Contr. Tert. Quatern. Geol. 34(3-4) 53-67 10 figs., 1 tab. Leiden, October 1997
Review of the lithostratigraphy of the Middle Eocene
in northern Belgium
Bart Fobe
GEOLOGISCH INSTITUUT
UNIVERSITEIT GENT
GENT, BELGIUM
Fobe, Bart. Review of the lithostratigraphy of the Middle Eocene in northern Belgium. — Contr. Tert. Quatern. Geol., 34(3-4): 53-67, 10
figs, 1 tab. Leiden, October 1997.
The lithology of Middle Eocene deposits, and that of stone layers in particular, was studied in subcrops in northwestern Belgium, allowing
the conclusions their be drawn. On of its brown the of the Pittem following regarding lithostratigraphy to account colour (lignite), upper part
Member (Gent Formation) has proved to often be a conspicuous key horizon. On the basis of a study of the geometry of the deposits in
various boreholes and of the sandstone facies it can now be confirmed that the Beemem Member (previously referred to the Aalter or
Knesselare formations) in fact belongs to the Vlierzele Formation. The Oedelem Formation(new name) consists of fossil-rich sand (Aalter
Member or Aalter sands on of which the which sand. sensu stricto) top rests Evergem Member (new name), comprises glauconitic In
borehole interpretations, this unit has been confused with the Vlierzele sand or with the Wemmel sand. Previous records of Lede Formation
strata in the area between Gent and the North Sea coast are here confirmed.
Key words — Eocene, Belgium, lithostratigraphy.
Fobe, Instituut, Universiteit B. dr. sc., Geologisch Gent, Krijgslaan 281 S8, B-9000 Gent, Belgium; and, Herentalsesteenweg 66, B-2220
Heist-op-den-Berg, Belgium.
Contents aspects of these. Stone layers in the Belgian Eocene often
show typical petrographic features, which makes them
useful in and correlations. Introduction p. 53 lithostratigraphic interpretations
studies have been made of the Lithostratigraphic framework p. 54 Comparable recently borehole lithostratigraphy of the Kallo 1988), Ursel- Study of sections and stone layers p. 55 (Fobe,
of stone 59 Maldegem (De Breuck et al., 1989), Mol, Oostham and Stratigraphy layers p. Kwaadmechelen Beerzel, Booischot and Discussion p. 62 (Fobe, 1989),
Rillaar boreholes. The stone facies recorded Conclusions p. 65 (Fobe, 1993a)
from boreholes with those in the Acknowledgements p. 66 were compared occurring in References 66 outcrop area northern Belgium. p.
Both calcite- and silica- (opal or chalcedony-)
cemented stone layers occur in the deposits studied. Their
Introduction origin will not be discussed in the present paper; the reader
is referred to Fobe (1990) for a discussion of silica-
This paper presents a new interpretation of the cemented sandstones and to Fobe (1986) for that of sandy
lithostratigraphy of Middle Eocene strata in the area limestones. between Antwerp and the North Sea coast (NW Belgium), Thin sections were stained following the method
where these deposits are almost exclusively known from described by Evamy (1963) in order to distinguish ferroan boreholes. from non-ferroan calcite. Whenever necessary, X-ray
In results here based part, presented are on a diffraction analysis (XRD) was used to check the
of cemented which petrographic investigation layers occur mineralogy.
in these with reference the lateral shows the location of the and deposits, particular to Figure 1 outcrops and vertical distribution of stone facies and their boreholes studied, while Fig. 2 gives the key to the
lithostratigraphic significance rather than to diagenetic lithology of all other figures, except Fig. 6. 54
(1988) to comprise the Merelbeke, Pittem and Vlierzele
the Gent Formation members. In the present study, use of
in which it follows Fobe's (1996) new definition,
comprises only the Merelbekeand Pittem members.
3 - Vlierzele Formation
Formation defined Steurbaut & Nolf The Vlierzele was by
(1986), who showed that in its type section, the Ursel-
Maldegem borehole, this unit comprised the Pittem sandy
clay and the Vlierzele sands (sensu stricto) of previous
authors. Fobe (1996) presented a new definition and
1. of northwestern Belgium and contiguous French Fig. Map excluded the Pittem sandy clay. In the area between Gent territory, showing the location of outcrops and boreholes and the North Sea coast, the Vlierzele Formation was
studied for the Abbreviations are as present paper. established in in described from and auxiliary stratotypes
follows: AA - Aalter, BA - Balegem, BE - Beerlegem, the Hijfte and Ursel-Maldegem boreholes. According to
EG - Egem, EV - Evergem, HY - Hijfte, KA - Kallo, KL formation has lower and Fobe (1996), the a sharp upper - Kluizen, KN - Knokke, KR - Kruibeke, MO - Mol, NK boundary and can be subdivided into five members, from
- - Nieuwkerke-Waas, OE - Oedelem, RI - Rillaar, UR bottom to top: Hijfte (gravel and sand), Lochristi (clayey Ursel, WA - Waarschoot, WI - Wippelgem, ZE - Oosterzele Beernem and Zeebrugge. sand), (sand), (clayey sand) Drongengoed (sand). When compared with the legend to
the the new geological map (Jacobs et al., 1993b),
Vlierzele Formation corresponds to the (undifferentiated)
Vlierzele Member. Fobe (1996) argued that the concept of
undifferentiated Vlierzele sand unit which an passes
downwards gradually into the Pittem Member (sandy clay)
used in the the lead as legend to geological map, may to
correlation errors. The validity of the Vlierzele Formation
as proposed by Fobe (1996) will be further discussed in the
present paper.
4 - Oedelem Formation
In the area between Gent and the North Sea coast, resting Fig. 2 Key to the lithological logs in Figs 3-5 and 7-10. sands on top of the Vlierzele are poorly exposed sands, Abbreviations used in these figures are as follows: Fm. - which were referred to as Paniselian' on the old Formation, Mbr. - Member, We - Wemmel Member, 'Upper
- 1:40 The name 'Aalter sands' B.N. - Bande Noire, EV - Evergem Member, AA Aalter geological map (scale 000).
- - introduced Leriche Member, DR Drongengoed Member, BE Beernem was by (1941).
Member, OO - Oosterzele Member, LO - Lochristi Nolf (1972) established the Den Hoorn Formation to
Member, HY - Hijfte Member, PI - Pittem Member, ME comprise the Oedelem and Aalter members, with the latter
- MerelbekeMember and EG - Member. Egem occurring in gullies incised into the former. Jacobs &
the Geets (1977) added the Beernem Member as
the Knesselare lowermost unit in what they defined as LITHOSTRATIGRAPHIC FRAMEWORK Formation, concluding that only the Oedelem Member
extended throughout nearly the entire area between Gent
1 - Ieper Formation and the North Sea coast. Jacobs & Geets (1977) described
the Aalter Member (corresponding to the Aalter sands s.
the studied in the of local at Aalter and Underlying stratigraphic sequence str.) as an infilling (i.e. Gent) gullies present paper is the Egem Member (sand) of the leper in the Oedelem Member. The areal extension of the
Formation of Early Eocene age. Beernem Member was limited to the region
south/southeast of Brugge, which means that the
Knesselare Formation mainly comprised only the Oedelem
2 - Gent Formation Member.
