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Foraminifera) and Lithostratigraphy of the Cauvery Basin, Southeast India

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Foraminifera) and Lithostratigraphy of the Cauvery Basin, Southeast India The Middle to Late Cretaceous microbiostratigraphy (foraminifera) and lithostratigraphy of the Cauvery Basin, Southeast India by Archana Tewari, B.Sc, M.Sc. A thesis submitted to the University of Plymouth in partial fulfilment for the degree of DOCTOR OF PHILOSOPHY Department of Geological Sciences University of Plymouth Drake Circus, Plymouth PL4 8AA, UK. June 1996 BEEERENCE ONLY LIBRARY STORE UNiVERSITY OF PLYMOUTH IteI m No. Oato Contl.No, •I UBRAaVSBRVieES 90 0318871 2 Abstract The present research is on the Cretaceous microbio- and litho-stratigraphy of the Cauvery Basin, Southeast India. The planktonic and benthonic foraminifera are used to establish microbiostratigraphic zonations for the mid-Cretaceous succession in the Basin; leading to the first proposal of a benthonic foraminiferal zonation scheme. The schemes are primarily defined for regional application. In the absence of a formal lithostratigraphic classification for the Cretaceous succession in the Basin, a revised lithostratigraphy, in line with standard stratigraphic procedure, is proposed. The systematic taxonomy of the foraminifera studied is documented and revised in line with Western standards. The study shows that, in contrast to the standard European forms, the fauna fi-om the Cauvery Basin is composed of more robust individuals. The study also shows some interesting differences in the planktonic foraminifera fi*om the standard Tethyan assemblage. Comparative studies indicate a longer time range for some of the "index" species and more ornamented forms in the Cauvery Basin. The study records two levels, (I) in the late Albian and (2) fi-om the late Cenomanian to mid-Turonian, when anoxic conditions developed in the Basin. These anoxic events record major taxonomic changes in the planktonic foraminiferal assemblage. The study shows that the anoxic events had a major affect on the microfaunal community and that the post anoxic microfaunal population was dominated by more robust and heavily ornamented individuals. The planktonic foraminifera are used to identify the mid-Cretaceous sea-level changes in the Basin. The pattern of evolution and expansion of the planktonic foraminifera suggest a continuously rising sea-level in the mid-Cretaceous; with four periods of major transgressions. These levels are, at the late Albian, mid-Cenomanian, late Cenomanian-early Turonian and mid-Turonian. The pattern of sea-level changes in the Cauvery Basin followed , in general, the global sea-level curve, but has been influenced by local factors particularly tectonics. A pilot study demonstrates how palaeontology (including ichnology) in conjunction with sedimentology and stratigraphy is used to apply sequence stratigraphy concepts to the late Turonian-Coniacian succession in the Basin. A comprehensive study of Teredolites-infested fossil wood documents the morphological characters of the wood and its palaeoenvironmental significance. The study shows that there exists a close link between the influx of the fossil wood and sea-level dynamics. Declaration This is to certify that the work submitted for the Degree of Doctor of Philosophy under the title "The Middle to Late Cretaceous microbiostratigraphy (foraminifera) and lithostratigraphy of the Cauvery Basin, Southeast India" is the result of original work. All authors and works consulted are fully acknowledged. No part of this work has been accepted and/or submitted in substance for any other degree, nor is it being currently submitted for candidature for any other degree. During the course of this research the following papers have been pubUshed or submitted for publication on the results obtained: 1. Tewari, A., Hart, M.B. & Watkinson, M.P. 1996. Foraminiferal recovery after the nud-Cretaceous oceanic anoxic events (OAEs) in the Cauvery Basin, southeast India. In: Hart, M.B. (ed.), Biotic Recovery from Mass Extinction Events. Geological Society Special Publication, 102, pp. 237-244. 2. Tewari, A., Hart, M.B. & Watkinson, M.P. 1996. A revised lithostratigraphic classification of the Cretaceous rocks of the Trichinopoly District, Cauvery Basin, Southeast India. In: Pandey, J., Azmi, R.J., Bhandari, A. & Dave, A. (eds). Contributions to XVth Indian Colloquium on Micropalaeontolopv and Stratigraphy, pp. 789-800. 3. Hart, M.B., Tewari, A. & Watkinson, M.P. 1996. Wood boring bivalves from the Trichinopoly Sandstone of the Cauvery Basin, South-east India. In: Pandey, J., Azmi, R.J., Bhandari, A. & Dave, A. (eds). Contributions to XVth Indian Colloquium on Micropalaeontology and Stratigraphv. pp. 529-539. 