Table Of ContentAccretion of
Extraterrestrial Matter
Throughout Earth's History
Accretion of
Extraterrestrial Matter
Throughout Earth's History
Edited by
Bernhard Peucker-Ehrenbrink
Woods Hole Oceanographic Institution
Woods Hole, Massachusetts
and
Birger Schmitz
Earth Sciences Center, University of Getenburg
Gotenburg, Sweden
Springer Science +B usiness Media, LLC
Library of Congress Cataloging-in-Publication Data
Accretion of extraterrestrial matter throughout earth's history /edited by Bemhard
Peucker-Ehrenbrink and Birger Schmitz.
p. cm.
Includes bibliographical references and index.
ISBN 978-1-4613-4668-5 ISBN 978-1-4419-8694-8 (eBook)
DOI 10.1007/978-1-4419-8694-8
1. Geology. 2. Interstellar matter. 3. Accretion (Astrophysics) 1. Peucker-Ehrenbrink,
Bemhard. II. Schmitz, Birger.
QE33 .A23 2001
551.3'97-dc21
2001038586
ISBN 978-1-4613-4668-5
© 2001 Springer Science+Business Media New York
Origina1ly published by Kluwer Academic / Plenum Publishers, New York in 2001
Softcover reprint of the hardcover 1s t edition 2001
10987654321
A c.I.P. record for this book is available from the Library of Congress.
All rights reserved
No part of this book may be reproduced, stored in a retrieval system, or transmitted in
any form
or by any means, electronic, mechanical, photocopying, microfilming, recording, or
otherwise,
without written permission from the Publisher
IN MEMORIAM
Paolo Farinella (1953-2000)
Albert Einstein, in his celebration address on the occasion of Max Planck's
60th birthday, stated that scientists were much like the "builders of temples" -
they had to possess exceptional talent, passion, and dedication, but they also
had to be modest enough to recognize that their contributions would never
approach the complexity of Nature itself. Paolo Farinella, who passed away
on March 25, 2000 at the peak of his scientific productivity, was acknowl
edged to be one of the few planetary scientists of his generation endowed
with all of these attributes.
Inspired by the innovative lectures of Giuseppe Colombo in Pisa in the mid
1970s, Paolo quickly attained a position of a recognized researcher in plane
tary science. Like Colombo, Paolo was challenged and energized by the most
difficult problems in the field. Paolo's studies included the collisional history
of small bodies in the solar system (with a particular emphasis on asteroids),
the identification and evolution of asteroid families, the transport mechanisms
capable of delivering asteroids and meteorites from the main belt to the inner
solar system (and Earth), the motion of the artificial satellites and space
debris, as well as the peculiar but important role of non-gravitational forces
on the orbital and rotational evolution of small bodies in the solar system.
Paolo's approach to these problems was that of a distinguished scientist: start
ing from an original idea or, in many cases, an intuitive hunch, he was able to
quickly recognize the physical nature of many problems in planetary science,
gauge their importance, and describe them by means of precise mathematics.
Paolo greatly enjoyed the process where seemingly divergent data sets could
be brought together to create new research directions. Grounding his ideas in
the physical or astronomical context he was interested in, Paolo would fre
quently create sophisticated models of the complex systems he studied, often
in conjunction with young colleagues whose ability and enthusiasm were sim
ilar to his own. Finally, when results were obtained, Paolo was very careful to
shape the final publication so that other scientists could clearly follow and
understand their arguments.
v
vi In Memoriam
Paolo Farinella (middle) with his friends and collaboratorS/colleagues Alessandro Rossi (left,
CNUCE/CNR in Pisa) and Francesco Marzari (right, University of Padova) in September 1998.
Unlike some scientists, Paolo enjoyed to read the literature of many different
fields in astronomy and astrophysics, distilling their essence to find connec
tions and insights relevant to the problems he studied. This method was ulti
mately responsible for much of his success.
