Geological Methods in Mineral Exploration and Mining (eBook)

Preface 5
Acknowledgments 8
Contents 9
1 Prospecting and the Exploration Process 14
1.1 Definition of Terms 14
1.2 Generating New Projects and Prospects 14
1.3 Some Ways of Generating New Exploration Ideas 16
1.4 A Check-List of Negative Assumptions 17
1.5 Stages in Prospect Exploration 18
1.5.1 Target Generation 18
1.5.2 Target Drilling 19
1.5.3 Resource Evaluation Drilling 19
1.5.4 Feasibility Study 19
1.6 Maximizing Success in Exploration Programmes 20
1.7 Different Types of Exploration Strategy 22
1.8 Exploration Feedbacks 22
1.9 Breaking Occam's Razor 23
References 24
2 Geological Mapping in Exploration 26
2.1 General Considerations 26
2.1.1 Why Make a Map? 26
2.1.2 The Nature of a Geological Map 27
2.1.3 Intelligent Mapping 28
2.1.4 Choosing the Best Technique 31
2.1.5 Choosing the Best Scale 33
2.1.6 Measuring and Recording Structures 35
2.1.7 Using Satellite Navigation (GPS) 36
2.2 Mapping Using Reflectance Imagery as a Map Base 38
2.2.1 General 38
2.2.2 Acquiring Air Photographs 39
2.2.3 Geological Interpretation 39
2.2.4 Determining Scale 40
2.2.5 Stereoscopic Image Pairs 42
2.2.6 Image Handling Techniques 44
2.2.7 Working with Enlarged Air Photographs 47
2.2.8 Data Transfer to Base Map 50
2.3 Mapping with a Plane Table 51
2.4 Mapping on a Pegged Grid 54
2.4.1 Requirements of the Grid 54
2.4.2 Making the Map 56
2.5 Mapping with Tape and Compass 60
References 62
3 Mine Mapping 63
3.1 General 63
3.2 Mapping in Open Cuts 63
3.3 Mapping Underground Openings 68
3.4 Safety in Mines 72
Reference 73
4 Trenching and Underground Development 74
4.1 Preamble 74
4.2 Pitting and Trenching 74
4.3 Underground Development 75
4.4 Safety and Logistics in Trenching 76
4.5 Geological Mapping 77
4.6 Geochemical Sampling 80
4.7 Examples of Successful Exploration Programmes 82
References 83
5 Drilling: A General Discussion the Importance of Drilling 85
5.1 Types of Drilling 85
5.2 Choosing the Right Technique 86
5.3 Targeting Holes 89
5.4 Drilling on Section 93
References 94
6 Rotary Percussion Drilling 95
6.1 Rotary Percussion Drilling 95
6.1.1 Reverse Circulation Drilling (RC) 95
6.1.1.1 Geological Logging 96
6.1.1.2 Display and Storage of Cuttings 98
6.1.1.3 Sampling 100
6.1.1.4 Sampling Below the Water Table 102
6.1.1.5 Capping and Marking the Hole Collar 102
6.1.2 Air Core Drilling 103
6.1.3 Rotary Air Blast (RAB) Drilling 103
6.1.3.1 Drilling Technique 103
6.1.3.2 Geological Logging 104
6.1.3.3 Sampling 105
6.2 Auger Drilling 106
Reference 107
7 Diamond Drilling 108
7.1 Preamble 108
7.2 Some Definitions 109
7.3 Before You Begin 111
7.4 Setting Up a Diamond Hole 111
7.5 Geological Observation 112
7.6 Recognizing and Interpreting Structures in Core 113
7.6.1 Statement of the Problem 113
7.6.2 Planar Structures 113
7.6.3 Faults 114
7.6.4 Linear Structures 116
7.6.5 Folds 118
7.6.6 The Scale Problem 119
7.6.7 Vergence 121
7.7 Measuring and Recording Structures in Core 122
7.8 Core Logging Systems 125
7.8.1 Prose Logging 125
7.8.2 Graphical Scale Logging 126
7.8.3 Analytical Spreadsheet Logging 128
7.9 Down-Hole Surveying 132
7.9.1 Procedure 132
7.9.2 Using Down-Hole Survey Data to Plot Sections and Plans 133
7.9.2.1 Plotting an Approximate Section 135
7.9.2.2 Plotting an Exact Plan and Section 135
7.10 When Should Core Be Oriented 136
7.11 Sampling and Assaying 136
7.12 Core Handling 139
