Table Of ContentTIMESCALES OF MAGMATIC PROCESSES
Timescales of Magmatic Processes: From Core to Atmosphere
Edited by Anthony Dosseto, Simon P. Turner and James A. Van Orman
© 2011 Blackwell Publishing Ltd. ISBN: 978-1-444-33260-5
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Timescales of Magmatic
Processes
From Core to Atmosphere
EDITED BY
Anthony Dosseto, Simon P. Turner
and James A. Van Orman
A John Wiley & Sons, Ltd., Publication
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This edition first published 2011, © 2011 by Blackwell Publishing Ltd.
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Library of Congress Cataloguing-in-Publication Data
Timescales of magmatic processes : from core to atmosphere / edited by Anthony Dosseto, Simon P. Turner,
James A. Van Orman.
p. cm.
Includes index.
ISBN 978-1-4443-3260-5 (cloth) – ISBN 978-1-4443-3261-2 (pbk.) 1. Magmatism. 2. Magmas. 3. Volcanic
ash, tuff, etc. 4. Geological time. I. Dosseto, Anthony. II. Turner, Simon P. III. Van Orman, James A.
QE461.T526 2010
551.1′3–dc22
2010023309
A catalogue record for this book is available from the British Library.
This book is published in the following electronic formats:
eBook [9781444328516]; Wiley Online Library [9781444328509]
Set in 9/11.5pt TrumpMediaeval by SPi Publisher Services, Pondicherry, India
1 2011
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Contents
List of Contributors, vi 7 Time Constraints from Chemical
Equilibration in Magmatic Crystals, 125
Introduction to the Timescales of Fidel Costa and Daniel Morgan
Magmatic Processes, 1
8 Magma Cooling and Differentiation –
Anthony Dosseto, Simon P. Turner, Fidel Costa
Uranium-series Isotopes, 160
and James A. Van Orman
Anthony Dosseto and Simon P. Turner
1 Extinct Radionuclides and the Earliest 9 Defining Geochemical Signatures and
Differentiation of the Earth and Moon, 9 Timescales of Melting Processes in the
G. Caro and T. Kleine
Crust: An Experimental Tale of Melt
Segregation, Migration and
2 Diffusion Constraints on Rates of Melt
Emplacement, 181
Production in the Mantle, 52
Tracy Rushmer and Kurt Knesel
James A. Van Orman and Alberto E. Saal
10 Timescales Associated with Large Silicic
3 Melt Production in the Mantle:
Magma Bodies, 212
Constraints from U-series, 68
Olivier Bachmann
Bernard Bourdon and Tim Elliott
11 Timescales of Magma Degassing, 231
4 Formulations for Simulating the Kim Berlo, James E. Gardner and
Multiscale Physics of Magma Ascent, 87 Jonathan D. Blundy
Craig O’Neill and Marc Spiegelman
Index, 256
5 Melt Transport from the Mantle to the
Colour plates appear in between
Crust – Uranium-Series Isotopes, 102
pages 154 and 155
Simon P. Turner and Bernard Bourdon
6 Rates of Magma Ascent: Constraints from
Mantle-Derived Xenoliths, 116
Suzanne Y. O’Reilly and W.L. Griffin
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List of Contributors
OLIVIER BACHMANN Department of Earth T. KLEINE Institut für Planetologie, Westfälische
and Space Sciences, University of Washington, Wilhelms-Universität Münster, Wilhelm-Klemm-
Johnson Hall, room 435, Mailstop 351310, Seattle, Str. 10, 48149 Münster, Germany
WA 98195-1310, USA
KURT KNESEL Department of Earth Sciences,
KIM BERLO Department of Earth and Planetary University of Queensland, Brisbane, Qld 4072,
Sciences, McGill University, 3450 University Australia
