Characterisation and Spatial Variability of the Magnetic and Electrical Resistivity Geophysical Properties of the Soils of Count
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Characterisation and Spatial Variability of the Magnetic and Electrical Resistivity Geophysical Properties of the Soils of Counties Kildare and Wicklow, Eastern Ireland. Samar Alduraibi Supervisor: Doctor Paul Gibson Thesis submitted for the degree of Ph.D. Faculty of Social Science Department of Geography Maynooth University May 2018 CONTENTS ABSTRACT………………………………………………………………….... XIV ACKNOWLEDEGMENTS…………………………………………………… XV CHAPTER 1 INTRODUCTION 1.1 Introduction ..........................................................................................................1 1.2 Geographical characteristics of the study area .....................................................2 1.3 Aims and Objectives and Research Question ......................................................7 1.4 Layout of the thesis ..............................................................................................8 CHAPTER 2 Theoretical Concepts and Research Methodology 2.1 Introduction .......................................................................................................10 2.2 Magnetic methodology and theoretical concepts............................................... 10 2.2.1 Introduction .........................................................................................10 2.2.2 Magnetic domains ...............................................................................12 2.2.3 Remanent Magnetism .........................................................................13 2.2.4 Field collection procedures for magnetic data.................................... 13 2.2.5 Laboratory measurement of mass specific susceptibility................... 20 2.2.6 Frequency dependent magnetic susceptibility ....................................24 2.2.7 Magnetic susceptibility of fractional data ...........................................25 2.2.8 Laboratory measurement of variation of volume susceptibility with temperature ………………………………………………………...………28 2.2.9 Collection of data for remanent magnetism measurements ................31 2.2.10 Laboratory measurement of remanent magnetism............................ 33 2.3 Resistivity methodology and theoretical concepts............................................ 37 2.3.1 Introduction......................................................................................... 37 2.3.2 Factors which control the resistivity/conductivity of a soil…............ 38 2.3.3 Resistivity of lithologies, unconsolidated sediments and soils........... 45 I 2.3.4 Collection of resistivity data in the field............................................. 46 2.3.5 Forward modelling of resistivity data………..................................... 56 2.3.6 Inverse modelling of apparent resistivity data.................................... 62 2.3.7 Azimuthal resistivity.......................................................................... 67 2.3.8 Time lapse ERT.................................................................................. 68 2.4 Summary ………………………………………………………………………68 CHAPTER 3 Literature Review of the Study Area 3.1 Introduction…………………………………………………………………… 70 3.2 Geological Evolution of the study area ..............................................................70 3.3 Glaciations in Ireland .........................................................................................75 3.4 Glacial processes and landforms in the study area ............................................78 3.5 Soil formation in Ireland ....................................................................................81 3.6 Soils of the study area ........................................................................................86 3.7 Geophysical Applications in Environmental Field ……………………………90 3.7.1 Introduction ………………………………………………………….90 3.7.2 Magnetic susceptibility applications ………………………………...92 3.7.3 Electrical Resistivity Methods ............................................................94 3.8 Geophysical Research in Ireland ………………………………………............96 3.9 Magnetic characteristics of Irish rocks…………………………………….......99 3.10 Magnetic characteristics of soils…………………………………………….104 3.11 Summary.........................................................................................................106 CHAPTER 4 MAGNETIC AND ELECTRICAL RESISTIVITY RESULTS FOR COUNTY KILDARE 4.1 Introduction.......................................................................................................108 4.2 Particle size distribution and clastic characteristics of County Kildare soils...109 4.3 Statistical characteristics of the bulk magnetic parameters of the Kildare soils.........................................................................................................................113 II 4.4 Spatial variability of the bulk magnetic parameters of the Kildare soils..........118 4.5 K-T data analysis..............................................................................................125 4.6 Measurement of remanent magnetic declination and inclination angles..........129 4.7 Statistical characteristics of the magnetic parameters of individual Kildare soils.........................................................................................................................133 4.8 Characteristics of the magnetic parameters of grain size fractions for individual and bulk Kildare soils.............................................................................................136 4.8.1 Statistical characteristics....................................................................136 4.8.2 Spatial variation for individual fractional sizes.................................138 4.8.3 Variation of lf and fd% with particle size......................................142 4.9 Resistivity data for Co. Kildare.........................................................................145 4.10 Summary………….........................................................................................151 CHAPTER 5 MAGNETIC AND ELECTRICAL RESISTIVITY RESULTS FOR COUNTY WICKLOW 5.1 Introduction.......................................................................................................153 5.2 Particle size distribution and clastic characteristics of County Wicklow soils.........................................................................................................................154 5.3 Statistical characteristics of the magnetic parameters of the Wicklow soils....157 5.4 Spatial variability of the bulk magnetic parameters of the Wicklow soils.......161 5.5 K-T data analysis..............................................................................................170 5.6 Statistical characteristics of the magnetic parameters of individual Wicklow soils.........................................................................................................................172 5.7 Characteristics of the magnetic parameters of grain size fractions for individual and bulk Wicklow soils...........................................................................................176 5.7.1 Statistical characteristics....................................................................176 5.7.2 Spatial variation for individual fractional sizes.................................177 5.7.3 Particle size distribution of lf and fd% for main Wicklow soils…179 5.8 Resistivity results for Co. Wicklow sites..........................................................185 5.9 Summary…………...........................................................................................188 III CHAPTER 6 Analysis and Discussion of Results 6.1 Introduction.......................................................................................................191 6.2 Spatial variation of the magnetic susceptibility, frequency dependent susceptibility and volume susceptibility of the study area......................................191 6.3 Characteristics of the magnetic properties of the soils of the study area..........196 6.4 Assessment of correlation between magnetic susceptibility and frequency dependent susceptibility for the soils of the study area..........................................199 6.5 Electrical resistivity properties of the soils of the study area...........................205 6.5.1 Introduction........................................................................................205 6.5.2 Time lapse resistivity results..............................................................205 6.5.3 Analysis of resistivity sites in the study area.....................................212 6.6 Principal Component Multivariate Analysis of GIS database……………….217 6.7 What are the biogeoscientific processes that result in different magnetic and electrical properties of soil?....................................................................................223 6.8 Summary...........................................................................................................230 CHAPTER 7 Summary and Conclusions 7.1 Introduction.......................................................................................................233 7.2 Research objectives fulfilment..........................................................................233 7.3 Research aims fulfilment..................................................................................238 7.4 Research question…………………………………………………………….243 7.5 Limitations of the current research…………………………………………...244 REFERENCES...................................................................................................248