Global Tectonics

Table of Contents:
Preface ix Acknowledgments x The geologic timescale and stratigraphic column xi 1 Historical perspective 1 1.1 Continental drift 2 1.2 Sea floor spreading and the birth of plate tectonics 6 1.3 Geosynclinal theory 7 1.4 Impact of plate tectonics 8 2 The interior of the Earth 9 2.1 Earthquake seismology 10 2.1.1 Introduction 10 2.1.2 Earthquake descriptors 10 2.1.3 Seismic waves 10 2.1.4 Earthquake location 11 2.1.5 Mechanism of earthquakes 12 2.1.6 Focal mechanism solutions of earthquakes 12 2.1.7 Ambiguity in focal mechanism solutions 14 2.1.8 Seismic tomography 17 2.2 Velocity structure of the Earth 19 2.3 Composition of the Earth 21 2.4 The crust 22 2.4.1 The continental crust 22 2.4.2 Upper continental crust 23 2.4.3 Middle and lower continental crust 23 2.4.4 The oceanic crust 24 2.4.5 Oceanic layer 1 24 2.4.6 Oceanic layer 2 25 2.4.7 Oceanic layer 3 26 2.5 Ophiolites 27 2.6 Metamorphism of oceanic crust 28 2.7 Differences between continental and oceanic crust 29 2.8 The mantle 30 2.8.1 Introduction 30 2.8.2 Seismic structure of the mantle 30 2.8.3 Mantle composition 31 2.8.4 The mantle low velocity zone 31 2.8.5 The mantle transition zone 32 2.8.6 The lower mantle 32 2.9 The core 33 2.10 Rheology of the crust and mantle 33 2.10.1 Introduction 33 2.10.2 Brittle deformation 34 2.10.3 Ductile deformation 36 2.10.4 Lithospheric strength profiles 37 2.10.5 Measuring continental deformation 39 2.10.6 Deformation in the mantle 41 2.11 Isostasy 42 2.11.1 Introduction 42 2.11.2 Airy’s hypothesis 43 2.11.3 Pratt’s hypothesis 43 2.11.4 Flexure of the lithosphere 44 2.11.5 Isostatic rebound 45 2.11.6 Tests of isostasy 46 2.12 Lithosphere and asthenosphere 48 2.13 Terrestrial heat flow 51 3 Continental drift 54 3.1 Introduction 55 3.2 Continental reconstructions 55 3.2.1 Euler’s theorem 55 3.2.2 Geometric reconstructions of continents 55 3.2.3 The reconstruction of continents around the Atlantic 56 3.2.4 The reconstruction of Gondwana 57 3.3 Geologic evidence for continental drift 58 3.4 Paleoclimatology 60 3.5 Paleontologic evidence for continental drift 61 3.6 Paleomagnetism 64 3.6.1 Introduction 64 3.6.2 Rock magnetism 64 3.6.3 Natural remanent magnetization 65 3.6.4 The past and present geomagnetic field 66 3.6.5 Apparent polar wander curves 67 3.6.6 Paleogeographic reconstructions based on paleomagnetism 68 4 Sea floor spreading and transform faults 72 4.1 Sea floor spreading 73 4.1.1 Introduction 73 4.1.2 Marine magnetic anomalies 73 4.1.3 Geomagnetic reversals 74 4.1.4 Sea floor spreading 77 4.1.5 The Vine–Matthews hypothesis 78 4.1.6 Magnetostratigraphy 79 4.1.7 Dating the ocean floor 84 4.2 Transform faults 84 4.2.1 Introduction 84 4.2.2 Ridge–ridge transform faults 88 4.2.3 Ridge jumps and transform fault offsets 89 5 The framework of plate tectonics 91 5.1 Plates and plate margins 92 5.2 Distribution of earthquakes 92 5.3 Relative plate motions 94 5.4 Absolute plate motions 97 5.5 Hotspots 99 5.6 True polar wander 103 5.7 Cretaceous superplume 106 5.8 Direct measurement of relative plate motions 107 5.9 Finite plate motions 110 5.10 Stability of triple junctions 113 5.11 Present day triple junctions 120 6 Ocean ridges 121 6.1 Ocean ridge topography 122 6.2 Broad structure of the upper mantle below ridges 125 6.3 Origin of anomalous upper mantle beneath ridges 127 6.4 Depth–age relationship of oceanic lithosphere 128 6.5 Heat flow and hydrothermal circulation 129 6.6 Seismic evidence for an axial magma chamber 131 6.7 Along-axis segmentation of oceanic ridges 133 6.8 Petrology of ocean ridges 140 6.9 Shallow structure of the axial region 141 6.10 Origin of the oceanic crust 142 6.11 Propagating