The Development of the Princess Charlotte Bay Chenier Plain
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THE DEVELOPMENT OF THE PRINCESS CHARLOTTE BAY CHENIER PLAIN DYLAN HORNE A thesis submitted in fulfilment of the requirements for the degree of Doctor of Philosophy. School of Physical, Environmental and Mathematical Sciences, University College, University of New South Wales. August 2011 i Abstract Chenier plains record changes in the mode of coastal progradation between periods of mudflat progradation and coarse sediment deposition. There are several environmental forces responsible for these changes. Chenier research worldwide has led to an understanding of these forces in some settings. In Australia, however, the causes of these changes are still not well understood. Several conflicting theories have been proposed to explain the development of a chenier plain in Princess Charlotte Bay on the eastern coast of Cape York, northern Queensland, Australia. These include an internal dynamic, climate fluctuations, and storm activity. Since these were put forward, both our methods and our understanding of Holocene environmental processes have improved. Improvements include new dating methods with luminescence techniques. Improvements to our understanding include a body of research regarding Holocene climate and sea level changes. These have allowed a re-examination of the development of the Princess Charlotte Bay chenier plain. Data was obtained from a different section of the bay than was examined previously. Optically-stimulated luminescence and radiocarbon ages from eight of the 11 chenier ridges yielded estimates of Holocene chenier ridge building phases. These were: (1) An early phase from around 4000 yr BP – 2000 yr BP (seven ridges built); (2) a phase centred on approximately 1350 yr BP (two ridges built); and (3) a phase since 820 yr BP (one ridge built). Six models for chenier plain formation were tested. It was proposed that the development of the chenier plain has been driven by several environmental forces acting in a morphodynamic hierarchy. From first order to fourth order, these forces are: (1) Holocene ii climate and sea level changes, (2) tropical cyclone activity, (3) mangrove distribution, and longshore currents, and (4) river channel changes. A statistical reassessment of Australian chenier ridge ages was also undertaken and revealed periods of non-localised chenier ridge building across multiple northern Australia sites at around 620, 1120, 1850, and 2230 cal yr BP, and around the entire continent between 2400 and 1300 cal yr BP. These results provide further support that sea level oscillations have played a role in chenier plain development in Australia. iii Acknowledgements I would like to thank the following people who have assisted me through my studies and the preparation of this thesis: Dr Alan Hogg at the University of Waikato, Hamilton, New Zealand for conducting the radiocarbon dating. Mr David Price at the University of Wollongong, Dr Kathryn Fitzsimmons at the Australian National University, Canberra, and Dr Matthew Cupper at the University of Melbourne for conducting the TL and OSL dating work and providing helpful comments on related thesis sections. Technical staff from the School of Physical, Environmental and Mathematical Sciences, UNSW@ADFA, for their assistance in organising field work. Rohan Coghlan for helping to source the topographic/bathymetric data, taking the time to create a figure and encouraging alternate pursuits that kept me sane. Dr Ben O’Neill for developing the statistical technique used in reassessing Australian chenier ridge ages and providing assistance in writing the related thesis sections. Dr David Paull for his co-supervision and very helpful comments on the draft. Ellie Rae and Melrose Brown for their selfless assistance in completing difficult field work and for providing support and friendship through the course of my studies. My partner Rachel for her love, patience and selfless support through the entire process. My family for their invaluable support. Finally, the most important person: Professor Brian Lees for his dedicated supervision and mentoring. Completing this research was only possible because of his knowledge, guidance and encouragement. I have felt honoured to work with him and I couldn’t imagine a better supervisor. Thank you. iv Aerial photography contained in this document has been provided by the State of Queensland (Department of Environment and Resource Management) 2009. In consideration of the State permitting use of this aerial photography it is acknowledged and agreed that the State gives no warranty in relation to the data and accepts no liability for any loss, damage or costs relating to the use of the aerial photography. v Contents Abstract i Acknowledgements iii Contents v Originality statement x 1. Introduction 1 1.1 Australian chenier plains and Princess Charlotte Bay 1 1.2 The value of studying chenier plains 4 1.3 Research aim 7 1.4 Structure of this thesis 7 2. Literature review 9 PART A - CHENIER PLAIN GEOMORPHOLOGY 2.1 Introduction: Cheniers and chenier plains 10 2.1.1 Definitions of chenier plains and how they have developed 10 2.1.2 Chenier plains worldwide and Australian study sites 13 2.2 Morphological similarities between chenier ridges and other features 17 2.3 Why study chenier plains? 