part of the Panisel Unit 5 (122.0m-116.0m). Sand, fine to Formation. Spherical reticulate radiolaria refer medium grained, glauconitic, moderately well able to 'Cenosphaera' are not common at Knokke, sorted, bioturbated, with argillaceous streaks and but are recorded at several levels between 189 m clay-filled burrows. and 154m. Benthonic zone NSB2, characterised by a very Unit 6 (116.0 m-c.108.5 m). Silty sand and limited microfauna of agglutinants, ·corresponds sandy silt: divided into two sub~units with to assemblages KN-1 and KN-2. The base of zone transitional boundaries: NSB3, defined by the incoming of calcareous benthonic microfauna, can probably be correlated Sub-Unit 6a (116.0 m-112.5 m). Sandy with the base of assemblage KN-3. Zone NSB3 silt/sandy clayey silt, glauconitic, rather poorly includes assemblages KN-3 to KN-5. Zone NSB4 sorted, with fine to coarse sand content and cannat be identified due to the absence of its occasional flint chips, thoroughly bioturbated, index-species. with discrete large vertical burrows, sorne clay- 82 80- 1 1 lined; large mica flakes common; fine woody debris common. Glauconite is particularly abun dant at the base. Unit 6b {c.11 2.0 m-c.1 08.5 rn). Silty sand 85- sandy silt, very fine grained, glauconitic, troughly bioturbated, with discrete large burrows and z sorne argillaceous streaks. 0...... 1- 0.:: c:C LLJ :::;;: co Unit 7 {c.1 08.5 m-1 04.5 rn). Very fine sand, 90- 0.:: :::;;: 0 LLJ glauconitic, highly bioturbated, moderately weil u. :::;;: sorted, with occasional argillaceous beds. The z :::;;: 0.:: LLJ 0 _J basal junction is transitional. 0 LLJ :::c 0 LLJ 95- z 0 The sequence between 133 rn and 108.5 rn, LLJ 0 't:' .....• although varying in grainsize, is characterized by the presence {and locally the abundance) of fine to medium-grained glauconite, the predominantly 100- poor sorting, with coarse sand grains and angular flint fragments, the consistent occurrence of fine woody debris, and the partial induration at sorne levels, due to silica cementation. Highly glauco ...... --! ...... 105- nitic horizons at 124.7 rn and 116 rn appear to mark sedimentary discontinuities; each forms the 7 base of coarsening-upwards sequences {Fig. 7). 110- B.· BIOSTRATIGRAPHY ·--. ----· Due to its permeability, the Mont-Panisel 115 1 • Formation in the Knokke borehole has been partially decalcified. Units 1, 5 and 7 are al most entirely decalcified; at other levels the calcareous fossils are often somewhat corroded or encrusted 120- by secondary calcite deposition. Nevertheless, this borehole provides the most complete faunal sequence yet studied in Belgium, as most outcrops are completely decalcified. 125- 1 1 1 r-_-_-_- Dia toms 2b . :-_: ._ r---- Pyritised diatoms (small biconcave and bi 1------r--:-_-:-_:_-- convex Coscinodiscus spp.) are corn mon in Unit 1. 130- ·-- .. - Occasional siliceous diatoms are recorded in Unit 1--·· 2 a ·_: :-. : ._- 2, and a distinctive «wide-rimmed» Coscinodiscus .. --- t--r_---=-r 1 1 sp. is common at the base of Unit 6 {115.5 m- 1 r-----::~ 115.0m). 135-1-----r--.-.....-,,...... ,.,-.,....,-+- >. .... "0 Seeds (/) «l .... c: ,..., •1""1 ltJ Q) s.. (.) (/) (/) Specimens of the seed Scirpus /akensis occur +' Q) ra rely but consistently in Unit 2 between 133.5 rn E Grains ize and 124.5 m. This species is characteristic of -.s:::: +'c. marginal marine and shallow marine sediments Q) 0 of the upper London Clay Formation (division 0) and the Wittering division of the Bracklesham Group in the Hampshire Basin (COLLIN SON et al., Fig. 7.- Lithostratigraphy of the Mont-Panisel and Knesselare 1981 ), and is believed to be derived from a (= Den Hoorn) Formations of the Knokke borehole marginal aquatic plant. 83 Benthonic foraminiferids present, although represented only by very ln Units 2, 4 and 6, a low-diversity assemblage fragmentary material. (usually c.1 0 species) is recorded, dominated by These records indicate correlation with pte Anomalinoides affine, Elphidium laeve, Cibici ropod Zone GP1 0 (Euchilotheca spp. Zone) of doides proprius, Cibicides Jobatulus, Pararotalia JANSSEN & KING (in press). C. prisca has not curryi, 'Pianu/ina' tendami and polymorphinids. been recorded in GP1 0 previously, and it seems Quinqueloculina spp. and Elphidium Jatidorsatum probable that GP10 can be divided into two occur at sorne levels. subzones; a lower subzone with C. prisca and No specimens of Nummulites planulatus have Euchilotheca (recorded here) - also in the top been recorded, although this species is recorded Egem Member and basal Panisel Formation at widely in the Mont-Panisel Formation at outcrop. Egem, and an upper subzone without C. prisca (represented in the Earnley Formation in England Planktonic foraminiferids and the lower Calcaire Grossier in the Paris Planktonic fora,miniferids (mainly Acarinina Basin). spp.) are recorded ra rely (P 3 %) in the upper part Ostracods of Unit 2, where they occur consistently between 129.0 rn and 125.5 m. 10 species of ostracods are recorded in the upper part of Unit 2. Schizocythere appendiculata Sponge spicules is dominant, associated with Cytheridea rigida Siliceous sponge spicules, including «Geodia», punctata, Eopaijenborchella lomata and isolated occur commonly to abundantly through the specimens of other species. section, except in Unit 1 and Unit 5. ln Unit 1, A single specimen of Quadracythere cf. ver small ovoid pyrite bodies which are believed to be miculata is recorded in Unit 3. casts of «Geodia» spicules are very common. ln Unit 6 only Leguminocythereis bu/lata is Annelids, bryozoa and corals recorded; it occurs commonly at 115.05 m. ln the upper part of Unit 2 and in Unit 3, C. CORRELATION bryozoa (Dittosaria sp., Lunulites sp.), are present. Solitary corals (Turbinolia sp.) occur in the upper Belgium part of Unit 2. Serpulids (Ditrupa sp.) occur in Unit The basal clay unit (Unit 1) can be correlated 3 and the lower part of Unit 4. These fossils have lithologically with the Merelbeke Clay (Pim); this not been identified specifically. correlation is confirmed by the evidence of the Benthonic molluscs pteropods. A washed residue from the Merelbeke Clay of the Kallo borehole (at 236.0 rn), supplied ln Unit 1 no identifiable specimens have been by Willy WILLEMS, contained common pyrite seen. ln Unit 2 a diverse mollusc assemblage is moulds of pteropods of the same species as present; at least 16 species of bivalves and recorded at Knokke in Unit 1. Although no data is gastropods are represented in the limited material available from other localities, this suggests that available, although most cannot be specifically this pteropod assemblage is probably widespread identified due to the small numbers of specimens in the Merelbeke Clay. and the rather fragmentary material. Phacoides squamulus and Turritella gr. imbricataria are the The alternating units of poorly sorted glau dominant species; Phacoides squamulus occurs conitic silts and sands which overlie the Merel abundantly at 131.0m-130.0m and 125.5m- beke Clay at Knokke are similar lithologically and 124.5 m. Other · common species include Tri macrofaunally to the «Sandy clays of Ander gonodesma lissa, Nucu/ana striata and Varicor lecht». Representatives of the Vlierzele Sands and bula muricina. At higher levels no molluscs have the «Aalterbrugge Complex» cannot be identified. been seen. lt is probable that these units are absent because of lateral facies changes, and it is also possible Pteropods that the Mont-Panisel Formation is more com ln Unit 1 pyritic moulds of pteropods are plete at Knokke than in the outcropping areas. common, including Spiratella sp. nov. A, S. Detailed comparison is difficult due to the mercinensis, Camptoceratops prisca and apical absence of adequate lithological/sedimentolo fragments of cf. Euchilotheca sp. gical logs for most outcrop and borehole sections. Severa! new lithostratigraphic units have re ln the upper part of Unit 2, rather crushed cently been introduced (e.g. Pittem Member), but apical fragments of Euchi/otheca cf. elegans are it is difficult to evaluate their significance. common. Camptoceratops prisca is probably also 84 The Knokke sequence includes at least two «Fisher's bed IV» of Whitecliff Bay and its lateral coarsening-upwards sequences which probably equivalents, including Unit W14 at Bracklesham reflect transgressive-regressive events. lt is pro Bay (CURRY et al., 1977), within the Wittering bable that one of these sequences corresponds to division of the Bracklesham Group (HASKINS the coarsening-upwards sequence from the San 1968-1971, KEEN 1978). The bivalve Phacoides dy Clays of Anderlecht to the Aalterbrugge squamulus, which is common in the lower part of Complex. the Panisel Formation, is one of the most common The microfaunas of the Mont-Panisel Forma molluscs in Fisher's Bed IV, and is recorded at tion elsewhere in Belgium are poorly known; only one other level in the Hampshire Basin. most outcrops are decalcified. The Kallo borehole However, these taxa have rather longer ranges in penetrated the Mont-Panisel Formation, but due Belgium; L. bu/lata and P. squamulus are corn to drilling difficulties little core was recovered mon at the top of the Ieper Formation (Egem (GULINCK, 1969). Member) at Egem. Nevertheless, they probably indicate a general correlation between part of the A calcareous microfauna has been obtained by Mont-Panisel Formation and Fisher's Bed IV. the author from th; base of the Mont-Panisel Fisher's Bed IV is overlain and underlain by Formation in the Ampe Ou arry at Egem (the «grès marginal-marine sediments without calcareous tendre, très fossilifère» of De CONINCK & NOLF fossils. 1978, Unit 6 of ISLAM 1982). This comprises a foraminiferid assemblage dominated by Cibicides, polymorphinids, Pararota/ia curryi and Elphidium /atidorsatum. The ostracods include common 4.- KNESSELARE FORMATION Schizocythere appendiculata, Eopaijenbosche/la /amata and Quadracythere cf. angusticostata. The A. LITHOSTRATIGRAPHY pteropods Spiratella sp. nov. A, Camptoceratops prisca and Euchilotheca sp. also occur at this Oedelem Member level, and the bivalve Phacoides squamulus is 104.5 m-79.0 m: Silty sand, thoroughly bio common. This assemblage is rather similar to the turbated, very fine grained, moderately weil fauna of Unit 2 at Knokke. sorted, glauconitic. The basal junction is sharply Woensdrecht borehole defined. Shell debris is present throughout, with prominent shell-rich horizons (shell beds) at The foraminiferid assemblage recorded by c.99.0 m-98.0 m (dominated by Venericor piani KAASSCHIETER (1961) from the Mont-Panisel costa) , at 88.25 m-87.5 m and at 82.5 m-81 ,8 m Formation of the Woensdrecht borehole (in the (dominated by Venericardia carinata). beds assigned by him to the «Sandy Clays of Anderlecht- Sands of Vlierzele») is closely com B. BIOSTRATIGRAPHY parable to that recorded in the Knokke weil. Of about 18 benthonic species recorded as «frequent Calcareous fossils occur throughout the Knes to abundant» at Woensdrecht, ali occur at Knokke, selare Formation, although there is partial decal and the commonest species at Woensdrecht cification at sorne levels, indicated by corrosion or (Cibicidoides proprius, C. /obatulus, Nonion affine, complete dissolution of shells and deposition of Globulina gibba, Guttulina irregularis, Pianu/ina calcite overgrowths. bur/ingtonensis v. tendami) are ali prominent members of the Knokke assemblage. No details Problematica are available of the other microfaunal groups at Calcareous «problematica» are common be Woensdrecht. tween 97.5 m-80.0 m, although at sorne levels DE CONINCK (1970) has demonstrated that they are poorly preserved or indeterminate due to there is a significant break between the Aalter calcite overgrowths in optical continuity. brugge Complex and the overlying Aalter Sands at The species Yvoniellina variabilis and Bigno outcrop, compared to the sequence in the tella polygona are dominant; at 93.0 m two Woensdrecht borehole, and Knokke is probably apparently undescribed Bignotel/a species are similar to Woensdrecht in this respect. also recorded. Southern England Benthonic Foraminiferids The Mont-Panisel Formation in the Knokke A relatively low-diversity assemblage is pre borehole has yielded the ostracods Cytheridea sent, dominated by Cibicidoides proprius, poly rigida punctata and Leguminocythereis bu/lata. morphinids (Giobulina spp., Guttu/ina spp., Pyru These are both recorded previously only from lina thouim) and Textularia agglutinans. Anoma- 85 ~ ~ ~ ~ w N ~ 0 Fig. 8.- Distribution of benthonic foraminiferids and ostracods in the Mont-Panisel and Knesselare Formations of the Knokke borehole 86 -" -" -" -" w N -" 0 10 0 0 0 0 0 g Depth (metres) PANISEL FORMATION DEN .HOORN FORMATION ...., -"1 N 11-"'1 c.n 1 0'1 1 Lill Il l 1 1 1 1 1 li 1 1 1 1 1 1 1 1 1 1 1 SAMPLE POSITIONS . . .CoscinodisÇJus spp • . Triceratiwn sp • DIA TOMS Scirpus Zakensis SEED . 