For a number of years now, the name Aalter Formation
The Gent Formation introduced Marechal & it is also used in the was by Laga has appeared in the literature; legend 55
Wemmelsand in the to the geological map (Jacobs et al., 1993a, b). The reason same area.
is that the The of the Lede Formation has been why the Knesselare Formation was abandoned presence recently
recorded Aalter & Nolf, and in the fossiliferous sands exposed in the Aalter type section and at (Steurbaut 1989) Breuck the Oedelem Member of boreholes north of Aalter were Ursel-Maldegem area (De et al., 1989).
assumed to be equivalent deposits (Jacobs et al., 1993a;
Maréchal, 1993). The Aalter Formation of the new
geological map (scale 1:50 000; Jacobs et al., 1993a, b) 7 - Maldegem Formation
comprises the Beemem and Oedelem members. However,
This unit referred Formation the Aalter Formation has never been defined formally (formerly to as Meetjesland consists of alternation of according to the guidelines for lithostratigraphic or Kallo Formation) an sandy & At its nomenclature (Hedberg, 1976). Occasionally, reference clay and clay deposits (Jacobs Sevens, 1988). the Asse Member clay), has been made to Steurbaut & Nolf's (1989) base, below (glauconitic sandy
comprehensive bio- and chronostratigraphic study of the occurs either a glauconitic sand, with upward-increasing
Aalter sands at the type locality. However, Steurbaut & clay content (Wemmel Member) or a glauconite-rich,
fossil-rich sand few Nolf (1989) did not provide a definitionnor a discussion of occasionally gravelly layer (a
of these did decimetres known the 'Bande Noire'. the lithostratigraphic position sands, nor they thick) as Brussels discuss their relationship with previously defined The Wemmel Member is known from the
and from the between Gent and the coast; the units, the Oedelem Member. area area lithostratigraphic e.g. latter is of interest in the On the Somewhat confusing also is the use of the facies name area present study. the Wemmel 'Aalter equivalent' as a part of the Aalter Formation, geological map (Jacobs et al., 1993b),
and, as is covering the Oedelem Member in boreholes in the North Member rests upon the Aalter Formation usual, overlain the Member. in the Sea (Jacobs & Sevens, 1993). in turn by Asse However, the Fobe (1996) proposed to reassign the Beemem Ursel-Maldegem boreholes, the lower part of
sands the Wemmel Member and probably also the basal part of the Oedelem glauconitic traditionally assigned to Formation Member (Drongengoed Member) to the Vlierzele Member have been correlated with the Lede on and evidence Breuck Formation, in view of the fact that the Beemem Member palaeontological petrographic (De et
this is discussed further. has also been encountered (as a sandy clay or clayey sand al., 1989). Below, problem
intercalation) outside the area designated by Jacobs et al.
confines of (1993b) on the geological map, but within the
LAYERS the Vlierzele Formation, and within the Vlierzele Member STUDY OF BOREHOLE SECTIONS AND STONE
considered to be of the geological map, there
undifferentiated.
definitionof the Oedelem Formation will be Sea coast A given A -Boreholes between Gent and the North
below.
Knokke
5 - Brussels Formation
Description — Total depth reached in the Knokke
located between = The main outcrop area of this formation is borehole (BGS 11 E 138; co-ordinates x = 78.776, y
it has been encountered in the Cambro- the Zenne and Gete rivers; 226.370, alt = + 5 m) was 433 m, ending in
the the Brussels reader is boreholes north of this area. In study area, Silurian basement. For a lithologic description the
Formation has only been recognised in the Kallo borehole referred to Vandenberghe et al. (1990). Under a cover of
(Fobe, 1988). Quaternary deposits (0-30 m) occurs the Eocene
(Maldegem Formation), with the base of the Asse Member
at 71.95 m. The section between 71.95 and 104.6 m
6 - Lede Formation consists of fine, sometimes clayey sand with glauconite,
shells and shell beds and stone layers (71.95-74 m
This formation is accessible outliers and hill and 79-104.6 mainly on Wemmel sands, 74-79 m Brussels Formation rivers. Its ridges between the Scheldt and Dijle presence m Oedelem Formation).
northern has also been confirmed in boreholes in Belgium. The interval between 104.6 and 124 m corresponds to
the old and new 124.75-124.2 Both on (1:40 000) (1:50 (XX)) the Vlierzele Formation ( sensu Fobe, 1996):
the Lede Formation 122-124.2 m Lochristi 116- geological maps (Jacobs et al., 1093b), m Hijfte Member, Member,
is absent in the between Gent and the in subcrops area 122 m Oosterzele Member, 108.5-116 m Beernem
North Sea On the 1:40 000 it is shown thin Member also coast. map to Member and 104.5-110 m Drongengoed (see
between the Vlierzele sands and the Asse few and the 'Mt Panisel out clay, a units 3 to 7 as described by King, 1990 the the Lede kilometres northwest of Gent. On new map, Formation' of the Knokke borehole).
the Oedelem sand and the sands pinch out between The sandy to silty clay between 124.75 and 133 m was 56
correlated with the Pittem Member, the clay between 133 loosely packed (35%), with 55% of opal matrix and about
stone with and 135 m with the Merelbeke Member and from 135 m, 10% of glauconite. Some layers are laminated,
alternation of and while the Egem Member. an sandy more opaline beds,
from the Oedelem others show mottled In the laminated Stone layers were sampled a texture. samples is concentrated in Formation (at depths of 92.8, 94.4 and 98.3 m), the (123.5 and 127.5 m), lignite fine-grained
Vlierzele Formation (at depths of 114.4, 117.2 and 124.2 layers. allowed the observation of well- m) and from the Pittem Member (at depths of 125.3, 127.5, An SEM analysis has
129.5,130.1and 131.5 m). shaped opal-CT lepispheres, which formed nearly the
whole cement. The size of the lepispheres is about 5 fm\.
— Within the calcite Petrography of stone layers Between 79 and 104.6 m lepispheres, blocky or platy fragments, remains of (Oedelem Formation), the coherent beds at depths of 92.8, 10-20 jum large, are found; these probably are framboidal 94.4 and 98.3 m are calcite cemented. They consist of 45% disintegrated calcareous skeletons. Some pyrite
with concretions have also been found. Most of of quartz, 45% of clear ferroan calcite cement some (7-10 fan large) others Some micritic inclusions, 5% of glauconite and 5% ofcalcareous them are spherical, elongated. blady clay was
fossils, mainly bivalve shells and foraminifera. found between opal-CT lepispheres.
