Quantification of the Indicative Meaning of A

Quantification of the indicative meaning of a • range of Holocene sea-level index points from the western North Sea. Volume One: Main text, References and Tables by Benjamin Peter Horton A thesis submitted in the fulfilment of the requirements for the degree of Doctor of Philosophy Department of Geography The University of Durham December 1997 The copyright of this thesis rests with the author. No quotation from it should be published without the written consent of the author and information derived from it should be acknowledged. 1 2 AUG 1998 n "The formula two and two makes five is not without its attractions" Dostoevsky Fedar Milkallovich ii Declaration This thesis is the result of my own work. Data from other authors which are referred to in the thesis are acknowledged at the appropriate point in the text. Copyright 1997 by B. P. Horton The copyright of this thesis rests with the author. No quotation from it should be published without his prior written consent and information derived from it should be acknowledged. in Abstract One of the main aims of the LOIS Special Topic Project Number 316, of which this thesis is a part, is to develop and validate models of some of the major characteristics of the Holocene evolution of the western North Sea. Establishing sea-level change is important to this. To meet this aim, the indicative meaning must be defined. The indicative meaning of a coastal sample is the relationship of the local environment in which it accumulated to a contemporaneous reference tide level. This thesis provides a method of estimating the indicative meaning based upon the contemporary relationship among relative sea-level, environmental conditions and the succession and seasonal variations of foraminiferal assemblages. Foraminiferal assemblages were collected over a period of twelve-months from the intertidal zone of four marshes along the margin of the western North Sea: Cowpen; Welwicic; Thontham; and Brancaster marshes. Statistical analyses indicate that the foraminiferal distributions are controlled predominantly by altitude. The contemporary foraminiferal distributions of each marsh display a vertical zonation with respect to mean sea level, though, their zonation dimensions differ. The foraminiferal assemblages are classified by multivariate analyses into two zones: a high, middle and low marsh zone dominated by agglutinated species such as Jadammina macrescens, Miliammina fusca and Trochammina inflata; and a low marsh and tidal flat zone dominated by calcareous species such as Elphidium williamsoni, Haynesina germanica and Quinqueloculina spp. The detailed foraminiferal data from each site has been combined to develop a quantitative reconstruction technique. This technique is used to estimate the indicative meanings of thirty-five sea-level index points which were chosen from specific locations and time periods during the Holocene. It is applicable to 'traditional' transgressive and regressive contacts, and more importantly, clastic sequences which have been previously ignored in the production of sea-level index points. iv Acknowledgements I would like to thank many people who have helped me towards the completion of this thesis. Firstly, I wish to express my gratitude to my supervisor, Professor Ian Sherman, and my second supervisor Dr Antony Long, for introducing me to the subject, for their help, advice, encouragement and involvement, especially during the final phase of this thesis. This thesis is one part of the Land -Ocean Interaction Study (LOIS) Speical Topic Project Number 316 and, therefore, I wish to thank members, past and present, of the Environmental Research Centre, University of Durham and other LOIS partners, who have helped me in my quest for wisdom, notably, Dr Ian Boomer„ Dr Roland Gehrels, Dr Jim Irmes, Dr Jerry Lloyd, Dr Andy Plater, Mairead Rutherford, Professor Michael Tooley and Dr Cheng Zong. I thank the following people who generously shared their knowledge, members of the Quaternary Laboratory and Cartographic section of the Department of Geography, University of Durham, Dr Heier- Neilsen, Professor Brian Huntley, Dr Steve Juggins, Niatnh McElherron and Dr John Whittaker. I wish to also thank my examiners, Professor John Birlcs and Dr David Brew, who provided many valuable suggestions. Secondly, I wish to thank the people who have made my time at Durham such an enjoyable and unforgettable experience. In particular, Eric Cantona, Robin Edwards, Dr Frances Green, Francis Greene, Jason Kirby, and Matt Wright, and Durham University Staff FC, and Manchester United FC. Most importantly, I wish to thank Sandra Grayson and my family for their support and loyalty, both in good and bad times (though they were few), throughout my time in Durham. It is to them that I dedicate this