Davies, H.L., Haslett, S.K., Mullins, G.L., O'Gorman, M.P. and Smith, J.S. 1991. An integrated palynological and micropalaeontological investigation of selected cretaceous/tertiary boundary sections from western Europe and north Africa. MSc Thesis: University of Southampton.

1. SELECTED CRETACEOUS/TERTIARY BOUNDARY SECTIONS
FROM
BY
Heather L. Davies
Simon K. Haslett
Gary L. Mullins
Margaret P. O'Gorman
James S. Smith
for the degree of Master of Science

2. Firstly, we would like to thank Professor J.W. Murray, Dr. Ron Austin, Dr. John
Marshall and Dr. Ian "holiday" Harding for their help and guidance throughout the year.
We would also like to thank Shir Akbari, Daphne Woods, Barry Marsh and Dr. Barbara
Cressey for their patience and unfailing willingness to help.
Jim and Margaret would like to express their thanks and appreciation to Drs Jeremy
Young and Andrew Gale who supplied the material for El Kef.
We would finally like to thank Jim for his unending patience with our lack of computer
knowledge.

3. Acknowledgments
1 Introduction 1
2 The Bidart Section (S.K Haslett) 3
2.1 Introduction 4
2.2 Location and Methods 4
2.3 Gelogical Setting 4
2.4 Planktonic Foraminifera 9
2.5 Calcareous Nannofossils 16
2.6 Calcareous Dinoflagellates 18
2.7 Discussion 19
2.8 Conclusion 20
3 The Zumaia Section (G.L Mullins) 21
3.1 Introduction 22
3.2 Lithostratigraphy 22
3.3 Biostratigraphy 24
3.4 The Distribution of CaC03 and Organic Carbon 27
3.5 Palynofacies 30
3.6 Dinoflagellate Palaeoecology 32
3.7 Conclusion 34
4 The Sopelana Section (H.L Davies) 36
4.1 Introduction 37
4.2 Lithostratigraphy 37
4.3 Biostratigraphy 40

4. 4.4 Palaeoecology 44
4.5 Conclusions 47
5 The EI Kef Section (M.P O'Gorman and J.S Smith) 50
5.1 Introduction (l.S.S) 51
5.2 Biostratigraphy (J.S.S) 54
5.3 Palynofacies and Organic Petrography (M.P.O'G) 58
6 Synthesis 70
6.1 Biozonal Schemes for the Cretaceous-Tertiary Boundary 71
6.2 Correlation Between Sites 73
6.3 Palaeoecological Simularities and Differences 77
References 79
Appendices 86
1 Proccessing Procedures 87
2 TOCPLOT 89
3 Taxonomy 90
Plates 100

5. 1. ABSTRACT / INTRODUCTION
The Cretaceous/Tertiary Boundary marks the (ii) Zumaia: This section is located approximately
position of one of the largest mass extinction in 55km to the east of Bilbao in the Guipuzcoa
the geological record. The extinction event Province, Northern Spain. It is a part of the
affected both terrestrial and marine realms. It northern most syncline formed by the Basco-
caused the extinction of life forms from as large Cantabric orogen.
as the dinosaurs and to as small as calcareous (iii) Sopelana: This is the southernmost section
nannoplankton. sampled from this area. It is located 15km to the
Calcareous micro- and nannoplankton North of Bilbao in the Basque country, Northern
were severely affected at the end of the Spain. It forms part of the Bilbao synclinorum in
Cretaceous. This can be seen from numerous the Basco-Cantabric basin.
sections around the world, (Hallam and Perch-
Nielsen, 1990). Organic walled phytoplankton, on
the other hand , appear to have survived the
Cretaceous/Tertiary boundary event, (Brinkhuis
and Leereveld, 1988).
Initially, a study of the microfauna and
flora across the Cretaceous/Tertiary boundary at
selected sites from the Basco-Cantabric basin in
the Basque region of south west Europe was
begun. Difficulties in extracting adequate amounts
of organic microfossils from a number of the
sampled sections necessitated the addition of
another study area. A sampIes section from the
Cretaceous/Tertiary boundary at El Kef, Tunisia
were chosen to compliment the proposed study.
The aims of the study are as follows: Figure 1.1 The locations of the European
(i) To process and extract the appropriate sections.
microfossils from the selected samples.
(ii) To study the biostratigraphy across the
Cretaceous/Tertiary boundary and observe any
changes therein.
(iii) To use any available parameters to interpret The final section studied is from the EI
the palaeoenvironment and come to some Kef area in Tunisia. The section is located
conclusions regarding the results. approximately 7km west of El Kef in
(iv) To attempt a correlation between the studied
sites. This correlation is to involve both
biostratigraphical and palaeoecological
conclusions.
Three of the study areas in this dissertation are
located in south west Europe. These are as
follows:
(i) Bidart: The Bidart samples were collected on
the Cote des Basques, France from an area south
Figure 1.2 The location of the EI Kef study
of Biarritz. This section represents the northern
section.
extreme of the "Flysch Calcaire", (Mathey, 1983)
and is situated within the Basco-Cantabric basin.

6. Northwestern Tunisia. Deposition at K/T from section to section is interpreted as an effect
boundary times took place on the margin of of the different levels to which each section has
Tethys (Meon, 1990). been condensed.
A vast amount of work has been written on the
Cretaceous/Tertiary boundary. Various
hypotheses have been put forward to explain the
mass extinctions. These theories range from the
tyingtogether of carbonatite eruptions, kimberlite
pipes and mass extinctions by Rampino and
Stothers in 1984, to the impact theory of Alvarez
et al. 1980.
Weidmann (1988) summarises these theories in
his paper on the Basque coastal sections of the
K/T boundary.
Various authors have written about the
K/T events from a micropalaeontological point of
view.Smit and Romein (1985) looked at faunas
from DSDP cores from all over the world and
also some land based sections and attempted to
tie the faunal extinctions in with the hypothesized
impacts.Hallam and Perch-Nielsen (1990) looked
at the biotic record of events in the marine realm
at the end of the Cretaceous. In this paper they
summarise the changes in calcareous, siliceous,
and organic-walled microfossils across the K/T
boundary. Keller (1988, 1989a and 1989b) has
looked at extinctions in planktonic foraminifera
across the boundary. For the changes in organic
walledphytoplankton across the boundary, studies
byHansen (1977), Kjellstrom and Hansen (1981),
De Coninck and Smit (1982), Brinkhuis and
Zachariasse (1988) and Brinkhuis and Leereveld
(1988) are a number of the published works on
the subject.
The previous work pertaining particularly
to each study section is described in the individual
chapters as is a more detailed description of the
geologicalsetting of the individual areas.
Detailed biostratigraphical correlation using
dinoflagellate cysts between EI Kef and Zumaia
proved impossible due to the greatly differing
assemblages. Correlation between Sopelana and
Bidart using planktonic foraminifera proved
possiblealthough the section at Bidart is markedly
condensed when compared with Sopelana.
Palaeoecologically the Late Maastrichtian
regression can be correlated across all of the
studied sections, as can the post boundary
transgression. The variation in palaeoproductivity

