A SEDIMENTOLOGICAL AND PALAEOECOLOGICAL STUDY OF OXFORDIAN (UPPER JURASSIC) CORAL-DOMINATED REEFAL CARBONATES IN WESTERN EUROPE (Volume 1: Text and Figures) by Enzo Insalaco A thesis submitted to the Faculty of Science of The University of Birmingham for the degree of DOCTOR OF PHILOSOPHY School of Earth Sciences Faculty o f Science The University of Birmingham November 1995 University of Birmingham Research Archive e-theses repository This unpublished thesis/dissertation is copyright of the author and/or third parties. The intellectual property rights of the author or third parties in respect of this work are as defined by The Copyright Designs and Patents Act 1988 or as modified by any successor legislation. Any use made of information contained in this thesis/dissertation must be in accordance with that legislation and must be properly acknowledged. Further distribution or reproduction in any format is prohibited without the permission of the copyright holder. S ynopsis The Late Jurassic was a time of intense reef development across much of western Europe, which lay on the northern margin of Tethys. There is a considerable diversity of coral reef types in terms of their architecture and geometry, palaeoecology and sedimentary regime. However, although many of these reefal units have been locally studied, there has hitherto been a lack of a coherent synthesis of Late Jurassic reef carbonates. The Oxfordian (Upper Jurassic) of England, France, Germany, Italy, Slovenia and Switzerland has been studied, and detailed comparative sedimentological and palaeoecological work has been carried out on twenty-four reef-bearing sections. This includes the description of a number of hitherto unstudied reef-bearing outcrops. The principal aims of this work are to: (1) identify and characterise different types of Late Jurassic coral reefs with regard to sedimentological and palaeoecological criteria; (2) identify the principal assemblages of macro-organisms, in particular the corals, and their facies occurrence within these reefs; (3) identify the major controls on Late Jurassic coral reef development; (4) develop a depositional model for Late Jurassic reef development relating these different reef types to each other within a spatial and temporal framework; and (5) assess the potential use of Late Jurassic corals as palaeoenvironmental indicators. From this work eight distinct reef types and one associated facies have been recognised, which are described in detail. These reef types are clearly distinct from each other in terms of a number of sedimentological and palaeoecological criteria. The development of these different structural and compositional types is interpreted as being primarily a function of light intensity, hydrodynamic energy levels and sediment balance. A conceptual depositional model based on these parameters is presented. This preliminary model can be used in two ways: (1) as a predictive tool for Late Jurassic reefal carbonates; and (2) to highlight sedimentological and palaeoecoloical trends in Late Jurassic reef development. The study has documented a decrease in coral generic richness with increasing palaeolatitute. It is assumed that this is correlated with temperature and a result of the “filtering-out” of stenotopic genera northwards. It has emerged that all high palaeolatitude coral faunas are of similar composition, regardless of facies, and are dominated by eurytopic forms. A growth rate study carried out on Thamnasteria concinna and Isastraea explanata revealed that they show marked variations in growth rate between reef types. However the study did not record a gradual decrease in coral growth rates with increasing palaeolatitude. It is argued that this is a consequence of the more equable Late Jurassic climate and the eurytopic nature of the two corals used in the study. Clear patterns with regard to coral growth forms and taxonomic composition are demostrated; these are described and their palaeoecological significance discussed. The study has also documented the importance of intra-reef microbialite in reef development and number of different types of microbialite have been identified. FRONTISPIECE ANUS, BURGUNDY, FRANCE. Burgundy has some of the best, yet most understudied, outcrops of Late Jurassic coral reefs in western Europe. It also has some of the most comical place names! (Anus, the place, can be found on the D300 9 km NNW of the Saussois reef section.) Dedication This thesis is dedicated to my family. I care for you more than words can say. Acknowledgements First and foremost I would like to thank Tony Hallam and Brian Rosen for their excellent supervision of this Ph.D. Their constant help, criticism and encouragement throughout the course of this work made the undertaking of this Ph.D. a most enjoyable and rewarding exercise. I am very grateful to Reinhart Gygi, Bernard Lathuiliere, Markus Bertling, Dragica Turnsek, Massimo Sarti and Neville Hollingworth for introducing me to various field areas and for helpful field discussion. I am also very grateful to the following for discussion on various aspects of this work: Nigel Cross, Jill Darrell, Rebbeca Day, Ian Fairchild, Jörn Geister, Ken Johnson, Reinhold Leinfelder, Noel Morris, Tim Palmer, Ewa Roniewicz, Arthur Satterley, Peter Skelton, Paul Taylor and Rachel Wood. In addition I would like to thank Reinhold Leinfelder, Tim Palmer, Finn Surlyk, Stephen Kershaw and Beris Cox for critically reviewing and improving the papers which form part of this thesis. I thank Paul Hands for his excellent preparation of thin sections and polished slabs. The financial and other help of Natural History Museum, and the funding of this work by NERC (studentship number: GT4/92/110/G) is gratefully acknowledged. Finally to the all the postgraduates, research assistants and research fellows, in particular Suzanne Burns, Stephanie Kape, Mat Haywood, Debbie Walker, Jackie Kilawee and Gavin Thomson, for making my years in the Birmingham unforgettable: thanks. CONTENTS SECTION 1: INTRODUCTION AND BACKGROUND TO THE PROJECT CHAPTER 1: Introduction, background and methods employed 1.1 Background.................................................................................................................................. 1 1.2 Project aim s.................................................................................................................................. 3 1.3 Study area and stratigraphic framework................................................................................ 3 1.4 Palaeogeography and palaeoclimate....................................................................................... 5 1.5 Methods, techniques and material 1.5.1. Fieldwork...................................................................................................................... 7 1.5.2. Type of field data collected......................................................................................... 9 1.5.3. Facies analysis............................................................................................................ 10 1.5.4. Diversity: definitions and its measurement................................................................ 10 1.6 Upper Jurassic coral taxonomy: systematics used and problems................................... 12 1.7 Previous classifications and models of Upper Jurassic coral reef development........... 14 1.8 Term inology................................................................................................................................. 20 SECTION 2: OBSERVATIONS CHAPTER 2: Burgundy 2.1: Introduction................................................................................................................................. 21 2.2: Chàtel-Censoir 2.2.1 Introduction and facies sequence............................................................................... 26 2.2.2 Reef structure and facies............................................................................................ 28 2.2.3 Palaeoecology.............................................................................................................. 29 2.2.4 Depositional environment............................................................................................ 29 2.3: Quatre Pieux 2.3.1 Introduction and facies sequence............................................................................... 30 2.3.2 Reef structure and facies............................................................................................. 30 2.3.3 Palaeoecology.............................................................................................................. 32 2.3.4 Depositional environment........................................................................................... 34 2.4: Bois du Parc 2.4.1 Introduction................................................................................................................... 35 2.4.2 Reef structure and facies .......................................................................................... 35 2.4.3 Palaeoecology.............................................................................................................. 36 2.4.4 Depositional environment......................................................................................... 37 2.5: Saussois 2.5.1 Introduction................................................................................................................... 38 2.5.2 Reef structure and facies............................................................................................