18 2.4 Approaches to the study of chenier plains 20 2.4.1 Physiographic description 21 2.4.2 Regional stratigraphy 21 2.4.3 Stratigraphic distinctions 22 2.4.4 Coastal process studies and morphodynamics 23 2.5 Theories regarding the development of chenier plains 24 2.5.1 Models of chenier plain development 25 2.5.1.1 River channel switching 26 2.5.1.2 Mud shoal migration 27 2.5.1.3 Climate fluctuations 30 2.5.1.4 Storm activity 31 2.5.1.5 Tsunami 33 2.5.1.6 Human impacts 34 2.5.1.7 Sea level oscillations 36 2.5.1.8 Fluctuations in shellfish populations or an internal dynamic 37 2.5.1.9 Summary and combinations of models 39 2.5.2 Shoreline processes 40 2.5.2.1 Winnowing and sorting 41 2.5.2.2 Wave deposition, in situ accretion and underlying deposits 42 2.5.2.3 Internal structure 44 2.5.2.4 Landward migration 45 2.6 Discussion: A fundamental condition for chenier plain development 47 vi 2.7 Summary 52 PART B - PALAEOENVIRONMENTAL CHANGES IN NORTHEASTERN QUEENSLAND AND PRINCESS CHARLOTTE BAY 2.8 Introduction 54 2.9 Palaeoclimates and change 55 2.9.1 Late Pleistocene climates in north eastern Queensland 56 2.9.1.1 The Last Glacial Maximum and aeolian activity 56 2.9.1.2 Post-glacial warming and climate change to the early Holocene 59 2.9.2 Holocene climates and change in north eastern Queensland 61 2.9.2.1 Late Holocene climates 61 2.9.2.2 The El Nino Southern Oscillation 64 2.9.2.3 The Medieval Warm Period and the Little Ice Age 65 2.9.2.4 Late Holocene sea surface temperatures 67 2.9.3 Holocene storm activity in the Princess Charlotte Bay region 68 2.10 Sea level changes 70 2.10.1 Glacial cycle sea level changes and interglacial high stands 71 2.10.2 Holocene sea level changes 74 2.10.2.1 Cessation of the post-glacial transgression 74 2.10.2.2 Smooth or oscillating late Holocene sea level curve? 75 2.10.2.3 Smooth sea level curve 76 2.10.2.4 Oscillating sea level curve 78 2.10.2.5 Possible geomorphic expressions of sea level oscillations 81 2.10.2.6 Hydro-isostacy and tectonic effects 83 2.11 Human occupation and fire in the Princess Charlotte Bay region 84 2.12 Summary 85 PART C - DATING TECHNIQUES 2.13 Introduction 87 2.14 Issues associated with using radiocarbon dating in chenier studies 88 2.14.1 Marine reservoir effects 88 2.14.2 Associating sample with event 89 2.14.3 A possible alternative to radiocarbon methods 90 2.15 Luminescence dating techniques 91 2.15.1 Reliability of luminescence dating techniques 92 2.15.2 A brief overview of luminescence concepts 94 2.15.3 Thermoluminescence and Optically Stimulated Luminescence 95 2.16 Summary 97 3. Research design 99 3.1 Introduction 99 3.2 Chenier plain development models Princess Charlotte Bay 100 3.2.1 Hypothesis (1): River channel switching 102 vii 3.2.2 Hypothesis (2): Mud shoal migration 103 3.2.3 Hypothesis (3): Climate fluctuations 104 3.2.4 Hypothesis (4): Tropical cyclone activity 104 3.2.5 Hypothesis (5): Human activity 106 3.2.6 Hypothesis (6): Sea level oscillations 107 3.2.7 A possible combination of other models 108 3.3 Reassessing the results of previous Australian chenier plain studies 109 3.4 Summary 111 4. Methods 113 4.1 Introduction 113 4.2 Site description and regional setting 114 4.2.1 Location, geology and regional setting 114 4.2.2 Climate 116 4.2.3 Fluvial characteristics 117 4.2.4 Marine characteristics 118 4.2.5 The chenier plain and study site 120 4.3 Air photo and imagery analysis 122 4.4 Topographic surveys 123 4.4.1 Surveying methods used in previous studies 123 4.4.2 DGPS and RTK DGPS 124 4.4.3 Surveying the Princess Charlotte Bay transect 125 4.5 Stratigraphic analysis and distinctions 125 4.6 Dating techniques 126 4.6.1 Luminescence dating 127 4.6.1.1 Sample collection in the field 127 4.6.1.2 Thermoluminescence laboratory procedure 128 4.6.1.3 Optically-Stimulated Luminescence laboratory procedure 131 4.6.2 Radiocarbon dating 133 5. Results 135 5.1 Introduction 135 5.2 Aerial photography, satellite imagery and regional observations 136 5.2.1 Aerial photography and images 136 5.2.2 Regional observations on ridges in Princess Charlotte Bay 144 5.3 Regional morphostratigraphy landward of the transect 146 5.4 Vegetation, stratigraphy and chronology of landscape units 151 5.4.1 Vegetation and general descriptions of chenier ridges 1 to 5 and 10 155 5.4.2 Vegetation and general descriptions of chenier ridges 6 to 11 160 5.4.3 Individual ridge characteristics and dating results 164 5.4.4 Samphire flat and saltmarsh 167 5.4.5 Modern beach and intertidal muds 168 5.5 Dating results 172 5.5.1 Thermoluminescence results 172 viii 5.5.2 Optically-Stimulated Luminescence results 176 5.5.3 Fire and bioturbation as sources of error in luminescence results 184 5.5.4 Radiocarbon results 185 6.