Igneous Rocks and Processes (eBook)

A Practical Guide

Robin Gill, Godfrey Fitton (Autoren)

eBook Download: PDF

2022 | 2. Auflage
John Wiley & Sons (Verlag)
978-1-119-45567-7 (ISBN)

Infos

IGNEOUS ROCKS AND PROCESSES

A practical introduction to igneous petrology for students and practitioners

The newly revised Second Edition of Igneous Rocks and Processes: A Practical Guide, delivers an authoritative introduction to igneous petrology and helps students to develop key skills and confidence in identifying igneous materials and in naming and interpreting unknown igneous rocks presented to them. It serves as both a conventional course text and a practical laboratory manual.

The authors review igneous nomenclature and subsequently describe specific compositional categories of magmatic rocks. Each chapter covers definitions, mineralogy, eruption and emplacement processes, textures and crystallization processes, geotectonic distribution, geochemistry, and aspects of magma genesis. Additional chapters address phase equilibrium experiments and physical volcanology.

This latest edition offers readers extensively updated chapters, as well as access to a companion website with supplementary material. It also provides:

• Thorough introductions to magmas, magmatic rocks, and magma differentiation
• Exercises for each chapter, with answers provided at the end
• A detailed summary of techniques and optical data for mineral identification using a polarizing microscope
• An introduction to petrographic calculations and an extensive glossary

Perfect for geoscience students taking courses in igneous petrology, Igneous Rocks and Processes: A Practical Guide, second edition will also earn a place in the libraries of postgraduate students and researchers in the field.

Robin Gill lectured in igneous petrology, geochemistry, and volcanology at Royal Holloway, University of London, UK.

Godfrey Fitton is Professor of Igneous Petrology at the University of Edinburgh, UK.