'Cenosphaera' sp. RADIOLARIA 1 1 ...... • YvonieZZina variabiZis . . BignoteZZa sp. nov. B . 1 . BignoteZZa poZygona 1 PROBLEMATICA 1 . BignoteZZa sp. nov. A . BignoteZZa cf. poZygona Sponge spicules ' SPONGES . -1-- "Geodia" sp • ----- . - . . TurbinoZia sp. CORAL - - Ditrupa sp. . • ScZerostyZa sp • ANNELIDS ·fo -·f- -. Dittosaria sp • . LunuZites sp. 1- - f----o BRYOZOA - AdeoneZZopsis sp. f- DiscoidaZ bryozoan -. - Phacoides squamuZus . NucuZa sp • AntaZis sp. . Trigonodesma Zissa ~·~ NucuZana striata -- TurriteZZa gr. imbricataria 0 .---~ . - VaricorbuZa muricina . Lucinid sp • . Naticid sp . . RingicuZa sp . . EuZimid sp • . CyZichnùl sp • ·~ PyramideZZid sp. ~~ CaryocorbuZa striata . Adeorbis sp • . . . . 1" 1- Crassostrea cf. muZticostata - - 1 1 Venericardia suZcata aizyensis .- -fo 'Pteria' sp . MOLLUSCS . Anomia sp . .... 1 CaZZocardia nitiduZa . MacaZiopsis sp • 1 1 • 1 CostacaZZista suberycinoides . Venericor pZanicosta •. PZeuromeris deaussata . Orthocardiwn sp . . SigmesaZia sp . . Corbula fZandrica -. cf. MacrosoZen sp • . EosoZen sp • . ef. Panope sp . . cf. RimeZZa sp. . ~aryocorbuZa cf. Zamarcki Venericardia aarinata . PetaZoaar4ia pectenifera cj'. EuchiZotheca sp. SpirateZZa mercinensis Spirate ZZa sp. nov •. A PTEROPODS Camptoceratops prisca -- EuchiZotheca cf. eZegans Fig. 9.- Distribution of fossils (excluding foraminiferids and ostracods) in the Mont-Panisel and Knesselare Formations of the Knokke borehole 87 linoides affine, Cancris subconicus, Cibicides two levels, associated with V. sulcata gizyensis, lobatulus, Elphidium laeve, Florilus scaphum, Crassostrea cf. multicostata and Turritel/a gr. Pararotalia curryi and Quinqueloculina spp. are imbricataria. At 81.0 m and 80.0 m a rather common at sorne levels. «Pianu/ina» tendami is limited fauna includes Crassostrea sp. and V. common at the top of the sequence (81 m-80 m). sulcata gizyensis. The overall assemblage is similar to that in the Mont-Panisel Formation, except for the fairly Ostracods consistent occurrenc~ of Textularia agglutinans. 28 species of ostracods are recorded. The richest and most diverse assemblages occur in Planktonic Foraminiferids the upper part of the section, between 85 m-80 m, These are recorded in several samples be although this may reflect the rather poor preser tween 104.5 m and 89.0 m; P ranges from Jess vation and partial decalcification at other levels. th an 1 % to c.5 %. Most specimens are referable The most common species are Legumino to Acarinina or Subbotina; Pseudohastigerina cythereis spp., Pterygocythereis cornuta, Cya wilcoxensis is recorded at 91.0 m. ~ mocytheridea mourloni, Oertliel/a aculeata, Co rais Cushmanidea mayeri and Cytheretta decipiens. Several species appear to be new and undes The solitary coral Turbinolia sp. is recorded at cribed; this probably reflects the Jack of previous two levels. study of ostracods from the Knesselare For Bryozoa mation. The bryozoan Lunulites sp. is consistently The ranges of the Leguminocythereis species present in most sa mples between 104.5 m and may be of significance in correlation. L. striato 83.0 m, wh ile Dittosaria sp., Adeonellopsis sp. punctata ranges throughout the sequence; L. and an unidentified discoïdal bryozoan are also bu/lata ranges from 104.5 m to 83 m, but is most recorded. common below 91 m; L. genappensis is recorded only from 85.0 m-83.0 m, wh ile L. oertlii is fou nd Annel ids only at 83.0 m, where it is corn mon. The serpulid Ditrupa sp. occurs commonly at sever al levels between 104.5 m and 83.0 m. The serpulid Sclerostyla sp. is recorded at 104.5 m C. CORRELATION and 97.5 m. Belgium Benthonic Molluscs The identification of this unit as the Oedelem Mollusc shells and shell debris occur more or Member of the Knesselare Formation is based on Jess commonly throughout the Knesselare For its lithological and palaeontological characteris mation. The shells of the aragonitic molluscs are tics. The microfauna and macrofauna of the fragile and partially decalcified, but a number of Oedelem Member have not yet been described in genera and species have been identified (see detail (except for the vertebrates and sorne Fig. 9). records of benthonic foraminifera). The compa Between 1 04.5 m and 99.0 m the rather risons made here are based upon samples sparse fauna includes Phacoides squamulus, collected by the author from the upper part of the Crassostrea cf. multicostata and Venericardia Oedelem Member at the «Wiedauw» locality, sulcata gizyensis. Between 99.0 m-98.0 m there Oedelem, from a water-flush boring casried out by is a shell bed dominated by Venericor planicosta. Dr. Dirk NOLF. This is the type locality of the At this level there is an increase in diversity and Oedelem Member (NOLF, 1972). abundance of the fau na; between 99.0 m and The limited mollusc assemblage obtained from 93.0 m juvenile Turritella gr. imbricataria are the Knokke borehole is closely comparable with abundant, associated with common Crassostrea the fauna from Wiedauw. The occurrence of cf. multicostata, Venericardia sulcata gizyensis, abundant Venericardia carinata in the upper part < 22 species of ostracods have been obtained CURRY (1967) already suggested correlation of from Wiedauw. They include Cyamocytheridea the Aalter Sands with this part of the English mourloni, Cuneocythere subovata, Cushmanidea succession on the basis of the general similarity mayeri, Leguminocythereis genappensis, L. oert of their lithology and mollusc assemblage. Sorne /ii, L. striatopunctata, Pterygocythereis cornuta additional support is given to this correlation by and Schizocythere appendicu/ata. There is a close the occurrence of the pteropod Spiratel/a similarity between this assemblage and that pygmaea at Wiedauw (author's collection); in present at Knokke between c.85 m-83 m. England this species is recorded only from the The ostracod assemblage at the top of the «Cardita bed» (CURRY, 1965). Oedelem Member at Knokke and Wiedauw The microfauna of the lower part of the includes severa! species (Leguminocythereis ge Earnley Formation has not yet been sufficiently nappensis, L. oertlii, Cytheretta aff. bambrug studied to provide any useful comparative data. gensis) which indicate an affinity with the Brussels Formation. The «problematica» Yvoniellina variabi/is and 5.- BRUSSELS FORMATION Bignotel/a polygona are common at Wiedauw; Voorthuyseniella keiji is also present. This as A. UTHOSTRATIGRAPHY semblage is very close to that from Knokke. These 74.0 m-71.75 m. Very fine sand (maximum species were originally described by WILLEMS grainsize c.180p), moderately weil sorted, bio (1975) from the top of the < Southern England Planktonic foraminiferids No planktonic foraminiferids are recorded. Venericardia carinata is an abundant and characteristic component of the mollusc assem Bryozoa and corals blage of the lower beds of the Earnley Formation, Specimens of the bryozoans Dittosaria and (including the < Ostracods Molluscs A diverse ostracod assemblage is recorded, lndeterminate shell debris is common. At comprising at least 21 species. The characteristic 73.0 rn abundant specimens of the bivalve Cal Brussels Formation species Aulocytheridea die lista proxima occur. Although partly crushed and gemensis is corn mon; other common taxa include very friable, they appear (by comparison with Leguminocythereis _striatopunctata, Pterygo topotype specimens in the author's collection cythereis cornuta and Eopaijenborchella longi from the Brussels Formation of Neder Ockerzeel) costa. One specimen of Leguminocythereis ge to be referable to the subspecies bruxellensis: nappensis, another characteristic species of the this is a characteristic mollusc of the Brussels Brussels Formation, is recorded at 74.0 m. Formation (GLIBERT, 1933). C. CORRELATION Belgium The Brussels Formation is generally absent in Oepth (metres) northwestern Belgium, where the lede For mation or the Wemmel Member rest unconfor EpistomineZZa oveyi . . mably on the Knesselare Formation or the Mont PyruZina thouini GuttuZina probZema Panisel Formation (see references in DEPRET & • WILLEMS, 1983). The occurrence of reworked • • GuttuZina irreguLaris • Nonion Laeve .., specimens of Nummulites laevigatus at the base 'PZanuLina' tendami 0 of these units supports the suggestion that the • • ::0 GLobuUna gibba ;x:. Brussels Formation was formerly present in this • • ...... 3: • TextuLaria aggLutinans :z...... area, as this species is recorded in situ in Belgium PararotaLia aurryi .., • • rTl only in the Brussels Formation. DEPRET & NonioneLLa wemmeLensis ::0...... 0 WILLEMS (1983) record the occurrence of N. NummuLites laevigatus 1./') laevigatus, with an associated microfauna indi Cibiaides LobatuLus cating a Lutetian date, in a thin interval between Hanzawaia produata • • the Oedelem Member and the Wemmel Member • • AnomaLinoides aautus Cibiaides westi in boreholes at Zeebrugge. They were uncertain if this interval was a representative of the Brussels MonsmirabiLia subovata Formation. Leguminocythereis oertLii The Knokke borehole confirms the occurrence • • EopaijenborcheLLa Lon~icosta of N. laevigatus in situ in this area; the section Schizocythere appendicuLata • • btween 71.75m-74.0m contains characteristic • • Cyamocyiheridea diegemensis Cytheridea sp. microfaunal and macrofaunal elements of the Loxoaonaha cf. subovata Brussels Formation, and it seems reasonable to Paraaytheridea cf. oertLii refer the interval to this Formation. The position Cytheromorpha sp. of the base of the Brussels Formation is uncertain 0 Cytheretta bambruggensis 1./') due to the core loss between 74 m-79 m. lt is a Iso il Leguminocythereis genappensis ;x:. uncertain if the very thin sequence preserved at n Leguminocythereis striatopunatata 0 • • 0 Knokke and Zeebrugge is a condensed equivalent 1./') Eahinoaythereis scabropapuLosa of the whole Brussels Formation, or represents • • Pterygocythereis aornuta only a part of it. lt seems to be unclear from the SahuLeridea perforata perforata published information whether N. laevigatus EopaijenborcheLLa eocaeniaa • • occurs elsewhere at a specifie stratigraphie level Ctithrocytheridea mourtoni Ctithroaytheridea faboides within the Brussels Formation, oris restricted to a Krithe rutoti particular facies. Brachycythere ventricosa • Hermanites paijenborahiana Southern England The Brussels Formation can be correlated (at • Yvoniettina oedetemensis least in part) with the middle to upper part of the • • Bignotetta batiformis Earnley Formation (Earnley division, Bracklesham • • Pseudarcetta sp. nov. A Group) by the presence of Nummulites laevigatus in both units. This correlation has been accepted Fig. 10.- Distribution of microfossils in the for many years. No significant additional evidence Brussels Formation of the Knokke borehole has been obtained from this investigation. 90 6.- KALLO FORMATION B. BIOSTRATIGRAPHY Dia toms A. LITHOSTRATIGRAPHY Pyritised diatoms are common throughout the Wemmel Member section between 65 m-35 rn, mainly small bi 71.75 m-c.71.32 rn: Very fine sand, biotur convex and biconcave specimens of Coscino bated, highly glauconitic, with abundant shell discus spp. Triceratium sp. is common at several debris and common Nummulites orbignyi. The levels. base is coarser grained, with subrounded quartz Radiolaria and chert grains up to 2 mm in diameter. The position of the upper boundary is poorly defined Siliceous or pyritised radiolaria are present at due to mixing qy bioturbation. several levels between 35.5 m-64 rn; they are particularly common in the Zomergem Member. Asse Member (Asb) At 38.0 m-41 .0 rn, a well-preserved and diverse c. 71.32 m-65.9 rn: Sandy clayey silt/clayey assemblage of siliceous radiolaria is present, silt, rather poorly s~rted, with abundant fine to including nasselariid, spongodiscid and spherical coarse-grained glauconite. The sand content is forms. mainly very fine to fine grained ( < 240p). «Problematica» lntensely bioturbated, with glauconite concen trated into streaks and lenses. Small silt or clay Single specimens of Voorthuyseniella gracilis filled Chondrites burrows are also common. The and Bignotella batiformis are recorded from the upper boundary is transitional. basal Asse Member. Both these species have been recorded from the Asse Member at Oedelem Ursel Member (Asc) by KEIJ (1969, 1970). 