A Continental Plate Boundary: Tectonics at South Island, New Zealand

369 Pages·32.878 MB·English

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Geophysical Monograph 175
A Continental Plate Boundary:
Tectonics at South Island, New Zealand
David Okaya
Tim Stern
Fred Davey
Editors
American Geophysical Union
Washington, DC
Published under the aegis of the AGU Books Board
Darrell Strobel, Chair; Gray E. Bebout, Cassandra G. Fesen, Carl T. Friedrichs, Ralf R. Haese, W. Berry Lyons,
Kenneth R. Minschwaner, Andrew Nyblade, and Chunzai Wang, members.
Library of Congress Cataloging-in-Publication Data
A continental plate boundary : tectonics at South Island, New Zealand / David Okaya, Tim Stern, Fred Davey, editors.
p. cm. -- (Geophysical monograph ; 175)
ISBN 978-0-87590-440-5
1. Plate tectonics--New Zealand--South Island. 2. Continental margins--New Zealand--South Island. I. Okaya, David
Akiharu. II.
Stern, Timothy A. III. Davey, Frederick J.
QE511.4C657 2007
551.1’3609937--dc22
2007045674
ISBN 978-0-87590-440-5
ISSN 0065-8448
Cover Photo:
The Huxley Valley leads towards Aoraki/Mt. Cook, New Zealand’s highest peak in the Southern Alps (3754 m elevation). This glaciated
valley follows structural trends associated with the transpressional Alpine fault, located only 30 km away, that separates the Pacific and
Indo-Australian plates. Photograph courtesy of Simon Cox.
Copyright 2007 by the American Geophysical Union
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CONTENTS
Preface
David Okaya, Tim Stern, and Fred Davey ..........................................................................................................  vii
Continent-Continent Collision at the Pacific/Indo-Australian Plate Boundary:
Background, Motivation, and Principal Results
David Okaya, Tim Stern, Fred Davey, Stuart Henrys, and Simon Cox ................................................................  1
SECTION I: Regional Framework of Pacific/Indo-Australian Plate Boundary
Regional Geological Framework of South Island, New Zealand, and its Significance for
Understanding the Active Plate Boundary
Simon C. Cox and Rupert Sutherland ...............................................................................................................  19
Geophysical Structure of the Southern Alps Orogen, South Island, New Zealand
F.J. Davey, D. Eberhart-Phillips, M.D. Kohler, S. Bannister, G. Caldwell, S. Henrys, M. Scherwath, T. Stern,
and H. van Avendonk ......................................................................................................................................  47
Kinematic Constraints From GPS on Oblique Convergence of the Pacific and Australian Plates,
Central South Island, New Zealand
John Beavan, Susan Ellis, Laura Wallace, and Paul Denys ...............................................................................  75
Seismic Anisotropy in South Island, New Zealand
Martha Kane Savage, Mathieu Duclos, Katrina Marson-Pidgeon ......................................................................  95
Crustal Thickness and Pn Anisotropy Beneath the Southern Alps Oblique Collision, New Zealand
S. Bourguignon, M. K. Savage and T. Stern ....................................................................................................  117
Compressional and Shear Wave Velocities in South Island New Zealand Rocks and Their Application
to the Interpretation of Seismological Models of the New Zealand Crust
Nikolas I. Christensen and David A. Okaya ...................................................................................................  125
SECTION II: The Plate Boundary (Alpine Fault) & Associated Mountain Building
(Southern Alps)
The Alpine Fault, New Zealand: Surface Geology and Field Relationships
Richard J. Norris and Alan F. Cooper .............................................................................................................  159
Deformation of the Pacific Plate Above the Alpine Fault Ramp and its Relationship to Expulsion of
Metamorphic Fluids: An Array of Backshears
Ruth H. Wightman and Timothy A. Little .......................................................................................................  179
Geophysical Exploration and Dynamics of the Alpine Fault Zone
Tim Stern, David Okaya, Stefan Kleffmann, Martin Scherwath, Stuart Henrys, and Fred Davey .....................  209
Do Great Earthquakes Occur on the Alpine Fault in Central South Island, New Zealand?
