PREFACE ........................................................ XI
ACKNOWLEDGEMENTS ............................................. XIII
INTRODUCTION ................................................. XVII
PART ONE
CHAPTER 1 The Earth's Internal Structure and Convection
in the Mantle ........................................ 1
1.1 Introduction ............................................... 1
1.2 Early planetary evolution .................................. 2
1.3 The Earth's internal structure ............................. 5
1.3.1 The crust ........................................... 7
1.3.2 The mantle ......................................... 11
1.3.3 The core-mantle boundary (CMB) and D'' layer ....... 20
1.3.4 The core ........................................... 25
1.4 Convection in the mantle; theories and models ............. 27
1.4.1 Theories and dynamics of convection ................ 29
1.4.2 Physical parameters of mantle convection ........... 31
1.4.3 Whole mantle and two-layers mantle convection
models ............................................. 32
1.5 Mantle geochemistry ....................................... 41
1.6 Mantle evolution through time and implications for
Earth's history ........................................... 46
1.7 Concluding remarks ........................................ 53
1.8 References
CHAPTER 2 Mantle Plumes and Superplumes; Continental
Breakups, Supercontinent Cycles and Ore Deposits .... 59
2.1 Introduction .............................................. 59
2.2 Hotspots: distribution and relationship to rifting ........ 61
2.3 Laboratory modelling, structure and dynamics of mantle
plumes .................................................... 65
2.4 Doming of the crust (hotspot swells) and associated
topographic and drainage features ......................... 71
2.5 Mantle plume-lithosphere interactions and plume-
generated melts ........................................... 77
2.5.1 Crustal stress regimes in response to mantle
plumes ............................................. 85
2.6 Superplumes and continental breakup ....................... 86
2.6.1 Gondwana and Rodinia breakups, mantle plumes or
plate forces? ...................................... 90
2.6.2 Supercontinent cycles and ore deposits ............. 94
2.7 The "other side" of the mantle plume theory .............. 100
2.8 Concluding remarks ....................................... 104
2.9 References ............................................... 105
CHAPTER 3 Oceanic Islands, Large Igneous Provinces, Mafic
Dyke Swarms, and Intracontinental Alkaline
Magmatism .......................................... 111
3.1 Introduction ............................................. 111
3.2 Oceanic volcanic islands ................................. 112
3.2.1 The Hawaiian-Emperor seamounts chain .............. 116
3.2.2 Marquesas Islands ................................. 119
3.2.3 Walvis Ridge and Tristan da Cunha ................. 119
3.2.4 Iceland ........................................... 124
3.2.5 Reunion Island .................................... 127
3.2.6 Geochemical and isotopic characteristics of
oceanic volcanic island basalts ................... 128
3.3 Large igneous provinces (LIP): oceanic plateaux and
continental flood basalts (CFB) .......................... 135
3.3.1 Introduction ...................................... 135
3.3.2 Isotope systematics ............................... 139
3.3.3 Oceanic plateaux .................................. 140
3.3.4 Volcanic-rifted continental margins ............... 149
3.3.5 Continental flood basalts (CFB) ................... 151
3.3.1 Continental flood basalts (CFB) ................... 151
3.4 Mafic dyke swarms ........................................ 183
3.4.1 Mafic dyke swarms in the Kaapvaal Craton, South
Africa ............................................ 189
3.4.2 The Mackenzie dyke swarm, Canada .................. 190
3.4.3 Paraná-Etendeka dykes ............................. 192
3.5 Intracontinental alkaline magmatism ...................... 193
3.5.1 Tectonic settings, ages and controls of
intracontinental alkaline magmatism in Africa ..... 194
3.5.2 The Damaraland alkaline province, Namibia ......... 198
3.5.3 Carbonatites ...................................... 199
3.5.4 Kimberlites and lamproites ........................ 200
3.6 Concluding remarks ....................................... 201
3.7 References ............................................... 202
CHAPTER 4 Rifting Processes, Volcano-Sedimentary Basins
and the Role of Mantle Plumes ..................... 215
4.1 Introduction ............................................. 215
4.2 Rifting dynamics: passive and active ..................... 220
4.2.1 Passive rifting ................................... 221
4.2.2 Active rifting .................................... 222
4.3 Rifting and basic formation related to compression in
thickened crust .......................................... 223
4.4 Geophysical signatures of rifts .......................... 227
4.5 Stratigraphic successions as records of basin
evolution ................................................ 230
4.5.1 The stratigraphic record of intracontinental
basins and aulacogens ............................. 230
4.6 The East African Rift System and the Afar Triangle:
examples of modern continental rifting where mantle
plume activity is recognised ............................. 239
4.6.1 Introduction ...................................... 239
4.6.2 The East African Rift System (EARS) ............... 240
4.7 Examples of ancient continental rifts where mantle
plume activity is assumed: Thuli-Sabi-Lebombo hotspot
junction; Damara and Irumide hotspot junctions ........... 244
4.7.1 Tuli-Sabi-Lebombo hotspot junction ................ 244
4.7.2 Damara and Irumide hotspot junctions,
southwestern Africa ............................... 248
4.8 Sequence stratigraphy, eustasy and mantle plumes ......... 252
4.9 Concluding remarks ....................................... 254
4.10 References ............................................... 256
CHAPTER 5 The Planetary and Meteorite Impact Context of
Mantle Plumes ...................................... 261
