Mantle Convection for Geologists

by Geoffrey F. Davies

• ISBN13: 9780521198004
• ISBN10: 0521198003
• Format: Hardcover
• Copyright: 2011-03-14
• Publisher: Cambridge University Press

Summary

Mantle convection is the fundamental agent driving many of the geological features observed at the Earth's surface, including plate tectonics and plume volcanism. Yet many Earth scientists have an incomplete understanding of the process. This book describes the physics and fluid dynamics of mantle convection, explaining what it is, how it works, and how to quantify it in simple terms. It assumes no specialist background: mechanisms are explained simply and the required basic physics is fully reviewed and explained with minimal mathematics. The distinctive forms that convection takes in the Earth's mantle are described within the context of tectonic plates and mantle plumes, and implications are explored for geochemistry and tectonic evolution. Common misconceptions and controversies are addressed - providing a straightforward but rigorous explanation of this key process for students and researchers across a variety of geoscience disciplines.

Table of Contents

Introduction	p. 1
Context	p. 4
Crust, mantle, core	p. 4
Lithosphere versus crust	p. 6
Topography	p. 8
Heat flux	p. 12
Why moving plates?	p. 13
The lead-up	p. 13
Wilson, plumes and plates	p. 15
Evidence for motion - magnetism	p. 19
Evidence for motion - seismology	p. 22
Evidence for motion - sediments	p. 24
Solid, yielding mantle	p. 26
Viscosity	p. 27
Viscosity of the mantle	p. 30
Dependence of viscosity on temperature	p. 35
Inevitable convection	p. 36
Convection	p. 38
Thermal expansion	p. 40
Buoyancy	p. 41
Plate velocity - simple mechanical version	p. 42
Heat conduction	p. 45
Plate velocity - thermo-viscous version	p. 50
The Rayleigh number and other fluid-dynamical beasts	p. 52
The plate mode of convection	p. 56
The strong lithosphere	p. 56
The role of the lithosphere in mantle convection	p. 59
Heat transport - the plates are mantle convection	p. 63
The geography of topography	p. 66
The geography of heat flow	p. 69
Numerical model of the plate mode	p. 69
Summary of the plate mode	p. 71
The plume mode of convection	p. 73
Inferring plumes from surface observations	p. 75
Hotspot swells, plume flows and eruption rates	p. 78
The dynamics and form of mantle plumes	p. 84
Plume heads and flood basalt eruptions	p. 95
Irregular volcanism and thermochemical plumes	p. 99
Summary of the plume mode	p. 101
Perspective	p. 104
Separate but interacting	p. 104
Common misconceptions	p. 107
Layered convection?	p. 112
Other modes and causes	p. 116
Pursuing implications	p. 122
Evolution and tectonics	p. 124
Parametrised thermal evolution	p. 125
Numerical thermal evolution	p. 130
The heat source puzzle	p. 132
Compositional buoyancy	p. 136
Intermittent plate tectonics	p. 147
Implications for tectonics	p. 147
Mantle chemical evolution	p. 154
Trace element and isotope observations	p. 155
Global budgets	p. 160
Incompatible trace elements in the mantle	p. 162
Mantle heterogeneity	p. 164
Melting in a heterogeneous mantle	p. 171
Previous estimates of trace element abundance	p. 176
Dynamical modelling of refractory incompatible elements	p. 184
Resolving the noble gas enigma	p. 193
Assessment of mantle chemistry	p. 205
Assimilating mantle convection into geology	p. 206
Exponential growth and decay	p. 208
Exponential solution	p. 208
Post-glacial rebound	p. 209
Rayleigh-Taylor instability	p. 210
Thermal evolution details	p. 211
Heat generation	p. 211
Parametrised thermal evolution model	p. 211
Numerical thermal evolution model	p. 213
Basalt tracers	p. 213
Models with basalt tracers	p. 214
Chemical evolution details	p. 216
Fraction of primitive mantle	p. 216
Fraction of crust in the mantle	p. 216
References	p. 218
Index	p. 230
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