CONTENTS<br>Preface xi<br>Acknowledgements xiii<br>1. Sea 16<br>Western United States 17<br>Other continental provinces 19<br>Location of intraplate volcanism 20<br>Hot-spots and mantle plumes 20<br>Flood basalts 22<br>2. Volcanism 24<br>Factors controlling eruption 25<br>The rise of magma 25<br>Viscosity of magmas Igneous activity at the present day 1<br>Ocean basins 2<br>The ocean floor 3<br>Oceanic islands 6<br>Ocean basin flood basalts 9<br>Island arcs and continental margins 9<br>Island arcs 9<br>Orogenic continental margins 11<br>Intracontinental orogenic belts 15<br>Continental regions 16<br>East African rift system and Red 26<br>Magmatic gases . 28<br>Temperature of eruption 29<br>Craters and calderas 30<br> <br>Lavas 39<br>Lava flows 39<br>Lava domes 41<br>Submarine lavas 44<br>Pyroclastic rocks 45<br>Scoria cones 46<br>Ash falls 47<br>Ash flows 48<br>Pyroclastic surge deposits 51<br>Lahars 52<br>Hyaloclastites 52<br>Major volcanic massifs 53<br>Lava plateaux 53<br>Shield volcanoes 57<br>Strato-volcanoes 59<br>Pyroclastic sheet deposits 62<br>3. Intrusion 66<br>Density of rocks and magmas 66<br>Felsic intrusions 71<br>Sloped stocks 71<br>Ring dykes and bell-jar plutons 75<br>Centred complexes 78<br>Sheeted intrusions 83<br>Diapiric plutons 84<br>Batholiths 90<br>Mafic intrusions 92<br>Flat-lying sheets 95<br>Cone sheets 100<br>Funnel-shaped intrusions 102<br>Funnel-dykes 106<br>Ring dykes and ring complexes 109<br>Lopoliths 111<br>Dykes and dyke swarms 114<br>Diatremes 119<br>4. The chemical composition of igneous rocks 120<br>Major elements 120<br>Magma variation 121<br>Normative compositions 122<br>Silica saturation 123<br>Alumina saturation 125<br>Trace elements 126<br>Geochemical affinity 128<br>Distribution of trace elements between crystals and liquids 132<br> <br>Partition coefficients 136<br>Distribution of trace elements in igneous rocks 143<br>5. Melting and crystallization 150<br>Temperatures and pressures 150<br>Temperatures 150<br>Pressures 151<br>Phase relations of silicates and silicate melts 152<br>Phase equilibria 152<br>Binary systems 154<br>Ternary systems 165<br>Systems of more than three components 174<br>High pressures 175<br>Systems containing water 176<br>Melting and crystallization of natural rocks 181<br>Melting compared with crystallization 184<br>Oxidation and reduction 185<br>6. Isotopic composition 189<br>Fractionation of stable isotopes 190<br>Oxygen and hydrogen isotopes 190<br>Sulphur isotopes 198<br>Radiogenic isotopes 199<br>Potassium-argon 200<br>Rubidium-strontium 202<br>Samarium-neodymium 207<br>Rhenium-osmium 209<br>Uranium-thorium-lead 209<br>7. Magmatic evolution 220<br>Crystal fractionation 221<br>Crystal-liquid separation mechanisms 223<br>Crystallization differentiation observed 229<br>Role of crystallization differentiation 241<br>Liquid immiscibility 245<br>Silicate-silicate immiscibility 246<br>Silicate-oxide and silicate-phosphate immiscibility 249<br>Silicate-carbonate immiscibility 250<br>Silicate-sulphide immiscibility 251<br>Silicate-water immiscibility 252<br>Liquid fractionation 255<br>Thermal diffusion 256<br>Gravitational diffusion 257<br>The role of liquid fractionation 258<br> <br>Contamination 259<br>Assimilation by melting 259<br>Assimilation without melting 261<br>Observed reactions of magma and contaminant 265<br>Petrographic and geochemical characteristics of contaminated<br>rocks 274<br>Large-scale contamination 276<br>Combined assimilation and fractionation 280<br>General significance of contamination 280<br>Zone melting 281<br>Mixing of magmas 283<br>Mixing of similar magmas 283<br>Mixing of