Provided by the author(s) and NUI Galway in accordance with publisher policies. Please cite the published version when available. Title Controls on upper Viséan (Carboniferous) depositional environments in Ireland Author(s) Barham, Milo Publication Date 2010-11-02 Item record http://hdl.handle.net/10379/2187 Downloaded 2021-09-28T11:08:54Z Some rights reserved. For more information, please see the item record link above. Controls on upper Viséan (Carboniferous) depositional environments in Ireland Volume I (of II) Text Milo Barham Supervisors: Dr. John Murray and Prof. D. Michael Williams A thesis submitted for the degree of Doctor of Philosophy Earth and Ocean Sciences School of Natural Sciences National University of Ireland, Galway November 2010 CONTENTS TABLE OF CONTENTS TABLE OF CONTENTS ……………………………………………………………………i ABSTRACT ...………………………………………………………………………………v ACKNOWLEDGEMENTS……………………………………………...………………… vi CHAPTER 1 - INTRODUCTION ............................................................................... 1 1.1 CONODONT BIOLOGY AND BIOFACIES ..................................................... 1 1.1.1 The conodont animal ................................................................................. 2 1.1.2 Conodont elements .................................................................................... 3 1.1.3 Upper Viséan to Serpukhovian conodont biofacies ....................................... 6 1.2 CARBONIFEROUS STRATIGRAPHY ............................................................ 8 1.2.1 Upper Viséan to Serpukhovian biostratigraphy .......................................... 10 1.3 THE CARBONIFEROUS GLACIATION ........................................................ 12 1.3.1 Timing .................................................................................................... 12 1.3.2 Magnitude ............................................................................................... 14 1.3.3 Causes .................................................................................................... 19 1.4 THE VISÉAN TO SERPUKHOVIAN OF IRELAND ...................................... 23 1.5 THE PROJECT .............................................................................................. 25 1.5.1 Background ............................................................................................. 25 1.5.2 Aims ....................................................................................................... 27 1.5.3 Methods .................................................................................................. 28 1.5.4 Thesis plan .............................................................................................. 31 CHAPTER 2 - THE GEOLOGY OF NW IRELAND: SUCCESSIONS IN COUNTIES SLIGO AND LEITRIM ................................................ 33 2.1 STRATIGRAPHY OF THE NW IRELAND SUCCESSIONS STUDIED .......... 33 2.1.1 The Mullaghmore Sandstone Formation .................................................... 34 2.1.2 The Benbulben Shale Formation ............................................................... 35 2.1.3 The Glencar Limestone Formation ............................................................ 35 2.1.4 The Dartry Limestone Formation .............................................................. 36 2.1.5 The Meenymore Formation ...................................................................... 37 2.1.6 The Glenade Sandstone Formation ............................................................ 38 2.1.7 The Bellavally Formation ......................................................................... 39 i CONTENTS 2.1.8 The Carraun Shale Formation ................................................................... 40 2.1.9 The Dergvone Shale Formation ................................................................ 42 2.1.10 The Briscloonagh Sandstone Formation .................................................... 43 2.2 SLIGO GROUP SECTIONS IN NW IRELAND .............................................. 44 2.2.1 Tievebaun Section (GL03, GLTV) ............................................................ 45 2.2.2 Glencar Section (DA01, DAGL) ............................................................... 48 2.2.3 Glenade Section (Leckanarainey stream, DA02, DAGN) ............................ 51 2.3 LEITRIM GROUP SECTIONS IN NW IRELAND .......................................... 53 2.3.1 Aghagrania Section (AGHA) .................................................................... 53 2.3.2 Carraun/Lugasnaghta Section (CNLG) ...................................................... 62 2.4 INTERPRETATION AND ANALYSIS OF FIELD DATA ............................... 72 2.5 CYCLICITY AND DIGITAL SPECTRAL ANALYSIS OF THE TIEVEBAUN SECTION ................................................................................ 79 2.6 DISCUSSION ................................................................................................ 84 CHAPTER 3 - THE SHANNON BASIN AREA ....................................................... 89 3.1 STRATIGRAPHY OF THE SHANNON BASIN AREA ................................... 89 3.1.1 The Burren Formation .............................................................................. 91 3.1.2 The Slievenaglasha Formation .................................................................. 91 3.1.3 The Magowna Formation ......................................................................... 92 3.1.4 The Clare Shale Formation ....................................................................... 92 3.1.5 The Ross Sandstone and Gull Island Formations ........................................ 93 3.2 GEOLOGY OF THE SECTIONS EXAMINED ON THE BURREN PLATFORM .................................................................................................. 95 3.2.1 Kilnamona Section (KMONA) ................................................................. 95 3.2.2 St. Brendan’s Well Section (BW) ............................................................. 97 3.3 EVOLUTION OF THE SHANNON BASIN AND BURREN REGION ........... 100 3.4 SIGNIFICANCE OF THE SITES INVESTIGATED ...................................... 104 CHAPTER 4 – MICROFAUNAL ANALYSIS ........................................................ 107 4.1 MICROFOSSIL SAMPLES AND RESIDUES ............................................... 107 4.1.1 Tievebaun Section ................................................................................. 107 4.1.2 Glencar Section ..................................................................................... 108 4.1.3 Glenade Section .................................................................................... 108 ii CONTENTS 4.1.4 Aghagrania Section ................................................................................ 109 4.1.5 Carraun/Lugasnaghta Section ................................................................. 109 4.1.6 Kilnamona Section ................................................................................ 109 4.1.7 St. Brendan’s Well Section ..................................................................... 110 4.2 CONODONT FAUNA .................................................................................. 111 4.3 TRANSITIONAL CONODONT FORMS, NATURAL VARIATION AND ABNORMALITIES ...................................................................................... 128 4.4 CONODONT BIOSTRATIGRAPHY, WITH AN EMPHASIS ON THE GENUS LOCHRIEA. .................................................................................... 132 4.5 ICHTHYOLITH FAUNA ............................................................................. 138 4.6 PRESERVATION OF VERTEBRATE REMAINS ........................................ 161 4.7 PALAEOENVIRONMENTAL SIGNIFICANCE OF MICROFOSSILS .......... 164 CHAPTER 5 - STABLE ISOTOPE ANALYSIS ..................................................... 167 5.1 INTRODUCTION TO STABLE ISOTOPES ................................................. 167 5.1.1 Stable isotopes of Oxygen ...................................................................... 168 5.1.2 Application to palaeoclimatology............................................................ 169 5.2 ANALYSIS OF BIO-APATITE FROM IRELAND ........................................ 174 5.2.1 δ18O results from NW Ireland ................................................................. 174 5.2.2 δ18O results from the Burren Platform, western Ireland ............................. 179 5.3 DISCUSSION .............................................................................................. 183 5.3.1 Understanding the isotopic signal ........................................................... 183 5.3.2 Isotopic discrepancy between the study regions. ...................................... 190 5.3.3 Inter- and intra-conodont and ichthyolith isotopic variations. .................... 197 5.3.4 Palaeoclimatic interpretation .................................................................. 201 CHAPTER 6 - DISCUSSION & CONCLUSIONS .................................................. 203 6.1 CARBONIFEROUS SEA-LEVELS AND SEQUENCE STRATIGRAPHY ..... 203 6.1.1 Global record of Carboniferous sea-levels ............................................... 203 6.1.2 Interpretation of upper Viséan and Serpukhovian sea-level variation in Ireland .................................................................................................. 205 6.2 CONTROLS ON NW IRELAND DEPOSITION – THE CARBONIFEROUS GLACIATION AND STABLE ISOTOPE RECORD .....................................