Archean and Proterozoic Earth - Pascal Philippot

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Biographie:

Introduction xi
Pascal PHILIPPOT

Chapter 1 Thermal Evolution of the Earth 1
St?phane LABROSSE

1.1 Brief historical note 1

1.2 The present-day heat budget 3

1.3 The Hadean Earth 5

1.4 Direct observations of thermal evolution 6

1.5 Parameterized models of evolution 9

1.5.1 Heat transfer by convection 9

1.5.2 Classic cooling models and thermal catastrophe 11

1.5.3 Effect of a different exponent ? 13

1.5.4 Effects of continents 14

1.5.5 Effects of Earth's layered structure 16

1.5.6 Thermal evolution of the core 17

1.5.7 Effects of a stratified mantle 20

1.6 Conclusion 25

1.7 References 26

Chapter 2 Dynamics of the Mantle, Lithosphere, and Crust in the Archean 33
Patrice REY and Nicolas COLTICE

2.1 Introduction 33

2.2 Change in the composition of the upper continental crust: plate tectonics or denudation? 35

2.2.1 A crustal perspective on continental growth 35

2.2.2 A mantle perspective on continental growth 39

2.3 Archean tectonics 42

2.3.1 Beyond observations: numerical geodynamics 44

2.4 Conclusions 59

2.5 References 61

Chapter 3 Precambrian Magnetic Field and Paleogeographic Reconstructions 73
Julie CARLUT and M?lina MACOUIN

3.1 Introductory overview of Earth's magnetic field 73

3.1.1 The magnetic field in the Ediacaran 75

3.1.2 The Proterozoic: tracing back to the Archean (from 635 to 2,500 Ma) 79

3.1.3 In the Archean (and before) 81

3.1.4 Life under an unstable and weak magnetic field 83

3.2 Using the Earth's magnetic field record to build paleogeographic reconstructions 84

3.2.1 Insights from paleogeographic reconstructions 84

3.2.2 Reconstructing the paleopositions of cratonic blocks and paleogeographies: paleomagnetism 85

3.3 Precambrian paleogeographic models 89

3.3.1 Supercratons/supercontinents 89

3.3.2 The Archean and paleoproterozoic 91

3.3.3 From the Paleoproterozoic to the Mesoproterozoic: Nuna supercontinent 92

3.3.4 From the Mesoproterozoic to the Neoproterozoic: the Rodinia supercontinent 92

3.3.5 The end of the Precambrian: toward the formation of Gondwana 93

3.4 References 95

Chapter 4 Archean Magmatism 103
Jean-Fran?ois MOYEN

4.1 Introduction 103

4.2 The lavas of the greenstone belts 106

4.2.1 Basic and ultrabasic lavas 108

4.2.2 Basic and intermediate lavas with arc affinity 113

4.2.3 Acidic lavas and pyroclastic rocks 114

4.3 Granitoids 114

4.3.1 Granitoids derived from the melting of crustal lithologies 117

4.3.2 Granitoids associated with a differentiation lineage: a mantle origin 123

4.4 Gray gneisses 124

4.5 Geodynamic considerations 127

4.5.1 The magmas of the present-day Earth and their geodynamic significance 127

4.5.2 Archean magmas and the dynamics of the ancient Earth 129

4.5.3 On subduction 129

4.5.4 The temporal evolution of Archean magmas 131

4.6 References 135

Chapter 5 Temperature and Chemical Composition of Precambrian Oceans 145
Johanna MARIN-CARBONNE and Christophe THOMAZO

5.1 Introduction 145

5.2 Very ancient oceans 146

5.2.1 Liquid water on Earth since the Hadean 146

5.2.2 The origin of water 150

5.3 Ocean temperature during the Precambrian 152

5.3.1 The faint young Sun paradox 152

5.3.2 The importance of cherts in paleo-temperature reconstructions 155

5.4 Characteristics and chemical evolution of the early oceans 161

5.4.1 Ocean s...

Sommaire:
It took nearly four billion years for the Earth to become a hospitable planet. Archean and Proterozoic Earth traces the geodynamic, biological, climatic and environmental upheavals that accompanied this evolution.

This book looks at the planet's secular cooling and its implications for the dynamics of the Earth's mantle and the development of plate tectonics, as well as the evolution of magma composition and the formation of a differentiated continental crust. It shows how variations in the intensity of the Earth's magnetic field have proved useful in reconstructing the movement of continents across the surface of the globe. The book also documents the origin of the oceans and the appearance of the first traces of life, and describes the evolution of the major biogeochemical cycles that led to the oxygenation of the atmosphere, the diversification of living organisms and the concentration of substances of economic interest, particularly metals....