65.9 m-65.5 rn: Silty clay, bioturbated, with Benthonic foraminiferids lenses rich in glauconite, transitional to: The Wemmel Member contains an abundant 65.5 m-c.58.0 rn: Silty clay, homogenous; and diverse benthonic foraminiferid assemblage, with streaks of silt and silt-filled Chondrites . including abundant Neoeponides karsteni (=Epo burrows between c.63.9 m-c.62.0 m. Pyrite nides schreibersi of KAASSCHIETER), Asteri 'sticks' and 'lumpy'. pyrite nodules are common. gerina bartoniana, Lamarckina cristellarioides c.58.0 m-c.50.1 0 rn: Silty, sandy clay; fine and Spiroplectammina carinata. The assemblage grained glauconite is present at sorne levels, is very similar to the foraminiferid fau na recorded Chondrites burrows are common. Pyrite 'sticks' from the Wemmel Sands by KAASSCHIETER and 'lumpy' nodules are common throughout. (1961, Table 6). Onderdale Member (s1) Nummulites orbignyi (=wemmelensis) is c.50.1 0 m-c.48.0 rn: Silty sand, very fine abundant, associated with common N. vario grained/sandy silt, bioturbated, micaceous, glau larius. conitic (glauconite very fine to fine grained). Specimens of Nummulites laevigatus are also common, mostly heavily abraded and often with Zomergem Member (a2) chambers infilled by glauconite, but including c.48.0 m-c.47.0 rn: Sandy clayey silt, intensely sorne almost undamaged specimens. These are bioturbated; Chondrites burrows are frequent. evidently reworked from the underlying Brussels Pyrite «sticks» are common. Formation. c.47.0 m-37.0 rn: Silty clay, mainly homo ln the lower part of the Asse Member (at geneous, but with siltier horizons between 71.0 rn and 70.0 rn), benthonic foraminiferids are 44.0 m-43.0 m. Pyrite «Sticks» are very corn mon. abundant. Asterigerina bartoniana is very corn The upper boundary is well-defined but intensely mon, associated with Spiroplectammina carinata, i nterbu rrowed. Cancris subconicus, Trifarina wi/coxensis, Loxo stomum teretum, Neoeponides karsteni and other Buisputten Member (s2) species, forming an assemblage similar to that 37.0 m-33.0 rn: Silty sand, very fine grained, recorded elsewhere at this level by KAASSCHIE intensely bioturbated; with thin clayey beds TER (1961, Table 6). The microfauna has a between 35.65 m-35.70 m. Micaceous, with fine somewhat «deeper-water» aspect than recorded grained glauconite; small pyrite nodules are at other localities in Belgium, indicated by the corn mon. occurrence of the nodosariids Nodosaria lateju- 91 gata and Vaginulinopsis [Marginulina] decorata, Members Lithology and common Globocassidulina globosa. . . - .. Nummulites orbignyi occurs abundantly at - - 71.0 rn, associated with N. variolarius. lt is 35- BUISPUTTEN - - present ra rely at 70.0 m. - - Above 69.0 rn a more restricted assemblage ·-·- --;-- occurs, without Nummulites. r-- - 1 --- 1 1 r-- - ln the lower part of the Ursel Member, - - - between 65.0 m-63.0 rn, a different assemblage r- - - 40- -- - is present, dominated by Cibicides pygmeus, C. 1------sp. cf. tene/lus, Anomalinoides acuta, Brizalina r------cookei, Spiroplectammina carinata, Uvigerina ZOMERGEM 1------farinosa and Pseudoclavulina sp. cf. cocoaensis. ~1----l ::.· These are associated with AG 1 agglutinants - - - > 1- - - including Haplophragmoides walteri and Glomo 45- - - - spira charoides. The AG 1 ratio is 5-1 5 %. Above 1-- - - - 63.0m the section is decalcified. Only aggluti r--- - -·- - nants persist, associated with pyritised moulds of .... -·- - Cancris subconicus; at stiJl higher levels (58 rn, ~- -. . 0.- .... - ---• • .. 0 •• 0. l 57 rn) only occasional pyritised moulds of C. ONDER DALE 1- ..... - subconicus are recorded. 50- ·_:. :~ :.;... -- - -· r-- -·- - - - · The Onderdale Member is barren. At the base r- -·- - of the Zomergem Member, at 47.3 rn, several - -- 1- -·- - pyrite moulds of small, high:y compressed Num - - - r- -·- - ' ' mulites sp. are recorded. These are too poorly - - - r- - -·- preserved for positive identification, as the septa 55- - - - 1 are not visible, but comparison with specimens of 1- -·- - -·- - Middle and Late Eocene Nummulites from the 1- -·-·- • North Sea Basin indicâtes that there is a close -·- - 1- -·- - URSEL - - _, resemblance only to N. prestwichianus. They are 1------he re referred to as N. cf. prestwichianus. Possible r- - - specimens of Numu/ites cf. prestwichianus, too 60- - - - r-- - poorly preserved to be definitely recognised even --- 1 as Nummulites, also occur in the next higher 1------sample studied (at 46.0 rn). ln higher levels of the r------Zomergem member, foraminiferids are repre r- -- - - ~ sented only by rare and poorly preserved agglu r-- - i tinants, including corroded specimens of Spiro 65- - - - 1- - - -1 - - _.... plectammina cf. carinata. A si mil ar assemblage is 1- -·- - recorded in the base of the Buisputten Member, ~------=- at 35.5 m. ·- - - - 1- - -- ASSE 1---·- -·- Planktonic foraminiferids .. ..-. - -·- 1- - -·- 70- - - - Planktonics occur very commonly in the 1- -·- - 1-:-_-:-_-:-.. , Wemmel Member and in the basal Asse Member t-- WEMMEL - (P=30% at 71.0 rn, and 35% at 70.0 rn). Pseu 1 1 1 dohastigerina is the dominant form. >. ... Q) Cl .... ~ Vl ...... Cl +-' ..c: -Q) (.) Vl Vl ..... They occur much more ra rely in the upper part +-'s.. s:: Q.+-' Q) 0 of the Asse Member and the lower part of the Q)Q) +-' u OE Grains ize ..... ::::1 ta s.. ta u Ursel Member (P=0.4% at 63.0 rn), but still >, ...... including Pseudohastigerina. At higher levels - c.. (.0 ::E they are absent. Sponge spicules Fig. 11.- Lithostratigraphy of the Kallo Formation in Pyritised and siliceous sponge spicules are the Knokke borehole frequent in the Buisputten Member and the upper 92 ...... U1 ... 0 "'0 0 0 Depth (metres) Il 1 Ill 1 Ill 1 1 1 1 Il 1 1 SAMPLE POSITIONS ... . Trifarina wiZcoxensis Bulimina parisiensis :: Hansawaia produata AnguZogerina muraZis FabuZaria beZZa Cibicidoides proprius FloriZ.us commune BrizaZina angZiaa ... LentiauZina sp • Epistominella acutimargo NW11111U Zi tes Zaevigatus (reworked) PyruZina sp. GZobuZina spp. • Anomali·noides acutus . . . KarrerieZZa siphoneZZa - GZobuZina gibba ~ .... ~ • Neoeponides karsteni Nummulites wemmelensis Nummulities variolarius '" TriZocuZina sp. ~ ~ Lamarckina cristellarioides ~ TextuZaria aggZutinans Sigmoi lina tenuis ~ . .. Cancris subconicus ~ ... SpiropZectammina cf. carinata ~ Asterigerina bartoniana ~ AZabamina bJOZZerstorfii QuinqueZocuZina spp. r- AnomaZinoides affine '"• GZoboaassiduZina gZobosa • Nonionella ~emmelensis • NonioneZZa spissa • Lagena striata . ~aginulinopsis decorata • Anomalinoides acutus anomalinoides • Asterigerina sp • (Kaasschieter) . . PraegZobobuZimina ovata .. Seabrookia Zagenoides . . Nodosaria Zatejugata Canaris auriculu.s primitivus -• • Loxostomum teretum • Lenticulina sp. cf. costa ta Cibiaides sp. - . Cibicides cf. ungerianus . PuUenia sp • • . Gyroidinoides octocameratus ... Cibicides sp. cf• teneUus ... Briaalina cookei ... Uvigerina farinosa ... Cibiaides pygmeus • . OridorsaZis umbonatus ...... HapZophragmoides waZteri . . Ammodisaus sp • ... Pseudoc Zavu Zina sp. cf• cocoaensis • LentiauZina gutticostata . GZomospira aharoides . cf• Troahammina sp. . cf• Rhabdammina sp. . HapZophragmoides burrowsi • NW11111UZites cf• prestwichianus . NW11111UZites sp? .__._ Spi~opZeatammina carinata Reophax sp. .- Indeterminate agglutinants 0 N c: :z 0 )> c 3: V> V> l'Tl l'Tl MEMBERS V> "'l'Tl c ~ fT1 .... )> "' l'Tl"' .... "'3: l'Tl ~ Fig. 12.- Distribution of benthonic foraminiferids in the Kallo Formation of the Knokke bore ho le 93 part of the Zomergem Member. Pyritised ?Geodia C. CORRELATION spicules are common at severa! levels between 61.0 m-41.0 m. Belgium Bryozoa The Wemmel Member at Knokke rests unconformably on the Brussels Formation. The Orbitulopora petiolus is recorded in the base of occurrence in the Wemmel Member and the basal the Asse Member. Asse Member of fossils reworked from the Benthonic molluscs Brussels Formation and the Lede Formation indicates that a more complete sequence formerly lndeterminate bivalve shell debris is abundant existed here. in the Wemmel Member. This includes highly abraded ostreid (oyster) debris, which may be part The succession within the Kallo Formation can of the reworked component. At the base of the be readily correlated lithologically with the Asse Member (71.0 m-70.0 rn) poorly preserved «Standard>> sequence present elsewhere in molluscs are corn man. Lentipecien cf. corneum is norther Belgium (JACOBS, 1978). The micro frequent; this species is characteristic of the Asse faunas of the Wemmel Member and the Asse Member. Above this level only pyrite casts and Member are comparable to those recorded else moulds are preserved; these are fairly corn mon in where in Belgium (KAASSCHIETER, 1961; KEIJ, the lower part of the Ursel Member, including 1957). The microfauna of the higher parts of the Turritella sp. and Pitar sp. Kallo Formation («Kallo complex>>) has been studied only in the Kallo borehole (DROOGER in Pteropods GULINCK, 1969) and is stiJl very imperfectly Poorly preserved pteropods are recorded in the known. This is partly due to the decalcification of lower part of the Ursel Member. These include a much of the sequence, but as the present study specimen of cf. Skaptotion bartonense at 64.0 m. has shawn, it is stiJl possible to obtain useful This suggests correlation with the Skaptotion biostratigraphic data. bartonense pteropod Zone (Zone GP11 of JANS The record of a Nummulites horizon at the SEN & KING, in press). base of the Zomergem Member, and the presence of a diverse radiolarian assemblage in the upper Ostracods part of the Zomergem Member, are new disco A diverse ostracod assemblage is recorded varies at Knokke, and further investigations may from the Wemmel Member, comprising 22 spe reveal their presence at other localities in cies. The most common .taxa are Krithe barto Belgium. Their importance in regional correlation nensis, Cyamocytheridea mourloni and Legumi is discussed below. nocythereis striatopunctata. The assemblage is very similar to that recorded elsewhere in the Hampshire Basin Wemmel Member (KEIJ, 1957). Severa! speci The Wemmel Member is currently correlated mens of ?ldiocythere barioniana were found; this with the upper part of the Bracklesham Group species has previously been recorded only in the (upper Selsey division/Huntingbridge division) upper part of the Bracklesham Group and in the (CURY et al., 1977), based on comparisons of the Barton Beds, in the Hampshire Basin (HASKINS, mollusc and nannoplankton assemblages. The 1968-1971, KEEN, 1978). Asse Member is tentatively correlated with the Ostracods are corn mon at the base ofthe Asse Huntingbridge division. The benthonic macro Member, at 71.0 rn and 70.0 rn, including Legu faunas and microfaunas are difficult to compare minocythereis striatopunctata, Krithe bartonen in detail, due to differences in facies between the sis, Cytheridea intermedia and Cyamocytheridea two areas. heizelensis. They occur more rarely in the upper There is a major environmental break in part of the Asse Member. The occurrence of Belgium at the base of the Ursel Member, from a isolated specimens of Boldel/a deldenensis and shelly, sandy, glauconitic sequence with a diverse Cytheretta eocaenica, which are characteristic of microfauna and marofau na (Wemmel and Asse the Lede Formation, suggets th at sorne reworking Members) to a sequence of largely decalcified from the Lede Formation may have taken place. silty clays and sandy silts with limited micro Rare fragments of Pterygocythereis fimbriata fauna, but common pyritised diatoms. This event fimbriata are recorded in the lower part of the is paralleled in the Hampshire Basin by a similar Ursel Member. biofacies and lithofacies change at the base of the Huntingbridge division (see KEMP et al., 1979). lt 94 -...J en en 0'1 0'1 w 0 0'1 0 U'1 0 U'1""" 0""" U'1 Depth (mettes) rrrnnrrnnrrnnnrTlnrnnn n n SAMPLE POSITIONS 1 1 1 •1 Triceratium sp. • Coscinodiscus spp • • • .....3: - - Radio Zaria Vl • - • Sponge spicuZes ;> 1 1 _1 l ·~- ?Geodia sp. ..., - Voor~huysenieZZa graciZis ;;o 0 - - - BignoteZZa batiformis c:> 1 1- 1 1 1 Fterygocythereis fimbriata fimbriata Leguminocythereis striatopunctata 11-- Schizocythere batjesi - Krithe bartonensis 1 1 1 l-11 1 Echinocythereis scabropapuZosa - CythereZZa compressa --Il Ptergyocythereis cornuta 1• 1 1 1 1 MonsmirabiZia triebeZi Cytheridea intermedia -Il• SchuZeridea perforata perforata Bythocypris cuisensis J.: 1 1 1 1 EopaijenborcheZZa eocenica - Eucytherura dentata 0 - Paracytheridea gradata Vl -i Cyamocytheridea heizeZensis ;;o -1- 1 1 1 1 ):> (""') CZithrocytheridea mourZoni 0 • t:l • TrigingZymus anguZatopora Vl Cytheretta eocaenica .[ 1 1 1 1 czithrocytheridea faboides - BoZdeZZa deZdenensis - PZate Ua gy rosa Paracypris contracta ~ 1 1 1 1 - CythereZZoidea dameriacensis 1 Cytheretta decipiens MonsmirabiZia subovata ~ 1 1 1 1 MonsmirabiZia foveoZata - Leguminocythereis oertZii - Cushmanidea grosjeani EopaijenborcheZZa Zongicosta 1 1 1 1 1 - Idiocythere bartoniana - - Indet. bivaZves - - - Indet. gastropods 1 1 - 1 1 1 Retusa sp. - - TurriteUa sp. 3: 0 r - cf. Pitar sp. r c: 1 1 1 1 1 Lentipecten corneum Vl • (""') - NucuZa sp. Vl - RingicuZa sp. Anomia sp. ~ 1 1 1 1 pectenid sp. indet. ..., - pteropod sp. indet. -i cf. Skaptotion bartonense ;;o1"1'1 1- • OrbituZopora petioZus BRY. c:> Il 0 N c: :z 0 ..... :e: ):> c: t:l 3: Vl 1"1'1 ::0 1"1'1 3: Vl ;;o 1"1'1 ..., Vl V> ;;o c: ::;;:: 1"1'1 t:l MEMBERS 1"1'1 1"1'1 ):> en -i r r 1"1'1 -i r ::;;:: 1"1'1 Il 1"1'1 :z Fig. 13.