The Distribution of the Foraminiferida in the Albian and Cenomanian of S.W. England. by M.B. Hart, B.So., F.C.S. Thesis Submitt
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The Distribution of the Foraminiferida in the Albian and Cenomanian of S.W. England. by M.B. Hart, B.So., F.C.S. VOL Thesis submitted for the Degree of Doctor of Philosophy of the University of London. February 1970. 2 Abstract An attempt has been made at resolving some of the difficulties of British mid—Cretaceous stratigraphic correlation using Foraminiferida. Over six hundred samples have been collected from all the major Albian and Cenomanian sections in south and south west England and these have been processed for their foraminiferal content. Over two hundred species and varieties from eighty six genera have been documented, many for the first time. These fossils have been used in the ratification of a zonal scheme and as a testing ground for a correlation technique based on the varying proportions of planktonic and benthonic individuals in each sample. The results of these investigations have demonstrated the value of Foraminiferida in the solution of stratigraphic problems, and as a result of this a new correlation scheme for the Albian and Cenomanian of southern England has been tentatively suggested. The Albian/Cenomanian and Cenomanian/Turonian boundaries have also been determined in the British lithological successions and characteristic faunas for each stage outlined. The main feature of stratigraphic interest has been the determination of a period of mid,-Cenomanian folding and its resulting affect on the stratigraphy. 3 Table of Contents page Abstract 2 Table of Contents 3 Index of Figures 4 Index of Text Plates 5 Index of Plates 6 Index of Enclosures 7 Acknowledgements 8 Chapter 1. Introduction 10 Chapter 2. History of Previous Research 15 Micropalaeontology 15 Stratigraphy 18 Chapter 3. Techniques .. 26 Sampling 26 Processing 28 Method of Study 28 Compilation of Data 30 Preparation of Illustrations 39 Chapter 4. Location of Sections 42 Chapter 5. Systematic Micropalaeontology 77 Chapter 6. Stratigraphic Summary 226 Chapter 7. Conclusions 268 General Bibliography 274 Micropalaeontological Bibliography 280 Plates of Foraminiferida 301 4 Index of Figures, page Fig.l. Outline of Processing Techniques 29 Fig.2. Outline of Zonal Scheme 32 Fig.3. Key for C.F.P. Graphs 36 Fig.4. Details of the Membury Quarry excavations 74 Fig.5. Sketch map of the south of England shoWing the main axes of mid—Cenomanian folding 75 Fig.6. Evolutionary trends within the genus qtrenobulimina'.. 106 Fig.7. Evolutionary trends within the genus 'Arenobulimina'.. 108 Fig.8. Evolutionary trends within 0.1enticularis (Blum) 119 Fig.9. Evolutionary trends within the Globigerinacea 186 Fig.10. Evolutionary trends within the Globigerinacea 198 Fig.11. Evolutionary trends within the genus 'Gavelinella' 218 Fig.12. Evolutionary trends within the genus 'Lingulogavelinella' 222 Fig.13. Schematic illustration of the main facies variations related to the non—sequence 239 Fig.14. Details of the Fetcham Mill Borehole 257 5 Index of Text Plates T.Plate 1. Rhythmic sedimentation in the Lower Chalk of Culver Cliff, Isle of Wight. T.Plate 2. a) General view of the Lower Chalk succession at Culver Cliff. b) General view of the Lower Chalk succession at Compton Bay. T.Plate 3. a) Reef of Exanthesis labrosus (T.Smith) in the Chalk Marl of Culver Cliff. b) Washout channel in the Upper Cenomanian of Culver Cliff. T.Plate 4. a) General view of the Lower Chalk succession at Durdle Door, Dorset. b) Enlarged view of the Basement Bed at Durdle Door. T,Plate 5. a) General view of the Snowdon Hill Quarry, Chard, Somerset. b) General view of the Dead Maid. Quarry, Mere, Wiltshire. T.Plate 6. a) The Cenomanian Limestone succession at Tom Tizzards Hole, Beer, Devon. b) General view of the Cenomanian Limestone succession at the southern end of Beer Bay. T.Plate 7. a) General view of Purley Quarry, Membury, Devon. b) The Fallen Block at the Pinnacles, Little Beach, Branscombe, Devon. T.Plate 8. Enlarged view of the Fallen Block at the Pinnacles. T.Plate 9. a) The Cenomanian Sands succession, Bovey Lane Sandpit, Beer, Devon. b) The Cenomanian Sands succession, White Hart Sandpit, Wilmington, Devon. 6 Index of Plates Plate 1. Ammodiscacea& Lituolacea. Plate 2. Lituolacea. Plate 3. Lituolacea, Plate 4. Lituolacea. Plate 5. Lituolacea. Plate 6. Lituolacea. Plate 7. Lituolacea, Miliolacea, Nodosariacea. Plate 8. Nodosariacea. Plate 9. Nodosariacea. Plate 10. Nodosariacea. Plate 11. Nodosariacea. Plate 12. Nodosariacea. Plate 13. Nodosariacea. Plate 14. Nodosariacea. Plate 15. Buliminacea & Discorbacea. Plate 16. Discorbacea, Spirillinacea, Globigerinacea. Plate 17. Globigerinacea. Plate 18. Globigerinacea. Plate 19. Globigerinacea. Plate 20. Globigerinacea. Plate 21. Globigerinacea, Orbitoidacea, Cassidulinacea. Plate 22. Cassidulinacea. Plate 23. Cassidulinacea. Plate 24. Cassidulinacea. Plate 25. Cassidulinacea & Robertinacea. 