The calcite-cemented beds in this interval are
comparable to sandy limestonesof the Oedelem Formation
in the Kallo borehole (BGS 27 E 148) between 200 and Oedelem
and in the 206 m depth (Fobe, 1988) Ursel-Maldegem
Breuck — Of this cored borehole 23 E 88, co- boreholes at a depth of 34.5 m (De et al„ 1989). Description (BGS
= ordinates = 77.185, = 208.902, alt + 10 no results The sandstone bed at 114.4 m is fine grained, opal-CT x y m),
with 40% of 50% of and have been in the cemented, some quartz, cement published yet; a preliminary description
10% of glauconite. The opal matrix is rich in calcareous files of the Belgian Geological Survey is as follows:
particles and contains a minor amount of small wood
fragments. 0-3 m Wemmel sand
The sandstone at 117.2 m is a coarse-grained opal- 3-23 m Oedelem sand
of 23-46 Vlierzele sand cemented concretion. The larger quartz grains (59%) are m
that of the sand. 46-53 Pittem a size comparable to surrounding m sandy clay Merelbeke Glauconite grains (8%) are mainly rounded. The cement 53-60 m clay
60-65 Sand matrix (33%) is quite pure, with only a minor amount of m Egem (final depth)
calcareous particles and pyrite. Sorting is poor and the
own matches this preliminary texture very heterogeneous. In places, the quartz grains are My interpretation largely
while elsewhere with fine very closely packed, pockets description:
sand and more cement are found.
Wemmel Member A scanning electron microscopy analysis (Philips SEM 0-3 m
3-23 Oedelem Formation 535, Philips-Eindhoven) has shown the cement of this m
concretion to consist also of typical opal-CT lepispheres, 23-44 m Vlierzele Formation
5-10 in size. 23-33 m Beernem Member
33-40 m Oosterzele Member The sandstone at 124.2 m is an opal-cemented
40-43 m Lochristi Member sandstone as well. Point-counting has shown this level to
43-44 Member contain about 26% of quartz grains, 38% of opal and 6% of m Hijfte Gent Formation glauconite. 44-60 m
46-53 m Pittem Member Between 124.75 and 133.0 m, sandstone beds occur in
53-60 Merelbeke Member sandy clay, brownish-grey in colour on account of the m
wood. the lowermost 60-65 m leper Formation, Egem Member (final depth) presence of fragments of Only metre
The sandstone beds in this is greenish grey in colour.
to sheet 13 of the geological section are cemented by opal. The opal matrix contains According (Brugge) map the Oedelem borehole is situated and calcareous silt The et al. 1993b), pyrite numerous particles. quartz (Jacobs ,
within the of the Beernem Member grains are poorly sorted. Glauconite grains are rounded to provenance area
lobate. Some calcareous fossils are present, mainly (Aalter Formation; see above). encountered of foraminifera and bivalve shell fragments. Siliceous fossils Stone layers were at depths 26.95, 27.6,
in 44.95 and 47.6 m. are scarce; small wood fragments, present all samples, 28.8, 34.4,
and do cell The sandstone beds — Stone layers from are opaque not preserve structures. Petrography of
27.6 and 28.8 m consist of fine sand sandstone bed at 129.5 m has yielded remains of a possible depths of 26.95, very
and silt, cemented The cement contains root structure, with the epidermal layer fairly well coarse by opal-CT. mouldsof preserved. calcareous particles and clay. A few mica plates,
refilled with and Point-counting has shown the quartz grains to be rather sponge spicules (empty or chalcedony) 57
small bivalve shell fragments have also been encountered the Vlierzele Formation, level 60.6 m containing wood in small amounts. The main composing elements are fragments) and from 72.25 and 79.0 m (opal-cemented quartz grains (50%), opal cement (40%) and glauconite sandstones of the Pittem Member). grains (10%). The sample from 27.6 m contains somewhat
than the other while that from 26.95 coarser quartz beds, m is laminated(quartz-opal alternations). Waarschoot
The stone layer at a depth of 34.4 m is coarser grained
= than those from the 26-29 m interval. The cement also In this borehole (BGS 39 E 48, x = 97.325, y 205.275, alt consists of opal-CT, and two size populations of quartz = + 8 m), calcareous sands, overlain by clays of Bartonian occur. The size of most of the grains is about 70-90 were encountered at a depth of 26 m. In the original pm, age, but a minor is coarser to about 150 Glauconite well description, these sands were assigned to the Lede group pm.
but limestone at 29.8 E grains (5%) belong to the larger size population. This Formation, a sandy sampled m (39
showed them to to the Oedelem sandstone leveloccurred in lignitic sand and is very rich in 48/15) belong Formation,
the facies of the being comparable to wood fragments, up to 2 mm in size. The texture is mottled petrographic sample
beds in the Knokke and quartz and cement are unevenly distributed. Wood stone (90-104 m), Ursel-Maldegem
and Kallo boreholes. fragments are found mainly in opal-rich patches. (34.5 m) (200-206 m)
Of the stone layers in the 44-53 m interval, the one at
44.95 m is also an opal-cemented sandstone with poorly sorted, bimodal quartz (around 100-400 but with a Wippelgem (Evergem) smaller fraction around 30-50 The sandstone contains
BGS 40 W 346 (co-ordinates x = 105.416, = 203.232, alt a few bivalve shell fragments, the matrix also yielding y
= + 6.7 m) is a cored borehole, the description of which is calcite particles and wood fragments. Glauconite grains
as follows (Jacobs & De Ceukelaire, 1992a): (10%) are strongly lobate and belong to the population of the coarsest quartz grains.
0-26.3 m Pleistocene The sandstone bed at 47.6 m is comparable in quartz and 26.3-36.65 m Maldegem Formation glauconite grain size to the bed at 44.95 m. Intense
26.3-29.9 m Asse Member bioturbation yielded a strongly mottled texture. A few burrow walls lined 29.9-36.65 m Wemmel Member are partially preserved; they are by a Member 36.6-44.7 m AalterFormation, Oedelem rim of opal. Remains of previously destroyed burrows are
44.7-60.0 m Gent Formation, Vlierzele Member preserved as opaline patches, of diameters up to 3 mm.
Generally, this sample contains less lignite and fewer calcite Samples of cemented layers at depths of 29.7 and 41.9 m fragments than the 44.95 m level and its cement both represent ferroan calcite-cemented beds, showing appears very pure. characteristics similar to that of the Oedelem Formation
facies in the Ursel-Maldegem, Kallo and Knokke
boreholes. In a preliminary interpretation (Jacobs & De Ursel-Maldegem cemented Ceukelaire, 1992a), the uppermost layer (29.7
m) is assigned to the Maldegem Formation. Of two boreholes, BGS 39 W 212 (co-ordinates x =
The from 32.6 m was identified as a = sample pyrite 87.910, y 204.260, alt = + 29 m) and BGS 39 W 213 (co-
concretion, which showed no further ordinates = particular x = 86.860, y = 205.900, alt + 21 m), detailed characteristics. descriptions were published by De Breuck et al. (1989).
