Table of Contents
1 Prospecting and the Exploration Process 1
1.1 Definition of Terms 1
1.2 Generating New Projects and Prospects 1
1.3 Some Ways of Generating New Exploration Ideas 3
1.4 A Check-List of Negative Assumptions 4
1.5 Stages in Prospect Exploration 5
1.5.1 Target Generation 5
1.5.2 Target Drilling 6
1.5.3 Resource Evaluation Drilling 6
1.5.4 Feasibility Study 6
1.6 Maximizing Success in Exploration Programmes 7
1.7 Different Types of Exploration Strategy 9
1.8 Exploration Feedbacks 9
1.9 Breaking Occam's Razor 10
References 11
2 Geological Mapping in Exploration 13
2.1 General Considerations 13
2.1.1 Why Make a Map? 13
2.1.2 The Nature of a Geological Map 14
2.1.3 Intelligent Mapping 15
2.1.4 Choosing the Best Technique 18
2.1.5 Choosing the Best Scale 20
2.1.6 Measuring and Recording Structures 22
2.1.7 Using Satellite Navigation (GPS) 23
2.2 Mapping Using Reflectance Imagery as a Map Base 25
2.2.1 General 25
2.2.2 Acquiring Air Photographs 26
2.2.3 Geological Interpretation 26
2.2.4 Determining Scale 27
2.2.5 Stereoscopic Image Pairs 29
2.2.6 Image Handling Techniques 31
2.2.7 Working with Enlarged Air Photographs 34
2.2.8 Data Transfer to Base Map 37
2.3 Mapping with a Plane Table 38
2.4 Mapping on a Pegged Grid 41
2.4.1 Requirements of the Grid 41
2.4.2 Making the Map 43
2.5 Mapping with Tape and Compass 47
References 49
3 Mine Mapping 51
3.1 General 51
3.2 Mapping in Open Cuts 51
3.3 Mapping Underground Openings 56
3.4 Safety in Mines 60
References 61
4 Trenching and Underground Development 63
4.1 Preamble 63
4.2 Pitting and Trenching 63
4.3 Underground Development 64
4.4 Safety and Logistics in Trenching 65
4.5 Geological Mapping 66
4.6 Geochemical Sampling 69
4.7 Examples of Successful Exploration Programmes 71
References 72
5 Drilling: A General Discussion the Importance of Drilling 75
5.1 Types of Drilling 75
5.2 Choosing the Right Technique 76
5.3 Targeting Holes 79
5.4 Drilling on Section 83
References 84
6 Rotary Percussion and Auger Drilling 85
6.1 Rotary Percussion Drilling 85
6.1.1 Reverse Circulation Drilling (RC) 85
6.1.2 Air Core Drilling 93
6.1.3 Rotary Air Blast (RAB) Drilling 93
6.2 Auger Drilling 96
References 97
7 Diamond Drilling 99
7.1 Preamble 99
7.2 Some Definitions 100
7.3 Before You Begin 102
7.4 Setting Up a Diamond Hole 102
7.5 Geological Observation 103
7.6 Recognizing and Interpreting Structures in Core 104
7.6.1 Statement of the Problem 104
7.6.2 Planar Structures 104
7.6.3 Faults 105
7.6.4 Linear Structures 107
7.6.5 Folds 109
7.6.6 The Scale Problem 110
7.6.7 Vergence 112
7.7 Measuring and Recording Structures in Core 113
7.8 Core Logging Systems 116
7.8.1 Prose Logging 116
7.8.2 Graphical Scale Logging 117
7.8.3 Analytical Spreadsheet Logging 119
7.9 Down-Hole Surveying 123
7.9.1 Procedure 123
7.9.2 Using Down-Hole Survey Data to Plot Sections and Plans 124
7.10 When Should Core Be Oriented? 127
7.11 Sampling and Assaying 127
7.12 Core Handling 130
7.13 Core Photography 135
References 136
8 Satellite Imagery 137
8.1 General Discussion 137
8.2 How Earth Observation Satellites Work 139
8.3 Display of Satellite Images 140
8.4 Geological Interpretation 140
8.5 Analysis of Reflectance Data 142
References 142
9 Geophysical and Geochemical Methods 143
9.1 General Discussion 143
9.2 Magnetic Surveys 146
9.3 Gravity Surveys 149
9.4 Radiometric Surveys 150
9.5 Electromagnetic (EM) Surveys 150
9.6 Electrical Surveys 151
9.7 Hybrid Electrical and Magnetic Surveys 152
9.8 Advances in Instrumentation and Data Modelling 153
9.9 Stream Sediment Sampling 155
9.10 Soil Sampling 157
9.11 Heavy Mineral Concentrate (HMC) Sampling 158
9.12 Rock Chip Sampling 160
9.13 Laterite Sampling 161
References 162
10 Geographical Information Systems and Exploration Databases 165
10.1 Definition 165
10.2 The Need for Digital Exploration Databases 165
10.3 GIS Storage of Map Data 168
10.3.1 Digitised Line Format 168
10.3.2 Polygon or Vector Format 170
10.3.3 Raster Format 170
10.4 Validation 170
10.5 Georeferencing 171
10.5.1 Geographical Coordinates 171
10.5.2 Cartesian Coordinates 171
10.5.3 Map Datums 172
10.5.4 Map Registering 173
10.6 Manipulation of GIS Data 173
10.7 Presentation of GIS Data 174
Appendix A Notes on the Use of Graphical Scale Logging 179
A.l Column 1 (Hole Depth) 180
A.2 Column 2 (Core Recovery) 180
A.3 Column 3 (Core Quality) 180
A.4 Column 4 (Sample No.) 180
A.5 Column 5 (Assay Results) 180
A.6 Column 6 (Mapping Logs) 180
A.7 Column 7 (Histogram Logs) 181
A.8 Column 8 (Geology Notes) 182
A.9 Column 9 (Summary Log) 182
A.10 Remarks Area 182
Appendix B Oriented Drill Core: Techniques and Procedures 183
B.1 Techniques for Orienting Drill Core 183
B.1.1 Non-mechanical Means 183
B.1.2 Mechanical Means 183
B.2 How to Handle Oriented Core 188
B.3 How to Measure Structures in Oriented Core 190
B.3.1 Before You Measure 190
B.3.2 How Many Measurements Are Needed? 191
B.3.3 Using a Core Frame 192
B.3.4 Using Internal Core Angles 195
B.3.5 Discussion on the Best Measuring Technique 201
B.3.6 Plotting Structure Measurements on Drill Section 202
Appendix C Calculating Strike and Dip from Multiple Diamond Drill Holes 205
C 1 The Three Point Problem 205
C.2 Solution Using Structure Contours 205
C.3 Solution Using a Stereonet 206
C.4 An Elegant Solution to Determining the Attitude of Planes in Non-oriented Core 208
Appendix D How to Use a Stereo Net to Convert Internal Core Angles to Geographic Coordinates 211
D.l The Solution for Planar Structures 211
D.2 The Solution for Linear Structures 213
Appendix E Practical Field Techniques 215
E.l Choosing the Right Compass 215
E.2 Understanding Your Compass 215
E.3 Measuring the Strike and Dip of Planes 217
E.4 Measuring the Trend and Plunge of Lineations 218
Appendix F Suggested Further Reading 223
Acronyms and Abbreviations 229
Index 233