Paolo was also a careful mentor and a person who nurtured the early careers
of many young scientists in Europe. His profile would not be complete with
out mentioning his activity in several nuclear- and conventional-weapon dis
armament organizations. Paolo was also concerned about the risks of space
debris for artificial satellites and manned spacecraft.
Paolo considered important to transmit the joy that scientists experience in
unraveling the mysteries of the solar system and the universe to the public.
Most of his nearly 100 papers in amateur journals still represent a fresh read
ing on various subjects in astronomy.
A colleague of Paolo once said that he had a "sixth sense for what is happen
ing in the heavens." Though we shall hear the echoes of Paolo's thoughts for
a long time, in particular through the work of his numerous friends and col
laborators, many of us shall painfully miss his sparkle and the inspiration of
his unique ideas.
David Vokrouhlickf
Contributors
Walter Alvarez, Department of Earth and Planetary Science, University of
California-Berkeley, Berkeley, CA 94720, USA, [email protected].
Timothy A. Becker, Berkeley Geochronology Center, 2455 Ridge Road, Berkeley,
CA 94709, USA, [email protected].
Philip A. Bland, Planetary Science Research Institute, The Open University, Walton
Hall, Milton Keynes MK7 6AA, UK, [email protected].
Donald Brownlee, Department ofA stronomy, Box 351580, University of Washington,
Seattle, WA 98195, USA, [email protected].
Timothy S. Culler, Department of Earth and Planetary Science, University of
California-Berkeley, and Lawrence Berkeley National Laboratory, MS 50-232,
Berkeley, CA 94720, USA, [email protected].
Stanley F. Dermott, Department of Astronomy, University of Florida, Gainesville,
FL 32611, USA, [email protected].
Paolo Farinella (deceased), Department of Astronomy, University of Trieste, Via
G.B. Tiepolo 11,1-34131 Trieste, Italy.
Kenneth A. Farley, Division of Geological and Planetary Sciences, California Institute
of Technology, MS 170-25, Pasadena, CA 91125, USA, [email protected].
George J. Flynn, Department of Physics and Department of Mathematics, State
University of New York-Plattsburgh, lOl Broad Street, Plattsburgh, NY 12901, USA,
[email protected].
Debra A. Fogle, Department of Astronomy, University of Florida, Gainesville, FL
32611, USA, [email protected].
Thomas Graf, Pharmacology and Toxicology, University ofZiirich, Winterthurerstrasse
190, CH-8057 ZUrich, Switzerland, [email protected].
Jennifer A. Grier, Planetary Science Institute, 620 North Sixth Avenue, Tucson, AZ
85705-8331, USA, [email protected].
Richard A. F. Grieve, Earth Sciences Sector, Natural Resources Canada, Room 209,
601 Booth Street, Ottawa, Ontario KIA OE8, Canada, [email protected].
Keith Grogan, Goddard Space Flight Center, Greenbelt, MD, USA.
Ian Halliday, 825 Killeen Avenue, Ottawa, Ontario K2A 2X8, Canada,
[email protected].
vii
viii Contributors
Mihaly Horanyi, Laboratory for Atmospheric and Space Physics, University of
Colorado, Boulder, CO 80309, USA, [email protected].
Antal Juhasz, Department of Space Physics, KFKI Research Institute for Particle
and Nuclear Physics, P.O. Box 49, 1525 Budapest, Hungary, [email protected].
A. J. Timothy Jull, NSF Arizona AMS Facility and Department of Geosciences,
University of Arizona, Tucson, AZ 85721, USA, [email protected].
Christian Koeberl, Institute of Geochemistry, University of Vienna, Althanstrasse
14, A-I090 Vienna, Austria, [email protected].
Stephen J. Kortenkamp, Department of Astronomy, University of Maryland, 1204
CSS Building, Stadiwn Drive, College Park, MD 20742, USA, and Department of
Terrestrial Magnetism, Carnegie Institution of Washington, 5241 Broad Branch Road
NW, Washington, DC 20015, USA, [email protected].
James H. Lever, US Army Cold Regions Research and Engineering Laboratory, 72
Lyme Road, Hanover, NH 03755, USA, [email protected].