The main subdivisions are (see also Fobe, 1996):
0-26 m Maldegem Formation Hijfte
24-29 m Lede Formation
Description — Of this cored borehole BGS 40 E 373 (co- 29-44 m Oedelem Formation
ordinates x = 111.130, = 200.390, alt = + 8 Jacobs & 44-69 m Vlierzele Formation y m),
De Ceukelaire a 69-84 m Gent Formation (1992b) presented preliminary description: 69-79 m Pittem Member
79-84 m Merelbeke Member
84-102 m leper Formation, Egem Member(final depth) 0-18.0 m Pleistocene
18.0-36.0 m Maldegem Formation
Stone levels have been studied from depths of 26 and 28.9 18.0-26.5 m Ursel Member m (sandy limestones of the Lede Formation), 34.5 m 26.5-28.2 m Asse Member
(Oedelem Formation, named Oedelem Member of the 28.2-36.0 m Wemmel Member
Knesselare Formation by De Breuck et al., 1989), 56.5 and 36.0-43.0 m AalterFormation, Oedelem Member
60.6 m (opal-cemented, medium-grained sandstones from 43.0-74.4 m Gent Formation 58
43.0-58.6 m Vlierzele Member B - Outcrop area
58.6-74.4 m Pittem Member
Member 74.7-77.0 m Tielt Formation, Egem (final
depth) Balegem
of the in the (co-ordinates x = 110.8, It has been argued (Fobe, 1996) that the upper part Exposed Balegem sandpit y the Vlierzele Formation Pittem Member (58.6-67.5 m) is clearly different in colour = 179.1, alt = + 66 m) are overlain the entire Lede (greenish grey) and lithology (very fine clayey sand, with (Oosterzele Member), by
from the lower which Formation and the basal of the thin clay laminae) part (67.8-74 m), (5.5 m thick) part
two consists of brown-grey, slightly lignitic sandy clay with Maldegem Formation. The Lede Formation contains
levels of the characteristic sandy limestone at its stone layers and which strongly resembles the Pittem Clay Balegem the base. facies from the cored Oedelem, Ursel-Maldegem and base and at 0.5-0.8 m above Balegem stone
contains about 40-50% of dominated the Knokke boreholes. Both are separated by a sandy quartz grains, by
basal 63-125 with a small (3%) but significant intercalation with a marked, 10-15 cm thick, gravel qm fraction, considered the of rounded than 250 Glauconite of clay chips (67.7-67.8 m), to represent amount grains coarser qm.
Hijfte Member (base of Vlierzele Formation): content rarely exceeds 5%, while fossils (mainly
foraminifera, echinoid remains and bivalve shell
fragments) amount to about 10%. The cement consists of
43.0-67.8m VlierzeleFormation ferroan of FeC0 (3% 3) microsparite.
43.0-49.8 m Drongengocd Member
49.8-53.7 m Bcernem Member
53.7-59.0 m Oosterzele Member Egem
59.0-67.5 m Lochristi Member
67.5-67.8 m Hijfte Member Exposed in the Egem sand and claypit (co-ordinates x = Member 67.8-74 Gent Formation, Pittem Member 70.275, = 189.575, alt = + 46 is the m y m) Egem overlain the Pittem (20 m of sand with thin clay layers), by
The base Member (5 m, sandy clay with sandstone beds).
— The from 30.6 consists of 60 thick Description of stone layers sample m of the latter member a cm sandstone, its base and reworked comprises a cemented layer of very fine-grained sandy coarse-grained at containing benthic limestone with a ferroan calcite cement. In its fine grain of macrofossils from the Egem Member (e.g. the
and it resembles foraminifer quartz, glauconite content cement texture, Nummulitesplanulatus Bruguiere, 1792).
the sandy limestones at depths of 26 and 28 m in the Ursel-
facies of Maldegem borehole, which were identified as a
the Balegem stone (Lede Formation). Oosterzele-Betsberg
is ferroan calcite-cemented The sample from 32.2 m a
= the Oedelem facies. = sandy limestone comparable to stone In a borehole on the Betsberg (co-ordinates x 109.9, y
The from 53.5 is concretion of silica- = 53 the could be sample m a a 183.25, alt + m), following sequence
of cemented sandstone, its cement consisting of a sequence studied: 0-1.7 m Quaternary, 1.7-1.9 m Maldegem
in and 8.9-19 opal rims around detrital grains, followed by chalcedony Formation, 1.9-8.9 m Lede Formation, m
This is the facies Formation the remaining intergranular space. typical Vlierzele Formation. The Vlierzele (Beernem
Vlierzele and in alternationof sand and with of sandstones from the Formation, Member) consists of an clay,
particular of those developed in the Beernem Member. sand layers containing compact sandstones (opal-
Samples from 68.3, 68.95 and 72.3 m are mottled opal- chalcedony cement). Some sand and clay levels are dark
cemented sandstones with wood fragments. The concretion brown and rich in lignite.
from 68.3 m is rather coarse, silt sized.
Beerlegem
= 104.5, = Kallo The Beerlegem sandpit (co-ordinates x y
situated in the of the 178.05, alt = + 56 m) is outcrop area
co-ordinates = Two facies In the Kallo borehole (BGS 27 E 148; x Vlierzele sands, southeast of Gent. were
= alt = + 3 limestones of the 1982-1985, the lower 4-6 m 144.85, y 218.0, m) sandy exposed in the period
Oedelem Member (201, 202 and 206.9 m), showing the consisting of cross-stratified glauconitic sand with very
characteristics in the beds the three same as those Ursel-Maldegem (34.5 thin clay (Oosterzele Member), upper
m) and Knokke (92.8, 94.4 and 98.3 m) boreholes, are metres including sandstone beds. The lower levels were
Formation the separated stone of the Lede (180-188 brittle, were not in beds, parallel to by layers very arranged lay
with limestone beds of the cross-bedded and contained small of m) by a sequence sandy portions, fragments
Brussels Formation (Fobe, 1988). wood. Exposed in the uppermost metre were two levels of 59
consistent sandstone blocks with more (40 cm thick), many STRATIGRAPHY OF STONE LAYERS (often silicified) wood fragments.
The unit was about 3 - upper (Beernem Member) m 1 Gent Formation, Pittem Member thick. showed It a subhorizontal alternation of clay and
sand Often, sand and 5 layers. clay layers were only cm The Pittem Member contains several laminated to mottled
thick. In thicker sand intercalations (of at least 10 cm), (bioturbated) opal-cemented sandstone beds. They were
hard and sandstone beds to very compact (up 20 cm thick) sampled in the Knokke, Oedelem, Ursel-Maldegem and often occurred. A number of eleven sandstone beds were Hijfte boreholes. Glauconite, calcareous bioclasts and
counted, with a cumulative thickness of about 1.2 m. Sand wood fragments are the commonest secondary intercalations often showed subhorizontallaminations. components.
Except for two layers, all sandstones were closely This type of sandstone is fairly common in the Belgian
packed and cementedby a of short sequence opal coatings, Eocene and has no formation-specific characteristics. All
fibrous and radiaxial also chalcedony chalcedony (see these sandstone beds occur in a brownish (on account of
Fobe, 1990). The two other layers were slightly less the presence of wood fragments) grey sandy clay. The and had dominated clear densely packed a cement by opal amount of wood decreases lower in the section. The
with a minor amount of chalcedony. The opal-chalcedony combination of sandstones in a brownish grey clay cemented sandstones from the Oosterzele and Beernem constitutes a conspicuous horizon in borehole sections in members facies of the undifferentiated are typical stone northwestern Belgium. It differs from the overlying 'Vlierzele Member' of the traditional lithostratigraphic greenish grey sandy and sandy clay members by its colour and scheme, were also encountered in smaller in discussion outcrops (see in Fobe, 1996) and is even detectable in
the area southeast of Gent (Fobe, 1986). flush wells.