rifts and microplates 145 6.12 Oceanic fracture zones 148 7 Continental rifts and rifted margins 152 7.1 Introduction 153 7.2 General characteristics of narrow rifts 155 7.3 General characteristics of wide rifts 162 7.4 Volcanic activity 169 7.4.1 Large igneous provinces 169 7.4.2 Petrogenesis of rift rocks 172 7.4.3 Mantle upwelling beneath rifts 175 7.5 Rift initiation 176 7.6 Strain localization and delocalization processes 178 7.6.1 Introduction 178 7.6.2 Lithospheric stretching 179 7.6.3 Buoyancy forces and lower crustal flow 181 7.6.4 Lithospheric flexure 183 7.6.5 Strain-induced weakening 184 7.6.6 Rheological stratification of the lithosphere 188 7.6.7 Magma-assisted rifting 192 7.7 Rifted continental margins 193 7.7.1 Volcanic margins 193 7.7.2 Nonvolcanic margins 196 7.7.3 The evolution of rifted margins 198 7.8 Case studies: the transition from rift to rifted margin 202 7.8.1 The East African Rift system 202 7.8.2 The Woodlark Rift 204 7.9 The Wilson cycle 208 8 Continental transforms and strike-slip faults 210 8.1 Introduction 211 8.2 Fault styles and physiography 211 8.3 The deep structure of continental transforms 224 8.3.1 The Dead Sea Transform 224 8.3.2 The San Andreas Fault 224 8.3.3 The Alpine Fault 228 8.4 Transform continental margins 230 8.5 Continuous versus discontinuous deformation 232 8.5.1 Introduction 232 8.5.2 Relative plate motions and surface velocity fields 233 8.5.3 Model sensitivities 236 8.6 Strain localization and delocalization mechanisms 239 8.6.1 Introduction 239 8.6.2 Lithospheric heterogeneity 239 8.6.3 Strain-softening feedbacks 242 8.7 Measuring the strength of transforms 246 9 Subduction zones 249 9.1 Ocean trenches 250 9.2 General morphology of island arc systems 251 9.3 Gravity anomalies of subduction zones 252 9.4 Structure of subduction zones from earthquakes 252 9.5 Thermal structure of the downgoing slab 259 9.6 Variations in subduction zone characteristics 262 9.7 Accretionary prisms 264 9.8 Volcanic and plutonic activity 271 9.9 Metamorphism at convergent margins 275 9.10 Backarc basins 279 10 Orogenic belts 286 10.1 Introduction 287 10.2 Ocean–continent convergence 287 10.2.1 Introduction 287 10.2.2 Seismicity, plate motions, and subduction geometry 289 10.2.3 General geology of the central and southern Andes 291 10.2.4 Deep structure of the central Andes 294 10.2.5 Mechanisms of noncollisional orogenesis 297 10.3 Compressional sedimentary basins 302 10.3.1 Introduction 302 10.3.2 Foreland basins 302 10.3.3 Basin inversion 303 10.3.4 Modes of shortening in foreland fold-thrust belts 304 10.4 Continent–continent collision 306 10.4.1 Introduction 306 10.4.2 Relative plate motions and collisional history 306 10.4.3 Surface velocity fields and seismicity 309 10.4.4 General geology of the Himalaya and Tibetan Plateau 312 10.4.5 Deep structure 316 10.4.6 Mechanisms of continental collision 318 10.5 Arc–continent collision 330 10.6 Terrane accretion and continental growth 332 10.6.1 Terrane analysis 332 10.6.2 Structure of accretionary orogens 336 10.6.3 Mechanisms of terrane accretion 342 11 Precambrian tectonics and the supercontinent cycle 346 11.1 Introduction 347 11.2 Precambrian heat flow 347 11.3 Archean tectonics 349 11.3.1 General characteristics of cratonic mantle lithosphere 349 11.3.2 General geology of Archean cratons 350 11.3.3 The formation of Archean lithosphere 351 11.3.4 Crustal structure 355 11.3.5 Horizontal and vertical tectonics 358 11.4 Proterozoic tectonics 361 11.4.1 General geology of Proterozoic crust 361 11.4.2 Continental growth and craton stabilization 363 11.4.3 Proterozoic plate tectonics 364 11.5 The supercontinent cycle 370 11.5.1 Introduction 370 11.5.2 