7. CHAPTER 2
BIDART
SIMON K. HASLETT

8. walled microfossils as part of this study but failed
to yield significant concentrations (Smith,
TheCretaceous-Tertiary (KIT) boundary sections personnel communication). This particular project
of south-west France, are considered to be some is concerned primarily with planktonic
of the best and most complete KIT boundary foraminifera, nannofossils and calcareous
sections in south-west Europe (Seyve, 1990). A dinoflagellates, specifically the range and
relatively complete coastal section called the abundance of individual species throughout the
Pointe-Sainte-Anne section (also known as the section. Apart from biostratigraphic refmement, it
Bay of Loya section) is situated to the north of is hoped that data collected will shed light on late
Hendaye, near the Spanish-French border. Mesozoic and early Cenozoic oceanic
However, this section is particularly difficult to environments and perhaps elucidate on the
studybecause access is hazardous (Seyve, 1990). circumstances which brought about mass
Inland sections, such as at Pont Labau (south of extinction at the end of the Cretaceous Period.
Pau), are readily accessible. Unfortunately, a
sedimentological hiatus has been identified at the
critical boundary level (Seyve, 1984), thus
reducing its suitability to detailed
micropalaeontological study. By far the most The Bidart KIT boundary section is located on
suitable KIT boundary section in south-west the Cote des Basques, south-west France, between
France, in terms of accessibility and Bidart and Ville les Ailes, near Caseville, south of
sedimentological completeness, is the section Biarritz (coordinates M.T.U. X = 614 and Y =
situated on the coast near Bidart, south of 4810,8) (see Fig. 2.2.1 for location). It can be
Biarritz. reached by walking for 10-15 minutes northwards
The Bidart section, because of its along the beach from Bidart, until the
suitability, has received much attention from characteristically grey and brown marls of the
geologists studying the KIT boundary. Maastrichtian give way to the pale-grey and red
Geochemical research that has been carried out Palaeocene limestones. The boundary itself is
includesstable isotope studies (Romein & Smit, exposed near the base of a small protruding cliff
1981;Renard, et. al., 1982; Clauser, 1987; and of Danian limestone (Fig. 2.2.2).
Nelson, et. at., 1991) and the detection of the The lithological log of the section that
infamousKIT boundary iridium anomaly (Smit & was sampled is illustrated as Fig. 2.2.3. Altogether
Ten Kate, 1982; Bonte, et. at., 1984). 57.20m was logged and samples taken at irregular
Magnetostratigraphic analysis has been carried intervals as shown on Fig. 2.2.3. Seventeen
out in detail (Delacotte, et. at., 1985) and an samples were taken from both the Maastrichtian
appraisal of the regions structural geology has and Palaeocene with fourteen of the samples
been undertaken (Bodou, 1974). Yet despite this clustered around the KIT boundary itself. Every
interest little palaeontological work has been third sample was systematically examined, with
done. other samples being picked when necessary e.g. to
General biostratigraphic accounts have pinpoint first and last occurrences of species. The
been given (Bonte et. at., 1984; and Delacotte et. number of individuals picked per sample was not
at., 1985). Detailed work on calcareous uniform, with the actual number picked being
nannofossils has been carried out for the dependent on needs e.g. samples picked in order
boundarylayer and the strata immediately above to determine first or last occurrences of species
and below the boundary (Martini, 1%1; Perch- were picked until the taxa in question was
Nielsen,1979a; and Seyve, 1990) and nannofossil recovered or until 250 specimens had been
zoneshave been identified throughout the en~ire collected. The samples were processed for
Campanian and Maastrichtian exposed at Bidart calcareous microfossils as described in the
(Clauser, 1987), although Clauser did not extend Appendix.
his study into the Palaeocene. However, the
rangesof other microfossils have not as yet been
studied from the Bidart section. Benthic
foraminifera, ostracods, radiolaria, diatoms and
silicoflagellatesare other possible candidates for 2.3.1. Stratigraphy
futurestudy. Samples were processed for organic- The 37m of Maastrichtian strata sampled at

9. Bay of
Biscay
N
1
Fig. 2.2.1. Location of Bidart and the KIT boundary section. Key to ornamentation:- brickwork = cretaceous;
largedots = tertiary; small dots = beach; diagonal lines = cliffs and exposed rock; horizontal lines in inset
= Atlantic Ocean.

10. a
Fig. 2.2.2. Bidart KIT boundary section; a) the KIT boundary is located at the foot of the small pale-grey
cliff of Danian limestone, seen left of centre on the photograph, the silhouetted figure on the skyline marks
the extended outcrop of the boundary; b) detail of the KIT boundary, red Maastrichtian calc-argillite in the
bottom left gives way to the soft green-brown boundary clay horizon, overlain by hard pale-grey Danian
limestone.

11. _ Micrite (undifferentiated)
1)1 Clay, red calc-argillite
+-'
.c
o
F _ Green unweathered micrite
BM10
--BM11
BM12
F
CD
C
CD
o
o
<J.)
l CO
-
CO
a..
J

12. Bidart is represented by approximately 200m of s;umping.
grey and brown marls (calc-argillites) assigned to The 21m of Palaeocene strata exposed at
the 'flysch calcaires' (Mathey, 1983), with Bidart is terminated by the emplacement of a
occasional green or blue/green horizons which Triassic diapir which is characterised by deep-red,
represent unweathered zones. Macrofossils are bright-green and black clays, in association ".ith
uncommon with the echinoid Stegaster dominating numerous veins of anhydrite. The Tertiary strata
the sparse fauna in association with poorly is exposed again further north with the Eocene
preserved bivalves. Ichnofossils such as Plallolites sections of Handia and Biarritz.
are present.
No ammonites were found in this study, 2.3.2. Tectonic and depositional setting
but Ward (1988) found four species of ammonite, The Bidart K/T boundary section is located
Pachydiscus jacquoti, Diplomoceras cylilldraceum, within the Basque-Cantabric Basin (Plaziat, 1975).
Pseudophyllites indra and Sagltalillites sp., ranging The section occurs within a flysch zone which
up to within 1m of the K/T boundary. persisted from Albian to Eocene times (Fig.
Anapachydiscus fresltvillellsis, Ten uipteria sp., 2.3.1). An interpretation of the depositional
Gaudryceras sp., andPltyliopachycerasforbesiallu11l setting of Bidart has already been attempted
were also found within the section sampled in the (Seyve, 1984). It is thought to have been situated
present study. Unfortunately, these ammonite in close proximity of a palaeoslope to the north-
occurrences cannot be referred to the
Maastrichtian ammonite zonal scheme proposed
by Wiedmann (1988b) as some specimens found
by Ward (1988) apparently fall outside the
previously known ranges of the species concerned.
The K/T boundary is marked by a sharp
lithological change with a conspicuous clay
horizon 60cm thick. This boundary clay is green at
its base and passes up through grey-brown to red
clays at the top. The lithology gradually becomes
more calcareous towards the top. This observation
ties in well with the reduction in total bulk
carbonate at the K/T boundary reported by
Renard, et. al. (1982), which then increases
throughout the boundary clay horizon.
The well-known K/T boundary iridium Fig. 2.3.1. Extent of flysch in Basque-Cantabric
anomaly, first noticed in the Italian Gubbio basin (after Lamolda, et. at., 1983). Scale bar =
section (Alvarez, et. al., 1979), has been identified 50km.
at Bidart (Delacotte, 1982; and Bonte, et. al.,
1984),although an earlier attempt failed to detect
it (Smit & Ten Kate, 1982). The iridium anomaly
peaks at around 6 parts per billion (p.p.b.),
against a background reading of 0.5 - 1 Pi.b., and
corresponds exactly with a drop in the 01 C curve
(Bonte, et. al., 1984).
The boundary clay horizon is overlain by
red and pale-grey limestones and clay layers.
Numerous hardgrounds and highly bioturbated
horizons exist ·throughout the section indicating
staggered sedimentation, condensed sequences
and hiatus (Bonte, et. al., 1984). As already noted
by Seyve (1990) the Palaeocene limestones are
slumped in places and possess other
sedimentological structures indicative of a Fig. 2.3.2. Depositional setting of Bidart during
turbiditic depositional environment. At this point the Palaeocene, in proximity of a palaeoslope to
it may safely be assumed that any microfossils the the north-east (after Seyve, 1984).
Palaeocene lithologies yield may be affected by
reworking or may not be ill situ due to extensive