Figure 3 presents a correlationof lithological units and
Brugge their stone layers in the Gent Formation between boreholes
in NW Belgium, illustrating the lateral distribution of the in 1986 there Early was a temporary exposure for the lignite-containing Pittem Member.
construction of a sewage collector along the Kerkebeek,
south of the town of Brugge (co-ordinates x = 68.20, y =
207.55, alt = + 5 At the base of the section m). exposed, 10 2 - Vlierzele Formation of cm grey glauconitic sand was noted, on top of which
rested 50 of cm grey clay with wood fragments. Above the This formation contains several facies of silica-cemented
clay, about 2 m of glauconitic sands with were lignite sandstones (see also Fig. 3). At the level of the sandy exposed, containing small sandstone concretions. Oosterzele Member, poorly sorted, medium- to coarse-
The basal sand is assigned to the Hijfte Member, while grained closely packed sandstones with a rather pure opal- the of the clay Lochristi Member is in turn overlain by the CT cement found. were Wood fragments may be present to Oosterzele Member. abundant (Oedelem borehole, Brugge outcrop). In the The sandstone beds in this showed exposure a Ursel-Maldegem borehole, a similar opal-cemented
heterogeneous texture, from sandstone ranging closely packed layer (with wood fragments) was noted (De
sandstone with an cement to opal-chalcedony loosely Breuck et al., 1989), but its grain size was better sorted. cemented packed patches by opal. Wood fragments may be The Beernem Member in the Knokke and Oedelem
abundant. This sandstone facies is the level comparable to boreholes contains stone of layers consisting very fine sand sampled at a depth of 34.4 m in the Oedelem borehole. and coarse silt, cemented by opal-CT. The cement contains
calcareous particles and clay, mica plates, moulds of Aalter sponge spicules, a minor amount of wood fragments and
small bivalve shell fragments. Their appearance is Steurbaut & Nolf (1989) described a the of sandstone temporary outcrop comparable to common type beds in the
near Aalter and sampled two sandy limestone levels. Pittem Member.
Petrographic investigation of these levels revealed that the At Ursel-Maldegem and Hijfte, the Beernem Member bed 'L' of uppermost (level Steurbaut & Nolf, was contains 1989) sandstone beds which more closely resemble the the base of the Lede Formation, which confirmed those fades of the Oosterzele and Beernem members in their authors' interpretation. The lowermost bed (level 11 of outcrop areas: closely packed, well-sorted, medium-sized Steurbaut & is Nolf, 1989) a sandy limestone, comparable sandstones with cement of a pure opal-CT or opal-
with the stone facies of the Oedelem Member. The ferroan chalcedony. Just as in the outcrop area (e.g. the Beerlegem calcite cement is finer and less rich in iron than grained sandpit) these sandstones occur in the sandy portions of usual. The stone layer further contains 2% of glauconite, sand-clay couplets of the lower part of the Beernem of non-ferroan micrite and some patches macrofossils such Member (Fig. 4). tubes of as the serpulid worm Ditrupa strangulata
Deshayes, 1825 and bivalve shells. 60
Fig. 3. Correlation of lithological units and their stone layers in the Gent and Vlierzele formations recorded from the Knokke, Oedelem,
Ursel and Hijfte boreholes. 61
Fig. 4. Correlation of lithological units and their stone layers in the Vlierzele and Lede formations recorded from the Hijfte borehole and in
the Oosterzele, Beerlegem and Balegem outcrops (southeast of Gent). 62
both there be of main viz. In stone-containing members, seems to an Formation in NW Belgium consists two units,
evolution in since in the northwest fossil-rich lower and less fossiliferous barren lithology, (Knokke, a part a or
Oedelem) loosely packed, poorly sorted opal-cemented upper part (Fig. 5).
sandstones prevail, while in a southeasterly direction The upper, poorly fossiliferous or barren, glauconitic
southeast sand. This it (going from Ursel to the outcrop area of Gent) sand resembles the Vlierzele explains why
sands in the closely packed and coarser-grained opal-chalcedony was actually confused with the Vlierzele
cements are commoner. Kluizen flush well (Fobe, 1993b) and with the Wemmel
sand in the Wippelgem and Flijfte boreholes by Jacobs &
De Ceukelaire (1992a, b). Its thickness is about 6-7 m in
3 - Oedelem Formation the Hijfte and Wippelgem boreholes. It most probably
corresponds to unit 12 of Steurbaut & Nolf (1989) at
and truncated the Lede The stone fades of the Oedelem Formation is Aalter, which is only 2.3 m thick by
characterised ferroan by a calcite-cemented sandy Formation there, and which reaches some 5 m (29-34.5 m)
limestones, mixed with non-ferroan lime mud, displaying a at Ursel-Maldegem. rather distinct facies throughout the study area in northern
Belgium (Knokke, Ursel-Maldegem, Waarschoot,
Wippelgem, Hijfte and Kallo boreholes, Aalter outcrop),
altogether over an area of at least 85 km (Knokke-Kallo).
4 - Lede Formation
The stone facies assigned to the Lede Formation in the
Ursel-Maldegem boreholes (De Breuck et al., 1989) was also encountered in the Hijfte borehole. The facies is
from the comparable to Balegem stone outcrop area of the
Lede Formation (Fig. 4).
DISCUSSION
A - Ieper-Gent formations
Attention is drawn to the occurrence of a 2 m thick
intercalation between the Merelbeke and Pittem members of the Gent Formation (sensu Fobe, 1996), which often is
partially cemented by opal-CT (e.g. Ursel-Maldegem borehole at 79.0 m). This problem will be discussed further
by Fobe (submitted), who proposes a correlation with the Fig. 5. Correlation of lithological units and their stone layers in 60 cm thick sandstone layer at the base of the Pittem the Oedelem and Lede formations recorded from the Memberin the Egem sandpit. Hijfte and Wippelgem boreholes.