Inhalt

Cover 1
Title Page 5
Copyright Page 6
Contents 7
Preface to the second edition 8
Preface to first edition 9
Acknowledgements 11
About the companion website 13
Chapter 1 An introduction to magmas and magmatic rocks 15
Why study magmatic rocks? 15
What is ‘magma’? 16
The diversity of natural magma compositions 17
What do we mean by magma (or rock) composition? 17
How widely do natural magma compositions vary? 19
Parameters used to classify igneous rocks 20
Classification by qualitative criteria – grain size 20
Classification by mineral proportions – colour index 20
Classification by chemical composition – acidic versus basic 22
Devising a basic petrographic nomenclature for igneous rocks 22
What is a basalt? 22
‘Essential’, ‘type’, ‘accessory’ and ‘post-magmatic’ minerals 23
Devising a full petrographic name 24
Chemical subdivision of igneous rocks and magmas 27
Geochemical qualifiers 29
Review 33
Using this book 34
Exercises 34
Chapter 2 Basalts and related rocks 36
The nomenclature and mineralogy of basaltic rocks 36
Definition 36
Subdividing basalts 37
Related rocks 39
Eruptive processes and volcanic forms 40
Subaerial lava flows 40
Pillow basalts and subaqueous sheet flows 42
Basaltic pyroclastic eruptions: scoria cones 44
How basalt magmas crystallize – evidence from textures 44
Vesicles and volatile solubility 45
Forms of basaltic glass 46
Textures involving variations in crystal size 48
Alteration and metamorphism of basalts 50
Another look at the chemical subdivision of basalts – norms 51
Where basalts occur 58
Mid-ocean ridge basalts (MORBs) 58
Ocean island basalts (OIB) 67
Large igneous provinces (LIPs): oceanic plateaux and continental flood basalts (CFBs) 68
Intra-continental rift basalts 71
Subduction-related basalts 71
Extraterrestrial basalts 74
Where and how are basalt magmas formed in the Earth? 75
Source materials for basaltic melts 75
Conditions required for melting to occur in the mantle 76
What determines the composition of melt formed in the mantle? 80
Review – what information can we glean from basalts? 81
Exercises 82
Chapter 3 Magma differentiation 83
The causes of magma diversity 83
Phase equilibrium experiments 84
Experiments with simplified compositions 85
Melting and crystallization experiments on real rocks 102
Major element variation diagrams for natural volcanic rock series 103
Magma interaction with the crust 106
The contribution of partial melting to magma variability 110
Review 110
Exercises 111
Chapter 4 Gabbroic rocks 112
The nomenclature of gabbroic rocks 112
Definitions 112
Subdividing gabbros and dolerites 116
The scale and emplacement of doleritic and gabbroic intrusions 116
Minor intrusions 116
Gabbro plutons 121
Internal forms, structures and layering 122
Minor intrusions 122
Igneous layering in gabbro plutons 122
Metalliferous mineral deposits associated with layered mafic intrusions 135
How dolerites and gabbros crystallize – evidence from textures 135
Grain size, nucleation and order of crystallization 136
Cumulate textures, zoning and changes in melt composition 136
Intra-crystalline textures 138
Reaction textures 138
Other post-magmatic textures 139
Where dolerites and gabbros are found 139
Oceanic spreading centres 139
Oceanic islands 142
Large igneous provinces 142
Intra-continental rift intrusions 143
Subduction-related complexes 143
Anorthosites, norites and troctolites 143
Archaean calcic anorthosites 144
Proterozoic ‘massif’ anorthosites 145
Lunar anorthosite 148
Review – what can one learn from the study of gabbroic rocks? 148
Minor intrusions 148
Layered intrusions 150
Exercises 150
Chapter 5 Ultramafic rocks 151
The nomenclature of ultramafic rocks 152
Definitions 152
Type minerals 153
Alteration 153
‘Stratiform’ ultramafic cumulates in layered intrusions 155
Ultramafic cumulates in ophiolites 160
Ultramafic bodies of Alaskan type 160
Mantle-derived peridotites 162
Mantle xenoliths in basalts and kimberlites 162
Orogenic peridotite massifs 166
Textures in xenolithic and orogenic peridotites 167
Abyssal peridotites from the ocean floor 167
Komatiites, picrites and related high-MgO volcanic rocks 168
Detail and significance of spinifex texture 172
Magma genesis of komatiites and picrites 175
Mineral deposits associated with komatiites 177
Review – what can we learn from the study of ultramafic rocks? 179
Ultramafic cumulates 179
Mantle peridotites 179
Komatiites and picrites 179
Exercises 180
Chapter 6 Andesite, dacite and rhyolite 181
The nomenclature of intermediate and silicic volcanic rocks 181
Definitions 181
Composition, grain-size and colour in hand specimen 184
Boninites 185
Related rocks 189
Eruptive processes and volcanic forms 189
Andesite lava flows 189
Dacite lava domes and spines 189
Pyroclastic eruptions 195
How andesites, dacites and rhyolites crystallize – textural evidence 195
Textures involving variations in crystal size and groundmass crystallinity 195
Intra-crystalline textures 197
Volcanic glass, devitrification and related textures 201
Chemical subdivision of andesites, dacites and rhyolites 202
The concept of a ‘calc-alkali’ path of magma evolution 202
The effect of water on magma evolution 204
Low-K, medium-K and high-K associations 206
Where andesites, dacites and rhyolites occur 207
Island arcs 207
Continental arcs 214