13. east. During the Maastrichtian the sedimentation considered to have limited use in biostratigraphy
rate is thought to have been stable at due to heterochronous homeomorphy. Cretaceous
~ppro~mately 40mm kyr-1 (Nelson, et. a/., 1991), and Cenozoic forms were thought to belong to the
m a distal deep-sea fan environment, fed by a same families and in some cases the same genera.
narrow submarine canyon. During Palaeocene However, by close examination of wall structures
times however, increased activity on the keels and apertural structures, it has proved
slope,either tectonic or climatic induced, brought possible to discern between Mesozoic and
numerous slumped blocks into the area in Cenozoic forms. Cretaceous taxa can possess up
association with turbidites (Fig. 2.3.2). to two murico-carina keels, whilst keeled
Cenozoic forms have a single solid keel. The
2.3.3. Palaeogeography & structures associated with apertures are always
perforate in Cenozoic forms and generally non-
palaeoceanography
perforate in the Cretaceous, with the development
!he Bidart K/T boundary section is particularly
of portici and tegilla. Further hinderance in the
Important because of its situation.
study of changes in planktonic foraminifera across
Palaeogeographically it lies intermediately
the K/T boundary lay in the failure, until quite
between Tethys and the north Atlantic (Fig.
recently, to universally recognise the Danian as
2.3.3). Although the south Atlantic is thought to
the basal Tertiary stage rather than the uppermost
hav~ had good communications with Tethys
Cretaceous subdivision (e.g. Eames, 1%8).
dunng late Mesozoic times, oceanographic
The first detailed K/T boundary
communications between the north and south
biostratigraphic studies of planktonic foraminifera
Atlantic are thought to have been restricted.
were carried out in Denmark, the Danian type
Therefore, the fauna and flora of the north
area (Bronnimann, 1953; Berggren, 1960, 1%2;
Atlantic would have been essentially different
and Hofker, 1960). Here the typical Maastrichtian
from the south Atlantic-Tethyan realm.
faunas are superceded by a fauna dominated by
Isotopic work carried out by Renard, et.
G/oboconusa daubjergensis. A later study at
a/. (1982) suggest that the Maastrichtian of Bidart
Gubbio in Italy (Luterbacher & Premoli-Silva
was deposited under Tethyan influences, whilst
1%4) revealed an older Palaeocene faun~
the Palaeocene was primarily influenced by the
characterised by the small globigerinid
north Atlantic. Therefore, one would expect
Parvu/arugog/obigerina eugubina. The recognition
Maastrichtian microfaunas and floras of Bidart to
of this older fauna meant that the previously
possess the characteristics of the south Atlantic-
studied type section in Denmark is incomplete.
Tethyan realm, whilst Palaeocene microfossils
This early Palaeocene fauna has now been
shouldbelong to the north Atlantic province.
reported from many localities worldwide
If this hypothesis does prove to be the
(Premoli-Silva, 1977). In addition an intermediate
caseit does not necessarily follow that the change
zone has been defined between the last
between the oceanographic provinces took place
Cretaceous planktonic foraminiferal zone of
~t the K/T boundary. Indeed, such a change is
Abathompha/us mayaroensis and the P. eugubina
likelyto be gradual and further isotopic work by
zone (Smit, 1977).
Clauser(1987), who extended his study down into
The Late Maastrichtian is divided into
the Campanian, identified a marked temporary
two zones as defined by Bronnimann (1952), the
increaseof 5180 at the Campanian/Maastrichtian
Gansserina gansseri partial range zone, from the
~o~d~ry which he interpr.eted as r~presenting an
first occurrence of G. gansseri to the first
InjectIOnof north Atlantic water mto a domain
occurrence of A. mayaroensis, an~ the A.
still submitted to the influence of Tethys"
mayaroensis total range zone. In addition to the
(Clauser, 1987, p. 579). It is probable therefore
above zones nominate taxa Racemiguembelina
that the change from Tethyan to north Atlantic
fructicosa, Contusotruncana contusa
influences at Bidart was a gradual process
Rugog/obigerina reiche/i, G/obotruncanella cita~
occurring throughout the Late Cretaceous
and G/obotruncanita conica are also typical of the
culminatingat or near the K/T boundary. '
uppermost Maastrichtian (Caron, 1985).
In one of the most complete K/T
2.4. Planktonic boundary sections known, near Caravaca in south-
Foraminifera east Spain, Smit (1977) discovered a thin clay

14. Fig. 2.3.3. Palaeogeographic setting of Bidart during a) the Maastrichtian, and b) the Palaeocene (after
Renard, et. al., 1982).
layer above the last occurrence of A. mayaroe1lsis. zone, M. u1lci1lata zone and the M. a1lgulata zone
This thin layer contained an unreworked (Tourmarkine & Luterbacher, 1985).
Cretaceous fauna of Archaeoglobigeri1la blowi,
Globigen'1lelloidessp.,Hedbergella m01lmouthe1lsis, 2.4.1. Previous work
and Guembelitria cretacea. This sparse fauna was The main biostratigraphic work of the Bidart
then joined by P. eugubi1la (marking the base section, using planktonic foraminifera, carried out
ofthe P. eugubi1la zone of Luterbacher & Premoli- prior to the present study, was undertaken by
Silva, 1964), P. fri1lga, and Chiloguembeli1la sp., Delacotte, et. al. (1985). As previously noted
before all the Cretaceous species, with the (Bonte, et. al., 1984), Delacotte, et. al. report that
exception of G. cretacea, became extinct. A. mayaroe1lsis, the uppermost Maastrichtian
Similar results were simultaneously index fossil, was not present in the 8m of
reported by Gamper (1977) from Mexico, who Maastrichtian strata they studied. Instead R.
defined this 'intermediate' zone of Smit (1977) as fructicosa and C. C01ltusa are used to infer an A.
the A. mayaroe1lsis IP. eugubi1la interval zone, mayaroe1lsis zone age for the Maastrichtian strata
between the last occurrence ofA. mayaroe1lsis and directly below the KIT boundary. Nelson, et. al.
the first appearance of P. eugubi1la. Later this (1991) however, record the first occurrence of A.
zonewas renamed the Guembelitria cretacea zone mayaroe1lsis at Bidart as 108m below the KIT
(Smit, 1982) although the definition remained boundary.
unchanged. However, there is a strong case for Above the KIT boundary the first few
retaining Gampers' (1977) original name because centimetres of the clay horizon is characterised by
G. cretacea is not restricted to this zone, but large benthic foraminifera (Bonte, et. al., 1984)
occurs throughout the Upper Maastrichtian and and reworked Heterohelicids and Globotruncanids
lowermost Danian, whereas A. mayaroe1lsisIP. (Delacotte, et. al., 1985). The first specimens of P.
eugubi1la interval zone is perhaps a better eugubi1la are encountered OAcm above the KIT
description because the zone is temporally boundary according to Smit (personal
bounded by the last and first occurrences of the communication, in Bonte, et. al., 1984).
nominate taxa respectively, and therefore unique Guembelitria exists in the P. eugubi1la zone fauna
to this zone. for a short time but soon becomes outnumbered
The standard zones which successively by Woodri1lgi1la. The M. pseudobulloides zone is
occur above the P. eugubi1la ZOne include the positively identified, whilst the overlying M.
Morozovella pseudobulloides zone, M. tri1lidade1lsis tri1lidade1lsis zone is inferred by the presence of