· Distribution of fossils (excluding foraminiferids) in the Kallo Formation of the Knokke borehole 95 g ~ ~ 1__ Depth (metres) IEPER FORMATION ""~"' ~ i~~ LITHOSTRATIGRAPHY FLANDERS MEMBER i~ ~ ~ 1x Mm J:l 1 (Not studied) DINOFLAGELLATES :::':i~"'""'·'· .. 1 1 IIII~ ~ ;~y:. ·Yi * i :_;~,~ ,·f~,;~:,~. r:?'\'''''''' 1:{::::=:::::.: .. OSTRACODS ~ .,,,,,,,,,,,,,,,;"'fj'"j' NORTH SEA MICROFAUNAL :::::::::::::: ZONATION j_ • Numm. cf. prestrJichianus 1---+--+---+---+---1 Pseudohastigerina spp. • cf. ·skaptotion bartonense ...._... Neoeponides karsteni H Nummulites oPbignyi • Nummulites Val'iolarius ,...._. Bignotella batifoJ."'llis H Pseudarcet'la sp. nov. A H Nunmu'Lites laevigatus (in situ) H Callista proxima .cf. bl'U:l:e'Llensis J.t Cyamocytheridea diegemensis 1-~- Leguminocythe:reis genappenst.-3 1--l----t-----l'PZanuU.na' tendami 11----- Yvonieltina va.riabiliB 1----I[Big,,oteZ.Za polygona >---< [Vene,,ica,..iio carinata 1---t-----< bulla.ta >t-----1--,_-+___., ~:~~:::.~;:~~::;:!•a PigUJa ,punctota li Euchilotheca cf•. ele!:ans 1---f--+---+----J--+---+----J...... Spiratella merainensis 1--+---t---+- 'Cenosphaera.' sp. p---f-< EciOinocJ~theP<•i•• ~f· ret<,,uZat''""""" ·.S~i.atei Za >--+----+< VaginuUnopsis tüetheroe'LZU Osangularia pZwnmezoae Cytheretta scN-bf.cuZopZ• >- • • • • • • < Te%tdaPia smit~>> >--f-t sp. ' paZeocenica 1 8 1 ~ VePneuilina subeocaena 1 Fig. 14.- Significant fossil ranges and biostratigraphic zones identified in the Eocene sequence of the Knokke borehole is suggested here that these events are due to nus. lt is therefore concluded that this Nummulite eustatic sea-level changes and can be directly horizon at Knokke may be a correlative of the correlated. Nummulites prestwichianus bed. If correct, this is Detailed correlation of the Ursel Member and an important advance in the correlation of these higher units is difficult, but the Nummulite beds. Other biostratigraphic evidence for dating horizon in the Zomergem Member may be and correlating these beds is discused in the significant. Nummulites spp. occur at three following sections. discrete horizons in the Huntingbridge division Southern North Sea and the Lower Barton Beds: The Wemmel Member, the Asse Member and 1) The Afton «Nummulite bed» (CURRY, 1942) the lower part of the Ursel Member can be in the lower part of the Huntingbridge division assigned to planktonic Zone NSP6. (Pseudohas (KEMP et al., 1979) (N. cf. variolarius). tigerina wilcoxensis zone) of KING 1983, by the 2) The «Nummulites prestwichianus» bed and occurrence of Pseudohastigerina. The sa me units immediately overlying beds, at the base of the contain Neoeponides karsteni, an index-fossil of Barton Beds (N. prestwichianus) the lower part of benthonic Zone NSB5 in the 3) Beds A2 and A3 in the upper part of the southern North Sea (KING, 1983). Lower Barton Beds (N. rectus). A partially cored borehole (borehole 79/06) The specimens from the base of the Zomer driled by the lnstitute of Geological Sciences in gem Member are referred to N. cf. prestwichia- the southern North Sea (about 80km of the 96 Knokke borehole), is described by HUGHES quences exists in Belgium than in England, where (1981 ). It penetrated Oligocene (Rupelian) clays, the generally more marginal sequences are poor resting on an Eocene sequence of alternating fine in planktonic foraminiferids (except for parts of sands and clays (125.6 m-202.2 m). HUGHES the London Clay Formation) and contain a rather briefly describes and illustrates a diverse and «patchy» sequence of nannoplankton. The dino abundant siliceous radiolarian and diatom as flagellate sequence is better known in England, semblage occurring through the interval142 m to but this is a reflection of more intensive study. 202.2 m, which compares closely with the as 2) Correlation of biostratigraphic events or semblage recorded here in the Zomergem Mem ranges of short-ranging species (e.g. the «Osan ber. This evidence, together with the Iithological gularia datum» in the London Clay Formation or similarity of the two sequences, indicates that the «Nummulites prestwichianus bed» at the base these beds can be correlated with the Kallo of the Sarton Beds). ln general, identification of Formation. More detailed comparison is difficult, events (first appearances of taxa or significant as the upward extension of the radiolarian faunal «breaks») is more reliable than compari assemblage in the Kallo Formation is not yet sons of the total vertical ranges of species, as the known. latter are more liable to be affected by environ HUGHES records a glauconitic sand with mental contrais. A number of biostratigraphic Nummulites cf. orbignyi near the top of the events, e.g. the «planktonic datum» in the London Eocene sequence (at 1 30 m). This bed is probably Clay Formation (KING, 1981) are probably related too high to be correlated with the Nummulites cf. to basin-wide or eustatic sea level changes, and prestwichianus levet recorded at the base of the are thus effectively synchronous, but care is Zomergem Member, and the illustrations suggest always necessary in their use in correlation. The that the two records are of different species. It best criterion of their reliability is their consis may weil correlate with the sandstone containing tency as tested against other techniques of Nummulites cf. orbignyi recorded by GULINCK correlations. (1969) at the base of the Bassevelde Sands in the 3) Correlation of distinctive lithostratigraphic Kallo Borehole (124-127 m). units (e.g. the «ash-series») or of sedimentary «cycle-bou ndaries» (event-stratig raphy). «Paracy clic» sequences of sedimentation, which are most 7.- CORRELATION OF THE BELGIAN clearly exemplified in southern England (e.g. AND ENGLISH EARLY AND MIDDLE KING, 1981; PLINT, 1983), are probably largely EOCENE the reflection of eustatic sea levet changes. Similar types of cyclic sequence exist in Belgium, A. PREVIOUS STUDIES but direct correlation between these and the The most recent general su rn mary of the inter English cycles is still at an early stage. If regional correlation of the English and Belgian calibrated by available biostratigraphic data, cor Eocene is by CURRY et al. (1978). relation of sedimentary cycles should eventually yield precise «tie-points» between the two areas. The additional biostratigraphic and lithostra tigraphic data provided by the Knokke borehole, Ali three techniques should obviously yield together with other recently published biostrati coherent results. If not, then the «most probable» graphic information both in England and Belgium, solutions must be applied. suggests that the time is appropriate to briefly The data available from techniques (2) and (3) review and synthesise the correlation between have been dealt with in preceding sections; here the English and Belgian Early and Middle Eocene the available data on planktonic microfossils are successions, and the correlation of both with the summarised. «standard» planktonic zonal schemes. C. BELGIUM B. TECHNIQUES OF CORRELATION Ieper Formation Three distinct but interlocking techniques of correlation are available, each with limitations Oinoflagellages which must be taken into account: The W. meckelfeldensis, D. similis, D. varie 1) Correlation of stratigraphie units with the longituda and K. coleothrypta dinoflagellate zones standard planktonic zonal sequences (based on were identified in the Ieper Formation of the Kallo nannoplankton, planktonic foraminiferids or dino borehole by COSTA & DOWNIE (1976) and sorne flagellates). A more complete record of the of these zones are also recognised at other nannoplankton and planktonic foraminiferid se- localities (see DE CONINCK, 1975). 97 The Mt. Heribu Member in the Mons-Tournai Planktonic foraminiferids area is assigned to the W. meckelfeldensis zone The planktonic foraminiferids from the Ieper (DE CONINCK et al., 1983). Formation are mainly long-ranging taxa, but in At Knokke, «Member X» is assigned to the the Mol borehole at 395.5 m-382.5 m, Zone P8 is upper part of the A. hyperacanthum zone, and the identified (HOOYBERG HS, 1983a). base of the Flanders Member corresponds appro The first occurren-ce of Pseudohastigerina ximately to the base of the W. mecke/fe/densis wilcoxensis in the upper Ieper Formation- and at zone (DU PUIS et al.,_ this volume). This confi~ms equivalent levels in the uper London Clay- is not the correlation with the London Clay Formation equivalent to the Pseudohastigerina datum of discussed above, based on the diatoms and the Berggren (base of subzone P6b) but is younger. microfaunal assemblages. The W. astra zone has not been recorded in Belgium, but is such a thin Mont-Panisel Formation & Knesselare Forma unit in the London Basin that it nevertheless tion could be present in the basal part of the Flanders Member. The W. 11Jeckelfeldensis zone is iden The sequence from the Mont-Panisel For tified in the Mt. Heribu Member in its type-area mation to the Asse Member ali lies within the K. (DE CONINCK et al., 1983), confirming the coleothrypta Zone (s.l.), but correlation with Zones diachronism of this unit. The position of the base W7 to W9 has not yet been established. of the Wetzeliella similis zone is only defined at The Knokke borehole has yielded a good Kallo (COSTA & DOWNIE, 1971 ), where it is sequence of nannofossil assemblages from the recorded at 357 m. Mont-Panisel Formation and Knesselare For The base of the W. varie/ongituda zone is mation (STEURBAUT, this volume) which for the again only defined at Kallo (COSTA & DOWNIE, first time permits an adequate evaluation of this 1976). Here it coïncides with the «glauconite interval. Zone NP 13 (Discoaster sub/odoensis level». zone) is identified between 132.50 m and 103.50 m (within the Mont-Panisel Formation The base of the Kisse/ovia coleothrypta zone is and the basal Knesselare Formation) and NP14 located in the upper part ofthe Flanders Member (Discoaster lodoensis zone) between 99.25 m and at a depth of 266 m in the Kallo section (COSTA& 80.0 m (within the Knesselare Formation). No DOWNIE, 1976). data from other localities is available. The base of the Kisselovia coleothrypta ro The planktonic foraminiferids of these forma tundata zone (Zone W7 of CHATEAUNEUF & tions have not yet been studied in detail. GRUAS - CAVAGNETTO) is identified by ISLAM (1981) in the topmost part of the Egem Member Brussels Formation («Sables de Mons-en-Pevele») at Egem. Samples from the Brussels Formation at Calcareous n~nnoplankton Knokke are assigned to nannoplankton Zone The lower part of the Ieper Formation has not NP14 (D. sub/odoensis zone) by STEURBAUT (this yielded calcareous nannoplankton at any locality volume). This is in agreement with previous studied so far. records of this zone from the Brussels Formation by MARTINI (1971 :757) and MULLER (in DEPRET The Discoaster binodosus zone (Zone NP11) is & WILLEMS, 1983). identified between 245.50 m and 220.60 m at Knokke (STEURBAUT, this volume). Zone NP11 is The Nannotetrina fu/gens zone (NP15) is identified at Kallo between 325.5 m and 306 m recorded in the Brussels Formation by BIGG (MULLER & WILLEMS, 1981 ). ( 1982). The zonal attributions of BIGG are discussed extensively by AUBRY (1983:19-20), The upper part of the Ieper Formation is and are not entirely consistent with other results. decalcified at Knokke. At Kallo the Marthasterites tribrachiatus zone (NP1 2) is identified between The Brussels Formation at Mol and Haacht is 306 m and the top of the Ieper Formation assigned to planktonic foraminiferid Zone P1 0 by (MULLER & WILLEMS, 1981). The base of this HOOYBERGHS (1983a, 1983b). zone corresponds to the «glauconite level», which Lede Formation may mark a discontinuity. The Lede Formation at Bambrugge was ten The upper part of the Flanders Member in the tatively assigned to Zone NP15 by MARTINI claypit at Kortemark is assigned to the M. (1971:758). tribrachiatus zone (NP12) by HAY & MOHLER (1967), MARTINI (1971:756) and BIGG (1982). Planktonic foraminiferids from the Lede For- 98 mation at Mol and Balegem are referred by D. SOUTHERN ENGLAND HOOYBERG HS ( 1983a, 1983b) to the uppermost part of Zone P1 O. Dinoflagellate zonations have been developed by COSTA & DOWNIE (1976), and BUJAK et al. Kallo Formation (1980). The Asse Member at Oedelem (CHATEAU Severa! partial studies of the calcareous NEUF, 1980) yields a dinoflagellate assemblage nannoplankton (see references in AUBRY, 1983) similar to that of the Upper Bracklesham Beds. have been followed by a thorough investigation by This assemblage is referred by COSTA& DOWNIE AUBRY (1983), from which most of the following (1976) to the W. coleothrypta zone (s.l.). information is abstacted, with sorne revision and correction of the lithostratigraphic terminology. Dinoflagellates · Planktonic foraminiferids are of low diversity, At the depth of 1 29 rn in the Kallo borehole and (except in parts of the London Clay Formation) (i.e. within a3) CHATEAUNEUF records an as are generally rare or absent. Sorne species are semblage with RhQmbodinium porosum, refer illustrated by MURRAY & WRIGHT (1974) and rable to the R. porosum Zone (W11 ). MURRAY et al. (1981 ), but their contribution to Calcareous nannoplankton stratigraphical correlation with the standard planktonic foraminiferid zonation is at present A sample from the Wemmel Member of the negligible. Knokke borehole (at 71.65 rn) is referred to the N. fu/gens nannoplankton zone (NP1 5) (STEURBAUT, London Clay Formation this volume). MARTINI (1971 :758) had previously identified this zone at Wemmel itself. Di noflagellates BIGG (1982) refers the Wemmel Member to Data up to 1980 are summarised in KING the Reticulosphaera umbilica subzone or higher (1981 ). Subsequent revisions are as follows: (NP16). He attributes the presence of Nannote 1) The base of the Wetzeliella similis zone trina fu/gens in this unit to reworking; but this falls within division A3 in the Hampshire Basin species has not been recorded in older units in (KNOX et al., 1983). Belgium. 