7 Index of Enclosures Enc. 1. Geological Maps of Southern England — with locality details. Enc. 2. Eastbourne (Beachy Head). Enc. 3. Culver Cliff (Isle of Wight). Eno. 4. Compton Bay (Isle of Wight). Enc. 5. GaUlt/Lower Chalk — including the Cambridge Greensand. Enc. 6. The Dorset Coast. Enc. 7. The Mid—Dorset Area (1). Enc. 8, The Mid—Dorset Area (2). Enc. 9. Devon — Coastal Sections. Enc. 10. Devon — Inland Sections. Enc. 11. Devon — (Inland) and Somerset. Enc. 12. Upper Greensand of the Devon/Dorset Coast. Enc. 13. Lower Chalk (Wilts and Bucks). Enc. 14. C.F.P. Correlations (1). Enc. 15. C •P•1 11 • Correlations (2). 8 Acknowledgements The author is primarily indebted to D.J. Carter of Imperial College who has guided the research from its inception in 1966 when the first material was collected from the mid-Dorset area. It was after this preliminary excursion that the value of a full scale research venture was realised and since that time the author has benefitted in many ways from the experienced guidance of Mr. Carter. For all this help and guidance the author is deeply grateful. The author is also indebted to Dr. B. Denness (ex-Imperial College) for his assistance in the collection of material from the Isle of Wight, and to Dr. W.J. Kennedy (Oxford University) for discussion of the macrofossil distribution in the Lower Chalk. Many other people deserve a mention at this stage but, for reasons of space, they cannot all be mentioned in the above manner. The author apologises for this and trusts that the following will serve as an acknowledgement of their assistance. Discussion of Stratigraphy Mr. D. Curry, Dr. J.M. Hancock, Dr. C. Jeans, Dr. R.P.S. Jefferies, Dr. W.J. Kennedy, Dr. H.G. Owen. Discussion of Palaeontology Dr. R. Casey, Dr. J.M. Hancock, Dr. C. Jeans, Dr. W.J. Kennedy, Dr. H.G. Owen, Dr. C.J. Woods. Discussion of Micropalaeontology - including those who have sent reprints of papers and comparative material. Dr. C.G. Adams, Dr. O.L. Bandy, Dr. A. Butt, Mr. D. Curry, Dr. C.G. Douglas, Dr. D.L. Eicher, Dr. Z.R.M. El-Naggar, F. Jannin, Dr. R.P.S. Jefferies, M. Malapris, Dr. T. Neagu. 9 Photography and production of plates Mrs. M. Culpam, Mr. J. Gee, Dr. M. Muir, and Mr. E. Lawson (Newcastle). General assistance and discussion S.S. Ali, I. Al—Kassab, P.J. Bigg, B. Cann, S. Darmoian, W.L. Diver, R.J.O. Hamblin, Jaworski, Dr. M.S, Norvick, G.M. Williams. The author is also indebted to members of the Staff at the University of Newcastle upon Tyne and in particular to Professor T.S. Westoll, for assistance in the completion of this thesis. The author gratefully acknowledges the award of a Research Studentship from the Natural Environmental Research Council during the tenure of which (1966-69) the work for this thesis was executed. Finally there are the thanks to my wife who has helped in almost every field of the research, from the collection of samples to the preparation of the final plates. Apart from these more active pursuits there are the countless times when patient silence was the greatest assistance one could have wanted. 10 CHAPTER l Introduction During the past five years most geologists have been involved to a greater or lesser degree in a new wave of stratigraphio inter- pretation. Commissions and Committees have been set up in many countries to consider where and on what grounds stratigraphic divisions can be drawn. There are naturally many factors to be taken into consideration when dealing with divisions of this magnitude but for the purpose of most geological work only two main conditions must be fulfilled. They are:- 1. Time units (stages, zones, etc.) should be defined palaeontologically and should not be based on lithological units unless direct palaeontological evidence is lacking. 2. In defining these units only the base of each unit should be so defined. In this situation the base of one unit is of necessity the top of the preceding unit. In this country we have a classic situation in the mid-Cretaceous where these two rules have been greatly abused. For the last one hundred and fifty years geologists have been studying this part of the geological record in great detail and it is somewhat surprising to find that there are large gaps as well as anomalies in our knowledge. If one follows the course of research from the original sources to the present time one can immediately see where judge- ment and science have gone astray. A detailed account of this shall follow but in order to delimit the scope of the present research a few comments must be made here. William Smith was the first to begin this particular dialogue when he divided the Cretaceous into the basic lithological units of 11 the Chalk, Greensand, Gault clay, etc. He amplified this in his writings by saying that some of the beds could be identified by the fossils they contained.