15. P/anorota/ites d. compressus (Delacotte, et. a/., section, and Rugoglobigerina reicheli is also lost
1985). 1m below the boundary, 16m above its first
appearance.
2.4.2. Stratigraphic distribution The appearance and disappearance of
The stratigraphic distribution of planktonic species throughout the duration of Maastrichtian
foraminifera species found at Bidart are shown in may not be attributable to the innovation and
Fig. 2.4.1. Species that are present throughout the extinction of the species, but may be due to the
Maastrichtian include ContusotfUncana contusa, C. varying abundances of the species concerned
walfischensis, G/obotfUncana aegyptiaca, G. arca, between the samples. However, it is much more
G. dup/eub/ei, G. esnehensis, G/obotruncanel/a certain that the disappearance of 28 species at the
havanensis, G/obotfUncanita angu/ata, G. end of the Cretaceous is due to extinction. It is
stuartifonnis, P/anog/obu/ina acervu/inoides, also likely that the disappearance of species, down
Pseudotextu/aria deform is , P. e/egans, to 6m below the boundary, is due to extinction.
Racemiguembe/ina fructicosa, Rugog/obigerina A single well-preserved specimen of
rugosa, Spirop/ecta americana, S. g/obu/osa, S. Globigerina triloculinoides was found in the
striata, and S. venti/abrel/ifonnis. topmost Maastrichtian sample, but was not
Approximately 10m above the base of the encountered again until above the boundary clay
section a flood of species appear that were not horizon. This specimen may be a contaminant,
previously encountered. Of these species only although the matrix is typical of this sample. The
G/obotfUncana fa/sostuarti, G. rosetta, first Palaeocene (boundary clay) sample contained
G/obotruncanita petersi, G. stuarti, a diverse benthic foraminifera fauna and
Pseudoguembe/ina costu/ata, P. exco/ata, P. numerous reworked Cretaceous planktonic
palpebra and Rugog/obigerina hexacamerata occur foraminifera. Amongst the Cretaceous taxa
throughout the remainder of the Maastrichtian. recovered, four specimens of Rugog/obigerina
Gansserina weidenmayeri, GlobotfUncana insignis, hexacamerata were picked and some uncertainty
and Rugog/obigerina scotti also first appear at this exists as to whether they are reworked or in situ.
horizon, but G. weidenmayeri and G. insignis Chi/oguembe/ina sp., Guembelitria
vanish 2m above this level. R. scotti however, is cretacea,Parvu/afUgog/obigerina eugubina, P. fringa,
lost from the section 10m above this level and is and Woodringina sp. are first encountered lOcm
joined by the disappearance of RugotfUncana above the KIT boundary and range throughout
subpennyi and ContusotfUncana fomicata which the remainder of the boundary clay horizon.
were both present at the base of the section. Morowvel/a pseudobul/oides and Planorota/ites
Simultaneous with the disappearance of compressa first occur in a G/obigerina
R. scotti, R. subpennyi and C. fomicata is the first tri/oculinoides dominated fauna, 25m above the
appearance in the samples of GlobotfUncanel/a boundary and range up to the top of the section.
peta/oidea, Rugoglobigerina reicheli and Globoconusa daubjergensis, Morozovella
Rugotruncana subcircumnodifer. G. petaloidea inconstans, and M. trinidadensis make their first
ranges from this point up to the KIT boundary. appearance 85m above the KIT boundary. M.
However, R. subcircumnodifer disappears 30m angulata is encountered 16m above the boundary.
above the base of the section with The preservation of the abundant
Globotruncanel/a minuta, which first occurred 10m planktonic foraminifera in the samples examined
abovethe base of the section, and Hedbergel/a sp. was poor to fair, with many morphological
whichhad been present from the base of section. features obscured by calcite overgrowths. The
Also at this point ContusotfUncana patelliformis, umbilical side of tests were particularly
C. p/icata, and Pseudotextularia varians first occur. overgrown, with the umbilicus and umbilical
Eight species disappear approaching the apertures often infilled with calcite. Other
KjT boundary. The' long ranging Gansserina umbilical features such as tegilla and portici uf the
gansseriand C. patel/iformis disappear 25m below Globotruncaniidae were frequently obscured.
the boundary. Archaeoglobigerina blowi, However, some perfectly preserved specimens
were encountered, particularly from the
Globigerinel/oidessubcarinata and Rugoglobigerina
macrocephala which have ranged up from the Palaeocene.
base of the section are lost 1m below the KIT
boundary. Globotruncanella citae and
G/obotruncanita conica also disappear at this level
after first appearing 10m above the base of the

16. Palaeocene
' .. +
,
OJ OJ OJ
~ ~
OJ~o
o ~
~
I)
98 S ---.J
(Jl
I
---J ~ ~3 ~3
.lc.
N
0 0
3
Arelzaeoglobigerina blowi
COlltusotnmeana conlllsa
Contusotnmealla fomicala
Contusolnmealla walfischeruil
GallSserilla gamseri
Globigerinelloides sllbcarinala
Globolnmcana aegypliaca
Globotrunealla area
Globotnmearza duplcllblei
GlobolruncanG esnchensis
Globolruneanella havanellSu
Globotruneanila angulata
Globotnmermita slllarti[onliU
Hedbergella sp.
Planoglobulina acervlliinoides
Pseudolexlularia defomlis
Pseudolcxtularia elcgallS
Raeenziguenzbelina [nlcticosa
Rugoglobigerina macrocepl:afa
RUSoglobigerilla rugosa
~golruncalla subpennyi
Spiropleela amen"cana
Spirapleeta globulosa
Spiroplecla sln"ata
Spiropleeta velllilabrclllfonliU
GarlSserina wiedenl1laycri
Globotnmcana falsoslllarti
Globotnmewza insignis
Globolnmcana rosella
Globotruncallita conica
Globotrullearlila pelersi
Globolruncanita stuarti
~ a ~. ""l
;:l .., Globotnmcanella eiwc
0- ~ Globotruncanella minlllu
N
0
3 N
;:l S· ~ Pseudoguembelina costulata
(i> 8'e-"
.., Pseudoguembelina excola/a
'" ~ ~
0.: .., Pseudoguembelina palpcbra
(1l~ Rugoglobigerina hexacalllcra/a
g .., ~(")
5-i 0 uq'
.., Rugoglobigen"na scotti
p.. '" ~
(i> '" Globotnlllewlelia pc/aloidea
..•
c-~
(i>
_. Rugoglobigerina reicheli
(")
Rugotruneana subcircwlInodifi
:r:i
.........
0-
Contusotruneana palcllifonliU
..., fa'
.., Pseudotextularia varians
0-: Colltusotruneana plica/a
cr g
0 Globigerina triloeulinoides
c: o'
;:l Ciziloguembelina sp.
0- ;:l
~ ,...,
0 Guembelitn"a erelacca
~ '0 Parvularugoglobigerina ellgllbin
~ ~;:l Parvularugoglobigenlza jn11sa
O:l"" Woodrillgina sp.
0.:0 Morozovella pseudobulloides
~ ;:l .
.., ;:;
,.... Planorotalites compressa
Globoeonusa daubjergensis
Morozovella inconslalls
Morozovella lrinidadcnsis
Morozovella angulala
:-0
~ ,..
>
~
,..
l ""
~ §. N
>
"~
~
N
0
" ~~
f '"
" ~ '1 Z
2
;; ~ ~ ~ en
C/l
~.
~

