Geological Methods in Mineral Exploration and Mining, Second Edition

Roger Marjoribanks, "Geological Methods in Mineral Exploration and Mining, Second Edition"
Springer | 2010 | ISBN: 3540743707 | 238 pages | PDF | 5,6 MB

This practical step-by-step guide describes the key geological field techniques needed by today's exploration geologists involved in the search for metallic mineral deposits. The techniques described are fundamental to the collection, storage and presentation of geological data and their use to locate ore. This book explains the various tasks which an exploration geologist is asked to perform in the sequence in which they might be employed in an actual exploration project. Hints and tips are given and the steps are illustrated with numerous examples drawn from real programmes on which the author has worked. Traditional skills are emphasised to show how they can be combined effectively with modern high-technology approaches. For instance this second edition also reviews new techniques geophysics along with GPS applications in exploration and the application of state-of-the-art software to mapping, 3D modelling and resource estimation. Another important facet is the discussion of harm minimisation, especially during the exploration stage, beginning with landowner and community consultation, through exploration planning, leading to sustainable and environmentally responsible mining practices.

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 WhyMake aMap? . . . . . . . . . . . . . . . . . . . 13
2.1.2 TheNature of aGeologicalMap . . . . . . . . . . . . 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 DataTransfer toBaseMap . . . . . . . . . . . . . . . 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 theMap . . . . . . . . . . . . . . . . . . . . . 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 inMines . . . . . . . . . . . . . . . . . . . . . . . . . . 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 TargetingHoles . . . . . . . . . . . . . . . . . . . . . . . . . . 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 SomeDefinitions . . . . . . . . . . . . . . . . . . . . . . . . . 100
7.3 BeforeYouBegin . . . . . . . . . . . . . . . . . . . . . . . . . 102
7.4 Setting Up a Diamond Hole . . . . . . . . . . . . . . . . . . . 102
7.5 GeologicalObservation . . . . . . . . . . . . . . . . . . . . . 103
7.6 Recognizing and Interpreting Structures in Core . . . . . . . . . 104

7.6.1 Statement of theProblem . . . . . . . . . . . . . . . . 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-HoleSurveying . . . . . . . . . . . . . . . . . . . . . . 123
7.9.1 Procedure . . . . . . . . . . . . . . . . . . . . . . . . 123
7.9.2 Using Down-Hole Survey Data to Plot Sections andPlans . . . . . . . . . . . . . . . . . . . . . . . . 124
7.10 When Should Core Be Oriented? . . . . . . . . . . . . . . . . . 127
7.11 Sampling andAssaying . . . . . . . . . . . . . . . . . . . . . . 127
7.12 CoreHandling . . . . . . . . . . . . . . . . . . . . . . . . . . 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 GravitySurveys . . . . . . . . . . . . . . . . . . . . . . . . . . 149
9.4 RadiometricSurveys . . . . . . . . . . . . . . . . . . . . . . . 150
9.5 Electromagnetic (EM) Surveys . . . . . . . . . . . . . . . . . . 150
9.6 ElectricalSurveys . . . . . . . . . . . . . . . . . . . . . . . . 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 SoilSampling . . . . . . . . . . . . . . . . . . . . . . . . . . . 157
9.11 Heavy Mineral Concentrate (HMC) Sampling . . . . . . . . . . 158
9.12 RockChipSampling . . . . . . . . . . . . . . . . . . . . . . . 160
9.13 LateriteSampling . . . . . . . . . . . . . . . . . . . . . . . . . 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 GISStorage ofMapData . . . . . . . . . . . . . . . . . . . . . 168
10.3.1 Digitised Line Format . . . . . . . . . . . . . . . . . . 168
10.3.2 Polygon or Vector Format . . . . . . . . . . . . . . . . 170
10.3.3 RasterFormat . . . . . . . . . . . . . . . . . . . . . . 170
10.4 Validation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 170
10.5 Georeferencing . . . . . . . . . . . . . . . . . . . . . . . . . . 171
10.5.1 Geographical Coordinates . . . . . . . . . . . . . . . . 171
10.5.2 CartesianCoordinates . . . . . . . . . . . . . . . . . . 171
10.5.3 MapDatums . . . . . . . . . . . . . . . . . . . . . . . 172
10.5.4 MapRegistering . . . . . . . . . . . . . . . . . . . . . 173
10.6 Manipulation ofGISData . . . . . . . . . . . . . . . . . . . . 173
10.7 Presentation ofGISData . . . . . . . . . . . . . . . . . . . . . 174
Appendix A
Notes on the Use of Graphical Scale Logging . . . . . . . . . . . . . 179
A.1 Column 1(HoleDepth) . . . . . . . . . . . . . . . . . . . . . 180
A.2 Column 2(CoreRecovery) . . . . . . . . . . . . . . . . . . . . 180
A.3 Column 3 (Core Quality) . . . . . . . . . . . . . . . . . . . . . 180
A.4 Column 4 (SampleNo.) . . . . . . . . . . . . . . . . . . . . . 180
A.5 Column 5 (AssayResults) . . . . . . . . . . . . . . . . . . . . 180
A.6 Column 6 (Mapping Logs) . . . . . . . . . . . . . . . . . . . . 180
A.7 Column 7 (HistogramLogs) . . . . . . . . . . . . . . . . . . . 181
A.8 Column 8 (GeologyNotes) . . . . . . . . . . . . . . . . . . . . 182
A.9 Column 9 (SummaryLog) . . . . . . . . . . . . . . . . . . . . 182
A.10 RemarksArea . . . . . . . . . . . . . . . . . . . . . . . . . . . 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 HowtoMeasureStructures inOrientedCore . . . . . . . . . . 190
B.3.1 BeforeYouMeasure . . . . . . . . . . . . . . . . . . 190
B.3.2 How Many Measurements Are Needed? . . . . . . . . 191
B.3.3 UsingaCoreFrame . . . . . . . . . . . . . . . . . . . 192
B.3.4 UsingInternalCoreAngles . . . . . . . . . . . . . . . 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 TheThreePointProblem . . . . . . . . . . . . . . . . . . . . . 205
C.2 SolutionUsingStructureContours . . . . . . . . . . . . . . . . 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.1 The Solution for Planar Structures . . . . . . . . . . . . . . . . 211
D.2 The Solution for Linear Structures . . . . . . . . . . . . . . . . 213
Appendix E
Practical Field Techniques . . . . . . . . . . . . . . . . . . . . . . . 215
E.1 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

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