B - Oedelem Formation Obviously, these 'Vlierzele-like' sands may be cause for
confusion in borehole interpretations. The similarities
Lithostratigraphic stone — In significance of layers between the Vlierzele sands and the upper sands of the boreholes and in NW the Oedelem the the outcrops Belgium, Oedelem Formation are probably reason why
Formation contains a characteristic limestone facies, sandy occurrence of the latter was not noted on the old geological recognised in the Kallo, Hijfte, Wippelgem, Knokke and where the basal map in the area between Gent and Aalter, Ursel-Maldegem wells and in the Aalter outcrop. In the fossil-rich portion emerged locally from the Pleistocene
and this facies identified Hijfte Wippelgem boreholes, was cover (Fig. 6).
in stone levels in the unit referred to as Wemmel Member
Jacobs & Ceukelaire by De (1992a, 1992b). The presumed Comparison with previous definitions: the Den Hoorn, Wemmel Member in the latter fine description comprises — Knesselare and Aalterformations In the Oedelem area, fossiliferous with small humic sands, slightly or barren, Nolf (1972) and Jacobs & Geets (1977) described the
spots and becoming slightly clayey down section. sands of following sequence: lignitic (Aalterbrugge facies
This leads to the conclusion that the Oedelem of the Vlierzele sands), overlain by some 10-12 m sandy 63
clay (Oedelem Member of Nolf, 1972; Beernem Member Member of Nolf (1972) in fact matches the Beernem of Jacobs & Geets, 1977) and by fossiliferous sands Member of Jacobs & Geets (1977). The latter authors also
(named Oedelem and/or Aalter sands in Nolf, 1972; Jacobs described a 3 m thick poorly fossiliferous base of the
in the Aalter & Geets, 1977) (Fig. 7). In the present interpretation, the Oedelem Member (representing, fact, lignitic sands are correlated with the Oosterzele Member Member of Nolf, 1972), but this deposit did not equate
(Fobe, 1996). Nolf (1972) described the Aalter Member as with the non-fossiliferous sands in Nolf (1972), but a channel deposit, cut into the Oedelem Member. probably corresponded to Steurbaut & Nolf's (1989)
Correlations show that the Beernem Member also belongs poorly fossiliferous unit 1.
similar to the Vlierzele Formation, but the unit which normally In the area between Ursel and Aalter (Fig. 6), a overlies the is encountered section of the Aalter it, Drongengoed Member (Vlierzele sequence (type
Formation) (see Fobe, 1996), is either thin or missing in Member of Nolf, 1972; Jacobs & Geets, 1977), resting the Oedelem area. directly on lignitic Vlierzele sands. However, according to
the interpretation of the Ursel-Maldegem boreholes (De
Breuck et al„ 1989), the Drongengoed Member is also
level in the Oosterzele lignitic in that area. The lignitic
which well in the Oedelem Member, was very developed
area, was also recognised in the Ursel-Maldegem
boreholes (stone layer at 60.6 m). Therefore, the first
appearance of lignitic Vlierzele sands ('the Aalterbrugge
of the Den Hoorn facies'), on which the lithostratigraphy
or Knesselare Formation was based (Nolf, 1972; Jacobs &
Geets, 1977; Steurbaut & Nolf, 1989) cannot be used as
marker bed. This makes the concept of the shelly Aalter
Sands, locally occurring in deep gullies incised into the
underlying Oedelem sands (Nolf, 1972) invalid, since it
was based on a mix-up of the two lignitic sand levels in the
Vlierzele Formation.
Fig. 6. Correlation of lithological units of the Oedelem
Formation between the Ursel borehole and the Aalter
outcrop, illustrating the thinning-out of the Evergem
Member (upper glauconitic, non-fossiliferous sands of the
Oedelem Formation).
Fig. 8. Correlation of lithological units of the Vlierzele and
Oedelem formations recorded in the Zeebrugge, Ursel,
Kluizen, Wippelgem, Hijfte and Nieuwkerke-Waas
boreholes.
The Aalter Formation on the legend to the new geological
and map (Jacobs et al., 1993a, b) comprises the Beernem
Oedelem members. The fossiliferous sands exposed in the
the Oedelem Member Aalter type section and occurring in
in borehole sections north of Aalter are considered to be
equivalent deposits. Basically, this assumption is correct, Fig. 7. Correlation of lithological units of the Oedelem but the legend completely ignores the poorly fossiliferous Formation between the Ursel and Oedelem boreholes and or barren, glauconitic 'Vlierzele-like' sands occurring the Den Hoorn borehole (after Nolf, 1972). with Wemmel above them, which are confused the
Member. As demonstrated previously (Fobe, 1996) as well
It should be stressed that the Oedelem in the the Beernem Member also (Fig. 7) original as present paper, occurs 64
beyond its type area and belongs to the Vlierzele Gent) in a southerly direction.
Formation. Thickness — between 7 and 12 m.
— Definition of the Oedelem Formation The Oedelem Distribution — as for the Oedelem Formation.
Formation roughly corresponds to the stratigraphic interval
Hoorn formerly known as 'Upper Paniselian', 'Den
Formation' (proparte), 'KnesselareFormation' (except for Evergem Member the Beernem Member), 'Aalter sands' and 'Aalter
Formation'. It differs from the previous concepts mainly Name — after the municipality of Evergem.
of its different Whilethe Den — member. on account sequence. Hoorn, Rank new
Knesselare and Aalter formations were described as a Holostratotype — Wippelgem borehole BGS 40 W 346 lower unit overlain an = 105.416, = alt = + 6.7 sandy (Oedelem Member) by upper, (co-ordinates x y 203.232, m),
unit Aalter sands ravinating shelly (Aalter Member, s. str.), depth 30-36.5 m. the Oedelem Formation is defined as a shelly unit overlain Parastratotype — Hijfte borehole BGS 40 E 373, depth is by a sandy unit. The Oedelem Formation subdivided into 31-37 m.
the Aalter and members. The — two members, Evergem Lithology This member consists of fine- to medium- Formation in northern north of Oedelem occurs Belgium, glauconitic sand with a few humic patches, shells and a the line Antwerp-Sint Niklaas-Gent-Brugge; the original few clay layers.
extension of the unit is unknown — at present (Figs 8, 9). Underlying unit Aalter Member (Oedelem Formation).
Overlying unit — Lede or Maldegem formations.
Thickness — about 6 to 10 m.
Former correlations — generally erroneous correlations
with the Wemmel Member, the Lede Formation or the
sandy members of the Vlierzele Formation.
Distribution — as for the Aalter Member; because of
ravination by the Lede Formation, the Evergem Member is
missing in the outcrop area of the Oedelem Formation.
Details on the distribution of the Oedelem Formation —
The application of the above-defined lithostratigraphic
units enables a revision of previous borehole 9. Distribution of the Oedelem Formation, also the Fig. showing interpretations.
location of the cross section illustrated in Fig. 8.
Lectostratotype is the Wippelgem borehole BGS 40 W 346 Zeebrugge (co-ordinates x = 105.416, y = 203.232, alt = + 6.7 m),
the depth 30-45 m, in municipality of Evergem. The offshore borehole SEWB was described by Jacobs & Parastratotype is the Hijfte borehole BGS 40 E 373 (co- Sevens (1993), with the Oedelem Member (Aalter ordinates x = 111.130, y = 200.390, alt = + 8 m), depth 31- Formation) subdivided into the Beernem Member (43.0-
43 m. 33.1 m), Oedelem Member (33.1-19.2 m) and the 'Aalter
equivalent' (12.0-19.2 m). According to the description of Aalter Member borehole SEWB (Jacobs et al. 1990), the section 19.2-32 ,
m was highly fossiliferous. The 'Aalter equivalent'
Name — after the municipality of Aalter. consists of glauconitic sand and may well represent the
Rank — for the of the an existing name shelly part Evergem Member of the Oedelem Formation. The formation to the of the originally assigned upper part fossiliferous sands of 19.2-32.0 m correlate with the Aalter
Knesselare the Den Hoorn formations. or Member. Laminated sands, described from between 32.0-
— of Aalter Steurbaut & Holostratotype municipality (see 33.1 m correspond to the Drongengoed Member of the
Nolf, 1989: units 1-10). VlierzeleFormation (Fig. 8).