Pre-Mesozoic reconstructions 370 11.5.3 A Late Proterozoic supercontinent 370 11.5.4 Earlier supercontinents 373 11.5.5 Gondwana–Pangea assembly and dispersal 374 12 The mechanism of plate tectonics 379 12.1 Introduction 380 12.2 Contracting Earth hypothesis 380 12.3 Expanding Earth hypothesis 380 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 12.4 Implications of heat flow 382 12.5 Convection in the mantle 384 12.5.1 The convection process 384 12.5.2 Feasibility of mantle convection 386 12.5.3 The vertical extent of convection 387 12.6 The forces acting on plates 388 12.7 Driving mechanism of plate tectonics 390 12.7.1 Mantle drag mechanism 391 12.7.2 Edge-force mechanism 391 12.8 Evidence for convection in the mantle 393 12.8.1 Introduction 393 12.8.2 Seismic tomography 393 12.8.3 Superswells 394 12.8.4 The D” layer 395 12.9 The nature of convection in the mantle 396 12.10 Plumes 399 12.11 The mechanism of the supercontinent cycle 401 13 Implications of plate tectonics 404 13.1 Environmental change 405 13.1.1 Changes in sea level and sea water chemistry 405 13.1.2 Changes in oceanic circulation and the Earth’s climate 406 13.1.3 Land areas and climate 411 13.2 Economic geology 412 13.2.1 Introduction 412 13.2.2 Autochthonous and allochthonous mineral deposits 413 13.2.3 Deposits of sedimentary basins 420 13.2.4 Deposits related to climate 421 13.2.5 Geothermal power 422 13.3 Natural hazards 422 Review questions 424 References 428 Index 463

About the Author :
PHIL KEAREY was Senior Lecturer in Applied Geophysics in the Department of Earth Sciences at Bristol University, U.K. prior to his premature death in 2003. In his research he used various types of geophysical data, but gravity and magnetic data in particular, to elucidate crustal structure in the eastern Caribbean, Canadian shield and southern England. KEITH KLEPEIS is a Professor in the Department of Geology at the University of Vermont, U.S.A. He specializes in the areas of structural geology and continental tectonics and has worked extensively on the evolution of orogenic belts and fault systems in New Zealand, Patagonia, West Antarctica, Australia, British Columbia and southeast Alaska. FREDERICK J. VINE is an Emeritus Professor in the School of Environmental Sciences at the University of East Anglia, Norwich, U.K. He was made a Fellow of the Royal Society of London and has received numerous awards for work on the interpretation of oceanic magnetic anomalies and ophiolites, fragments of oceanic crust thrust up on land, in terms of sea floor spreading.

Review :
"Many readers will be familiar with this excellent textbook . . . The subject coverage is more comprehensive than in previous editions with many of the processes and concepts being illustrated with case studies drawn from the recent literature. " (Mar Geophys Res, 2009) "A massive list of mostly critical references cites the most important works the world over." (CHOICE, November 2009)"An excellent in‑depth overview on one of the most revo­lutionary topics in the earth sciences. … Not only clear and comprehensive, but also pleasant to read. It is a highly recommended must‑have on the bookshelves of earth scien­tists for some time to come." (Geologos, December 2009) "Global Tectonics will find its place in all well equipped libraries and a personal copy will be of use for any geoscientist who needs a comprehensive overview." (Surveys in Geophysics, September 2009) "This textbook provides a comprehensive overview of the field of global tectonics. Because the field has changed significantly since the last edition was published, the majority of text and figures in the third edition are new." (Book News, September 2009)