SELECTED CRETACEOUS/TERTIARY           BOUNDARY SECTIONS

                          FROM




                            B...
Firstly, we would like to thank Professor J.W. Murray, Dr. Ron Austin, Dr. John
Marshall and Dr. Ian "holiday" Harding for...
Acknowledgments

      1 Introduction                                                        1

      2 The Bidart Section...
4.4 Palaeoecology                                           44

         4.5 Conclusions                                  ...
1. ABSTRACT / INTRODUCTION

The Cretaceous/Tertiary Boundary marks the           (ii) Zumaia: This section is located appr...
Northwestern Tunisia. Deposition at K/T                 from section to section is interpreted as an effect
boundary times...
CHAPTER 2

    BIDART

SIMON K. HASLETT
walled microfossils as part of this study but failed
                                                       to yield signi...
Bay of
                  Biscay




                                                                                     N...
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 ...
_     Micrite (undifferentiated)


                   1)1   Clay, red calc-argillite

             +-'
             .c
   ...
Bidart is represented by approximately 200m of                s;umping.
grey and brown marls (calc-argillites) assigned to...
east. During the Maastrichtian the sedimentation         considered to have limited use in biostratigraphy
rate is thought...
Fig. 2.3.3. Palaeogeographic    setting of Bidart during a) the Maastrichtian,    and b) the Palaeocene       (after
Renar...
P/anorota/ites d. compressus        (Delacotte,     et. a/.,    section, and Rugoglobigerina reicheli is also lost
1985). ...
Palaeocene
                                                                  ' .. +

                                     ...
2.4.3.Heterohelicid/'Globotruncanid'                 diversity between samples in the present study is
                  r...
QJ
     C
     QJ
     u
40   o
     QJ
      ro
     ---
      ro
     0..

30


20


10



           FiJ.:. 2..a.2. SI~...
eugubina 10cm above the KjT boundary marks
          Fig. 2.4.2e displays the planktonicjbenthic   the base of the P. eugu...
significant drop in sea-level. Following the            the lowermost Palaeocene Markalius in versus
boundary it does appe...
Maastrichtian                                Palaeocene
                            f
                                    ...
obscuredby calcite overgrowths. Therefore, many        however, recognised the base of the C. tenuis
of the numerous spher...
zones. The first to be named the T. opercu/ala
            2.6.1. Previous work                        partial range zone,...
increase,rather than decrease as seen at El Kef,                Population    changes     within    the
of large 'Globotru...
CHAPTER 3