Parastratotype — Hijfte borehole BGS 40 E 373, between
37 and 43 m.
Lithology — This member consists of medium- or coarse- Kluizen grained glauconitic fossiliferous sand, with several shell beds. According to Fobe (1993, 1996), resting on top of the
— Vlierzele Formation Underlying unit (Drongengoed or Ypresian in borehole Kluizen, BGS 40 W 327 (co-
Beernem lower ordinates = = 204.3(H), alt = + was the members), sharp boundary. x 103.550, y 5 m)
— Member Overlying unit Evergem (Oedelem Maldegem Formation at a depth of 35 m. The remainderof
Formation - Formation), ravinated by the Lede (Aalter, the section was as follows: 35-43 m medium sand with 65
sandstone (Drongengoed Member); 43-51 m - fine sand The glauconitic sands between the Aalter sands and the
sand with rich in shells correlated with and clayey sandstone, (Beernem Asse clay have been (Jacobs et al., 1993b)
Member); 51-56 m - coarse sand (Oosterzele Member); the Wemmel Member. In the Ursel-Maldegem boreholes
56-64 - medium sand and 64-67 - fine sand this with m m (Lochristi (De Breuck et al., 1989), the lower part of unit,
67-70 - sand limestone correlated with the Lede Member); m coarse (Hijfte Member) sandy beds, was
70-78 - (Vlierzele Formation); m silty clay, greenish grey, Formation, mainly on account of stone facies, grain-size
78-86 - brown at the top (Pittem Member); m clay distribution and micropalaeontological characteristics.
- fine (Merelbeke Member); 86-90 m very clayey sand They are overlain by glauconitic sand, fining-upward,
(Egem Member) (leper Formation). referred to as the Wemmel Member. The Hijfte borehole
The Kluizen borehole drilled (flush well) was only a shows a comparable sequence, consisting of glauconitic
few kilometres from the cored well. The with away Wippelgem sand with a cemented layer (at 29.7-32.0 m) a sharp
following revision is proposed (Fig. 8): basal limit, overlain by fining-upward sand, grading into
sandy clay. In the Wippelgem borehole, the glauconitic
Oedelem Formation sand with a cemented bed is absent and resting on the
35-43 Member m Evergem Aalter sands is a thin (20-30 cm) 'Bande Noire', passing
43-50 m Aalter Member immediately into the Asse Member.
Vlierzele Formation
50-54 m Drongengoed Member (medium sand
comparable to the 35-43m section) CONCLUSIONS
54-62 m Beemem Member(fine sand)
62-65 m Oosterzele Member(brown, medium sand)
65-67 m Lochristi Member
67-70 m Hijfte Member(coarse sand)
Nieuwkerke-Waas
The section of borehole BGS 27 137 W (co-ordinates x =
136.650, y = 210.780, alt = + 8 m) was originally
interpreted as follows: 121-127 m - medium sand with
sandstone (Drongengoed Member); 127-136 m - sandy
clay with sandstone, fossil-rich sandy clay and sandy clay
(Beernem Member); 136-139 m - medium sand
(Oosterzele Member); 139-142 m - fine sand with clay
(Lochristi Member); 142-145 m - medium to coarse sand
(Hijfte Member) (Vlierzele Formation); 145-153 m - sandy
but brown in the clay, usually green, uppermost two metres
(Pittem Member); 153-170 m - clay (Merelbcke Member);
170-184 m - very fine sand with Nummulites planulatus
(Egem Member) (leper Formation).
A review of data, inclusive of unpublished geophysical
logs, has now shown that the section between 121-127and
127-136 m corresponds to the Evergem and Aalter
members ofthe Oedelem Formation, respectively (Fig. 8).
Kruibeke
In the Kruibeke borehole BGS 42 E 314 (co-ordinates x =
= 142.350, y 205.850, alt = + 11 m), described by Fobe
(1993, 1996) as well, there was no indication of the
of the Oedelem This presence Formation. could mean that
the Oedelem Formation thins out in subcrop south of Sint
Niklaas.
Fig. 10. Composite section of Middle Eocene formations and
C - Lede Formation, Wemmel Member members in northwestern Belgium. 66
1976. International Guide. Figure 10 illustrates a composite section of Middle Eocene Hedberg, H.D. (ed.), Stratigraphic
borehole New York (John Wiley and Sons), vxii + 200 formations, as compiled from the Ursel and Hijfte pp. & M. De 1992a. Borehole 40 Vlierzele Jacobs, P. Ceukelaire, description sections. In the present study, the validity of the
W 346 (Evergem). — Internal Report Belg. unit and its subdivision into five Wippelgem Formation as a separate Geol. Dienst (unpubl.). members (Fobe, 1996) is confirmed by analyses of stone Jacobs, P. & M. De Ceukelaire, 1992b. Borehole description 40 E facies. 373 Hijfte (Lochristi). — Internal Report Belg. Geol. Dienst The Vlierzele Formation is overlain by the Oedelem (unpubl.).
Formation which a lower (new name), comprises Jacobs, P., M. De Ceukelaire, E. Sevens & M. Verschuren, fossiliferous unit (Aalter Member) and an sandy unit upper 1993a. Philosophy and methodology of the new geological
It to of the Northwest (Evergem Member; new name). proved possible map Tertiary formations, Flanders,
determine the upper limit of the Oedelem Formation by Belgium. — Bull. Belg. Ver. Geol., 102: 231-241.
P. & S. 1977. Nieuwe in de kennis means of an analysis of stone facies. Jacobs, Geets, ontwikkelingen
het Boven-Paniseliaan. — Natuurwet. 59: 47- The Lede Formation represents a discontinuous deposit van Tijdschr.,
93. between the Oedelem and Maldegem formations. The Jacobs, P., R. Maréchal, M. De Ceukelaire & E. Sevens, 1993b. Wemmel Member is less important in thickness than kaart 1/50.000 Kaartblad 13 Geologische op (Brugge). previously thought, being reduced to the 'Bande Noire' in Brussel (Bestuur Natuurlijke Rijkdommen en the area. 38 Energie/Belgische Geologische Dienst), pp.
Jacobs, P. & E. Sevens, 1988. Lithostratigrafie van de Eo-
Oligocene overgangslagen in noordwest België. — Belg. ACKNOWLEDGEMENTS Geol. Dienst, Prof. Paper, 1988/5 (no. 235): 1-60.