4. Tewari, A., Hart, M.B. & Watkinson, M P. (accepted). Teredolites and its paleoenvironmental significance in the Ganidamangalam Sandstone Formation (late Turonian-Coniacian) from the Cauvery Basin, southeast India. Submitted to Ichnos. Copies of the published papers are bound into this thesis as Appendix 1 Candidate Archana Tewari Research Supervisors Prof Malcolm B. Hart to my parents with love Acknowledgements This research was conducted as a 'TSrehai Centenary British Fellowship" holder (December 1992 - June 1996) sponsored by the British Council, at the University of Plymouth under the supervision of Prof. Malcohn B. Hart. During the course of study several people have helped. Whilst it is impossible to mention each individual, the support of all those involved is acknowledged with sincere appreciation. The author is grateful for the study grant made available from the British Council and the supervision of Prof Malcolm. B. Hart; without the two this research would not have been accomplished. Throughout the course of research the guidance, encouragement and attention given by my supervisor Prof Hart was overwhelming. The persistent interest, enduring patience and unreserved support of Malcohn helped me through the daunting moments of the course. I thank Dr. Mathew P. Watkinson for co-supervising this research. The stimulating discussions and positive criticism by both the supervisors has added to the quality of this research. I thank the following scientists and technical staff for their contributions. Their help has been indispensable in the final completion of this work. Field assistance; Prof M B. Hart & Dr. M P. Watkinson (University of Plymouth); Dr. Govindan, Dr. Pandian & Dr. Ravindran (Oil and Natural Gas Commission); Dr. Venkatachalapathy (Madras University) and Mr. Lakshminarayanan (Dahnia Cement Company). Macrofossil identification: Dr. M. Thomson of British Antarctic Survey Group & Prof P. Bengston of Heidelberg University (ammonites); Dr. P. Doyle of Greenwich University (belemnites) and Dr. P. Skelton of Open University (rudist bivalves). Palvnological studies: Paul Dodsworth of Sheffield University. Thin section foraminiferai study: Prof M B. Hart. Translating French and German text: Prof M.B. Hart. Scientific discussions &/or comments, reprints and comparative material provided: M. Apthorpe, K. Ayyasami, R. Badve, R. Baneiji, P. Bengston, S. Bengston, P. Dodsworth, K. Doming, P. Doyle, A. Govindan, V. Kumar, M. Lamolda, S. Lakshminarayanan, S. Mohan, M. Mohanti, V. Narayanan, S. Pandian, D. Peacock, V. Phansalkar, D. Peryt, I. Premoli-Silvia, V. Ragothaman, K. Rajasekaran, C. Rajshekhar, D. Raju, K. Ramamoorthy, V. Ramasamy, C. Ravindran, M. Singh, P. Skelton, D. TarUng, M. Thomson, J. Thurow, J. Whittaker, A. Wonders. Technical assistance: J. Abraham (drafting Figures 2.1, 2.9, 3.2, 5.1, 6.1, 7.1-7.3 and Tables 3.1 & 3.2); M. Ashton (thin sections); M. Grimbly (micro-photography); IV A. Smith & D. Griffiths (photography); B. Lakey, R. Moate & J. Green (scanning electron micro-photography); D. Peacock & H. Shi (computer) and J. Brown & Ian Norton (inter-library loan). The staff of the Department of Geological Sciences, University of Plymouth are thanked for making me feel welcomed. Don Tarling and David Peacock are acknowledged for their advice and encouragement during the course and their honest opinion on the text they read. Tim Griffiths, Marylyn Luscott-Evans and Maureen Loton are thanked for all their favours. Philip Green, Sheila Stubbles, Meriel Fitzpatrick, Peter Bell and the staff at the International Office (University of Plymouth) are thanked for helping me to adjust to the social and the academic life in Plymouth. Finally I would like to extend my personal gratitude to the people whose silent presence has been of greatest assistance. The warmth and the affection I received from my landlady Maria and the landlord Nicholas have been humbling. I feel privileged to have enjoyed the luxury of parental attention out of home. The personal attention of "The Security" (University of Plymouth) towards my safety, during my out-of-hours working schedule, is very much appreciated. Dr. & Mrs. Saha; Margaret Stevens & family and Carole Wright are thanked for their thoughtfulness. The overwhelming flow of letters, cards and "remembering you" notes from my family and friends in India were always a welcome relief Last but not the least I thank my parents. My mother's trust and my father's memories are the bedrock of this achievement. During solitary, dark nights of lost confidence their thought has been my only strength. I dedicate this work to my parents. Contents Pai Abstract i Declaration ii Acknowledgements iv Contents vi Chapter 1 Introduction. 1 1.1 Introduction 2 1.2 Scope of the research 2 1.3 Experimental and analytical procedures 3 1.3.1 Sample collection 3 1.3 .2 Sample preparation 5 1.3.2.(i) Processing of samples 5 1.3.2.(ii) Thin section preparation 6 l.3.2.(iii) Lapped sections 7 1.3.3 Examination
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