Oceanic spreading centres 218
Continental LIPs 219
Continental rifts 219
Large-scale rhyolite eruptions 219
How are intermediate and silicic magmas formed in the Earth? 220
Arc volcanism 220
Origins of non-arc intermediate-to-silicic magmas 229
Review – what can we learn from andesites, dacites and rhyolites? 230
Exercises 231
Chapter 7 How magmas erupt – an introduction to pyroclastic processes and products 233
The nomenclature of volcanic eruptions and deposits 233
Effusive versus explosive volcanism 233
Styles of volcanic eruption 234
Nomenclature of pyroclasts and pyroclastic deposits 243
Internal structures of pyroclastic deposits 249
Pyroclastic fall deposits 249
Pyroclastic current deposits 249
Edifice Instability 256
Microscopic textures 257
Pumice 258
Lapilli-tuff 260
Calderas 261
Review – the significance of pyroclastic eruptions 263
Exercises 263
Chapter 8 Granitic rocks 265
The nomenclature of intermediate and silicic plutonic rocks 265
Definitions of granitic rock types 265
Related rocks 266
Form and scale of granitic intrusions 268
Individual plutons 268
Batholiths 271
Emplacement of granitic intrusions: the ‘space problem’ 274
Forming granite in situ: ‘granitization’ and migmatite 275
Stoping 276
Cauldron subsidence 276
Diapiric upwelling 276
Ballooning 278
Emplacement of tabular plutons and batholiths 278
Synkinematic plutons 279
Internal structures in granitic intrusions 279
Inclusions 279
Igneous layering 279
Evidence of multiple phases in injection 282
Miarolitic cavities (vugs) 283
Mineral fabric 284
How granitic magmas crystallize – textural evidence 285
Variations in crystal size: K-feldspar megacrysts 285
Overgrowths 286
Intergrowths 286
Intra-crystalline textures 288
Late-stage processes, alteration and mineralization associated with granitoids 288
Pegmatite and aplite 288
Alteration 290
Mineralization 291
Geochemistry and the chemical subdivision of granitoids 291
Where granitic magmas occur 294
Volcanic arcs 294
Active continental margins 294
Continental collision zones 296
Intra-plate granitic rocks 299
Ocean spreading centre granites 299
Geochemical discriminants and tectonic association of granitoids 302
Archaean TTG suite 303
Proterozoic AMC suites 304
How are granitoid magmas formed? 304
Plagiogranites 305
Cordilleran granitoids 305
Archaean TTG suite 309
Collision-related leucogranites 310
Intra-plate granites 313
Charnockites and the AMC suite 313
Is granite peculiar to the Earth? 314
Review – what can we learn from granitic complexes? 314
Exercises 315
Chapter 9 Alkali rocks 317
The nomenclature of fine-grained alkali rocks 319
Definitions for sodic and mildly potassic rock types 319
Potassic and ultrapotassic rocks 323
Associated rock types 324
Eruptive processes and volcanic forms 325
The eruption of foidite magmas – the lesson of Nyiragongo 20025 325
Nomenclature of coarse-grained alkali rocks 329
Intrusive forms and processes in alkali plutons 331
Diatreme-hypabyssal systems 331
Ring intrusions 331
Lopoliths 334
Igneous layering in alkali intrusions 334
Textures – mineral identification and crystallization processes 335
Textures involving variations in crystal size and matrix crystallinity 335
Intra-crystalline textures and mineral identification 336
Groundmass textures 336
Reaction and alteration textures 336
Chemical attributes and the subdivision of alkali rocks 337
Alkalinity: peralkaline versus metaluminous 337
Silica undersaturation 337
Where alkali rocks occur 342
Ocean islands 343
Continental rifts 346
Continental anorogenic provinces less clearly associated with rifting 351
Subduction-related alkali rocks 355
How are alkali magmas formed in the Earth? 357
Geochemical evidence 357
Hot spot-related oceanic alkali basalts and related rocks 363
Plume-related continental rift magmatism 365
Other continental rifts and alkali provinces 368
Subduction-related alkali rocks 370
Review – the significance of alkali igneous magmatism 372
Exercises 373
Appendix A Mineral identification using a polarizing microscope 374
Introduction 374
Observations in plane-polarized light 377
Observations in crossed polars 379
Crossed polars used with parallel light 379
Crossed polars used with convergent light 380
Appendix B Petrographic calculations 385
Simplified CIPW norm calculations 385
Stages of CIPW norm calculation 385
Calculation Procedure 387
Plotting data in ternary and quaternary diagrams 389
Mixing calculations 391
Exercises 391
Appendix C Symbols, units and constants used in this book 392
Glossary 395
Answers to exercises 411
Bibliography 425
Index 446
Supplemental Images 467
EULA 499

Produkt-Details

• Erscheint lt. Verlag: 9.8.2022
• Sprache: englisch
• Themenwelt: Naturwissenschaften ► Geowissenschaften ► Geologie
• Schlagworte: earth sciences • Geowissenschaften • Igneous & Metamorphic Petrology and Volcanology • Igneous petrology • igneous petrology exercises • igneous petrology guide • igneous petrology handbook • igneous petrology intro • igneous petrology laboratory manual • igneous petrology text • igneous rock identification • magmatic rock identification • Petrologie • Petrologie u. Vulkanologie eruptiver u. metamorpher Systeme • Structural Geology & Tectonics • Strukturgeologie • Strukturgeologie, Tektonik
• ISBN-10: 1-119-45567-7 / 1119455677
• ISBN-13: 978-1-119-45567-7 / 9781119455677