R. Sutherland, D. Eberhart-Phillips, R.A. Harris, T. Stern, J. Beavan, S. Ellis, S. Henrys, S. Cox, R.J.
Norris, K.R. Berryman, J. Townend, S. Bannister, J. Pettinga, B. Leitner, L. Wallace, T.A. Little, A.F.
Cooper, M. Yetton, and M. Stirling ................................................................................................................  237
SECTION III: Plate Boundary Dynamics
Three-Dimensional Geodynamic Framework for the Central Southern Alps, New Zealand:
Integrating Geology, Geophysics and Mechanical Observations
Phaedra Upton and Peter O. Koons ...............................................................................................................  255
Transpression Models and Ductile Deformation of the Lower Crust of the Pacific Plate in the
Central Southern Alps, a Perspective From Structural Geology
Timothy Little, Ruth Wightman, Rodney J. Holcombe, and Matthew Hill ......................................................  273
Modeling Strain and Anisotropy Along the Alpine Fault, South Island, New Zealand
M. K. Savage, A. Tommasi, S. Ellis, and J. Chery ............................................................................................  291
SECTION IV: Comparisons
A Comparison Between the Transpressional Plate Boundaries of South Island, New Zealand,
and Southern California, USA: The Alpine and San Andreas Fault Systems
Gary S. Fuis, Monica D. Kohler, Martin Scherwath, Uri ten Brink, Harm J.A. Van Avendonk,
and Janice M. Murphy ...................................................................................................................................  309
Taiwan and South Island, New Zealand—A Comparison of Continental Collisional Orogenies
F. Wu, F. Davey, and D. Okaya .....................................................................................................................  331
Seismogenic, Electrically Conductive, and Fluid Zones at Continental Plate Boundaries in New Zealand,
Himalaya, and California, USA
George R. Jiracek, Victor M. Gonzalez, T. Grant Caldwell, Philip E. Wannamaker, and Debi Kilb ................  349
PREFACE
Continental collision is a fundamental geologic process more complex active orogenic regions where deformation
in plate tectonics that impacts on continental growth, con- is broader or occurred over a much longer period, such as in
tinental deformation, the development of natural resources, the Cordillera of western North America where the width of
and the occurrence of natural hazards. Convergent plate deformation exceeds several hundreds of kilometers.
boundaries where continents collide are often broadly dis- In the early 1990s an international collaboration formed be-
tributed and, where strain rates are high, result in major tween New Zealand and United States geoscientists in order
deformation of the continental lithosphere and the develop- to study continental collision at the Pacific/Indo-Australian
ment of mountain ranges. Within mountain belts, compres- plate boundary. The selection of this site in central South Is-
sion, thrust faulting, and erosion can combine to generate land was attractive because of supposed similarities to the
uplift and overthickened crust, and exhume large sections Transverse Ranges in southern California (of direct interest
of high-grade, once deeply buried rocks, associated faults, to the U.S. investigators); easy access well into the heart of
and sutures. Although the well-exposed surface geology of the Southern Alps; a low population density which improved
some mountain chains provides an important starting point field experiment logistics, permitting, and signal-to-noise
for understanding the deformational processes acting at the levels; a narrow island width, which allowed marine seismic
plate boundary, well designed geophysical investigations methods to be applied onto both sides of the land-situated
are essential to understand the dynamics of a convergent orogen; and an established foundation of scientific knowl-
continental plate boundary and constrain the deformational edge built by an excellent in-country scientific community.