2) The base of the Kisse/ovia coleothrypta A sample from the Asse Member at Knokke is zone is within the upper part of division D in the assigned to NP15 (STEURBAUT, this volume). The Isle of Sheppey (Kent) (ISLAM, 1981; KING, Asse Member at Oedelem and in the Kallo 1984). borehole was assigned to NP16 by MARTINI (1971 :758). These results are not necessarily Calcareous nannoplankton inconsistant, as the highly glauconitic Asse The lower part of the London Clay Formation Member may be a condensed deposit which (division A) has not yielded indigenous calcareous spans the NP15/ NP16 boundary. Samples from nannoplankton. BIGNOT & LEZAUD (1969) iden the lower part of the Ursel Member at Knokke are tified Zone NP11 at Alum Bay and Whitecliff Bay assigned to NP16 (STEURBAUT, this volume). (Isle of Wight), most probably in division B2, Above this level the Meetjesland Formation is although the precise level from which their decalcified; the Nummulites prestwichianus bed samples were obtained is not stated. AUBRY at Whitecliff Bay (Isle of White), which is believed ( 1983:59, fig. 13) refers samples from the Manor to correlate with the base of the Zomergem Farm Pit at Lower Swanwick (Hampshire) to the Member, is probably in the upper part of Zone upper part of NP11 :·this section is within division NP16 (AUBRY, 1983:268). B2 (KING 1981, Text-Fig. 27). Higher levels in the London Clay Formation have so far not yielded Planktonic foraminiferids calcareous nannofossils. Selected samples from The upper part of the Wemmel Member in divisions C, D andE submitted by the author to D. Brussels is referred to the Zone P11 /P12 bound CURRY for study ali proved to be barren (D. ary (HOOYBERGHS, 1984a). The base of the Asse CURRY, pers. corn.). Member in the Mol borehole is referred to the upper part of Zone P12 (HOOYBERGHS, 1983a). Bracklesham Group The Berg Sands at Mol fall within Zones P14-P17 The Bracklesham Group falls entirely within (HOOYBERGHS, 1983a). the Kisselovia coleothrypta zone of COSTA & 97 The Mt. Heribu Member in the Mons-Tournai Planktonic foraminiferids area is assignee! to the W. meckelfe/densis zone The planktonic foraminiferids from the Ieper (DE CONINCK et al., 1983). Formation are mainly long-ranging taxa, but in At Knokke, «Member X» is assigned to the the Mol borehole at 395.5 m-382.5 m, Zone P8 is upper part of the A. hyperacanthum zone, and the identified (HOOYBERGHS, 1983a). base of the Flanders Member corresponds appro The first occurr.ence of Pseudohastigerina ximately to the base of the W. meckelfe/densis wilcoxensis in the upper Ieper Formation- and at zone (DU PUIS et al.,_ this volume). This confi~ms equivalent levels in the uper London Clay - is not the correlation with the London Clay Formation equivalent to the Pseudohastigerina datum of discussed above, based on the diatoms and the Berggren (base of subzone P6b) but is younger. microfaunal assemblages. The W. astra zone has not been recorded in Belgium, but is such a thin Mont-Panisel Formation & Knesselare Forma unit in the London Basin that it nevertheless tion could be present in the basal part of the FI anders Member. The W. fheckelfeldensis zone is iden The sequence from the Mont-Panisel For tified in the Mt. Heribu Member in its type-area mation to the Asse Member ali lies within the K. (DE CONINCK et al., 1983), confirming the co/eothrypta Zone (s.l.), but correlation with Zones diachronism of this unit. The position of the base W7 to W9 has not yet been established. of the Wetzeliella similis zone is only defined at The Knokke borehole has yielded a good Kallo (COSTA & DOWNIE, 1971 ), where it is sequence of nannofossil assemblages from the recorded at 35 7 m. Mont-Panisel Formation and Knesselare For The base of the W. varie/ongituda zone is mation (STEURBAUT, this volume) which for the again only defined at Kallo (COSTA & DOWNIE, first time permits an adequate evaluation of this 1976). Here it coïncides with the «glauconite interval. Zone NP 13 (Discoaster sublodoensis level». zone) is identified between 132.50 m and 103.50 rn (within the Mont-Panisel Formation The base of the Kisse/ovia coleothrypta zone is and the basal Knesselare Formation) and NP14 located in the upper part of the Flanders Member, (Discoaster /odoensis zone) between 99.25 rn and at a depth of 266 m in the Kallo section (COSTA& 80.0 rn (within the Knesselare Formation). No DOWNIE, 1976). data from other localities is available. The base of the Kisselovia coleothrypta ro The planktonic foraminiferids of these forma tundata zone (Zone W7 of CHATEAUNEUF & tions have not yet been studied in detail. GRUAS - CAVAGNETTO) is identified by ISLAM (1981) in the topmost part of the Egem Member Brussels Formation («Sables de Mons-en-Pevele») at Egem. Samples from the Brussels Formation at ) Calcareous nannoplankton Knokke are assigned to nannoplankton Zone The lower part of the Ieper Formation has not NP14 (D. sublodoensis zone) by STEURBAUT (this yielded calcareous nannoplankton at any locality volume). This is in agreement with previous studied so far. records of this zone from the Brussels Formation by MARTINI (1971 :757) and MULLER (in DEPRET The Discoaster binodosus zone (Zone NP11) is & WILLEMS, 1983). identified between 245.50 m and 220.60 m at Knokke (STEURBAUT, this volume). Zone NP11 is The Nannotetrina fu/gens zone (NP1 5) is identified at Kallo between 325.5 m and 306 m recorded in the Brussels Formation by BIGG (MULLER & WILLEMS, 1981 ). (1982). The zonal attributions of BIGG are discussed extensively by AUBRY (1983: 19-20), The upper part of the Ieper Formation is and are not entirely consistent with other results. decalcified at Knokke. At Kallo the Marthasterites tribrachiatus zone (NP12) is identified between The Brussels Formation at Mol and Haacht is 306 m and the top of the Ieper Formation assigned to planktonic foraminiferid Zone P1 0 by (MULLER & WILLEMS, 1981 ). The base of this HOOYBERGHS (1983a, 1983b). zone corresponds to the «glauconite level», which Lede Formation may mark a discontinuity. The Lede Formation at Bambrugge was ten The upper part of the Flanders Member in the tatively assigned to Zone NP15 by MARTINI claypit at Kortemark is assigned to the M. (1971 :758). tribrachiatus zone (N P12) by HAY & MOHLER (1967), MARTINI (1971 :756) and BIGG (1982). Planktonic foraminiferids from the Lede For- 98 mation at Mol and Balegem are referred by D. SOUTHERN ENGLAND HOOYBERGHS (1983a, 1983b) to the uppermost part of Zone P1 O. Dinoflagellate zonations have been developed by COSTA & DOWNIE (1976), and BUJAK et al Kallo Formation (1980). The Asse Member at Oedelem (CHATEAU Severa! partial studies of the calcareous NEUF, 1980) yields a dinoflagellate assemblage nannoplankton (see references in AUBRY, 1983) similar to that of the Upper Bracklesham Beds. have been followed by a thorough investigation by This assemblage is referred by COSTA& DOWNIE AUBRY (1983), from which most of the following (1976) to the W. coleothrypta zone (s.l.). information is abstacted, with sorne revision and correction of the lithostratigraphic terminology. Dinoflagellates · Planktonic foraminiferids are of law diversity, At the depth of 1 29 m in the Kallo borehole and (except in parts of the London Clay Formation) (i.e. within a3) CHATEAUNEUF records an as are generally rare or absent. Sorne species are semblage with Rhombodinium porosum, refer illustrated by MURRAY & WRIGHT (1974) and rable to the R. porosum Zone (W11 ). MURRAY et al. (1981 ), but the ir contribution to Calcareous nannoplankton stratigraphical correlation with the standard planktonic foraminiferid zonation is at present A sample from the Wemmel Member of the negligible. Knokke borehole (at 71.65 m) is referred to the N. fu/gens nannoplankton zone (NP1 5) (STEURBAUT, London Clay Formation this volume). MARTINI (1971 :758) had previously identified this zone at Wemmel itself. Dinoflagellates BIGG (1982) refers the Wemmel Member to Data up to 1980 are summarised in KING the Reticu/osphaera umbilica subzone or higher (1981 ). Subsequent revisions are as follows: (NP16). He attributes the presence of Nannote 1) The base of the Wetzeliella similis zone trina fu/gens in this unit to reworking; but this falls within division A3 in the Hampshire Basin species has not been recorded in aider units in (KNOX et al., 1983). Belgium. 2) The base of the Kisse/ovia coleothrypta A sample from the Asse Member at Knokke is zone is within the upper part of division D in the assigned to NP15 (STEURBAUT, this volume). The Isle of Sheppey (Kent) (ISLAM, 1981; KING, Asse Member at Oedelem and in the Kallo 1984). borehole was assigned to NP16 by MARTINI (1971 :758). These results are not necessarily Calcareous nannoplankton inconsistant, as the highly glauconitic Asse The lower part of the London Clay Formation Member may be a condensed deposit which (division A) has not yielded indigenous calcareous spans the NP15/ N P16 boundary . Samples from nannoplankton. BIGNOT & LEZAUD (1969) iden the lower part of the Ursel Member at Knokke are tified Zone NP11 at Alum Bay and Whitecliff Bay assigned to NP16 (STEURBAUT, this volume). (Isle of Wight), most probably in division B2, Above this level the Meetjesland Formation is although the precise level from which their decalcified; the Nummulites prestwichianus bed samples were obtained is not stated. AUBRY at Whitecliff Bay (Isle of White), which is believed (1983:59, fig. 13) refers samples from the Manor to correlate with the base of the Zomergem Farm Pit at Lower Swanwick (Hampshire) to the Member, is probably in the upper part of Zone upper part of NP11 : this section is within division NP16 (AUBRY, 1983:268). B2 (KING 1981, Text-Fig. 27). Higher levels in the London Clay Formation have so far not yielded Planktonic foraminiferids calcareous nannofossils. Selected samples from The upper part of the Wemmel Member in divisions C, D and E submitted by the author to D. Brussels is referred to the Zone P11 /P12 bound CURRY for study ali proved to be barren (D. ary (HOOYBERGHS, 1984a). The base of the Asse CURRY, pers. corn.). Member in the Mol borehole is referred to the upper part of Zone P12 (HOOYBERGHS, 1983a). Bracklesham Group The Berg Sands at Mol fall within Zones P14-P17 The Bracklesham Group falls entirely within (HOOYBERGHS, 1983a). the Kisse/ovia coleothrypta zone of COSTA & 99 DOWNIE (1976). The base of the K. c. rotundata 1) The time-scale, and the correlation be zone of CHATEAUNEUF & GRUAS-CAVAGNETTO tween the P Zone and NP Zones are taken from (W7) lies withing the Wittering division, at the BERGGREN et al. (1985). Correlation between the base of Unit W14 at Bracklesham Bay (Sussex) Wetzeliellaceae (dinoflagellate) zones and these equivalent to the middle of Fisher's bed IV at zones are based on BERGGREN et al (1985), Whitecliff Bay (ISLAM, 1980). The position of modified by the relationships observed in the Zones W8 and W9 has not yet been identified. present study. The lowest horizon-in the Bracklesham Group The zonal schemas used on Figure 15 are to yield calcareous nannofossils is Fisher's bed IV taken from BERGGREN et al (1985). The dino at Bracklesham Bay, in the middle of the flagellate zonal scheme is based on the Wetzeliel Wittering division (CURRY et al., 1977). AUBRY laceae and is a combination of the schemas of (1983:60, 63, Figs. 17, 18) identifies Zone NP12 COSTA& DOWNIE (1976), and CHATEAUNEUF& at both localities, and probably a Iso the lower part GRUAS-CAVAGNETIO (1978). of Zone NP1 3 at Whitecliff Bay. 2) The stratigraphie breaks shown between The next level to yield an adequate assem the formations in Belgium are of arbitrary length, blage is the Numm/llites laevigatus bed (Unit E8) although as far as possible they conform to the in the Earnley Formation (middle of the Earnley available data. They are intended to indicate the division), which probably lies within the upper probable incompleteness of the section, as indi part of Zone NP14 (AUBRY, 1983: 71, 74). cated by the regional overstepping and trunca The Selsey division yields richer assemblages; tion, and the frequent intraformational reworking Zone NP15 is identified in Fisher's beds 19 and 20 of fossils. at Bracklesham Bay (Units S9 and S10 of CURRY et al., 1977) by AUBRY (1973:71) and at equiva 3) The correlations based on benthonic fora lent levels elsewhere by MARTINI (1971 :758) and miniferids, pteropods, dinoflagellates and cal HODSON & WEST (1970). The base of Zone NP16 careous nannoplankton produce concordant re is identified in Fisher's bed 21(= Unit S11) sults. (AUBRY, 1983:71 ). Samples from the stream-section at Studley ACKNOWLEDGEMENTS Wood, in the New Forest (Hampshire) are referred to Zone NP16 by AUBRY (1983: 71, Fig. 21 ). 