Page 6 - Global Tectonics

Contents

Preface ix 2.8 The mantle 30
Acknowledgments x 2.8.1 Introduction 30
The geologic timescale and stratigraphic column xi 2.8.2 Seismic structure of the
mantle 30
2.8.3 Mantle composition 31
2.8.4 The mantle low velocity
1 Historical perspective 1 zone 31
2.8.5 The mantle transition zone 32
1.1 Continental drift 2 2.8.6 The lower mantle 32
1.2 Sea fl oor spreading and the birth 2.9 The core 33
of plate tectonics 6 2.10 Rheology of the crust
1.3 Geosynclinal theory 7 and mantle 33
1.4 Impact of plate tectonics 8 2.10.1 Introduction 33
2.10.2 Brittle deformation 34
2.10.3 Ductile deformation 36
2.10.4 Lithospheric strength profi les 37
2 The interior of 2.10.5 Measuring continental
the Earth 9 deformation 39
2.10.6 Deformation in the mantle 41
2.1 Earthquake seismology 10 2.11 Isostasy 42
2.1.1 Introduction 10 2.11.1 Introduction 42
2.1.2 Earthquake descriptors 10 2.11.2 Airy’s hypothesis 43
2.1.3 Seismic waves 10 2.11.3 Pratt’s hypothesis 43
2.1.4 Earthquake location 11 2.11.4 Flexure of the lithosphere 44
2.1.5 Mechanism of earthquakes 12 2.11.5 Isostatic rebound 45
2.1.6 Focal mechanism solutions 2.11.6 Tests of isostasy 46
of earthquakes 12 2.12 Lithosphere and asthenosphere 48
2.1.7 Ambiguity in focal 2.13 Terrestrial heat fl ow 51
mechanism solutions 14
2.1.8 Seismic tomography 17
2.2 Velocity structure of the Earth 19
2.3 Composition of the Earth 21 3 Continental drift 54
2.4 The crust 22
2.4.1 The continental crust 22 3.1 Introduction 55
2.4.2 Upper continental crust 23 3.2 Continental reconstructions 55
2.4.3 Middle and lower continental 3.2.1 Euler’s theorem 55
crust 23 3.2.2 Geometric reconstructions
2.4.4 The oceanic crust 24 of continents 55
2.4.5 Oceanic layer 1 24 3.2.3 The reconstruction of
2.4.6 Oceanic layer 2 25 continents around the
2.4.7 Oceanic layer 3 26 Atlantic 56
2.5 Ophiolites 27 3.2.4 The reconstruction of
2.6 Metamorphism of oceanic Gondwana 57
crust 28 3.3 Geologic evidence for
2.7 Differences between continental and continental drift 58
oceanic crust 29 3.4 Paleoclimatology 60

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