    ZUMAIA

GARY L. MULLINS
I.z   ZUMAIA     I




Figure 3.1.1 A location map for the KIT boundary                    section at Zumaia, Guipuzcoa   ...
Lithological Log
                                                                                                         ...
extremities of turbidites (Wiedmann 1988b) and                 Unit 5) 114m of green-grey limestone with
some exhibit segm...
An integrated palynological and micropalaeontological investigation of selected cretaceous/tertiary boundary sections from...
An integrated palynological and micropalaeontological investigation of selected cretaceous/tertiary boundary sections from...
An integrated palynological and micropalaeontological investigation of selected cretaceous/tertiary boundary sections from...
An integrated palynological and micropalaeontological investigation of selected cretaceous/tertiary boundary sections from...
An integrated palynological and micropalaeontological investigation of selected cretaceous/tertiary boundary sections from...
An integrated palynological and micropalaeontological investigation of selected cretaceous/tertiary boundary sections from...
An integrated palynological and micropalaeontological investigation of selected cretaceous/tertiary boundary sections from...
An integrated palynological and micropalaeontological investigation of selected cretaceous/tertiary boundary sections from...
An integrated palynological and micropalaeontological investigation of selected cretaceous/tertiary boundary sections from...
An integrated palynological and micropalaeontological investigation of selected cretaceous/tertiary boundary sections from...
An integrated palynological and micropalaeontological investigation of selected cretaceous/tertiary boundary sections from...
An integrated palynological and micropalaeontological investigation of selected cretaceous/tertiary boundary sections from...
An integrated palynological and micropalaeontological investigation of selected cretaceous/tertiary boundary sections from...
An integrated palynological and micropalaeontological investigation of selected cretaceous/tertiary boundary sections from...
An integrated palynological and micropalaeontological investigation of selected cretaceous/tertiary boundary sections from...
An integrated palynological and micropalaeontological investigation of selected cretaceous/tertiary boundary sections from...
An integrated palynological and micropalaeontological investigation of selected cretaceous/tertiary boundary sections from...
An integrated palynological and micropalaeontological investigation of selected cretaceous/tertiary boundary sections from...
An integrated palynological and micropalaeontological investigation of selected cretaceous/tertiary boundary sections from...
An integrated palynological and micropalaeontological investigation of selected cretaceous/tertiary boundary sections from...
An integrated palynological and micropalaeontological investigation of selected cretaceous/tertiary boundary sections from...
An integrated palynological and micropalaeontological investigation of selected cretaceous/tertiary boundary sections from...
An integrated palynological and micropalaeontological investigation of selected cretaceous/tertiary boundary sections from...
An integrated palynological and micropalaeontological investigation of selected cretaceous/tertiary boundary sections from...
An integrated palynological and micropalaeontological investigation of selected cretaceous/tertiary boundary sections from...
An integrated palynological and micropalaeontological investigation of selected cretaceous/tertiary boundary sections from...
An integrated palynological and micropalaeontological investigation of selected cretaceous/tertiary boundary sections from...
An integrated palynological and micropalaeontological investigation of selected cretaceous/tertiary boundary sections from...
An integrated palynological and micropalaeontological investigation of selected cretaceous/tertiary boundary sections from...
An integrated palynological and micropalaeontological investigation of selected cretaceous/tertiary boundary sections from...
An integrated palynological and micropalaeontological investigation of selected cretaceous/tertiary boundary sections from...
An integrated palynological and micropalaeontological investigation of selected cretaceous/tertiary boundary sections from...
An integrated palynological and micropalaeontological investigation of selected cretaceous/tertiary boundary sections from...
An integrated palynological and micropalaeontological investigation of selected cretaceous/tertiary boundary sections from...
An integrated palynological and micropalaeontological investigation of selected cretaceous/tertiary boundary sections from...
An integrated palynological and micropalaeontological investigation of selected cretaceous/tertiary boundary sections from...
An integrated palynological and micropalaeontological investigation of selected cretaceous/tertiary boundary sections from...
An integrated palynological and micropalaeontological investigation of selected cretaceous/tertiary boundary sections from...
An integrated palynological and micropalaeontological investigation of selected cretaceous/tertiary boundary sections from...
An integrated palynological and micropalaeontological investigation of selected cretaceous/tertiary boundary sections from...
An integrated palynological and micropalaeontological investigation of selected cretaceous/tertiary boundary sections from...
An integrated palynological and micropalaeontological investigation of selected cretaceous/tertiary boundary sections from...
An integrated palynological and micropalaeontological investigation of selected cretaceous/tertiary boundary sections from...
An integrated palynological and micropalaeontological investigation of selected cretaceous/tertiary boundary sections from...
An integrated palynological and micropalaeontological investigation of selected cretaceous/tertiary boundary sections from...
An integrated palynological and micropalaeontological investigation of selected cretaceous/tertiary boundary sections from...