8oth 1 wish to sincerely thank the Belgian Geolo the top of the Selsey division (bedA of STINTON, gical Survey, Brussels for the opportunity to 1970) and the base of the Huntingbridge division contribute to the study of the Knokke borehole, (beds B-D) are exposed here. lt is not clear from and for the help in the examination and sampling AUBRY's diagram which levels were sampled, but of the cores. according to D. CURRY (pers. comm.) beds A (sample 7), and 8 were sampled. Samples from the The late Willy WILLEMS (formerly Geological top of the Huntingbridge division at Alum Bay are lnstitute, R.U. Gent) provided much assistance in also referred to Zone NP16 (AUBRY, 1983:74). the study of Belgian stratigraphy and micro faunas, and without the basis of his extensive Barton Beds work, particularly on the Ieper Formation, the present study would have been very difficult. His The base of the Rhombodinium draco zone recent tragic death has deprived us of a much (W1 0) corresponds to the base of the Barton Beds respected colleague and friend. (the Nummulites prestwichianus bed) (BUJAK et al., 1980). The base of the R. porosum zone (W11) Dr. Dirk NOLF (Royal Natural History Museum, lies within the Middle Barton Beds. Brussels), Dr. Etienne STEURBAUT (Geological lnstitute, R.U. Gent) and Dr. Christian DUPUIS The Lower Barton Beds are referred to Zone (Faculté Polytechique de Mons) introduced the NP16, and the Middle and Upper Barton Beds to author to sorne classic Eocene localities in Zone NP1 7 (AUBRY, 1983:75). Belgium. Dr. Margaret COLLINSON (Dept. of Plant CONCLUSIONS Science, Birkbeck Collage, London) identified specimens of seeds. Dr. Robert KNOX (British Geological Survey, Keyworth) examined suspect The data summarised above, taken together ad ashes from the basal Ieper Formation. with the biostratigraphic and lithostratigraphic correlations discussed in previous sections, are Dennis CURRY (ltchenor, West Sussex) re synthesised in Figure 15. Thefollowingcomments viewed the manuscript and made useful sugges apply to this figure : tions for its improvement. 100 PLANKTON ZONES LITHOSTRATIGRAPHY 0 LLJ 0 <.!l ~----~----~------t------,---~------~------~ ..... cl: <:.: 1- DINOFLAGE HAMPSHIRE LONDON Vl BELGIUM ~ LLATES BASIN BASIN 40;-~~---+---4------~~,------4-r------~------~ Ma P15 l ;:: (part) Rhombodinium ~ UPPER NP17 porosum 1 :il .....~ (Wll) ~ :z: z ~ IBUISPUTTEN MBR. := MIDDLE := ~ <:.: c.: P14 ------~ l ;ii ;ii 1----1 Rhombodinium ê5 ------1----1 draao (WlOJ ..... 1 ZOMERGEM MBR. LOWER Fr -t P13 ..._ r-- - !;,ë 1- --- -~~ -- :....e_re~ :::e: URSEL HUNTINGBRIDGE êl MEMBER DIVISION NP16 cl:~L ---- -?- -?- -? P12 "J~' ASSE G:il LLJ MEMBER 45- LLJ :El z w. LLJ u artiaulata 0 ---- LLJ (W9) r WEMMEL SELSEY LLJ MEMBER ..J DIVISION 0 .....0 (higher units ::;;: not included on this chart P11 for lack of NP15 tl " data) => ""' 0 j l:B- -?-- -?- ""' ~ ~ "" K. aoleo Vl g .thrypta LEDE ~ .~ fasaiata FORMATION ~ 50- 1----1 5 (WB) liTliDilJJDI[ N:""laëvl- N ~ Q) cgatus P10 ...."' BRUSSELS EARNLEY b"L, - :.::"' FORMATION DIVISION NP14 1.. 1'Tu"rrit DEN HOORN -ella bd' Kisselovia 'Ca r Fig. 15.- Correlation of the Early and Middle Eocene successions in Belgium and southern England with the standard planktonic zonal sequences 101 REFERENCES sorne Eocene deposits in Belgium. Prof. Paper Serv. Géol. Belg.. 182: 53 pp. GLIBERT, M., 1933. Monographie de la faune malacologique du AUBRY, M.P., 1983. Biostratigraphie du Paléogène Epicontinentale de Bruxellien des environs de Bruxelles. Mem. Mus. roy. Hist. Nat. Belg., l'Europe du Nord-Ouest. Etude Fondée sur les nannofossiles calcaires. 53, 214 pp. Docum. Lab. Géol Lyon. 89, 317 pp. GRADSTEIN, F.M. & BERGGREN, W.A., 1981. Flysch-type aggluti BERGGREN, W.A., KENT, L. & FLYNN, J.J., 1985. Paleogene geo nating foraminifera and the Maestrichtian to Paleogene history of the chronology and biostratigraphy in SNELLING (ed.): Geochronology and Labrador and North Seas. Mar. Micropaleont., 6: 211-268. the Geological Record. Geol. Soc. London, Memoir 10. GULINCK, M., 1969. Le Sondage de Kallo (au Nord-Ouest d'Anvers). BIGG, P.J., 1982. Eocene planktonic foraminifera and calcareous Mém. Exp/. Cartes Géol. et Min. de la Belgique, 11 : 42 pp. nannoplankton of the Paris Basin and Belgium. Rev. Micropaléont., 25: HASKINS, C.W., 1968-1971. Tertiary Ostracoda from the Isle of Wight 69-89. and Sarton, Hampshire (7 parts). Rev. Micropaléont., 10-13. BIGNOT, G. & LEZAUD, L., 1969. Sur la présence de Marthasterites HAY, W. & MOHLER, H.P., 1967. Calcareous nannoplankton from Early tribrachiatus dans I'Yprésien du Bassin anglo-franco-belge. Rev. Tertiary rocks at Pont-Labau, France and Paleocene-Early Eocene Micropaléont., 12: 119-122. correlations. JI. Paleont., 41 : 1505-154. BUJAK, J.P ., DOWNIE, C., EATON, G.L. & WILLIAMS, G.L., 1980. Di HEIN, J.R. et al.. 1978. Diagenesis of Late Cenozoic diatomaceous noflagellate cysts and acritarchs from the Eocene of southern England. sediments and formation of the bottom simulating reflector in the Spec. Pap. Palaeont., 24. southern Bering Sea. Sedimentology, 25: 155-181. CHATEAUNEUF, J.J., 19ao. Palynostratigraphie et paléoclimatologie HODSON, F. & WEST, I.M., 1970. Calcareous nannoplankton from an de I'Eocène supérieur et de l'Oligocène du Bassin de Paris (France). Upper Bracklesham horizon at Fawley, Hampshire. Rev. Micropaléont., Mém. Bur. Rech. géol minier., 116, 360 pp. 13: 165-187. CHATEAUNEUF, J.J.& GRUAS-CAVAGNETTO, C., 1978. Les zones de HOOYBERGHS, H.J.F., 1983a. Contribution to the study of Planktonic Wetzeliellaceae (Dinophyceae) du Bassin de Paris, Bull. B.R.G.M. (IV). Foraminifera in the Belgian Tertiary. Aard Meded., 2: 1-129. No 2 : 59-93. HOOYBERGHS, H.J.F., 1983b. Middle Eocene planktonic foramil)ifera COLLINSON, M.E., FOWLER, K. & BOULTER, M.C., 1981. Floristic recorded from the Brussels Sands Formation at H11acht (Belgium). changes indicate a cooling climate in the Eocene of Southern England. Tertiary Res., 5: 9-24. Nature, 291: 315-317. HOOYBERGHS, H.J.F., 1984a. Planktonic foraminifera from the COSS MANN, M., 1886-1913. Catalogue illustré des coquilles fossiles Wemmel Sands Member of the Asse Formation at Strombeek Bever de I'Eocène des environs de Paris. Ann. Soc. r. malacol. Belg.: 21-39. (Belgium). Tertiary Res., 6 : 93-106. COSSMAN, M. & PISSARRO, G., 1904-1913. Iconographie complète HOOYBERGHS, H.J.F., 1984b. Planktonic foraminifera from the Lede des coquilles fossiles de I'Eocène des environs de Paris. 2 vol. Paris. Sands Formation at Balegem. Tertiary Res .. 6: 165-175. COSTA, L. & DOWNIE, C., 1976. The distribution of the dinoflagellate HUGHES, M.J., 1981. Contribution on the Oligocene and Eocene Wetzeliella in the Palaeogene of North-Western Europe. Palaeontology, microfaunes of the southern North Sea: 186-204, in J.W. NEALE & 19 : 591-614. M.D. BRASIER (Eds.): Microfossils from Recent and Fossil Shelf Seas CURRY, 0., 1942. The Eocene succession at Afton brickyard, I.O.W. (Chichester : Ellis Horwood Ltd.). Proc. Geol. Ass., 53:88-101. ISLAM, M.A., 1981. Early and Middle Eocene organic microplankton of CURRY, 0., 1965. The English Palaeogene Pteropods. Proc. ma/ac. the Anglo-Belgian Basins. Unpublished Ph. O. Thesis. University of Soc. Land.. 36: 357-371. Sheffield. CURRY, 0., 1967. Problems of correlation in the Anglo-Paris-Belgian ISLAM, M.A., 1982. Dinoflagellate age of the boundary between Ieper basin. Proc. Geol. Ass., 77: 437-467. and Panisel Formations (Early Eocene) at Egem, Belgium, and its significance. N. Jb. Paliiont. Mh. H .. 8: 485-490. CURRY, O. et al.. 1978. A correlation of Tertiary rocks in the British Isles. Geol. Soc. London Special Report No. 12, 72 pp. JACOBS, P., 1978. Litostratigrafie van het Boven-Eoceen en van het Onder-Oiigoceen in Noordwest-België. Prof. Paper Serv. Géol. Belg., CURRY, 0., KING, A.D., KING, C. & STINTON, F.C., 1977. The 151 :93 pp. Bracklesham Beds (Eocene) of Bracklesham Bay and Selsey, Sussex. Proc. Geol. Ass.. 88: 243-254. JANSSEN, A.W. & KING, C. (in press). Pteropod zonation: Tertiary North Sea Basin in Final Report of Project 124, the NW European DE CONINCK, J., 1975. Microfossiles à paroi organique de I'Yprésien Tertiary basin (Hannover : lnternation Geological Correlation Pro du bassin belge. Prof. PaperServ. GéolBelg., No. 1975/12.151 pp. gramme). DE CONINCK, J., 1976. Een afzettingshiaat tussen het leperiaan en JONES, T.R., 1857. A Monograph of the Tertiary Entomostraca of het Lutetian te Melle-Heusden. Natuurwet. Tijdschr., 57: 224-229. England. Palaeontogr. Soc. (Monogr.}, 69 pp. DE CONINCK, J., 1980. Espèces indicatrices de microfossiles à paroi JONES, T.R. & SHERBORN, C.D., 189. A supplementary Monograph of organique des dépôts de I'Yprésien supérieur et du Lutétien dans le the Tertiary Entomostraca of England. Pa/aeontogr. Soc. (Monogr.}, sondage de Kallo. Bull Soc. belge Géol., 89: 309-317. 55 pp. DE CONINCK, J., GEETS, S. & WILLEMS, W., 1983. The Mont-Heribu KAASSCHIETER, J.P.H., 1961. Foraminifera ofthe Eocene of Belgium. Member : Base of the Ieper Formation in the Belgian Basin. Tertiary Mem. lnst. r. Sei. nat. Belg., 147: 271 pp. Res .. 5 : 83-104. KEEN, M.C., 1978. The Tertiary : Palaeogene : in A Stratigraphical DE CONINCK, J. & NOLF, 0., 1978. Notes sur les couches de la base de index of British Ostracoda: 385-450 (Ed. R. BATE & E. ROBINSON). la Formation du Panisel entre Torhout et Tielt. Bull. Soc. belge Géol., Geol. J. Spec. Issue No. 8 (Seel House Press). 87: 171-178. KEIJ, A., 1957. Eocene and Oligocene Ostracoda of Belgium. Mem. DE GEYTER, G. & WILLEMS, W., 1982. Sponge Spicules from the lnst. r. Sei. nat. Belg., 136: 210 pp. Landen Formation in Belgium. Tertiary Res., 3: 153-160. KEIJ, A.J., 1969. Problematic calcareous microfossils from the Eocene of Belgium. Proc. Kon. Ned Akad Wet. Ser. 872: 4-13. DEPRET, M. & WILLEMS, W., 1983. A record in situ of Nummulites laevigatus (GRUGUIERE 1792) in sediments of Lutetian age in the area KEIJ, A.J., 1970. Taxonomy and stratigraphical distribution of Voort around Zeebruge (NW-Belgium) and its stratigraphical consequences. huyseniella (Problematica). Proc. Kon. Ned. Akad. Wet. Ser. B 72: 479- Tertiary Res., 5 : 25-37. 499. DUPUIS, C., DE CONINCK, J., GUERNET, C. & ROCHE, E., KEMP, O.J., KING, A. O., KING, C. & QUAYLE, W.J., 1979. Stratigraphy 1987. Biostratigraphic data- Ostracods and organic walled microfossils and Biota of the Elmore Formation (Huntingbridge division, Brack - of the Landen Formation and the base of the Ieper Formation in the lesham Group) at Lee-on-the-Soient, Hampshire. Tertiary Res., 2: 93- Knokke borehole (this volume). 103. GERITS, M., HOOYBERGHS, H. & VOETS, R., 1981. Quantitative KING, C., 1981. The stratigraphy of the London Clay and associated distribution and paleoecology of benthonic foraminifera recorded from deposits. 148 pp (Rotterdam : Brill). 102 KING. c .. 1983. Cainozoic micropalaeontological biostratigraphyofthe SHERBORN, C.D. & CHAPMAN, F., 1886. On sorne Microzoa from the North Sea. Rep. lnst. Geol. Sei. No. 82/7. 40 pp. London Clay exposed in the Drainage Works, Piccadilly, London 1885. KING, C.• 1984. The stratigraphy of the London Clay Formation and JI. R. Microscop. Soc. (2) 6: 736-763. Virginia Water Formation in the coastal sections of the Isle of Sheppey STEURBAUT, E., 1987. Calcareous nannoplankton assemblages (this (Kent, England). Tertiary Res.• 5: 121-160. volume). KNOX, R.W.O'B .• HARLAND, A. & KING, C.• 1983. Dinoflagellate cyst STINTON, F.C., 1970. Field Meeting in the New Forest, Hants: Report analysis of the basal London Clay of southern England. Newsl Stratigr. by the Director. Proc. Geol. Ass.• 81 : 269-274. 