17. 2.4.3.Heterohelicid/'Globotruncanid' diversity between samples in the present study is
ratio shown graphically in Fig. 2.4.2c. It is clear that the
The Heterohelicid/'Globotruncanid' ratio refers Maastrichtian is relatively species rich, with
to the proportions of the planktonic foraminiferal between 21 and 36 species present in anyone
faunawhich are classified within the superfamily sample. There is a very sharp drop in the number
Heteroheliacea and the superfamilies of species across the K/T boundary with 29
Planomalinacea,Rotaliporacea, Globotruncanacea species present in the uppermost Maastrichtian
and Globorotaliacea (here informally grouped sample, and no planktonic species at all in the
together and termed 'Globotruncanids') fIrst Palaeocene sample. The remainder of the
respectively.This ratio is used here to quantify Palaeocene samples have characteristically low
'casual'observations reported by various workers species diversity, with between 3 and 7 species
of a declining 'Globotruncanid' population prior present in anyone sample, but does generally
to the K/T boundary (e.g. Keller, 1987). increase up section.
Results from the present study are The above method of species diversity
plottedin Fig. 2.4.2a 'Globotruncanids' are seen evaluation does not however, take into
to gradually decline in numbers throughout the consideration variations in the actual number of
Maastrichtiansection until 25m below the K/T individuals picked per sample. Understandably,
boundary when they undergo a percentage the more individual planktonic foraminifera
populationincrease. Following the K/T boundary picked, the higher the likelihood is of recovering
Heterohelicids decline rapidly with a higher number of species. As already stated, not
Chiloguembelina sp. and Woodringina sp. all the picked samples contain the same number
vanishing 2.20m above the K/T boundary, after of individuals, therefore this variable is important
which'Globotruncanids' comprise 100% of the and must be accounted for.
fauna.This increase in 'Globotruncanids' shortly This disparity can be levelled out using
beforethe Cretaceous termination at Bidart is the the a index of Fisher, et. af. (1943). The a index
oppositeof that reported from EI Kef (Keller, values for anyone sample of over 100 individuals
1987) and from DSDP sites 528 and 577, which can be read off a graph, such as given by Murray
possessan impoverished 'Globotruncanid' fauna (1991, his Fig. A.3). The a index values for the
priorto the K/T boundary. present study are plotted in Fig. 2.4.2d. Although
this plot resembles that of Fig. 2.4.2c, it does
2.4.4. Test size distribution reveal however, that fluctuations in species
diversity in the Maastrichtian (as shown on Fig.
Fig.2.4.2b shows the size distribution of the
2.4.2c) are in fact not real, but are a product of
largestindividual planktonic foraminifera per
variations in total assemblage counts. Therefore
sample.In the Maastrichtian Globotnmcanita
the species diversity throughout the Maastrichtian
stuarr; is usually the largest planktonic
sampled is more or less constant, but species
foraminifera,however Contusotruncana contusa
diversity does noticeably tail off towards the
and C. patellifonnis represent the largest
boundary.
planktonic foraminifera in a few samples.
Throughouthe boundary clay horizon individuals
t
of P. eugubina are the largest planktonic 2.4.6. Planktonic/Benthic ratio
foraminifera, whilst members of Morowvella are The planktonic/benthic ratio was established by
important throughout the remainder of the Murray (1976) as a crude method for estimating
Palaeocene. distance from shore and to broadly defIne the
Throughout the majority of the environment in which a sediment was
Maastrichtian sampled, test size decreases accumulated. In general a ratio of >70: < 30
gradually. owever, test size starts increasing
H represents an upper continental slope
rapidly6m below the K/T boundary and environment, 40-70:60-30represents an outer shelf
culminatesn the last Maastrichtian sample. No
i environment, 10-60:90-40 represents a middle
planktonic foraminifera were recovered from the shelf environment, and < 20: > 80 represents an
first alaeocene sample, but following that test
P inner shelf environment (Murray, 1991). The ratio
size increasesgradually throughout the section. is calculated by converting the complete
foraminifera fauna to 100% and working out the
percentage that both planktonic and benthic
2.4.5. Species diversity
foraminifera comprise within the fauna.
Species
diversity refers to the number of species
found each sample. The changes in species
in

18. QJ
C
QJ
u
40 o
QJ
ro
---
ro
0..
30
20
10
FiJ.:. 2..a.2. SI~li~li('11 V:Ui"lion tlr planklllliC rOr.llnillikr.l Ihmlghoul Ihe: l1ilJ:1I1 ~C("llon; a) IIClcrohcliciJ/,CilolllrUllf;lnid' r"lio; h)
Tc~1 si/.e t1islribulion; c) Species divc",il)' (:1flu:1I); tl) SllC(ics tJi'crsily (••Iphil index); anJ f) 1'1.1nl..ll111if/Bclllhic ralin.

19. eugubina 10cm above the KjT boundary marks
Fig. 2.4.2e displays the planktonicjbenthic the base of the P. eugubina zone. Approximately
ratio for the Bidart section. It is clear that 2.5m above the KjT boundary the first occurrence
throughout the Maastrichtian planktonic of M. pseudobulloides marks the base of the M.
foraminifera comprise approximately 95% of the pseudobulloides zone, with the M. trinidadensis
foraminiferal fauna. Immediately following the zone beginning 805mabove the boundary.
KjT boundary planktonic foraminifera disappear M. angulata first occurs 16m above the
completely but flood back in shortly afterwards to KjT boundary, marking the base of the M.
comprise approximately 75% of the fauna. A angulata zone and the base of the Thanetian
subsequent brief decline is soon replaced once stage. Thanetian age strata have not previously
again by a gradual increase which levels off at been reported from Bidart. This is perhaps due to
85:15and persists to the top of the section. the abundance of reworked foraminifera typical of
Utilizing Murray's (1991) generalisations the M. trinidadensis zone found in association with
to interpret the section, it could be argued that rare M. angulata. Furthermore, the M. angulata
for most of the section deposition occurred on a zone strata must lie unconformably upon M.
continental slope environment but switched to an trinidadensis zone limestones because the M.
inner shelf environment immediately following the uncinata zone is not detected. It may be inferred
KjT boundary. This however is undoubtedly that a hiatus in sedimentation existed at Bidart for
incorrect and the p:b ratio of 0:100 following the a duration of 350-750 kyr-l. This lapse in
KjT boundary is attributable to the mass sedimentaion also explains the high density of
extinction of planktonic foraminifera at the KjT reworked Danian foraminifera in Thanetian
boundary rather than to a drastic change in sediments.
depositional setting. This view is further Planktonic foraminifera are of limited use
corroborated by the rapid return to a planktonic in palaeoecological interpretation, with the
dominated foraminifera fauna shortly after the exception of geochemical analysis. Since no
KIT boundary. geochemistry was carried out on foraminifera tests
as part of this study, only general interpretations
2.4.6. Interpretation of results can be made. All data plotted on Fig. 2.4.2 shows
The abundant planktonic foraminifera of Bidart similar patterns. From the data it is clear that
allows accurate biostratigraphic age throughout most of the Maastrichtian the
determinations throughout the section (Fig. 2.4.1). palaeoenvironment was stable under normal
AlthoughA. mayaroensis was not encountered in marine conditions, with only minor fluctuations.
this study, or by Bonte, et. al. (1984) and Within 205m of the KjT boundary the change in
Delacotte, et. al. (1985), as already mentioned it lithology, extinction of certain species, and the
has been reported from Bidart 108m below the incoming of large 'Globotruncanids' suggests that
KIT boundary (Nelson, et. al., 1991). Therefore, the environment began to change, culminating at
the A. mayaroensis zone must be present at the KjT boundary itself where drastic events took
Bidart,however it does not extend into the section place.
studied here. The last occurrence of A. According to Boersma & Shackleton
mayaroensis at Bidart should lie between 37m and (1981) large 'Globotruncanids' are deep-water
108mbelow the KjT boundary. Keller (1988b) dwellers (see Davies, this volume, for full
defmed the P. defonnis zone to represent the discussion). Therefore the general decline of large
period between the last occurrence of A. 'Globotruncanids' below the KjT boundary
mayaroensis and P. defonnis at EI Kef. P. defonnis represents a regression of deep-water from Bidart.
is found throughout the Maastrichtian of Bidart, However, this trend is reversed 2.5m below the
therefore the Cretaceous strata studied here is boundary, indicating a short lived rapid
assignedto the P. defonnis zone. transgression.
The KjT boundary marks the end of the The environment represented by the KjT
diverseCretaceous planktonic foraminifera fauna. boundary had an adverse effect so that all species
The first Palaeocene microfauna examined is of Maastrichtian planktonic foraminifera became
dominatedby benthic foraminifera, however this extinct. The 100% benthic population at this level
zone may represent the G. cretacea zone of Smit (Fig. 2.4.2e) suggests that sea-levels fell drastically
(1982), lthough this is uncertain as no planktonic
a at this time, however this is unlikely and the 100%
foraminiferaoccur, perhaps with the exception of benthic reading is probably an effect of the
R. hexacamerata. The first occurrence of P. combination of mass planktonic foraminifera
extinction and slight regression rather than a