5.1 Introduction ............................................. 261
5.2 Moon ..................................................... 263
5.3 Mercury .................................................. 265
5.4 Venus .................................................... 265
5.5 Mars ..................................................... 269
5.6 Large meteorite impacts and possible correlations with
mantle plumes ............................................ 274
5.6.1 Ore deposits and impact structures ................ 277
5.6.2 Can meteorite mega-impacts trigger continental
breakup and the ascent of mantle plumes? .......... 279
5.7 Concluding remarks ....................................... 285
5.8 References ............................................... 286
PART TWO
CHAPTER 6 Intracontinental Magmatism, Anorogenic
Metamorphism, Ore Systems and Mantle Plumes ........ 291
6.1 Introduction ............................................. 291
6.2 Intracontinental layered igneous intrusions .............. 291
6.3 Anorogenic prograde metamorphism and hydrothermal
convention in hotspot-related rift systems ............... 299
6.3.1 Anorogenic metamorphism in the Central Zone of
the Damara Orogen, Namibia ........................ 301
6.3.2 Anorogenic metamorphism in the eastern Pyrenees ... 302
6.3.3 Anorogenic metamorphism and intraplate magmatism
around the Vredefort Dome, South Africa ........... 303
6.3.4 Metamorphism and fluid generation;
metamorphogenic hydrothermal systems .............. 306
6.4 Concluding remarks ....................................... 317
6.5 References ............................................... 317
CHAPTER 7 Direct Links; Magmatic Ore Deposits -
Fundamental Features and Concepts ................. 323
7.1 Introduction ............................................. 323
7.1.1 Definitions and terminology ....................... 323
7.1.2 Geometry of layered intrusions and magmatic
processes ......................................... 331
7.2 Magmatic oxide ores ...................................... 342
7.2.1 Crystallisation of spinels from mafic-ultramafic
magmas ............................................ 344
7.3 Magmatic sulphides and platinum group elements (PGE)
ores ..................................................... 347
7.3.1 The formation of Ni sulphide ores ................. 347
7.3.2 Platinum group elements (PGE) ..................... 355
7.4 Concluding remarks ....................................... 378
7.5 References ............................................... 380
CHAPTER 8 Magmatic Ore Deposits .............................. 387
8.1 Introduction ............................................. 387
8.2 Large layered igneous complexes .......................... 388
8.2.1 The Great Dyke, Zimbabwe .......................... 389
8.2.2 The Bushveld Igneous Complex, South Africa ........ 401
8.2.3 Molopo Farms Complex, South Africa and Botswana ... 425
8.3 Magmatic ore deposits in igneous complexes associated
with continental flood basalts ........................... 426
8.3.1 Duluth Complex, Mid-continent Rift System, USA .... 426
8.3.2 NoriPsk-Talnakh, Siberian Traps, Russia ........... 428
8.3.3 The Insizwa Complex; Karoo Igneous Province ....... 433
8.3.4 Skaergaard and Кар Edvard Holm, East Greenland .... 438
8.4 magmatic ores in Proterozoic troctolite-anorthosite
complexes ................................................ 441
8.4.1 Voisey's Bay Ni-Cu-Co ............................. 442
8.5 Komatiite-related magmatic ore deposits .................. 445
8.5.1 Komatiite volcanology ............................. 446
8.5.2 Komatiite mineralogy and whole rock
geochemistry ...................................... 447
8.5.3 Komatiite-hosted Fe-Ni-Cu sulphide ores ........... 449
8.6 Hydrothermal Ni-cu and PGE mineralisation in
ultra-ultramafic rocks ................................... 453
8.7 Concluding remarks ....................................... 458
8.8 References ............................................... 459
CHAPTER 9 Indirect Links: Hydrothermal Mineral Deposits ...... 469
9.1 Introduction ............................................. 469
9.2.1 Ring complexes and carbonatites ................... 471
9.2.2 Proterozoic Cu-Au-U-REE-Fe deposits ............... 473
9.2.3 Mesothermal ore deposits .......................... 480
9.2.4 Carlin-type epithermal ore deposits ............... 483
9.2 Ore deposits associated with intracontinental
anorogenic magmatism ..................................... 471
9.3 Metallogeny of the Damara and Irumide orogens,
Southwestern Africa, and the Mid Continent Rift System,
USA ...................................................... 491
9.3.1 Metallogeny of the Damara and Irumide orogens ..... 491
9.3.2 Metallogeny of the Mid-continent Rift System,
North America ..................................... 497
9.4 Archaean lode Au deposits ................................ 498
9.5 Concluding remarks ....................................... 502
9.6 References ............................................... 504
CHAPTER 10 Indirect Links: Sedimentary Rock-Hosted Ore
Deposits. Epilogue ................................. 509
10.1 Introduction ............................................. 509
10.2 Metallogeny in modern rift settings ...................... 511
10.2.1 The East African Rift System ...................... 511
10.2.2 The Red Sea brine pools ........................... 516
10.3 Sedimentary-hydrothermal ore deposits .................... 520
10.3.1 Mississippi Valley-type sulphide deposits ......... 520
10.3.2 Sedimentary exhalative (SEDEX) massive sulphide
deposits .......................................... 523
10.3.3 Stratabound Cu-Ag and Cu-Co ore deposits .......... 528
10.4 Metalliferous black shales ............................... 531
10.4.1 Mo-Ni-V-PGE-Au in black shales, southern China .... 533
10.5 Iron-formations and manganese deposits ................... 534
10.6 Concluding remarks and epilogue .......................... 539
10.7 References ............................................... 540
APPENDIX ...................................................... 547
INDEX ......................................................... 549
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