processes and their drivers within the deeper crust and The initial collaboration, funded by the New Zealand Foun-
lithospheric mantle. dation for Research, Science, and Technology and the U.S.’s
The Pacific and Indo-Australian plates in South Island, National Science Foundation (Continental Dynamics Pro-
New Zealand, are separated by the transpressional Alpine gram), was quickly joined by additional scientists primarily
fault. Associated with this continental transform fault are the from New Zealand who performed their own relevant but
Southern Alps, a relatively simple and young orogen cre- independent studies. Thus a decade-long focus on the central
ated by continental collision whose zone of deformation is South Island transpressional plate boundary ensued. More
laterally narrow and uncomplicated by subsequent tectonic than fifty scientists and students participated in the overall set
overprinting. This mountain system offers the opportunity of studies, many of which involved substantial field observa-
to understand how lithospheric rocks deform within a devel- tion experiments, and which has led to forty journal publica-
oping orogen and how this deformation may have changed tions and a dozen graduate theses.
with time. Because relative plate motions are oblique, the This volume represents a collection of papers which pri-
Alpine fault needs to accommodate both convergence and marily summarizes the results that arose from our overall
lateral slip. Topical questions regarding this plate boundary New Zealand-U.S. collaboration. The chapters cover a range
relate to whether strain is partitioned and whether it is local- of geological and geophysical investigations and provide
ized or diffuse within the crust and/or lithospheric mantle. further insight into the deformation and evolution of con-
Furthermore, this transpressional plate boundary has often tinental collision. The volume is divided into four sections.
been compared to the Transverse Ranges of the San Andreas Preceding the first section, an inroductory chapter presents
fault (California, USA) and contrasted to the Dead Sea trans- the scientific questions that motivated the collaborations
form (Israel-Jordan), the Northern Anatolian fault (Turkey), and summarizes the key findings of the overall research.
and the Denali fault (Alaska, USA). Continental collision at The first section presents the regional framework of the Pa-
this plate boundary serves as a model to understand other cific/Indo-Australian plate boundary within South Island; its
six chapters summarize what is known of the geology and
geophysics of what is essentially the far-field region relative
to deformation at the plate boundary. The second section fo-
A Continental Plate Boundary: Tectonics at South Island, New Zealand
Geophysical Monograph Series 175 cuses on the plate boundary (Alpine) fault and the Southern
Copyright 2007 by the American Geophysical Union. Alps orogen; the two geological and two geophysical chap-
10.1029/175GM01 ters characterize the near-field region of the plate boundary.
vii
VIII
The third section contains three chapters which examine ment of the New Zealand-U.S. collaboration: Prof. Richard
the dynamics of the plate boundary - how mechanically the I. Walcott (Victoria University of Wellington), Prof. Tho-
plate boundary and its fault(s) accommodate both strike-slip mas L. Henyey (University of Southern California), and
and convergent motions. The final section presents three Prof. Thomas V. McEvilly (University of California, Berke-
chapters that compare the Alpine fault-Southern Alps sys- ley). Dick Walcott was one of the first geophysicists in the
tem to other transpressional and obliquely convergent plate 1970’s to investigate the deformation of New Zealand using
boundaries. We have included a CD-ROM that contains geodetic data; his studies of active deformation provided the
both color versions of figures that are printed in black & foundations for many scientists’ subsequent studies on the
white within the volume plus supplemental/oversize materi- kinematics and dynamics of New Zealand’s subduction and
als that provide added content to selected chapters. strike slip plate boundaries. Dick provided early guidance to
As editors, we acknowledge and greatly appreciate the our project scientific direction. His careful use of field obser-
contributions provided by the authors and reviewers. This vations to quantitatively constrain concepts was an approach
volume would not have been possible without the major that we applied throughout our South Island collaborations.