dissimilar magmas 283<br> <br>287<br>287<br>288<br>289<br>291<br>293<br>295<br>295<br>299<br>301<br>303<br>306<br>307<br>311<br>312<br>312<br>319<br>323<br>324<br>328<br>Basalts<br>Where basalts occur Parent materials of basalt<br>Peridotite as a source material<br>Eclogite as a source material<br>Peridotite or eclogite? Primar origins<br>Melting of peridotite and eclogite<br>Melting of peridotite in the presence of H2O and CO2<br>Degree of partial melting<br>Mantle heterogeneity Secondary origins<br>Fractionation<br>Contamination Basalt petrogenesis in relation to tectonic environment<br>Mid-ocean ridge basalts (MORB)<br>Oceanic island basalts (OIB)<br>Continental flood basalts<br>Basalts of island arcs and orogenic continental margins Komatiites<br> <br>331<br>331<br>331<br>334<br>336<br>339<br>344<br>346<br>348<br>Granites<br>The nature of acid magmas<br>The ways in which granite magma can be formed Melting of basalt or andesite Melting of sediments and metasediments Evidence of crustal melting Initiation of crustal melting Differentiation of basalt or andesite<br>The isotopic composition of granites<br> <br>The diversity of granite compositions 352<br>The range from felsic to mafic 353<br>Variation in the relative proportions of felsic constituents 358<br>Alumina saturation 358<br>Oxidation state of granites 360<br>Mineralogical variations 361<br>Granites in relation to tectonic environment 362<br>Ocean basins 362<br>Island arcs 363<br>Orogenic continental margins 364<br>Intra-continental orogenic belts 369<br>Anorogenic continental regions 374<br>Pegmatites and aplites 376<br>10. Andesites 380<br>Occurrence and associations 380<br>Primary origins 384<br>The source region of andesite 384<br>Partial melting of amphibolite 389<br>Partial melting of eclogite 390<br>Hydrous melting of peridotite 390<br>Formation of andesite magma by melting in the crust 392<br>Secondary origins 393<br>Fractionation 393<br>Contamination 396<br>Mixing of magmas 396<br>Geochemistry of andesites 398<br>Isotopic composition 398<br>Trace element contents 400<br>Discussion of andesite petrogenesis 401<br>Diorites 403<br>Diorites as contaminated rocks 403<br>Dioritic cumulates 404<br>11. Alkaline igneous rocks 407<br>The nephelinite-carbonatite association 407<br>Typical rock types 407<br>Fenitization 408<br>Occurrence of nephelinite and carbonatite 408<br>Origin of nephelinite magma 415<br>Origin of carbonatite magma 417<br>Felsic alkaline rocks 420<br>Peralkaline nepheline syenites 421<br>Origin of felsic alkaline magmas 424<br>Crossing the syenite divide 432<br> <br>12. Kimberlites and ultrapotassic igneous rocks 437<br>Kimberlites 437<br>Xenoliths in kimberlite 441<br>Origin of kimberlite 445<br>Potassium-rich basic lavas 452<br>Origin of K-rich mafic magmas 455<br>13. Peridotites 459<br>Alpine-type peridotites 460<br>Ultramafic rock types 461<br>Emplacement of peridotites 462<br>Ophiolites 463<br>Representative ophiolites 464<br>Ophiolites as oceanic crust 468<br>Non-ophiolitic Alpine peridotites 472<br>Lherz 472<br>Ronda 473<br>Beni-Bousera 474<br>Mount Albert 475<br>Finero 476<br>Alpe Arami, Switzerland 478<br>Origin of non-ophiolitic Alpine peridotites 479<br>14. Anorthosites 483<br>Anorthosite in layered basic intrusions 483<br>Proterozoic massif-type anorthosites 487<br>Occurrence 487<br>Igneous rocks associated with anorthosite 498<br>Mineralogy of massif-type anorthosites 500<br>Origin of Proterozoic massif-type anorthosites 500<br>Archaean megacrystic anorthosites 507<br>Lunar analogies 507<br>Appendix. A key to some common abbreviations 509<br>References 512<br>Index 546<br>