12: 71-74. WILLEMS, W., 1972. Problematic microfossils from the Ypres Forma KNOX, R.W. O'B. & MORTON, A., 1983. Stratigraphical distribution of tion of Belgium. Bull. Soc. belge Géol., Paléont., Hydrol, 81: 53-73. Early Paleogene pyroclastic deposits in the North Sea Basin. Proc. WILLEMS, W., 1973. Ostracoda from the Ieper Formation of the Kallo Yorkshire Geol. Soc.. 44: 255-363.3. weil (Belgium). Bull. Soc. belge Géol., Paléont.• Hydrol.• 82: 511-530. MARTINI, E., 1971. Standard Tertiary and Quaternary Calcareous WILLEMS, W., 1975. Microfossiles problématiques de I'Eocène moyen Nannoplankton zonation : 739-785; in A. FARINACCI (Ed.) Proceedings et supérieur du sondage de Kallo (Belgique). Rev. Micropaléont., 17 : JI Planktonic Conference Roma 1970 (Rome). 198-208. MOORKENS, T.L, 1975. Paleoekologische Bedeutung einiger Verge WILLEMS, W.. 1978. Ostrakoden van de leper-Formatie (Onder sellschaftungen von sandschaligen Foraminiferen aus dem NW Eoceen) in de boring van Tielt (Belgie). Biostratigrafische en Europaischen Alttertiiir und ihre Beziehung zu Muttergesteine. paleoekologische interpretatie en vergelijking met de leper-Formatie in Zeitschr. Erdol und Kohle, Erdgas. Petrochemie. Compendium: 75-95. de boring van Kallo. Natuurwet. Tijdschr .• 59 : 184-205. MULLER, C. & WILLEMS, W.,' 981. Nannoplankton en planktonische WILLEMS, W .• 1980. De foraminiferen van de leper-Formatie (Onder foraminiferen uit de leper-Formatie (Onder-Eoceen in Vlaanderen Eoceen) in het zuidelijk Nordzeebekken (Biostratigrafie, Paleoekologie, (Belg ie)). Natuurwet. Tijdschr .• 62 : 64-71 . Systematiek). Unpublished doctorate thesis, Rijksuniversiteit Gent, MURRAY. J.W., CURRY. 0., HAYNES. J.R. & KING, C., 1981. 222 p. Palaeogene: 228-267, in D.G. JENKINS & J.W. MURRAY (Eds.), WILLEMS. W .• 1982. Microfossil assemblages, zonations and plank Stratigraphical Atlas of Fossil Foraminifera (Chichester: Ellis Horwood tonic datum levels in the Ieper Formation (Ypresian s.s .• Early Eocene) Ltd). in Belgium. Prof. Paper Serv. Géol. Belg.. No. 194: 17 pp. MURRAY, J. & WRIGHT, C.A., 1974. Palaeogene Foraminiferida and WILLEMS, W., BIGNOT. G. & MOORKENS, T., 1981. •Ypresian• in palaeoecology, Hampshire and Paris Basins and the English Channel. POMEROL C. (Ed.) Stratotypes of Paleogene Stages. Bull. lnf. Geol. Spec. Pap. Palaeontology. 14: 171 pp. ': Bassin de Paris. Mém. Hors Ser. No. 2: 267-299. NOLF, O., 1972. Stratigraphie des Formations du Panisel et de Den WRIGLEY. A., 1949. Les opercules de serpulides de I'Eocène du Bassin Hoorn (Eocène Belge). Bull. Soc. belge Géol. Paléont.• Hydrol. 81 : 75- de Paris. Bull geol. Soc. Fr., 19 : 499-504. 94. WRIGLEY, A., 1954. Sorne Eocene serpulids. Proc. Geol. Ass.• 62: PLINT, A.G .• 1983. Facies. environments and sedimentary facies in the 177-202. Middle Eocene, Bracklesham Formation of the Hampshire Basin. Evidence for global sea-level changes?. Sedimentology, 30: 625-653. 103 Chapter VIII TOP OCCURRENCE OF SELECTED DINOPHYCEAE FROM THE CRETACEOUS OF THE DE HAAN WELL AND CORRELATION WITH THE KNOKKE WELL by S. LOUWYE ,, 1. W.O.N.L.-aspirant Laboratorium voor Paleontologie, Geologisch lnstituut, Rijksuniversiteit Gent The De Haan weil (Klemskerke, 22 W-27611b) is CLARKE & VERDIER (1967), FOUCHER (1979, located in the extreme northwest of Belgium, 5 km 1980), WILLIAMS & BUJAK (1985) and WILSON northeast of Ostend (coordinates x= 54.582, y= (1971, 1974). 216.649, z= +5.02 m). lt was drilled on behalf of 73 Dinophyceae species with Cretaceous and the Belgian Geological Survey. The percussion post-Cretaceous range have been recorded. Top drilled weil penetrated 41,5 m of Quaternary sample - 227,0 m yields Hystrichosphaeropsis sediments, 185,5m of Tertiary sediments, 72,5 m ovum DEFLANDRE 1935, Acanthaulax saetosa in of Mesozoic and 22,0 m of cored Palaeozoic WILSON 1974 and Membranilarnacia hapala in sediments and stopped at a depth of -321 ,0 m. The WILSON 1974. ln the Knokke weil they are not Mesozoic sediments consist of 68,5 m of white fou nd above - 376,8 m depth. This means that the chalk interbedded with flint horizons (from - top sequence of the Cretaceous interval in the De 226,5 m to - 295,0 m) and 4 m of glauconiferous Haan weil has an Early Campanian or older age. sandy chalk (from -295,0 m to - 299,0 m). The Other evidence is given by FOUCHER (1985) who Cretaceous interval is overlain by Lower Tertiary has found that Acanthaulax saetosa is limited to sand and rests unconformably on Lower Palaeo the Vaals Formation in the Maastricht area (Early zoic shales. Campanian). Canningia cf. colliveri COOKSON & 10 ditch-cutted samples from the Cretaceous EISENACK 1960 has its top occurrence in sample- interval have been analyzed for palynological 234,0 m. This allows a fairly good correlation with investigation. They were prepared using standard level - 382,5 m of the Knokke reference section maceration methods (WILSON, 1971 ). One sam (middle Early Campanian). Spongodinium deli pie was barren (- 258,0 m), seven yielded weil tiense (EHRENBERG 1838), Senoniasphaera pro preserved, rich and diversified assemblages trusa CLARKE & VERDIER 1967 and Hetero -227,0m, ~234,0m, -242,0m, -250,0m, -266,0m, sphaeridium heteracanthum (DEFLANDRE & -278,0 m, -286,0 m). The two lowermost ones COOKSON 1955) (samples -250,0 m, -266,0 m presented weil preserved but less diverse assem and -278,0 m) are abundant and a Iso indicate an blages (-294,0 m and -298,0 m). The associations Early Campa ni an age. The two lowermost samples were furthermore characterized by a great a mount (- 294,0 m and -298,0 m) yielded only poor to of palynodebris. During the investigation, moderate preserved ass.emblages among which emphasis was laid on Dinophyceae. The top Rhiptocorys veligera (DEFLANDRE 1937), Oligo occurrence of sorne selected Dinophyceae is given sphaeridium complex (WHITE 1842), Callaio in fig. 1. These top occurrences togettier with the sphaeridium asymmetricum (DEFLANDRE & assemblages are referred to the weil known COURTEVILLE 1939), Cometodinium whitei (DE reference section of the Knokke weil ( 11 E-13811d), FLANDRE & COURTEVILLE 1939), Sentusidinium situated 25 km more to the NE along the coast. aff. eisenackii (BOLTENHAGEN 1977) and Surcu Additional data concerning stratigraphical losphaeridium spinacongregatum YUN 1981. S. distribution of Dinophyceae is obtained from spinacongregatum allows an unequivocal corre- _. ~ VI n r-l )>o )>o ~ )> r- z :1: r- m,.. mo .... 0 ::oo 1 0 ~ 0 ~ ~ z m CHRONOSTRATIGRAPHV ~ ~ 0 -1 N m ~ ~ ~ 1 - , - 0 0 ::0 )>o ;;:: ::0 ::0::0 -t ,.... z -o ;:; z z -< :I: ·,.... 0 -t 'N -o o :1: N :1: (') w ~ , ~ < (') ai ~ DEPTH IN m ;;:f;: 1 (') c -i -fi!i:=!,...... ,"""f,.:..,~N-,...or ....~~N~NN~N ~ Z N rrJ ::0 ~~ ...... ~ .... ~ .... ~~ .... ~~..... ~ ...... ~ ~ 0 '-l )> ::0 -Iii~~ ...... ~1'"4,..., ~ A en rn rn ...... ,...... ,.... l ~ 1KNOKKE REFERENCE A t::l "11 Z .. ~ ...... ~ ...... ~ ,...,~lo.,j ...... ,.., ...... • ~ SECTION , ~ ::0 (') ~~~ ..... ,.., ...... ~~~~ .... ~ ...... ~ A <. )> 0 , -1 .'!'•. : ...... N N N ...... N ...... ,...... ,...., ..... N ...... ,...._ < z ~ 0 ù : ~ 0 -t ., 1 ,.... (') :I: l/) 1 - 0 , , 1 :::: :::0 0 ,.... ~ , ::0 , , -t ~-fi'H.Jill H H H H H~~ H ~P,I H H H H H ...., M -...( H HH.--,.-r.:.:t:: ;.. :,.:·: , (') -1 -:1~-tH 1;1 H t-1 t-t H H 1-f t-a H t-(~ H H H H H ..._. H 1-1 H H H 1-t H:::.:::·:: ..!... ,... :I: -1 -l-t -1 'i.._,.H H H 1-1 1-t H t-t ~ H H"~ t-t 1-C H H H H H H H H H. H H ;·:~·~:·:;: LITHOLOGV w l> l> m -1_.~.._..., t-tH H HHI-I H H H+"'H 1-C HHHHH H HHHHH.~:::.::·: CD -t )> 0 DE HAAN WELL t::l 0 z -4~ 1111-1 'il ~ 1-4 1-1 H H H hl H H'~ H H H H ...., H H 1-1 H H ._j H ..._. Y.:~i:~i -1 -1-11-f!H .... 1-1 H H ~H....., H ._~_bl_t-!id H ..._. ~-.~H H..,.. H•J_H H_!.·:'.l·;: e z N ..!, . --~-.-- ~ ,.l ,_:, ..:, ..:, ~ N N N =~:;: : ~ ~::; ~:::: 0 DEPTH SAMPLES IN m Oligosphaeridium complex (WHITE 1042) Rhiptocorys veligera (OEFLANDRE 1937) Surculosphaeridium spinicongregatum YUN 1981 Callaiosphaeridium asymmetricum (DEPLANDRE & COURTEVILLE 1939) Cometodinium whitei (DEFLANDRE & COURTEVILLE 1939) Sentusidinium aff. eisenackii (BOLTENHAGEN 1977) Exochosphaeridium? palmatum (DEFLANDRE & COURTEVILLE 1939) Heterosphaeridium heteracanthum (DEFJ.ANDRE & COOKSON 1955) Senoniasphaera protrusa CLARKE & VERDIER 1967 Spongodinium delitiense (EIIRENBERG 1838) Canningia cf~ colliveri COOKSON & EISENACK 1960 Acanthaulax saetosa !2 WILSON 1974 Hystrichosphaeropsis ovum DEFLANDRE 1935 Membranilarnacia hapala !2 WILSON 1974 105 lation with level - 431 ,6 m of the Knokke reference FOUCHER, 1979. Distribution stratigraphique des kystes de dina section (Santonian). flagellés et des acritarches dans le Crétacé Supérieur du Bassin de Paris et de l'Europe septentrionale, Palaeontographica, Àbt. B, 169, Lfg. 1-3: To summarize we can conclude that the 78-1 O!::i, Stuttgart, Miirz 1979. distribution of dinoflagellate cysts give biostra FOUCHER, 1980. Synthèse biostratigraphique de I'Aptien au Santo tigraphical evidence for an Early Campanian age nien du Boulonais à partir de sept groupes paléontologiques: foraminifères, nannoplancton, dinoflagellés et macrofaunes. ln for the chalk interval (- 226,5 m to- 295,0 m) and a ROBASZINSKY, F et AMEDRO, F. coord., Revue de Micropaléontologie, Santonian age for the glauconiferous sandy chalk 22, (4), Mars 1980. interval (- 295,0 m to - 299,0 m) in the De Haan FOUCHER, 1985. The Campanian-Maastrichtian boundary in the weil. chalky facies close to the type-Maastrichtian area.ln ROBASZINSKY, F. et al., Bull. Centres Rech. Explor.-Prod. Elf Aquitaine 9 (1): 1-113,35 fig., 22 pl., Pau, June 28 1985. WILLIAMS & BUJAK, 1985. Mesozoic and Cenozoic dinoflagellates./n REFERENCES Plankton stratigraphy, BOLLI et al., Cambridge University Press, 1032 pp. CLARKE & VERDIER, 1967. An investigation of microplancton WILSON, 1971. A Chfi!mical method for the palynological processing of assemblages from the Chalk of the Isle of Wight, England, chalk, The Mercian Geologist, 4 (1): 29-36. Verhandelingen der Koninklijke Nederlandse Akademie der Weten WILSON, 1974. Upper Campanian and Maastrichtian dinoflagellate schappen, Afdeling Natuurkunde, Eerste reeks, 24: 1-96, pl. 1-17. 1: cysts from the Maastricht region and Denmark, Unpubl. PhD thesis. LEGE ND . II Il chalk [23). sand ~ sandstone IZZI indurated chalk ITTI shale ~ bioclasts El flint bed luul glauconite 107 Chapter IX THE CORRELATION OF THE KNOKKE, DEN HAAN AND OOSTDUINKERKE WELLS by P. LAGA, N. VANDENBERGHE, J. HERMAN & J. BACCAERT Belgische Geologische Dienst, Brussel 1. THE WELLLOG STRATIGRAPHY 223-297 m : Upper Cretaceous chalk - The upper part is tentatively put equivalent with A. THE KNOKKE WELL. the Maisières chalk and the lower part with the Fortes Toises; both lithounits belong to the The Knokke weil stratigraphy is discussed in Upper Turonian. chapter 1 and further elaborated in the chapters V, The presence of Campanian towards the top VI and VIl. however is not excluded. On fig. 1 the geophysicallog data ofthe Knokke weil are represented.They include natural total 297-321 m: Revinian quartzic slates (Oisquerèq) gamma rays, resistivity, bulk density and acoustic - The top of which is altered to a reddish clay. transit time corrected with seismic check shots. The different lithological and stratigraphical units defined in the preceding chapters cana Iso be C. THE OOSTDUINKERKE WELL. on the base of the geophysical weil log data as shown on fig. 1. Based on the lithological description by J. BACCAERT and J. HERMAN (Belgian Geological B. THE DEN HAAN WELL. Surveyfiles 35E/142)andon geophysicallogs(fig. 3), the following stratigraphie sequence is The following stratigraphie sequence was established: established based on the cuttings and the cores (304,30-321 m) (for details, see Belgian Geolo 0-27 m : Holocene and Pleistocene gical Survey files 22W/276} and based on geophysical logs (fig. 2): 27-138,5 m : Ieper clay 138,5-180 m : Landen Formation - 138,5-154,5 m : fossiliferous sands, silts and 0-41 m : Holocene and Pleistocene clay 41 -193 m : Ieper Formation - 154,5-180 m : silty clay, glauconiferous - sandy clays and sands occur down to 43,5 m 180-264,45 m : Upper Cretaceous chalk (cored - silty clay occurs down to 56 m 253,80 m) - heavy clay occur from 60 m downwards - the main chalk mass is associated with the Upper Turonian Maisières chalk and Fortes Toises 193-223 m : Landen Formation - the Lower Turonian glauconitic Dieves are fou nd - 193-208,5 m : fossiliferous sands with two between ± 250,5 and± 262,40 m. important clay intervals ± 250,5-259,20 m : with Terabratula rigida and - 208,5-223 m : silty and fine sandy clay, lnoceramus labiatus glauconiferous 259,20 - ± 262,40 m : with Actinomax plenus 108 KNOKKE 11E nr. 138 gr. levet : • 4,9 m 00 depth O- in meter below . groundlevel - 50- 100- 150- 200- 250- 1-z w 300- m ca :t z 0 0 w 350- ....1 400- -oo mv 20 9 GAPI Q._~2----'J\"'""'m ___2ql0_. 240 INTERVAL TRANSIT TIME 4 1i0 L.------mTcï:OSëëciiiifs-tïërfiïôf" ______.....J SP GR SFLU 1 5 BULK OEN SITY ? gramms/cc Fig. 1.