Alfred S. McEwen, Planetary Image Research Laboratory, Lunar and Planetary
Laboratory, 1629 University Boulevard, University of Arizona, Tucson, AZ 85721,
USA, [email protected].
Stephen J. Mojzsis, Department of Geological Sciences, NASA Center for Astrobiology,
University of Colorado, Boulder, CO 80309-0399, USA, [email protected].
Alessandro Morbidelli, Observatoire de la Cote d' Azur, F-06304 Nice Cedex 04,
France, [email protected].
Richard A. Muller, Department of Physics, University of California-Berkeley, and
Lawrence Berkeley National Laboratory, MS 50-232, Berkeley, CA 94720, USA,
[email protected].
Daniel M. Murphy, Aeronomy Laboratory, National Oceanic and Atmospheric
Administration, 325 Broadway, Boulder, CO 80305, USA, [email protected].
William M. Napier, Armagh Observatory, College Hill, Armagh BT61 9DG,
Northern Ireland, [email protected].
Bernhard Peucker-Ehrenbrink, Department of Marine Chemistry and
Geochemistry, Woods Hole Oceanographic Institution, Mail Stop 25, 360 Woods
Hole Road, Woods Hole, MA 02543-1541, USA, [email protected].
Paul R. Renne, Berkeley Geochronology Center, 2455 Ridge Road, Berkeley, CA
94709, and Department of Earth and Planetary Science, University of California
Berkeley, Berkeley, CA 94720, USA, [email protected].
Graham Ryder, Lunar and Planetary Institute, 3600 Bay Area Boulevard, Houston,
TX 77058, USA, [email protected].
Birger Schmitz, Department of Marine Geology, Earth Sciences Center, University
of G6teborg, Box 460, SE-405 30 G6teborg, Sweden, [email protected].
Mario Tassinari, Paleo Geology Center, Viiner Musewn, Box 724, SE-531 17
Lidk6ping, Sweden.
Contributors ix
Susan Taylor, US Army Cold Regions Research and Engineering Laboratory, 72
Lyme Road, Hanover, NH 03755, USA, [email protected].
David Vokrouhlicky, Institute of Astronomy, Charles University, V. Holesovickach 2,
CZ-18000 Prague 8, Czech Republic, [email protected].
Rainer Wieler, Isotope Geology, ETH ZUrich, NO C61, CH-8092 Zurich,
Switzerland, [email protected].
Herbert A. Zook, NASA Johnson Space Center, Mail Code SN 2, Houston, TX
77058, USA, [email protected].
Foreword
Walter Alvarez
Department ofE arth and Planetary Science
University of California, Berkeley, USA
There once was a dichotomy between astronomers who looked up at the sky, and geol
ogists who looked down at the Earth. With their focus on exposures of ancient rocks,
geologists long missed recognizing material that had reached Earth from space.
Meanwhile, for much of the 20th century, astronomers devoted most of their attention
to stars and galaxies. The solar system received little attention until the lunar and space
missions began in the 1960s and the importance of impact events began to be appreci
ated in the 1980s. Things are very different now. As the 21st century begins, we have
a vibrant, multidisciplinary science that deals with the relation ofthe Earth to its solar
system environment. This new science is the special heir of the scientific revolution of
Copernicus, Tycho, Kepler, Galileo, and Newton, which explained the nature of plan
ets, their motions, and the physical laws that operate at solar-system scales.
As one product of this new science, we now recognize the significance of extrater
restrial matter of a broad spectrum of sizes reaching our planet. Single protons and
larger nuclei arriving as cosmic rays interact with atmospheric nuclei, producing
showers of daughter particles that can be detected using cloud chambers. Interplanet
ary dust particles in the 10 f.J.ffi range are light enough to be gently slowed in the upper
atmosphere without being destroyed, are collected on delicate filters carried by high
altitude aircraft, and contribute measurable amounts of 3He to deep-sea sediments.