efforts of the authors, who squeezed into their very full Tom Henyey similarly valued field observations; his initial
schedules the time to write summary and synthesis papers. interest in New Zealand was in the collection of heat flow
Reviewers, as usual, have carried out an essential and of- measurements in South Island lakes following a sabbatical in
ten underappreciated task; we thank Duncan Agnew, Thora 1982 at the Department of Scientific and Industrial Research
Arnadottir, Gary Axen, Geoff Batt, David Berryman, Tom (DSIR) in Wellington. Tom’s long-standing research in the
Brocher, Tim Byrne, Ramon Carbonell, James Connolly, tectonics of Southern California led to an early interest in
John Dewey, Donna Eberhart-Phillips, Susan Ellis, Andrew the comparison between the transpressional San Andreas and
Gorman, David Gray, John Hole, Keith Howard, Leon Teng, Alpine faults. Discussions of this comparison with one of us
Vadim Levin, Tim Little, Zhen Liu, John Louie, Peter Ma- (TS) beginning in 1988 led to concrete plans for a multi-
lin, Peter Molnar, Martin Reyners, David Rodgers, Martyn national geophysical examination of the Alpine fault plate
Unsworth, and five anonymous reviewers. We also thank boundary; Tom’s leadership was instrumental in assem-
Harm van Avendonk and Stuart Henrys for handling the edi- bling our trans-Pacific collaboration and steering it through
torial duties for two of the chapter papers. its original tenure. Tom McEvilly was the rare seismologist
We thank at AGU the book acquisition editors - initially who knew how to design at scales ranging from the inner
Allan Graubard and subsequently Jeffrey Robbins. The pa- workings of seismometers all the way up to effective struc-
tient support of the AGU books and special publications tures of national and international community organizations
staff, particularly Dawn Seigler, administrative assistant, and such as IRIS and FDSN. After providing sound advice at an
Maxine Aldred, program coordinator, is greatly appreciated. early planning workshop in Wellington, New Zealand, Tom
Funds to cover publication costs were provided by the became an active project participant. He led our passive seis-
U.S. National Science Foundation Continental Dynamics mic experiments, in planning and with shovel in hand, and
Program, the New Zealand Foundation for Research Science bird-dogged the seismic crew we contracted for seismic re-
and Technology, GNS Science, and Victoria University of flection profiling near Mount Cook. Tom, who passed away
Wellington. We particularly thank Dr. Leonard Johnson, in 2002, had a wry sense of humor that could defuse the ten-
Program Director of NSF-CD, who also provided funds for a sion or enliven the dullness of any meeting. As a mentor he
synthesis workshop held during June 2005, in Christchurch, had a knack for correcting us in such a way so that we thought
New Zealand, that led directly to the organization and con- we solved mistakes on our own. We extend our gratitude to
tents of this volume. We also direct special thanks to John Professors Dick Walcott, Tom Henyey, and Tom McEvilly,
McRaney, at the University of Southern California, who not who all led by their example how to accomplish high caliber
only arranged for additional funds to defray publication costs research and gave us strong encouragement to carry out the
but provided administrative and logistical support through- collaborative research presented in this volume.
out our New Zealand-US projects that facilitated our large
field experiments to take place. David Okaya
Finally, we wish to dedicate this volume to three scien- Tim Stern
tists who had profound influence on our interest in the South Fred Davey
Island transpressional plate boundary and on our establish-
Continent-Continent Collision at the Pacific/Indo-Australian Plate
Boundary: Background, Motivation, and Principal Results
David Okaya, Tim Stern2, Fred Davey3, Stuart Henrys3, and Simon Cox4
BACKGROUND Ranges in southern California. The structure and kinematic
regime of these transpressional orogens is thus, in all likeli-
Mountain belts are important and highly visible structural hood, more complex as a result of the need to accommodate
elements of the earth’s continental crust. They impact socie- large amounts of lateral slip, as well as convergence.
ties by providing natural resources, hosting processes which
produce natural hazards, and by their influence on weather WHY STUDY NEW ZEALAND?