- The geophysical logs of the Knokke weil, with their stratigraphie interpretation. 109 DE HAAN 22W nr. 276 gr. level: + 5,02 m 00 0-· depth in meter >a:: ~ a:: below w groundlevel ~ ::::l 0 50- 100- z 0 1- <{ ~ a:: 0 lL a:: w c... w 150- z 200- - z 0 w ;::: 0 <{ z ~ <{ a:: ...J 0 lL (/) ::::l 0 250- w u <{ 1- w a:: u a:: w c... c... ::::l 300- z <{ z 1-z 0 w 0 ~ i,Ocm w ...J ~ <{ <{ u al Fig. 2.- The geophysical logs of the Den Haan weil, with their stratigraphie interpretation. 110 OOSTDUINKERKE 35 E or 142 > gr: level: + 6,55m 00. a: <( 0- z depth a: in meter w ~ ::J below 0 groundlevel 50- z Q 1- <( ~ a: 0 LL. a: 100- w a. w - - - continental faci 150- z z 0 --- w 0 ~ z ~ marine <( a: ...J 0 LL. 200- tl) ::J 0 w u <( 1- UJ a: u a: w a. a. ::J 250- 100 mV 0 20 4Mm 45cm 0 100cps SP RES ln= 100 cm .__C~A-L...... ~...... ,G:':R::::--....___. Fig. 3.- The geophysical logs of the Oostduinkerke weil, with their stratigraphie interpretation. DEPANNE KOKSIJDE NIEUWPOORT MIDDELKERKE OOSTENDE BREDENE DE HAAN BLANKENBERGE ZEEBRUGGE KNOKKE 16 5 123 142 94 118 10 121 120 181 198 41 112 70 98 221276 6070 53 33 46 30 98 88 170 160 95 48138 0~ ~ f2l ~ 50- 100- 150- marine sitt. clay- 200• 250c 300- 3SOJ r-:;H SEA De Haan Brede~76w22W shist ~eloy PM0 sandy eloy j Oostende ~'- M.ddelkerkE>. 400j 1 .L .L .L cholk ~"C" shelts I::I:: colcoreous sondstone N.euwpoort BELGIUM loyer KOkSijde •142-3SE '1:~\!i:';~:.~{j sand DePanne phosphates - peot 450j UF~R~:L;------21W 35W 3SE 36W MIDDEL- 21E 22W IOW IGE 11W liE DE PANNE 1 OOSTDUINKERKE 1 NIEUWPOORT 1 KERKE 1 OOSTENDE DE HAAN 1 BLANKENBERGE 1 HEIST 1 WESTKAPELLE 0 5km Fig. 4.- Geological cross section along the Belgian coast. ...... 112 TIME 1 DEPTH curve 262,40-264,45 rn: paleconglomerate, containing DEPTH from SRO (m) quartzite pebbles with empty o œ zoo JOO TWO-WAV o+-~--'--~--'--~---'--~-'---'-- pyrite cubes, slate fragments; TRAVEL liME quartz slates, dolerite; with (ms) glauconite and lime; with shell fragments, a.o. Pecten. 100 lt is equivalent ofthe Cenoma nian base conglomerate (Pec ten) (Sarrasin de Bellignies) 200 - (MARLIERE, 1954, - 424- 425). 264,45 at the top: slightly altered (a.o. red clay - lOO 270,30 rn fillings), quartz-states with a tectonic breccia at 269 m. B,ased on LEGRAND (1968), this rocks are associated with the Salmian. "' Fig. 5.- Time (TWT)-depth (Stratigraphie Reference Datum) curve as measured in the Knokke weil, based on sonic log data and check shots. pp;;;; ...... - - . ( :«<< ))),H) ((\.((( ( (( (( H.hH TEPER .. Llt/U )}) )) <« -base ~ ·Fnrml -"- -"- 1 'lill 1 1 NORMAL REVERSE NORMAL REVERSE ZERO PHASE ZERO PHASE MIN. PHASE MIN. PHASE Fig. 6.- Synthetic seismograms constructed from log data in the Knokke weil, 45 Hz signal, (Schlumberger). 113 , m 2. THE CORRELATION m"' "' " ... ------·-· -··- i A comparison of fig s. 1, 2, 3 shows that the ~ different lithological units can easily be correlated 1l between the three wells, based on the response of ~ -~4- SP, gamma ray and resistivity logs. ln the Ieper Formation, the gamma ray log can --s . ·:.:. .-a- ... -·-·------be subdivided into different subunits, which are apparently consistent between the three wells. 0 The Landen Formation has a very different ··------·-·------g geophysical response for the marine rather homogeneous silts or silty clays, and on the other ha nd for the brackish fossiliferous sands and clays above. Hence the thinning and the disappearance of the marine unit to the northeast can easily be followed. Whilst the chalk in the Knokke weil does not show appreciable variations in its geophysical response, the variations in both other wells are significant and can probably be correlated as shown on figs. 2 and 3. There seems to,be little doubt that in the Oostduinkerke weil an important partis of Turonian age. This is a Iso thought for the Den Haan weil, although at Oostende the main part of the chalk is attributed to the Campanian Nouvelles chalk (HALET, 1939, file 21 E/1 22) and only a few m at the base is thought to be Turonian by HALET (1921 ). According to LOUWYE (this volume) no Turonian is fou nd in the Den Haan weil but the lowermost4 m ofthechalk in the Den Haan weil are Santonian in age. Although cutting samples have not been analysed for solving this stratigraphie question, it is clear from the work of BAL and VERBEEK (chapter VI) that the Turonian is lacking in Knokke and he nee the northern boundary of the Turonian sea, formed by a relative high in the Brabant Massif (MARLIERE 1954, p. 420) was probably located around Den Haan. After the Turonian the area north of Den Haan has started to subside relative to the southern a rea were Turonian had been deposited before. "'--A "' ln fig. 4 a geological cross section along coast is given incorporating older data kept in the BGS files, partly published together with the new data presented in this volume. The profile represents the Tertiary and the Mesozoic. The numbers refer to the wells in the BGS files. ------:·tJ'... ~ ___ , Fig, 7.- Synthetic seismograms constructed from log data in ""'1 '~·( the Knokke weil, high frequence speaker signal (EnTee ~~lill Energy Consultants), Arrows refer to table L 114 Table 1.- The correspondance between the major changes in sonic behaviour, the lithostratigraphic changes and the ir time depth relationship. The number of the prominent sonic features corresponds to the arrow numbers on fig. 7. Arrow nr. litholoeical m7aning depth from core TilT comments {prominent below sonic fe at ure) ~1SL msec. sandstone layer in Panisel 92m 105.96 formation 2 sandstone layer in Panisel 94m 108.19 formation no core recovery top of a sandy interval 105m 120.45 not very outspoken litholoe;ical wi thout sandstone con boundary cretions sandstone at the top of a 116m 132.70 coarse sand interval 6 base of the coarse interval 12h, 35m 141.50 in fact the base of the coarse inter val gradually becomes finer to the base, starting from 121m downwards till 124,35m ; this picture fits also the eamma ray re.s"Ponse 1 top of the heavy clay (P1m) 133m 150.48 interval 8 base of the heavy clay (P1m) 135,20m 153.26 interva.l 9 sandstone layer in sandy 143, 75m 163.10 probably a cornbination of sandstone Ieper formation top levels at 143,75m and sorne 30-40m above this level 10 top of the heavy clay 144m 163.32 the sanie kick between 145 and 146,50m Ieper formation is not explained neither by the cores nor by other logs 11 base of the heavy clay 282,30m 326.32 Ieper formation 12 base of the silty basal 288 ,60m 332.87 according to the drillina report a clay of the Ieper formation sandstone layer occurs below this level, in the top of the Landen formation 13 top of a clay interval in 297, 15m the Landen formation 14 fossil debris layer, compact 299, 1Om (Sparnacien type) about 12cm thiel\ 15 lithified fossil' debris 303m 346.92 layer 16 sandy interval in Landen 306m formation 308m 17 top of chalk 311m 354.63 silex level in the chalk 312,65m 355.47 19 hardground 321, 50m 362.76 it is difficult ta precisely locate hard 321 ,80m grounds in a core ; sanie transit times describe well porosity chânges and bence hardgrounds 20 hardground top 21 hardground 22 silex possibly 23 harde;round top 24 hardground possibly 25 coarser granular chalk top 419rn 442.76 rather a gradual event 26 phosphatic, giauconitic base 429,30m 450.57 rather a gradual event of the Cretaceous (top) 21 top Paleozoic (top) 432,05m the Paleozoic sequence is a hard rock sequence 115 3. THE USE OF THE KNOKKE BOREHOLE C. THE SYNTHETIC SEISMOGRAM WITH A DATA TO CALIBRATE SEISMIC WORK IN SPARKER INPUT SIGNAL. THE AREA Usi ng the sa me set of reflectivity coefficients as A. THE TIME-DEPTH FUNCTION. discussed under b, a sparker seismic source signal with a frequency range of 300-1000 Hz was used The sonic log combined with the sei smic check for the convolution. MSL was used as reference shots at the Knokke weJI have allowed to establish levet for the seismic section produced. at depth-time function graphically represented on The resulting seismogram is shown on fig. 7 fig. 5. This function allows the calculation of (produced by EnTee Energy Consultants). The depths from seismic time data and vice versa. arrows point to important kicks on the sanie log which are Jithostratigraphically interpreted in B. THE GEOGRAM FOR SIMPLE INPUT tabel 1. ft may be noticed that several of the WAVELETS AT LOW FREQUENCY (45Hz). lithological contrasts seen on the sonic log The combination of density · and corrected (arrows) have indeed a corresponding reflector velocity values for ~the different lithologies in the response. Several other reflectors do occur and Knokke weil allows to calculate acoustic impe can be checked for their significance through the dances for a sequence of intervals and a series of time-depth conversion and the comparison with reflectivity coefficients at these interval bound lithocolumn given in fig. 1 of chapter 1. aries. Using the time-depth function, the depth scale (in meters) can be converted into the time domain (in msec.). Nowa chosen seismic wavelet REFERENCES can be convolved with the reflectivity series, to HALET, F., 1921. Coupe géologique du littoral belge entre Bray-Dunes simulate a seismic section. (France) et Knokke. (unpublished) On figure 6,four such seismograms are shown LEGRAND, R., 1968. Le Massif du Brabant. Toel. Verh. Geai. Kaart en Mijnkaart van België, nr. 9, 148 pp. (produced by SCHLUMBERGER) with an interpre MARLIERE, R., 1954. Le Crétacé. ln: P. FOUR MARIER, Prodrome d'une tation of the most important reflectors. They have description géologique de la Belgique, Soc. Géol. Belg., Liège: 417-444. been calculated using simple 45Hz wavelets. 117 REFERENCE LIST OF PAPERS LAGA. P., VANDENBERGHE, N., HERMAN, J. & BACCAEIH, J., 1987. The correlation of the Knokke, Den Haan and Oostduinkerke PUBLISHED IN THIS VOLUME wells. ln: P. LAGA& N. VANDENBERGHE, The Knokke weil (11 E/138). With a description of the Den Haan (22W/276) and Oostduinkerke (35E/142) wells, 7 figs .• 1 table, Mém. Exp!. Cartes Géol Belgique/Toel. Verh. Geo/. België, 1990, N° 29, Ch. VI: 107-116. BAL, S.G.& VERBEEK,J.W., 1987. UpperCretaceousnannoplankton in LOUWYE, S., 1987. Top occurrence of selected Dinophyceae from the the Knokke weil. ln: P. LAGA & N. VANDENBERGHE, The Knokke weil Cretaceous of the Den Haan weil and correlation with the Knokke weil. (11 E/138). With a description of the Den Haan (22W/276) and ln: P.LAGA& N. VANDENBERGHE, The Knokke weil (11E/138). With a Oostduinkerke (35E/142) wells, 4 pp., 2 figs., Mém. Exp!. Cartes Géol description of the Den Haan (22W/276) and Oostduinkerke (35E/142) Belgique/Toel Verh. Geol. België, 1990, N° 29, Ch. VI: 63-66. wells, 3 pp., ;1 fig.,; Mém. Expl Cartes Géol Belgique/Toel. Verh. Geol. DUPUIS, C., DE CONINCK, J., GUERNET, C. & ROCHE, E., België, 1990, N° 29, Ch. VI: 103-106. 1987. Biostratigraphic data- Ostracods and organic walled microfossils MERCIER, M. & DUPUIS, Ch., 1987. Etude de la sédimentation - of the landen Formation and the base of the Ieper Formation in the argileuse Tertiaire du sondage de Knokke. ln: P. LAGA & N. Knokke borehole./n: P. LAGA & N. VANDENBERGHE, The Knokke weil VANDENBERGHE, The Knokke weil (11E/138). Withadescriptionofthe (11E/138). With a description of the Den Haan (22W/276) and Den Haan (22W/276) and Oostduinkerke (35E/142)wells, 5 pp., 3figs., Oostduinkerke (35E/142) wells, 13 pp., 5 figs., 1 table, 11 photographs, Mém. Exp/. Cartes Géol. Belgique/Toel. Verh. Geol België, 1990, N° 29, Mém. Exp/. Cartes Géol. Be/gique/Toel Verh. Geol België, 1990, N° 29, Ch. VI: 27-32. Ch. VI: 33-45. STEURBAUT, E., 1987. Calcareous nannoplankton assemblages from GEETS, S.& DEGEYTER, G., {987. Grain-size and heavyminerals of the the Tertiary in the Knokke borehole./n: P.LAGA&N.VANDENBERGHE, Tertiary strata in the Knokke weil. ln: P. LAGA& N. VANDENBERGHE, The Knokke weil (11 E/138). With a description of the Den Haan The Knokke weil (11 E/138). With a description of the Den Haan (22W/276) and Oostduinkerke (35E/142) wells, 16 pp., 2 tables, 54 (22W/276) and Oostduinkerke (35E/142) wells, 8 pp., 6 figs., 3 tables, photographs, Mém. Exp!. Cartes Géol. Belgique/Toel. Verh. Geol. Mém.Exp/. Cartes Géai. Be/gique/Toel Verh. GeolBelgië, 1990,N°29, België, 1990, N° 29, Ch. VI: 47-62. Ch. VI: 19-26. VANDENBERGHE, N., LAGA. P., HERMAN, G. & BACCAERT, J., KING, C., 1987. Eocene stratigraphy of the Knokke borehole (Belgium). 1987. lithological description of the Knokke weil. ln: P. LAGA& N. ln: P.LAGA& N. VANDENBERGHE, The Knokkeweii(11E/138). With a VANDENBERGHE, The Knokkeweii(11E/138). Withadescriptionofthe description of the Den Haan (22W/276) and Oostduinkerke (35E/142 Den Haan (22W/276) and Oostduinkerke (35E/142) wells, 9 pp., 1 fig., 7 wells, 15 figs., Mém. Expl Cartes Géol Belgique/Toel. Verh. Geo/. photographs, Mém. Exp/. Cartes Géol. Belgique/Toel. Verh. Geol. Be!gië, 1990, N° 29, Ch. VI: 67-102. België, 1990, N° 29, Ch. VI: 3-8.