An integrated palynological and micropalaeontological investigation of selected cretaceous/tertiary boundary sections from...
An integrated palynological and micropalaeontological investigation of selected cretaceous/tertiary boundary sections from...
An integrated palynological and micropalaeontological investigation of selected cretaceous/tertiary boundary sections from...
An integrated palynological and micropalaeontological investigation of selected cretaceous/tertiary boundary sections from...
An integrated palynological and micropalaeontological investigation of selected cretaceous/tertiary boundary sections from...
An integrated palynological and micropalaeontological investigation of selected cretaceous/tertiary boundary sections from...
An integrated palynological and micropalaeontological investigation of selected cretaceous/tertiary boundary sections from...
An integrated palynological and micropalaeontological investigation of selected cretaceous/tertiary boundary sections from...
An integrated palynological and micropalaeontological investigation of selected cretaceous/tertiary boundary sections from...
An integrated palynological and micropalaeontological investigation of selected cretaceous/tertiary boundary sections from...
An integrated palynological and micropalaeontological investigation of selected cretaceous/tertiary boundary sections from...
An integrated palynological and micropalaeontological investigation of selected cretaceous/tertiary boundary sections from...
An integrated palynological and micropalaeontological investigation of selected cretaceous/tertiary boundary sections from...
An integrated palynological and micropalaeontological investigation of selected cretaceous/tertiary boundary sections from...
An integrated palynological and micropalaeontological investigation of selected cretaceous/tertiary boundary sections from...
An integrated palynological and micropalaeontological investigation of selected cretaceous/tertiary boundary sections from...
An integrated palynological and micropalaeontological investigation of selected cretaceous/tertiary boundary sections from...
An integrated palynological and micropalaeontological investigation of selected cretaceous/tertiary boundary sections from...
An integrated palynological and micropalaeontological investigation of selected cretaceous/tertiary boundary sections from...
An integrated palynological and micropalaeontological investigation of selected cretaceous/tertiary boundary sections from...
An integrated palynological and micropalaeontological investigation of selected cretaceous/tertiary boundary sections from...
An integrated palynological and micropalaeontological investigation of selected cretaceous/tertiary boundary sections from...
An integrated palynological and micropalaeontological investigation of selected cretaceous/tertiary boundary sections from...
An integrated palynological and micropalaeontological investigation of selected cretaceous/tertiary boundary sections from...
An integrated palynological and micropalaeontological investigation of selected cretaceous/tertiary boundary sections from...
An integrated palynological and micropalaeontological investigation of selected cretaceous/tertiary boundary sections from...
An integrated palynological and micropalaeontological investigation of selected cretaceous/tertiary boundary sections from...
An integrated palynological and micropalaeontological investigation of selected cretaceous/tertiary boundary sections from...
An integrated palynological and micropalaeontological investigation of selected cretaceous/tertiary boundary sections from...
An integrated palynological and micropalaeontological investigation of selected cretaceous/tertiary boundary sections from...
An integrated palynological and micropalaeontological investigation of selected cretaceous/tertiary boundary sections from...
An integrated palynological and micropalaeontological investigation of selected cretaceous/tertiary boundary sections from...
An integrated palynological and micropalaeontological investigation of selected cretaceous/tertiary boundary sections from...
An integrated palynological and micropalaeontological investigation of selected cretaceous/tertiary boundary sections from...
An integrated palynological and micropalaeontological investigation of selected cretaceous/tertiary boundary sections from...
An integrated palynological and micropalaeontological investigation of selected cretaceous/tertiary boundary sections from...
An integrated palynological and micropalaeontological investigation of selected cretaceous/tertiary boundary sections from...
An integrated palynological and micropalaeontological investigation of selected cretaceous/tertiary boundary sections from...
An integrated palynological and micropalaeontological investigation of selected cretaceous/tertiary boundary sections from...
An integrated palynological and micropalaeontological investigation of selected cretaceous/tertiary boundary sections from...
An integrated palynological and micropalaeontological investigation of selected cretaceous/tertiary boundary sections from...
An integrated palynological and micropalaeontological investigation of selected cretaceous/tertiary boundary sections from...
An integrated palynological and micropalaeontological investigation of selected cretaceous/tertiary boundary sections from...
An integrated palynological and micropalaeontological investigation of selected cretaceous/tertiary boundary sections from...
An integrated palynological and micropalaeontological investigation of selected cretaceous/tertiary boundary sections from...
An integrated palynological and micropalaeontological investigation of selected cretaceous/tertiary boundary sections from...
An integrated palynological and micropalaeontological investigation of selected cretaceous/tertiary boundary sections from...
An integrated palynological and micropalaeontological investigation of selected cretaceous/tertiary boundary sections from...
An integrated palynological and micropalaeontological investigation of selected cretaceous/tertiary boundary sections from...