and climate. One important mechanism in mountain for-
mation is continent-continent collision at plate boundaries. New Zealand is a largely submarine continent that lies
Within mountain belts, compression, thrust faulting, and across the boundary between the Pacific and Australian
erosion can combine to generate uplift and over-thickened plates (Plate 1). Subduction of the Pacific plate beneath the
crust, and exhume large sections of high-grade, once deeply- Australian plate occurs at the eastern margin of North Island.
buried rocks and associated faults, sutures, and folds. The Subduction of the Australian plate occurs along the Puyse-
well-exposed surface geology of mountain belts provides an gur Trench and under the southwestern tip of South Island.
important starting point or “ground truth” for geological and Connecting these subduction zones of opposite polarity is a
geophysical investigations of continental dynamics and the continental transform fault - the Alpine fault - which runs
relevant processes in the deeper crust. obliquely through South Island (Plate 2). Present day rela-
Continent-continent collision occurs at two major plate tive velocity between the two plates is about 38 mm/y. A
boundary settings. The first is at convergent plate bound- component of compression has existed across the Alpine
aries where a continental lithospheric plate comes into Fault for at least the past 5–0 million years [Walcott, 998],
contact with another such plate, often creating spectacu- which has resulted in the building of the Southern Alps with
lar collisional orogens (e.g., the Himalayan system due to a maximum elevation of 3754 m.
Indian-Eurasian plate collision and the Zagros belt due to Central South Island has long been considered a premier
Arabian-Eurasian plate interaction). The second major set- site to study oblique continent-continent convergence [Mol-
ting is at strike-slip plate boundaries, where a component of nar, 988]. Rates of erosion and concomitant vertical move-
oblique convergence will often result in mountain building ment of crustal rock here are among the highest in the world
on either or both sides of the plate boundary. Notable cases (~0 mm/yr) [Blythe, 998], and the Alpine fault has com-
are the Southern Alps in New Zealand and the Transverse ponents of both strike-slip and dip-slip movement [Norris et
al., 990]. The orogen is young, and the zone of deformation
is relatively narrow (~80 km wide) and uncomplicated by
1Department of Earth Sciences, University of Southern Califor- subsequent tectonic overprinting (Plate 2). In many cases,
nia, Los Angeles, California. such as in southeast Asia or the Cordillera of western North
2School of Earth Sciences, Victoria University of Wellington,
America, the width of the zone of deformation exceeds hun-
Wellington, New Zealand.
dreds of kilometers and is often complicated by a lengthy
3GNS Science, Lower Hutt, New Zealand.
history of tectonic episodes [Dickinson, 2003].
4GNS Science, Dunedin, New Zealand.
The rapid deformation of central South Island [Walcott,
979; Beavan et al., 999] allows active processes to be
A Continental Plate Boundary: Tectonics at South Island, New Zealand
Geophysical Monograph Series 175 studied thoroughly using Quaternary geology, geodesy, ther-
Copyright 2007 by the American Geophysical Union. mochronology, and seismology, building on established pro-
10.1029/175GM02 grams in these disciplines within New Zealand. The geology

2 CONTINENT-CONTINENT COLLISION AT THE PACIFIC/INDO-AUSTRALIAN PLATE BOUNDARY
Plate 2. South Island, the Alpine fault and Southern Alps. (A) Ob-
lique-view image of South Island with SIGHT lines superimposed.
Visible is the Southern Alps orogen associated with the transpres-
sional Alpine fault. Space Shuttle image STS59-229-07 courtesy
of NASA. (B) Digital elevation image of South Island which re-
veals the linearity and sharpness of the Alpine fault. Elevation data
Plate 1. The plate tectonic setting of the New Zealand region. In collected by Shuttle Radar Topography Mission aboard NASA
South Island (box), the transpressional Alpine fault (dotted line) space shuttle. Image PIA0666 courtesy of NASA.
separates the Hikurangi and Puysegur trenches along the Pacific-
Australian plate boundary. Morphology in color. [From Davey et
al., this volume].