20. significant drop in sea-level. Following the the lowermost Palaeocene Markalius in versus
boundary it does appear that the early Palaeocene zone, she recognised that the Maastrichtian
environment was quick in re-establishing itself and nannoflora of Bidart is typical of the Tethyan
remaining stable throughout the duration of the realm. Variations between the Palaeocene
Palaeocene section studied. Certainly all data nannoflora of Bidart and at similar sections in
plotted on Fig. 2.4.2 reflect this scenario, so as to Denmark are attributed to latitudinal differences,
pin-point the KIT boundary precisely. although Perch-Nielsen does not go so far as to
compare the Bidart Palaeocene nannofloras with
2.5. Calcareous either the Tethyan or Atlantic provinces (see also
Perch-Nielsen, et. al., 1982).
Nannofossils Clauser (1987) recognised fivenannofossil
zones in the Maastrichtian of Bidart, with the
Bramlette & Martini (1964) were the first base of the Maastrichtian being identified by the
nannofossilworkers to recognise a great change in base of the Tetralithus trifidus zone and the
nannofloralassemblages occurring across the KIT uppermost Maastrichtian represented by the
boundary. Since then numerous studies of Micula prinsii zone as already recognised by
nannofloral changes across the KIT boundary Perch-Nielsen (1979a), the base of which he
havebeen carried out in various locations, such as identifies as occurring approximately 25m below
Denmark (Perch-Nielsen, 1969, 1979c & d), the KIT boundary. Clauser (1987) does not give
Zumaia, northern Spain (Percival & Fischer, any detailed information, but simply uses the
1977),Caravaca, south-east Spain (Romein, 1979), zones he recognises as a biostratigraphic
Gubbio, Italy (Monechi, 1977), the Alps (Herm, framework upon which carbon and oxygen stable
et. al., 1981), EI Kef, Tunisia (Perch-Nielsen, isotope data were plotted.
1981),and south-west France (Seyve, 1990). A much more detailed nannofossil study
In all the studies cited above most of the was carried out by Seyve (1990), who was solely
diverseMaastrichtian nannoflora becomes extinct concerned with the range of individual taxa across
at or shortly after the KIT boundary, with all the the KIT boundary. Seyve identified 51 species of
characteristically Cenozoic nannofossils evolving nannofossils, 80.4% of which originate in the
from twenty or so genera that survive the Maastrichtian and survive the KIT boundary,
boundary. The KIT boundary itself is in most 13.7% become extinct at the boundary and 5.9%
cases characterised by the blooming of certain first appear after the boundary.
species(Perch-Nielsen, 1985a) and is thought to Three blooming episodes were also noted
indicateharsh environmental conditions in which by Seyve (1990) immediately above the KIT
only certain tolerant species can survive and boundary. The first blooming event concerned the
thrive. calcareous dinoflagellate Thoracosphaera which
will be discussed later. The second bloom involves
2.5.1. Previous work Cyclagosphaera reinhardti which comprises 25% of
Someresults of nannofossil studies of the Bidart the nannoflora following the decline of
KIT boundary section have been previously Thoracosphaera. Braamdosphaera bigelowi blooms
published.Martini's (1961) purely taxonomic study prolifically approximately 60cm above the KIT
consideredonly two samples from the Palaeocene boundary where it comprises nearly 50% of the
of Bidart. Martini identified eight species as nannoflora. Some caution should be taken when
occurring in his samples, which (using updated directly interpreting these results as they represent
taxonomy)includes Micula mums, M. staurophora, relative rather than absolute abundances.
Calcu/ites obscums, Microrhabdulus decoratus, Therefore a population increase in one species
Braarudosphaera bigelowi, and Chiasmolithus would automatically decrease the percentage value
danicus. These species indicate an early of co-existing species, even though an actual
Palaeocene age, between the Marka/ius in versus population decline of a co-existing species may
(NNl) and Chiasmolithus danicus (NN3) zones of not have occurred.
Martini(1971).
Perch-Nielsen (1979a) examined 2.5.2. Stratigraphic distribution
numeroussamples from strata immediately above As already reported (Bonte, et. al., 1984) the
and below the KIT boundary at Bidart. In calcareous nannofossils of Bidart are poorly
addition to establishing the presence of the preserved and many of the diagnostic features are
uppermostMaastrichtian Micula prinsii zone and

21. Maastrichtian Palaeocene
f
- I
Cf (J1
~ r) coW
w 0 o o
3 :3 :3
Ceratliolithoides kamptncri
A1icrorhabdus belgieus
Mieula CO/Kava
Mieula deeussata
Micula murus
Quadrum trifidum
Tetrapod orh abdus deco/us
Ceratlzolitlzoides aeuleus
Braarudosplzacra turbinea
Bramudosplzaera bigelowi
Calculites obseUlus
Micula prinsii
Cyclagosphaera reinhard ti
M arkalius sp.
Chiasmolithus danicus
>-
:-0., >- 0
N
:-0., ~ N
0 N
N
N N 0 g-
Q g 0 §' 0 O
Q :J :J
:J
n
""2· Z
n ~
..., ~ ~
'" ;;;" n"
" §: t::
..., 1:; tT1
"" C/)

22. obscuredby calcite overgrowths. Therefore, many however, recognised the base of the C. tenuis
of the numerous spherical and elliptical species zone approximately 1m above the boundary.
were unidentifiable and positive identification The first occurrence of C. danicus 16m
could only be made concerning geometrically above the KIT boundary represents the base of
diagnosticspecies. the C. danicus zone which straddles the
The stratigraphic distribution of Danian/Thanetian boundary. Therefore, the first
calcareousnannofossils identified are shown in three standard Tertiary nannofossil zones are
Fig.2.5.1.In the lowermost Maastrichtian sample present at Bidart.
Tetrapodorhabdus decorus, Microrhabdus Nannofossils are of limited use for
belgicus,Micula decussata, M. concava, M. murus, palaeoecological interpretation. However, it
Ceratholithoides kamptneri and Quadrum trifidum appears that the palaeoenvironment was under
arepositivelyidentified. These species range up to relatively stable normal marine conditions
the KIT boundary and are joined 16m below the throughout the Maastrichtian. Adverse conditions
boundary by Ceratholithoides aculeus and at the KIT boundary caused the extinction of
Braarudosphaera turiJinea. Approximately 6m numerous species, but some taxa such as
below the boundary Micula prinsii, Calculites Braarudosphaera survived the boundary. Species
obscurus, and Braarudosphaera bigelowi are first diversity was slow to recover following the
encountered.All of the above mentioned species boundary, and this may reflect some sort of
arefound in the last Maastrichtian sample before environmental restraint on nannofloras.
the KIT boundary.
Throughout the boundary clay B. bigelowi
and Cyclagosphaera reinhardti (a new incoming
2.6. Calcareous
species)are extremely abundant, in association Dinoflagellates
with Markalius sp. and numerous Cretaceous
formswhich either survived the boundary or are The true affinities of the Cretaceous and Tertiary
reworked. Species diversity is fairly low 'calcispheres' was not realised until Tangen, et. al.
throughout the Palaeocene, but Chiasmolithus (1982) cultured the generotype of the genus
danicus was encountered 16m above the Thoracosphaera and found it to represent the
boundary. calcareous wall of the vegetative stage of a
dinoflagellate. Unlike the Neogene species
2.5.3.Interpretation of results Calciodinellum operosum Deflandre, which
The nannofossil zones interpreted as being possesses clear tabulation, the Cretaceous and
presentare included on Fig. 2.5.1. The M. murus Palaeogene taxa Pithonella Lorenz and
zone covers approximately 31m of the Thoracosphaera to a great extent lack surface
Maastrichtian section, with the remaining 6m morphology.
representedby the M. prinsii zone, with its base Thoracosphaera is the only genus
defined the first occurrence of M. prinsii. This
as common in Maastrichtian and Palaeocene
Maastrichtian zonation corroborates those of sediments. Out of the 20 or so species described
Perch-Nielsen (1979a) and Seyve (1990), who also for this genus, only 10 are now seen as valid
recognise base of the M. prinsii zone 6-8m
the (Fiitterer, 1977; and Jafar, 1979). The
below KIT boundary. Clauser (1987) however
the classification of Thoracosphaera species is based
putsthe base of the M. prinsii zone some 25m on the width, shape and outline of the
belowthe KIT boundary, and this scheme is archaeopyle, skeletal ultrastructure showing size,
followed Nelson, et. al. (1991). Due to poor
by shape and arrangement of skeletal elements, and
preservation nannofossils at Bidart it is often
of test size (Perch-Nielsen, 1985b).
difficultto distinguish M. prinsii from other Thoracosphaera is persistent throughout
Micula species, it is possible therefore that the Late Cretaceous, but is always uncommon.
Clauser 1987) misidentified the base of the M.
( However, blooms of Thoracosphaera occur at or
prinsiizone. shortly after the KIT boundary, and this event can
The base of the M. inversus zone is be used to recognise the KIT boundary. In the
identifiedy the extinction of typical Cretaceous
b present day Thoracosphaera inhabits open ocean
taxaat the KIT boundary. The duration of this normal marine environments, but during the KIT
zones uncertain because Cruciplacolithus tenuis,
i boundary period it is thought to have taken
theindexfossil for the successive zone, was not advantage of the lack of other calcareous
encountered this study. Perch-Nielsen (1979a)
in microplankton in the seas (Perch-Nielsen, 1985b).