An integrated palynological and micropalaeontological investigation of selected cretaceous/tertiary boundary sections from...
An integrated palynological and micropalaeontological investigation of selected cretaceous/tertiary boundary sections from...
An integrated palynological and micropalaeontological investigation of selected cretaceous/tertiary boundary sections from...
An integrated palynological and micropalaeontological investigation of selected cretaceous/tertiary boundary sections from...
An integrated palynological and micropalaeontological investigation of selected cretaceous/tertiary boundary sections from...
An integrated palynological and micropalaeontological investigation of selected cretaceous/tertiary boundary sections from...
An integrated palynological and micropalaeontological investigation of selected cretaceous/tertiary boundary sections from...
An integrated palynological and micropalaeontological investigation of selected cretaceous/tertiary boundary sections from...
An integrated palynological and micropalaeontological investigation of selected cretaceous/tertiary boundary sections from...
An integrated palynological and micropalaeontological investigation of selected cretaceous/tertiary boundary sections from...
An integrated palynological and micropalaeontological investigation of selected cretaceous/tertiary boundary sections from...
An integrated palynological and micropalaeontological investigation of selected cretaceous/tertiary boundary sections from...
An integrated palynological and micropalaeontological investigation of selected cretaceous/tertiary boundary sections from...
An integrated palynological and micropalaeontological investigation of selected cretaceous/tertiary boundary sections from...
An integrated palynological and micropalaeontological investigation of selected cretaceous/tertiary boundary sections from...
An integrated palynological and micropalaeontological investigation of selected cretaceous/tertiary boundary sections from...
An integrated palynological and micropalaeontological investigation of selected cretaceous/tertiary boundary sections from...
An integrated palynological and micropalaeontological investigation of selected cretaceous/tertiary boundary sections from...
An integrated palynological and micropalaeontological investigation of selected cretaceous/tertiary boundary sections from...
An integrated palynological and micropalaeontological investigation of selected cretaceous/tertiary boundary sections from...
An integrated palynological and micropalaeontological investigation of selected cretaceous/tertiary boundary sections from...
An integrated palynological and micropalaeontological investigation of selected cretaceous/tertiary boundary sections from...
An integrated palynological and micropalaeontological investigation of selected cretaceous/tertiary boundary sections from...
An integrated palynological and micropalaeontological investigation of selected cretaceous/tertiary boundary sections from...
An integrated palynological and micropalaeontological investigation of selected cretaceous/tertiary boundary sections from...
An integrated palynological and micropalaeontological investigation of selected cretaceous/tertiary boundary sections from...
An integrated palynological and micropalaeontological investigation of selected cretaceous/tertiary boundary sections from...
An integrated palynological and micropalaeontological investigation of selected cretaceous/tertiary boundary sections from...
An integrated palynological and micropalaeontological investigation of selected cretaceous/tertiary boundary sections from...
An integrated palynological and micropalaeontological investigation of selected cretaceous/tertiary boundary sections from...
An integrated palynological and micropalaeontological investigation of selected cretaceous/tertiary boundary sections from...
An integrated palynological and micropalaeontological investigation of selected cretaceous/tertiary boundary sections from...
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An integrated palynological and micropalaeontological investigation of selected cretaceous/tertiary boundary sections from western Europe and north Africa

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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.

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An integrated palynological and micropalaeontological investigation of selected cretaceous/tertiary boundary sections from western Europe and north Africa

  1. 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. 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. 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. 4.4 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. 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. 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. 7. CHAPTER 2 BIDART SIMON K. HASLETT
  8. 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. 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. 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. 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. 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. 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. 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. 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. 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. 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. 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. 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. 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. 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. 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. 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. 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. 25. CHAPTER 3 ZUMAIA GARY L. MULLINS
  26. 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. 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. 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

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