Page 9 - Global Tectonics

viii CONTENTS

11 Precambrian tectonics 12.5.3 The vertical extent of
convection 387
and the supercontinent 12.6 The forces acting on plates 388
cycle 346 12.7 Driving mechanism of
plate tectonics 390
11.1 Introduction 347 12.7.1 Mantle drag mechanism 391
11.2 Precambrian heat fl ow 347 12.7.2 Edge-force mechanism 391
11.3 Archean tectonics 349 12.8 Evidence for convection in
11.3.1 General characteristics of the mantle 393
cratonic mantle lithosphere 349 12.8.1 Introduction 393
11.3.2 General geology of 12.8.2 Seismic tomography 393
Archean cratons 350 12.8.3 Superswells 394
11.3.3 The formation of Archean 12.8.4 The D” layer 395
lithosphere 351 12.9 The nature of convection in
11.3.4 Crustal structure 355 the mantle 396
11.3.5 Horizontal and vertical tectonics 358 12.10 Plumes 399
11.4 Proterozoic tectonics 361 12.11 The mechanism of the
11.4.1 General geology of supercontinent cycle 401
Proterozoic crust 361
11.4.2 Continental growth and
craton stabilization 363
11.4.3 Proterozoic plate tectonics 364 13 Implications of
11.5 The supercontinent cycle 370
11.5.1 Introduction 370 plate tectonics 404
11.5.2 Pre-Mesozoic
reconstructions 370 13.1 Environmental change 405
11.5.3 A Late Proterozoic 13.1.1 Changes in sea level and sea
supercontinent 370 water chemistry 405
11.5.4 Earlier supercontinents 373 13.1.2 Changes in oceanic circulation
11.5.5 Gondwana–Pangea assembly and the Earth’s climate 406
and dispersal 374 13.1.3 Land areas and climate 411
13.2 Economic geology 412
13.2.1 Introduction 412
13.2.2 Autochthonous and
12 The mechanism of allochthonous mineral
deposits
plate tectonics 379 13.2.3 Deposits of sedimentary 413
12.1 Introduction 380 basins 420
12.2 Contracting Earth hypothesis 380 13.2.4 Deposits related to climate 421
13.2.5 Geothermal power 422
12.3 Expanding Earth hypothesis 380 13.3 Natural hazards 422
12.3.1 Calculation of the ancient moment
of inertia of the Earth 381
12.3.2 Calculation of the ancient
radius of the Earth 382 Review questions 424
12.4 Implications of heat fl ow 382 References 428
12.5 Convection in the mantle 384 Index 463
12.5.1 The convection process 384
12.5.2 Feasibility of mantle convection 386 Color plates appear between pages 244 and 245

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