thesis. Contents of Volume One Declaration Abstract Acknowledgements List of Contents List of Tables Contents of Volume Two List of Contents Volume One 1. Introduction 1 1.1 Preface 1 1.2 Background 1 1.3 Aims and objectives 4 1.3.1 Aims 4 1.3.2 Objectives 4 1.4 Structure of thesis 5 2. Sea-level Index Points 7 2.1 Introduction 7 2.2 Definition of sea level 7 2.3 Interpretation of former sea levels 8 2.4 Indicative meaning 10 2.5 Sea-level indicators 11 2.5.1 Diatom analysis 12 2.5.2 Foraminiferal analysis 12 2.5.3 Pollen analysis 12 2.5.4 Stratigraphical analysis 13 2.6 Radiocarbon dating 13 2.7 Sources of error 14 2.7.1 Levelling the altitude of stratigraphic boundaries 14 2.7.2 Indicative meaning 16 vi 2.7.3 Tidal range 16 2.7.4 Sediment compaction 18 2.7.5 Dating of sea-level index points 19 2.8 Interpretation of sea-level index points 20 2.9 Summary 23 3. Saltmarsh microfossils 24 3.1 Introduction 24 3.2 Foraminiferal analysis 24 3.2.1 Foraminifera and environmental variables 25 3.2.2 Post-depostional changes of foraminiferal assemblages 30 3.3 Foraminiferal sampling 33 3.3.1 Collection and preparation of forarniniferal samples 33 3.3.2 Determination of the life foraminiferal population 35 3.3.3 Life versus death versus total assemblage constituents 36 3.4 Diatom analysis 38 • 3.5 Pollen analysis 40 3.6 Summary 41 4. Contemporary intertidal environments 43 4.1 Introduction 43 4.2 Cowpen Marsh 45 4.2.1 Environmental setting 45 4.2.2 Geological history 46 4.2.3 Materials and methods 48 4.2.4 Foraminiferal assemblages 50 4.2.5 Diatom assemblages 50 4.2.6 Environmental variables 51 4.2.7 Relationships between foraminifera and environmental variables 52 4.2.8 Multivariate analysis of contemporary foraminifera 54 4.2.9 Seasonality 59 4.2.10 Summary 62 4.3 Welwick Marsh 64 4.3.1 Environmental setting 64 4.3.2 Geological history 65 vii 4.3.3 Materials and methods 66 4.3.4 Foraminiferal assemblages 67 4.3.5 Diatom assemblages 67 4.3.6 Environmental variables 68 4.3.7 Relationships between foraminifera and environmental variables 68 4.3.8 Multivariate analysis of contemporary foraminifera 69 4.3.9 Summary 71 4.4 Thornham Marsh 72 4.4.1 Environmental setting 72 4.4.2 Geological history 73 4.4.3 Materials and methods 73 4.4.4 Foraminiferal assemblages 74 4.4.5 Diatom assemblages 75 4.4.6 Environmental variables 75 4.4.7 Relationships between foraminifera and environmental variables 76 4.4.8 Multivariate analysis of contemporary foraminifera 77 4.4.9 Summary 78 4.5. Brancaster Marsh 80 4.5.1 Environmental setting 80 4.5.2 Geological history 81 4.5.3 Materials and methods 81 4.5.4 Foraminiferal assemblages 81 4.5.5 Diatom assemblages 82 4.5.6 Environmental variables 83 4.5.7 Relationships between foraminifera and environmental variables 83 4.5.8 Multivariate analysis of contemporary foraminifera 84 4.5.9 Summary 86 4.6 Discussion 87 4.7 Chapter Summary 91 5. Quantitative water level reconstructions 93 5.1 Introduction 93 5.2 Relationships between foraminifera and environmental variables 94 5.2.1 Materials and methods 95 5.2.2 Results. 96 5.2.3 Synopsis 97 viii 5.3 Quantitative reconstruction from contemporary foraminiferal death assemblages 98 5.3.1 Linear or unimodal foraminiferal-standardised water level index response 99 models 5.3.2 Weighted averaging regression and calibration 100 5.3.3 Modern analogue technique 106 5.4 Discussion 108 5.5 Summary 110 6. Holocene sea-level index points from the margin of the western North 112 Sea 6.1 Introduction 112 6.2 Materials 113 6.3 Methods 114 6.3.1 Sampling strategy 114 6.3.2 Lithostratigraphy 114 6.3.2 Biostratigraphy 115 6.3.3 Indicative meaning 115 6.3.4 Radiocarbon dating 118 6.3.5 Consideration of errors 119 6.4 Results 120 6.4.1 Northumberland 120 6.4.2 Teesside 122 6.4.3 Humber estuary 124 6.4.4 Lincolnshire Marshes 126 6.4.5 Fenland 131 6.4.6 North Norfolk 137 6.5 Discussion 145 6.5.1 The indicative meanings of Methods I and II 147 6.5.2 AMS dating of calcareous foraminifera 151 6.6. Summary 153 7. Foraminiferal assemblages as indicators of sea-level change 154 7.1 - Introduction 154 7.2 Contemporary investigations 154 7.2.1 Foraminifera and environmental variables 155 ix 7.2.2 The vertical zonation of foraminifera from the margin of the western North Sea 156 and comparisons with assemblages of other temperate intertidal zones 7.2.3 Seasonal variations of foraminiferal assemblages and standardised water level 159 indices 7.3 Foraminiferal-based transfer functions for reconstructing former sea-levels 160 7.3.1 Materials and methods 160 7.3.2 Results 161 7.4 Fossil investigations 162 7.4.1 Quantification of the indicative meaning 162 7.4.2 The indicative meaning and sea-level index points 163 7.4.3 The application of the indicative meaning to clastic sequences 165 7.5 Summary 168 8.

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