Street, Montreal, QC H3A 2A7, Canada
DANIEL MORGAN School of Earth and
JONATHAN D. BLUNDY Department of Earth
Environment, University of Leeds, LS2 9JT, UK
Sciences, University of Bristol, Wills Memorial
Building, Queen’s Road, Bristol BS8 1RJ, UK
CRAIG O’NEILL GEMOC ARC National Key
Centre, Department of Earth and Planetary
BERNARD BOURDON Institute of Geochemis-
Sciences, Macquarie University, Talavera Road,
try and Petrology, ETH Zurich, NW D 81.4, 8092
Sydney, NSW 2109, Australia
clausiusstrasse 25, Switzerland
G. CARO CRPG-CNRS, Nancy Université, 15 SUZANNE Y. O’REILLY GEMOC ARC National
rue Notre-Dame-des-Pauvres, Vandoeuvre-les- Key Centre, Department of Earth and Planetary
Nancy 54501 cedex, France Sciences, Macquarie University, Talavera Road,
Sydney, NSW 2109, Australia
FIDEL COSTA Departamento de Geofísica y
Georiesgos, Institut de Ciencies de la Terra TRACY RUSHMER GEMOC ARC National Key
‘Jaume Almera’, C/Lluís Solé i Sabarís s/n 08028, Centre, Department of Earth and Planetary
CSIC, Barcelona, Spain and Earth Observatory Sciences, Macquarie University, Talavera Road,
of Singapore, Nanyang Technological University, Sydney, NSW 2109, Australia
Singapore 637879
ALBERTO E. SAAL Department of Geological
ANTHONY DOSSETO GeoQuEST Research
Sciences, Brown University, 324 Brook Street,
Centre, School of Earth and Environmental
Box 1846, Providence, RI 02912, USA
Sciences, University of Wollongong, Northfields
Avenue, Wollongong, NSW 2522, Australia MARC SPIEGELMAN Lamont-Doherty Earth
Observatory of Columbia University, PO Box
TIM ELLIOTT Bristol Isotope Group, University
1000, Palisades, NY 10964, USA
of Bristol, Wills Memorial Building, Queen’s
Road, Bristol BS8 1RJ, UK
SIMON P. TURNER GEMOC ARC National Key
JAMES E. GARDNER Department of Geological Centre, Department of Earth and Planetary
Sciences, University of Texas at Austin, 1 University Sciences, Macquarie University, Talavera Road,
Station C1100, Austin, TX 78712, USA Sydney, NSW 2109, Australia
W. L. GRIFFIN GEMOC ARC National Key JAMES A. VAN ORMAN Department of
Centre, Department of Earth and Planetary Geological Sciences, 112 A.W. Smith Building,
Sciences, Macquarie U niver sity, Talavera Road, Case Western Reserve University, 10900 Euclid
Sydney, NSW 2109, Australia Avenue, Cleveland, OH 44106-7216, USA
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Introduction to the Timescales
of Magmatic Processes
ANTHONY DOSSETO1, SIMON P. TURNER2, FIDEL
COSTA3,4 AND JAMES A. VAN ORMAN5
1GeoQuEST Research Centre, School of Earth and Environmental Sciences,
University of Wollongong, Wollongong, Australia
2GEMOC ARC National Key Centre, Department of Earth and Planetary Sciences,
Macquarie University, Sydney, NSW, Australia
3Institut de Ciencies de la Terra ‘Jaume Almera’, CSIC, Barcelona, Spain
4Earth Observatory of Singapore, Nanyang Technological University, Singapore
5Department of Geological Sciences, 112 Case Western Reserve University,
Cleveland, OH, USA
The publication in 1928 of The Evolution of by measuring the trace abundance of isotopes
Igneous Rocks by Norman L. Bowen laid the produced by radioactive decay of uranium and
foundation to understand the formation and evo- thorium, it was possible to demonstrate that the
lution of igneous rocks. Most of the magmatic Earth is actually 4.55 billion years old.