Sand-and pebble-size micrometeorites make visible meteor trails when they bum up
in the atmosphere, but still contribute to the background levels of platinum-group ele
ments detected at the parts-per-trillion level in deep-sea sediments
Objects in the centimeter to meter range are slowed by atmospheric friction and
survive impact, yielding the meteorites that have long been collected randomly at the
Earth's surface. The discovery of concentrations of deep-frozen meteorites emerging
from the Antarctic ice has led to dramatic advances in meteoritics. As described in
this book, fossil meteorites are for the first time being recovered systematically from
the stratigraphic record.
Objects larger than a few tens of meters hit the Earth's surface at velocities greater
than the seismic velocity of rock. Ultimately these objects are largely destroyed
either melted or vaporized as a result of the impact-generated shock wave. On the
Earth's surface, impacts of this magnitude leave craters that were long ignored or
xi
xii Foreword
misinterpreted by geologists; more than 150 such craters are now known and are the
subject of intense research. The impact of a 10 km object, 65 Ma, is now strongly
linked to the mass extinction at the Cretaceous-Tertiary boundary. Impacts of kilo
meter-size objects may be recorded far from the crater site as anomalous concentra
tions of platinum group elements in the stratigraphic record, and as horizons of ejecta
derived from the target rock -especially shocked quartz grains, and spherules that
originated as melt droplets that traveled ballistically outside the atmosphere.
The impact of an object in the 500 km range would evaporate the ocean. Some years
ago it seemed that such an event would completely annihilate life, but recent evidence
for biota in cracks deep in the solid Earth calls impact sterilization into question. At
the extreme end of the size range, the impact of a Mars-sized object is widely consid
ered to be responsible for the origin of the Moon.
Objects reaching the Earth vary across a mass spectrum of as much as 50 orders
of magnitude, and it is not surprising that this spectrum is broken into distinct fields
in a variety of ways. Size and composition control the survival of the impactor in
complicated ways. An object around 100 m in size mayor may not hit the Earth's sur
face. Meteor Crater in Arizona, about 1.2 km in diameter, was produced by the impact
of a dense metallic object only few tens of meters in size. On the other hand, the 1908
Tunguska event in Siberia was produced by the airburst of a much larger but lower
density object, probably a comet up to 200 m in size. At larger sizes, however, it has
proven difficult to distinguish impact events caused by asteroids from those resulting
from comets.
Size also controls frequency of events. Cosmic rays are so frequent that they can
be observed simply by watching a cloud chamber for a few minutes. Meteor trails can
be seen occasionally on any clear night, especially during meteor showers, and can be
measured with dark-night, open-shutter photography experiments. A few times every
year a rock-sized meteorite is observed during atmospheric entry and recovered on
the ground. Crater-forming impacts fall off in frequency as size increases, with a 10-
km object hitting Earth roughly every 100 Myr. Objects much larger than that appar
ently have not hit this planet since it was accreting during the Hadean, from 4.6 to
about 4 Ga, a time during which the frequency of impacts of all sizes was much
greater than it has been since then. Lunar spherules, produced during impacts and dat
able with 40 Arj39 Ar geochronometry, are providing a new record of impact rates
through time, as discussed in this volume.
Size and frequency also control how events are viewed philosophically. Cosmic
rays, meteor streaks, and meteorite falls occur at intervals short compared to a human
lifetime and thus were acceptable to the Lyellian uniformitarianism that long con
trolled geological thinking. Larger events with repeat times much longer than a
human lifetime were ignored as unthinkable as long as uniformitarianism held sway,
but when they were established as having undeniably occurred, they led to the down
fall and abandonment of strict uniformitarianism.
In this volume Bernhard Peucker-Ehrenbrink and Birger Schmitz have collected a
suite of timely papers that give a detailed view of current research on many aspects
of the accretion of extraterrestrial material onto the Earth. It should be of great value
both as a summary of current understanding and as a spur to new discoveries and
improved quantification. This book bears witness to the interdisciplinary vibrancy of
our new science of Earth in its planetary setting.