Jacobs, P. & E. Sevens, 1993. Eocene siliciclastic continental
southern North Sea. I wish to thank the Belgische Geologische Dienst (Belgian shelf sedimentation in the Bight In'. in Research: 95-118. Geological Survey, Brussels) and the Flemish Natural Progress Belgian Oceanographic
borehole Brussels Academy of Belgium). Resources Division (Brussels) for access to (Royal Jacobs, P., E. Sevens, M. De Batist & J.-P. Henriet, 1990. Grain samples. facies and of Eocene size, sequence analysis West-Belgian
continental shelf deposits. — Zentralbl. Geol. Palaont., (1)8:
931-955. REFERENCES King, C., 1990. Eocene stratigraphy of the Knokke borehole
The (Belgium). In'. P. Laga & N. Vandenberghe (eds). De B. L. E. Steurbaut, E. Van Dyck & Breuck, W., Fobe, Lebbe, — Knokke well (11 E 138). Toel. Verh. Geol. Mijnk. België,
K. 1989. De van Ursel en Walraevens, boringen Maldegem. 29: 67-102.
Bijdrage tot de kennis van het Eoceen in Noordwest-Belgie. Leriche, M., 1941. Le Panisélien et la limite entre TYprésien et le
— Belg. Geol. Dienst, Prof. Paper, 1989/1 (no. 236): 1-98. — Géol., Paléont., Lutetien en Flandre. Bull. Soc. beige
Evamy, B., 1963. Application of a chemical staining technique to Hydrol., 50:211-214.
a study of dedolomitisation.— Sedimentology, 2: 164-170. Maréchal, R., 1993. A new lithostratigraphic scale for the Fobe, B., 1986. Petrografisch onderzoek van de coherente Palaeogene of Belgium. — Bull. Belg. Ver. Geol., 102: 215-
van het Eoceen in en Gent gesteenten Laag- Midden-Belgie. 229.
thesis 215 (Ph.D. Rijksuniv. Gent), pp. (unpubl.). Maréchal, R. & P. Laga, 1988. Voorstel lithostratigrafische Midden-Eoceen de Fobe, B., 1988. De steenbanken van het uit Commissies indeling van het Paleogeen. Brussels (Nationale
van Kallo: — boring lithologie en stratigrafische interpretatie. 208 voor Stratigrafie, Commissie Tertiair), pp. Bull. Belg. Ver. Geol., 97: 25-28. Nolf, D., 1972. Stratigraphie des formations du Panisel et de Den
Fobe, B., 1989. Het Eoceen tussen Mol en Beringen. — Belg. Hoorn (Eocène beige). — Buil. Belg. Ver. Geol., 81: 75-94. Geol. Dienst, Prof. Paper, 1989/4(no. 239): 1-10. Steurbaut,E. & D. Nolf, 1986. Revision of Ypresian stratigraphy Fobe, B., 1990. The sandstone and limestone beds from the Mont of Belgium and Northwestern France. — Meded. Werkgr. Panisel characteristics, boring: petrographical Tert. Kwart. Geol., 23: 115-172.
lithostratigraphy and diagenesis of silica-cemented sandstones Steurbaut, E. & D. Nolf, 1989. The stratotype of the Aalter Sands
in the of — Bull. Ver. Geol., 99: Ypresian Belgium. Belg. (Eocene of NW Belgium): stratigraphy and calcareous 323-336. nannoplankton. — Meded. Werkgr. Tert. Kwart. Geol., 26:
Fobe, 1993a. and B., Petrography lithostratigraphic significance 11-28.
of the Eocene in the boreholes of Beerzel, Booischot layers Vandenberghe, N„ P. Laga, J. Herman & J. Baccaert, 1990.
and Rillaar. — Geol. Dienst, Prof. 1993/3 (no. Belg. Paper, Lithological description of the Knokke well. In'. P. Laga & N. 261): 1-8. Vandenberghe (eds). The Knokke well (11 E 138). — Toel. Fobe, B., 1993b. Ypresian lithostratigraphy in Northern Belgium. Verh. Geol. Mijnk. België, 29: 9-17.
— Bull. Belg. Ver. Geol., 102: 254-257.
Fobe, B., 1996. Lithostratigraphy of the Vlierzele Formation
(Ypresian, NW Belgium). — Bull. Belg. Ver. Geol., 104
(1995): 133-149.
betekenis een Fobe, B., submitted. Lithostratigrafische van
Merelbeke en Pittem received 17 1996, revised version zandlaag tussen de kleien van (Eoceen Manuscript September
vanBelgie). — Natuurwet. Tijdschr. accepted 4 August 1997. 67
<<
■ U E (X)2 << Fm. w Mbr.X P-. Fm. Fm.E 1* i Ph fa Mbr.X w 'S s sMb Q Mbr. I-h' -1 SS o Mbr.1 Mbr. 3 II E Mbr. PJ §0 Fm. Mbr. STUDYH Fm. U Ph s Mbr. PJ u Ph N 0 c/d N ÏITïS'''''" q Ui i PJ tl pj C/O g£ a z § 'S d s ■4—> HH Q 09 MALDEGEM a Ö VLIERZELE Drongengoed PJ λ Wemmel/BN OEDELEMPJ £ 13 2 OosterzeleO Merelbeke s PJ ! LEDE Evergem Aalter Beernem Lochristio Hijfte GENT Pittem THIS S£ Oh i hJ O PJ < > Q O >~J j — Ü
al. 13 Fm.E Fm.E -t—» 0 Ph Ph ete Fm. Ph mi Si PJ Mbr.Xfe Mbr. Mbr. Mbr S * 3s Ü Fm.e' z Mbr. pj PJ e s 'S BREUCKBREUCK « Ph PANISEL lignite Q E al .5? PJ s -J g k-i I MALDEGEM Q KNESSELARE Merelbeke : PJ Oedelem Vlierzele URSEL 1993)1993) Wemmel LEDE MT. Pittem X (DE S£ hJ 2 o S> X i
>ï clayOS tn "o as Os1993) E "2 < Fm. ,< □ Ph t- sandy al. C/5 * 2 si e ë Mbr. AREA Fm. Mbr.X40 : et pj Mbr.5 Ph 5!Mbr. 2 -* ü S Fm. M f* U Mbr. SS Ph PJ 13 Mbr. -O II H H O R i N s ,-J u £ Z 4J ü B 3 ALTER u 5? 'S MALDEGEM< s Ö <^ AALTER< (JACOBS< Wemmel Oedelem PJGENT Vlierzele3 Pittem Merelbeke < Ö- 2 £ A< O Ü > s; Pittem
1 clay < ON1993) o 1 E Fm. : Ph << M AREA x> ARE al. |H 2^ si Mbr. X3 Fm. -o Mbr.X s Mbr. etu PJ Mbr. Mbr. '£ S 5 Ph£ Mbr.§ E'S "4 Fm. « Mbr. PJ Ph 8 0> M _1 PQ U fS s S Q E 53 ■^ pj O H | H N s ,?< _] u Z D MALDEGEM :S^
:
< E E KEY E Fm. Fm. 2 Fm. Ph ** 2 Ph -- AREA J ui si PJ O -o Mbr.X£ PJ Mbr. ■ö 5 Cr 5! sMbr. 2^ o 1972) o i o 1 Z HOORN Mbr. 0) •o PJ u PANISEL o < i» studied) Q E 3 c/i hJ c z a ■4-» LITHOLOGYH < § Oedelem MALDEGEM fc-ü OEDELEM PJ 13 OEDELE (NOLF Wemmel DEN Aalter Vlierzele (not§ Q < S>MT
Table 1. Previous lithostratigraphic schemes of the Middle Eocene of northwestern Belgium compared with the scheme proposed in the
present paper.