processes that he proposed are still used and dis- Great progress in understanding magmatic proc-
cussed today, and his search for the physical esses has been made by a combination of field-
parameters to understand these processes are work, geochemical analysis, experiments and
major themes of current research. At that time, numerical models (Young, 2003). On the one hand,
radioactivity had been known for 30 years, but there has been an avalanche of geochemical data
there were as yet no applications to dating of (e.g. databases PETDB, GEOROC and NAVDAT)
magmatic rocks. Thus any quantification of the that have allowed the relationship between plate
timescales of the processes that he proposed was tectonics and magma genesis and allowed the for-
not possible. Determining accurate isotope ratios mation and differentiation of the different reser-
of natural rocks for the purposes of dating and voirs of the Earth to be explored (Wilson, 1989).
understanding their formation would come dec- The detailed petrological and geochemical studies
ades later (Paterson, 1956). An example of how of individual rocks and crystals have shown that
critical the quantification of timescales is, and magmas can carry a mixture of components from
how radiometric dating revolutionized our under- various sources and with various ages (Davidson
standing of the world around us, is the determi- et al., 2007). On the other hand, experiments, the-
nation of the age of the Earth. Early scientific ory and numerical models have brought a robust
estimates varied widely (Dalrymple, 1994), but understanding of the conditions and intensive
variables under which magmas can be generated,
differentiated, and may erupt (Carmichael &
Timescales of Magmatic Processes: From Core to Atmosphere
Eusgter, 1987; MELTS algorithm of Ghiorso & Sack,
Edited by Anthony Dosseto, Simon P. Turner and James A. Van Orman
© 2011 Blackwell Publishing Ltd. ISBN: 978-1-444-33260-5 1995). Numerical models built upon robust physi-
cal properties of multicomponent silicate melts
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2 ANTHONY DOSSETO ET AL.
(viscosity, density and diffusivities; Stebbins et al., seemingly homogeneous proto-Earth differenti-
1995) can be used to investigate the dynamics of ated into different envelopes (core, mantle,
magmatic processes (Nicholls & Russell, 1990; crust). In the first chapter, Caro and Kleine show
Spera & Bohrson, 2001). how extinct radionuclides can be used to dem-
Early dating of rock and mineral suites by onstrate that differentiation of the Earth’s core
various radioactive decay systems (e.g.14C, and the initiation of plate tectonics all occurred
Rb-Sr, K-Ar, Sm-Nd, U-Pb) provided a calibrated very early in the Earth’s history. The differentia-
sequence of magmatic and volcanic events tion of the Earth into various reservoirs is still a
(eruption or emplacement of plutonic bodies) work in progress. Material is continuously trans-
that could be used for the first time to estimate ferred from the mantle towards the surface and
rates of magma production and evolution. surface material is recycled back into the mantle
However, the errors resulting from the large at subduction zones. To understand the mecha-
amount of sample required and the precisions of nisms that allow melting of mantle rocks and
the measurements did not allow distinction the transfer of produced magmas to the surface,
between eruption and crystallization ages, or it is necessary to quantify the timescales of pro-
for dating a series of eruptions from the same duction and transport of magmas below mid-
vent, which may record the magmatic differen- ocean ridges and at hotspots. Two complementary
tiation (Faure, 1986). approaches can be used to constrain the times-
A turning point in understanding the dynam- cales of magma production in the mantle:
ics of magmatic processes has occurred in the uranium-s eries disequilibrium and the diffusion
last 10 to 20 years, with technological advances of trace elements in minerals.