23. zones. The first to be named the T. opercu/ala
2.6.1. Previous work partial range zone, ranging from the base of the
All previous work on calcareous dinoflagellates section to the first occurrence of T. saxea, and the
from Bidart has been undertaken by nannofossil T. saxea zone which ranges from the first
workers. Perch-Nielsen (1979a) noted that occurrence of the nominate taxa to the top of the
Thoracosphaera sp. dominated her lowermost section studied. In essence these two zones
Palaeocene sample, with representatives of the represent the Maastrichtian and Palaeocene
genera found throughout the 8m section she respectively.
examined, but being rare in the Maastrichtian and The most valuable aspect of calcareous
abundant throughout the Palaeocene. Bonte, et. dinoflagellates concerns palaeoecological
a/. (1984) were only able to recognise the KIT information that can be inferred from variations
boundary micropalaeontologically by the "greater in abundances. Clearly the acme of
densityof Thoracosphaera". This great abundance Thoracosphaera at the KIT boundary is
of Thoracosphaera at the KIT boundary was also environmentally significant, as at this time all
noted by Delacotte, et. a/. (1985). other calcareous microplankton declined markedly
Seyve (1990) made a fairly detailed study (nannofossils) or suffered mass extinction
of Thoracosphaera across the KIT boundary at (foraminifera). Under normal marine conditions
Bidart. Seyve identified the principle blooming Thoracosphaera comprises only a small proportion
species at the KIT boundary as T. opercu/ata. T. of the plankton, as observed throughout the
saxea was also illustrated from the Pointe-Sainte- Maastrichtian. However, at times of adverse
Anne KIT boundary section at Hendaye, to the environmental conditions, Thoracosphaera blooms
south of Bidart, and T. deflandrei was mentioned and dominates at the expense of other calcareous
in his systematic list of taxa, although it is not microplankton. Blooms probably arise from
clear whether this species was found in the reduced competition for calcium carbonate and
Hendaye or Bidart sections or both. This record other nutrients, and certainly due to the ability of
is particularly interesting as T. deflandrei was calcareous dinoflagellates to survive the KIT
previouslythought to have been restricted to the boundary event that reduced the number of
Miocene (Fiitterer, 1977; Jafar, 1979; and Perch- competitors.
Nielsen,1985b).
2.6.2. Stratigraphic distribution
T. opercu/ata was the only species present in the The taxa described from Bidart are typical of KIT
Maastrichtian. It is never abundant in the boundary sections. The biostratigraphic zones
Cretaceous, however at the KIT boundary T. used are standard, with the exception of the P.
apercu/ata is extremely abundant. Within this defonnis zone recently defined by Keller (1988b).
bloom T. opercu/ata is joined by rare T. saxea, T. The hiatus recognised across the
heimii and T. tesseru/a. These four species range DanianlThanetian boundary using planktonic
up to the top of the section and remain fairly foraminifera is supported by the first occurrence
common,however never as abundant as at the of the nannofossil C. danicus, which was
KIT boundary. encountered in the same sample as M. angu/ala.
In other KIT boundary sections C. danicus is
2.6.3. Interpretation of results encountered much lower down in the Palaeocene,
Thepopulation explosion and increase in species near the top of the M. trinidadensis foraminifera
diversityat the KIT boundary of the calcareous zone, but its true first occurrence at Bidart is not
dinoflagellatesappears to be linked. It may be recorded due to hiatus.
postulated that within the large T. opercu/ata Data obtained for planktonic foraminifera
populationmorphological variation was common, is similar to other KIT boundary sections such as
withsome successful mutations giving rise to new Sopelana (Lamolda, el. aI., 1983), Caravaca (Smit,
species, illing niches possibly left vacant by other
f 1977), Gubbio (Luterbacher & Premoli-Silva,
planktonspecies which underwent extinction. 1964), Ben Gurion, Israel (D'hondt & Keller,
Calcareous dinoflagellates have limited 1991) and numerous DSDP sites. However,
usein biostratigraphy. In addition to the ability to although superficially similar, Bidart differs from
recognise KIT boundary simply on the great
the El Kef, which has been studied extensively by
abundanceof Thoracosphaera at that level, from Keller (1987, 1988a & b), Brinkuis & Zachariasse
thisstudy it is possible to erect two informal (1988) and others. The main difference lies in the

24. increase,rather than decrease as seen at El Kef, Population changes within the
of large 'Globotruncanids' prior to the K/T Maastrichtian planktonic foraminifera faunas are
boundary. similar to other K/T boundary sections (e.g. El
These differences can be tentatively Kef), however at Bidart large 'Globotruncanids'
attributed to the marginal situation of Bidart in increase close to the boundary, rather than
respect to Tethys. From the decrease as at El Kef. This faunal composition
Campanian/Maastrichtian boundary onwards change 2.5m below the boundary correlates with
influxes north Atlantic water occurred regularly
of lithological change, an increase in strontium,
at Bidart (Clauser, 1987). This influx of deep 5018, and a decrease in 513e. This evidence
waterinto a shallowing Tethys increased rapidly suggests that Bidart switched from a Tethyan
throughout the fInal 90m of Maastrichtian at dominated palaeoceanographic setting to a
Bidart, as shown in strontium stable isotope primarily north Atlantic influence prior to the
results (Renard, et. al., 1982; and Nelson, et. al., K/T boundary.
1991). However, despite this growing influence of
the north Atlantic, the nannofloras (Perch-
Nielsen, 1979a) and planktonic foraminifera
remaintypical of the Tethyan province, with the
fauna dominated by Heterohelicids as at Ben
Gurionand El Kef (D'hondt & Keller, 1991). At
El Kef Heterohelicids undergo a population
increaseclose to the boundary, however at Bidart
they suffer a decline starting 205m below the
boundary.
This horizon also corresponds with a
changein lithology, from grey through brown to
redcolouration. Furthermore, the 87Sr/86Sr ratio
increases at this level from 0.70779 to 0.70782
(Nelson,et. al., 1991), as does the 5018 from -2
to -1 (Clauser, 1987), and the 513C decreases
from approximately + 2 to + 1 (Renard, et. al.,
1982). This evidence tends to support the
hypothesis that a palaeoceanographic switch
betweenTethyan dominated and north Atlantic
dominateddeposition took place 205mbelow the
KIT boundary at Bidart, prior to the terminal
Cretaceousevent, whilst locations such as El Kef
and Ben Gurion remained under a Tethyan
influencethroughout K/T boundary times.
Therelatively complete K/T boundary section at
Bidartwas studied. The distribution of planktonic
foraminifera, nannofossils, and calcareous
dinoflagellateswere established throughout 37m
of Maastrichtian and 21m of Palaeocene strata.
All Cretaceous planktonic foraminifera became
extinct t the K/T boundary, whereas only 83% of
a
nannofossil species were eliminated at the
boundary,and no calcareous dinoflagellates were
lost. A biostratigraphic analysis revealed that
Thanetian age strata are for the fIrst time
reported from Bidart, and a significant hiatus
representing350-750 kyr-l was detected straddling
theDanian/Thanetian boundary.

