The Second Edition of this unique pocket field guide has been thoroughly revised and updated to include advances in physical volcanology, emplacement of magmas and interpreting structures and textures in igneous rocks. The book integrates new field based techniques (AMS and geophysical studies of pluton shape) with new topics on magma mixing and mingling, sill emplacement and magma sediment interaction. Part of the successful Field Guide series, this book includes revised sections on granitic and basaltic rocks and for the first time a new chapter on the engineering properties of igneous rocks. The Geological Field Guide Series is specifically designed for scientists and students to use in the field when information and resources may be more difficult to access.
Many editions have been updated for 2011 and the guides are:
Student-friendly in design and cost
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Pocket-sized
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Visit the series homepage at www.wiley.com/go/geologicalfield
Preface xi
Acknowledgements xv
1 Introduction and Occurrence 1
1.1 The Importance of Fieldwork 1
1.2 The Global Picture - Igneous Rocks in Relation to Regional Tectonics 2
1.3 Mode of Occurrence of Igneous Bodies 4
1.4 Summary 11
2 Field Skills and Outcrop Structures 15
2.1 Equipment 15
2.2 Preparing Maps and Basic Mapping 16
2.3 Notebooks and Data Recording 17
2.4 Primary Outcrop Structures 18
2.5 Secondary or Late Stage Outcrop Structures 28
2.6 Outcrop Contact Relationships 32
2.7 Summary of Igneous Outcrop Descriptions 33
3 Igneous Textures and Classification 37
3.1 Describing Rock Types 37
3.2 Colour and Composition 38
3.3 Texture, Grain-Size/Shape and Fabric 43
3.4 Mineral Identification 49
3.5 Naming and Classification 58
4 Volcanics 1 - Lava Flows 69
4.1 Lava Flow Emplacement Mechanisms 69
4.2 A Compositional Divide for Lava Flows 71
4.3 Mafic/Basaltic Lava Flows 73
4.4 Felsic/Silicic Flows 80
4.5 Pillow Lavas and Hyaloclastites 82
5 Volcanics 2 - Pyroclastic Rocks 93
5.1 Structures, Textures and Classification 93
5.2 Pyroclastic Flows and Ignimbrites 101
5.3 Scoria Cones 108
5.4 Water/Magma and Sediment/Magma Interactions 109
5.5 Epiclastic Deposits 112
6 Shallow-Level Intrusions 119
6.1 Sill and Dykes 119
6.2 Working Out Emplacement History 124
6.3 Volcanic Plugs and Diatremes 130
6.4 Shallow-Level Subvolcanic Intrusions 133
7 Granitic Complexes 137
7.1 Introduction 137
7.2 General Features and Occurrence 137
7.3 Zoned Plutons 142
7.4 Internal Structures and Textures 145
7.5 Internal Contacts 150
7.6 Emplacement Timing 158
7.7 Distinctive Granitoid Textures 162
7.8 Metamorphic Aureoles 164
7.9 Summary of the Field Characteristics of Granitic Complexes 165
8 Mafic Complexes 171
8.1 General Features and Occurrence 171
8.2 Continental Mafic-Ultramafic Intrusions 173
8.3 Ophiolite Complexes 177
8.4 Komatiites 183
8.5 Summary of the Field Characteristics of Mafic-Ultramafic Intrusions 184
9 Magma Mixing and Mingling 189
9.1 Magma Rheology 189
9.2 Magma Mixing 190
9.3 Magma Mingling 192
9.4 Synplutonic Dykes and Sills 196
9.5 Magma Mingling in Subvolcanic and Volcanic Environments 200
9.6 Xenoliths 201
9.7 A Word of Warning 202
9.8 Summary 203
10 Mineralisation and Geotechnical Properties 207
10.1 Mineralisation and Key Minerals 207
10.2 Mineralisation in Layered Mafic Intrusions 209
10.3 Geotechnical Properties of Igneous Rocks 213
10.4 Rock Mass Classification 216
10.5 Summary 226
Appendix 229
Further Reading 231
Index 233