in mass spectrometry and the accurate analysis Uranium and thorium-series isotopes compose
of short-lived radioactive isotopes of the U and the decay chains that start with 238U, 235U and
Th decay series (Bourdon et al., 2003), as well 232Th, and end with stable isotopes 206Pb, 207Pb and
as the possibility of in-situ dating of extremely 208Pb, respectively (Figure 0.1). These decay chains
small amounts of minerals (diameter of several are composed of radioactive systems where a par-
tens of μm (Hanchar & Hoskin, 2003) ). Further- ent nuclide decays into the daughter by alpha or
more, a large amount of data on the kinetics of beta emission. For instance, 230Th decays into
element migration in minerals together with 226Ra by alpha emission. For systems closed for
natural observations has led to the realization more than 1 Myr, all radioactive systems in the
that the chemical heterogeneities in crystals can decay chains are in secular equilibrium: the
also be used to extract time information on mag- activities (i.e. rates of decay) of parent and daugh-
matic processes. Thus, it is now possible to study ter nuclides are equal. For instance, (230Th) =
magmatic processes over timescales ranging from (226Ra), or (226Ra/230Th) = 1 (where parentheses
a few minutes to millions of years. This allows denote activities). This is the case for mantle
us to tackle critical questions about the evolu- rocks prior to melting. During geological proc-
tion of Earth systems: How long is a magma esses, such as partial melting or fractional crys-
stored in a reservoir prior to eruption? How long tallization, the different radionuclides behave
does it take to evolve from mafic to felsic magma differently inducing radioactive disequilibrium.
compositions? How long does it take for a magma Thus, because 226Ra is usually more incompatible
generated in the mantle to reach the surface? than 230Th (i.e. it partitions preferentially into
How long after the Earth was created did a metal- the magma relative to the residue during partial
lic core form? melting), magmas are often characterized by
In this book we bring together syntheses of (226Ra/230Th) >1. Once radioactive disequilibrium
work aimed at tackling these questions. is produced, the system returns to secular equi-
Although the age of the Earth is now well known, librium by radioactive decay over a times-
until recently little was known about how the cale that is about five times the half-life of the
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Introduction 3
238U 234U 235U
4.47(cid:2)102y (cid:4) 2.46(cid:2)104y 7.04(cid:2)102y
(cid:3) 234Pa (cid:3) (cid:3) 231Pa
4.196 4.776 4.395
MeV 6.69 h MeV MeV (cid:4) 3.28(cid:2)104y
(cid:3)
234Th 230Th 231Th 227Th
5.013
24.1 d 7.5(cid:2)104y 1.06 d MeV 10.7 d
(cid:3) 227Ac (cid:4) (cid:3)
4.688 6.038
MeV 21.8 y MeV
226Ra 223Ra
11.4 d
1500 Y
(cid:3) (cid:3)
4.784 5.176
MeV MeV
222Rn 219Rn
3.823 d 3.08 0
(cid:3) (cid:3)
5.490 6.819
MeV MeV
218Po 214Po 210Po 215Po
3.04 min (cid:4) 1.6(cid:2)104y (cid:4) 138.4 d 1.8(cid:2)1020
(cid:3) (cid:3) (cid:3) (cid:3)
214Bi 210Bi 211Bi
6.003 7.687 5.304 7.386
MeV 19.7 min MeV 5.01 d MeV MeV (cid:4) 2.14min
(cid:4) (cid:4) (cid:3)
214Pb 210Pb 205Pb 211Pb 207Pb
6.623
26.9 min 22.6 y 22.6 y 38.1min MeV 22.6 y
(cid:4)
207Tl
4.77min
Fig. 0.1 238U and 235U decay chains. See Plate 0.1 for a colour version of this image.
shorter-lived daughter nuclide. For example, if a ratios are time-dependent, they provide a critical
magma with (226Ra/230Th) >1 behaves as a closed tool for constraining the timescales of magmatic
system once the disequilibrium is acquired, secu- processes.
lar equilibrium will be attained after ∼8,000 years In Chapter 3, Bourdon and Elliott show that
(226Ra half-life is 1,602 years (Bourdon et al. 2003)) the study of the U-series isotope composition of
(Figure 0.2). Thus, because U-series isotopes frac- basaltic rocks can be used to constrain the con-
tionate during magmatic processes and their ditions and timescales of mantle melting. It is
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