7.13 Core Photography 144
References 145
8 Satellite Imagery 146
8.1 General Discussion 146
8.2 How Earth Observation Satellites Work 148
8.3 Display of Satellite Images 149
8.4 Geological Interpretation 149
8.5 Analysis of Reflectance Data 151
References 151
9 Geophysical and Geochemical Methods 152
9.1 General Discussion 152
9.2 Magnetic Surveys 155
9.3 Gravity Surveys 158
9.4 Radiometric Surveys 159
9.5 Electromagnetic EM Surveys 159
9.6 Electrical Surveys 160
9.7 Hybrid Electrical and Magnetic Surveys 161
9.8 Advances in Instrumentation and Data Modelling 162
9.9 Stream Sediment Sampling 164
9.10 Soil Sampling 166
9.11 Heavy Mineral Concentrate HMC Sampling 167
9.12 Rock Chip Sampling 169
9.13 Laterite Sampling 170
References 171
10 Geographical Information Systems and Exploration Databases 173
10.1 Definition 173
10.2 The Need for Digital Exploration Databases 173
10.3 GIS Storage of Map Data 176
10.3.1 Digitised Line Format 176
10.3.2 Polygon or Vector Format 178
10.3.3 Raster Format 178
10.4 Validation 178
10.5 Georeferencing 179
10.5.1 Geographical Coordinates 179
10.5.2 Cartesian Coordinates 179
10.5.3 Map Datums 180
10.5.4 Map Registering 181
10.6 Manipulation of GIS Data 181
10.7 Presentation of GIS Data 182
Appendix A Notes on the Use of Graphical Scale Logging 186
A.1 Column 1 (Hole Depth) 187
A.2 Column 2 (Core Recovery) 187
A.3 Column 3 (Core Quality) 187
A.4 Column 4 (Sample No.) 187
A.5 Column 5 (Assay Results) 187
A.6 Column 6 (Mapping Logs) 187
A.7 Column 7 (Histogram Logs) 188
A.8 Column 8 (Geology Notes) 189
A.9 Column 9 (Summary Log) 189
A.10 Remarks Area 189
Appendix B Oriented Drill Core: Techniques and Procedures 190
B.1 Techniques for Orienting Drill Core 190
B.1.1 Non-mechanical Means 190
B.1.2 Mechanical Means 190
B.2 How toHandle Oriented Core 195
B.3 How to Measure Structures in Oriented Core 197
B.3.1 Before You Measure 197
B.3.2 How Many Measurements Are Needed? 198
B.3.3 Using a Core Frame 199
B.3.4 Using Internal Core Angles 202
B.3.4.1 The Angles that Define Planar Structure 202
B.3.4.2 The Angles that Define Linear Structure 203
B.3.4.3 How to Measure Internal Core Angles 204
B.3.4.4 Converting Internal Core Angles to Strike and Dip Measurements 206
B.3.4.5 Mathematical Reduction 207
B.3.4.6 Reduction Using Stereonet 207
B.3.4.7 Problems with the Internal Core Angle Method 207
B.3.5 Discussion on the Best Measuring Technique 208
B.3.6 Plotting Structure Measurements on Drill Section 209
References 211
Appendix C Calculating Strike and Dip from Multiple Diamond Drill Holes 212
C.1 The Three Point Problem 212
C.2 Solution Using Structure Contours 212
C.3 Solution Using a Stereonet 213
C.4 An Elegant Solution to Determining the Attitude of Planes in Non-oriented Core 215
References 217
Appendix D How to Use a Stereo Net to Convert Internal Core Angles to Geographic Coordinates 218
D.1 The Solution for Planar Structures 218
D.2 The Solution for Linear Structures 220
Appendix E Practical Field Techniques 222
E.1 Choosing the Right Compass 222
E.2 Understanding Your Compass 222
E.3 Measuring the Strike and Dip of Planes 224
E.4 Measuring the Trend and Plunge of Lineations 225
Appendix F Suggested Further Reading 229
General 229
Chapter 1 229
Chapter 2 230
Chapter 4 231
Chapter 5 231
Chapter 6 232
Chapter 7 232
Chapter 8 232
Chapter 9 233
Chapter 10 234
Acronyms and Abbreviations 235
Color Plate 237
Index 238