25. CHAPTER 3
ZUMAIA
GARY L. MULLINS

26. I.z ZUMAIA I
Figure 3.1.1 A location map for the KIT boundary section at Zumaia, Guipuzcoa Province, Northern Spain
(after Lamolda et al., 1988).
of the Biscay Ocean (Engeser el al., 1984). The
Zumaia syncline possesses European
palaeomagnetic values (Vandenburg 1980) whilst
Zumaia village in Guipllzcoa province, synclines further south exhibit Iberian ones. Voort
lies approximately 55km east of Bilbao on the (1964) stated that the Zumaia syncline therefore
northern coast of Spain. The Maastrichtian- belonged to the southern slope of the so called
Danian section, which is only accessible around Biscay High, which formed the SW e>.:tension of
periodsof low tide, lies WNW of the village (Fig. the European plate.
3.1.1) and can be reached by descending the small Zonal schemes have been erected using
set of steps that lie between Punta Aitzgorri and planktonic foraminifera (von Hillebrandt 1965)
the headland upon which the chapel is located. and ammonites and calcareous nannoplankton
The section at Zumaia, first described by were studied by Percival and Fisher (1977).
Gomez de Llarena (1954, 1956), has been Roggenthen (1976) was able to obtain good
important to the study of the Cretaceous-Tertiary magnetostratigraphic results for the lower
boundary for several reasons (Lamolda et al., Paleocene of Zumaia and Verosub (personal
1988). communication in Mary el a/1990) stated that the
1) The sedimentary continuity across the Maastrichtian palaeomagnetic results were not
KIT boundary. interpretable.
2) The relative abundance of fossil
remains throughout the Maastrichtian.
3) Absence, or near complete absence, of
turbidites in the purple marls and limestones of A lithological log of the section, showing
late Maastrichtian and early Paleocene ages. the location of sampling points,is displayed in Fig
4) The great thickness of the transitional 3.2.1, with an expanded log of the boundary
sequence shown in Figure 3.2.2. The succession
5.) The absence of tectonic deformation compnses:
withinthe transitional beds.
The section belongs to the northern most Unit 1) 42· 2m of purple marls of Maastrichtian
WNW-ESE striking syncline of the Basco- age, interbedded with thin (0' 02-0' 5m) green-
Cantabrian orogen, the Zumaia syncline (Engeser grey marls, sometimes slightly arenitic in nature.
et al., 1984). The syncline corresponds to a These layers represent the distal
sedimentary graben or half graben structure which
wasformed on a tilted block during the opening
Throughout this paper Zumaia is spelt with an "i", the true Basque spelling of the locality. The spelling of Zumaia with a
'y' has probably arisen by the translation to Catalan.

27. Lithological Log
OfZumaya
~~ ~ VI) ImertJecIded Thin Marls Om 1m 2m
~~ ~
~
t
c:
~~
!?. ~~ Purple Marl
~
~~~
C'kite Vc:m
.., ZD13 ~Mic:riIe
~limeotaDe
ZlJ2 + 'Ibk:Ir. Red Marls CJoeoD.Gcey AzlOIIilic Marl
~
.., Putple Micrite + ~U-
Hord 0..... Bmd& MoodyAm1ltlc
!
Buff Micri1e
~~
ZD12
0..... Horiz.oas LiJlu Orey 8o<mcIuy Cay
_ZV2 Dort Orey BoaDdory Oay
~~~
~~~ iDlaboddod Red
~~~
~~~
t
c:
Marls
ZDIl
Vtry Ran!
Putple + !!.
Clm:n_
~~~
Q
~~~
...
~~.•.
~ ~
~
~~
<>-
=:-'1
WI CoDooldU
Dark
PIII:ple
c:
!!.
VI
!
ZDIO
2D9
Marl &Ddo
~ [ ZDlS
~ ~ N
Buff CoIoured Top PinlrU-+
VII RecI Marls
-:l4
~
~~~ c:
!!.
~ ~~
~
~~
~
~~
~~~
! ZD8
~
,=:=...
~~
~~~
~~
ZD7
~
~
t
c:
Z06
See E.1:poDded
Seetial (Pia 0)
For Details Of
ZD5
!?. Iloulldary SompIiDa
~~~ VI PoilIts
~~~
ZD4
~ ~
~ ~ ~ c:
Z3 LomInaOOn. +
Ripples
~~~
..,
!?.
~ ._~I ~ ~~
~ ~
! ZV4

28. extremities of turbidites (Wiedmann 1988b) and Unit 5) 114m of green-grey limestone with
some exhibit segments of the Bouma sequence. green-grey marl bands.
For example the bed from which sample Z3 was Unit 6) 14·8m of pink-red micritic limestones
taken displays the A, B and C horizons of the with occasional red marl bands and hard green-
Bouma sequence. grey horizons.
Unit 2) 7-8m of hard purple micrites interbedded
with green beds and purple marls. This group of
lithologies forms a minor headland.
Unit 3) 10-5m of purple marls with intercalated To the author's knowledge no previous
green-grey beds. This unit forms the top palynological work has been undertaken on the
Cretaceous sediments. Maastrichtian-Paleocene boundary section at
Unit 4) 0-275m of grey marly clay with a O{)3m Zumaia. Biostratigraphic zones have been defmed
calcite vein at its base. Woody fragments are by the use of foraminifera (Herm 1%5, von
visible within the lower portion of this boundary Hillebrandt 1965) and ammonites (Wiedmann
bed. Lamolda et a/.,(1988) noted the anomalous 1988b).
enrichment of arsenic and cobalt and the slight Counts of 300 dinoflagellates and
increases of nickel and chromium within this bed. acritarchs were made from slides from each
Smit and Kate (1982) also recorded the sample. This enabled the calculation of the
occurrence of iridium within the rusty-pyritic relative abundances of individual taxa, the results
boundary layer. being plotted on two charts:
1) All taxa (Fig 3.3.1).
2) Taxa believed to be more biostratigraphically
useful (Fig 3.3.2).
Those slides for which counts of 300
palynomorphs could not be made are indicated
with an asterisk next to the sample number.
A number of taxa are found in both the
Maastrichtian and Paleocene ages. These taxa
Hard Grey Limestone
include Spiniferiles spp., Achomosphaera spp.,
With Marly Horizons Spiniferites sp. A, Areo/igera coronala (PI.8, fig 1),
Glaphyrocysla semitecla (P1.8, fig 4),
Hystrichosphaeridium tubiferum (PI. 9, fig 2),
Areoligera senonensis (P1.8, fig 3)
Exochosphaeridium sp. A (P1.9, fig 4) and
Trichodinium sp ..
From the sequence of first and last
occurrences of taxa at Zumaia a number of
apparently age diagnostic taxa become evident.
Light Grey Marly Clay
Dark Grey Marly Clay
"'v "'v"'v ----- Calcite Vein
.•...
..... ..... The dinoflagellate taxa which appear to
.•...
..........
.•...
ZV8~ ......•... be mainly restricted to the Maastrichtian are
ZV7~ Cannosphaeropsis untinensis (P1.8, fig 5),
Rigaudella ?apenninica (PI. 8,fig 6), Spongodinium
de/itiense (P1.10, fig 8), Disphflerogena
carposphaeropsis (PI.8, fig 2), Coronifera oceanica
(PI.9, fig 3), Codoniella campanulala (PI.11, fig 4)
and the acritarch species Cyclopsiella elliptica
(PI.11, fig 3). The recorded geological ranges of
some of these taxa varies between different
Figure 3.2.2 An expanded log of the KIT geographical localities and therefore their
boundary sequence at Zumaia. Legend as for Fig. accuracy as diagnostic taxa of the Maastrichtian
3.2.1. interval at Zumaia can not be proven until further