Tensile Fracturing in Rocks: Tectonofractographic and Electromagnetic Radiation Methods

580 Pages·2005·18.446 MB·English

by  Prof. Dov Bahat, Prof. Avinoam Rabinovitch, Dr. Vladimir Frid (auth.)

Dov Bahat
Avinoam Rabinovitch
Vladimir Frid
Tensile Fracturing in Rocks
Tectonofractographic and Electromagnetic
Radiation Methods
Dov Bahat
Avinoam Rabinovitch
Vladimir Frid
Tensile Fracturing
in Rocks
Tectonofractographic and
Electromagnetic Radiation Methods
With 302 Figures
Authors
Prof. Dov Bahat
Department of Geological and Environmental Sciences
Ben Gurion University of the Negev, POB 653
Beer Sheva, 84105 Israel
Head, the Deichmann Rock Mechanics Laboratory of the Negev
e-mail: [email protected], phone: [phone], fax: [phone]
Prof. Avinoam Rabinovitch
Physics Department
Ben Gurion University of the Negev, POB 653
Beer Sheva, 84105 Israel
The Deichmann Rock Mechanics Laboratory of the Negev
e-mail: [email protected], phone: [phone]
Dr. Vladimir Frid
Department of Geological and Environmental Sciences
Ben Gurion University of the Negev, POB 653
Beer Sheva, 84105 Israel
The Deichmann Rock Mechanics Laboratory of the Negev
e-mail: [email protected], phone: [phone]
Library of Congress Control Number: 2004108439
ISBN 3-540-21456-9 Springer Berlin Heidelberg New York
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Preface
‘Tensile Fracturing in Rocks’ presents field observations on fracturing of sedimen-
tary rocks and granite outcrops from various provinces in three continents. It also
combines results of recent experiments conducted at different laboratories around the
world with current theories on fracturing. In treating faults, this book limits itself to
faults that are associated with joint sets produced by definable causes and occasion-
ally to cases where interaction between the two types of fracture – faults and joints –
is not clear. The book’s subject matter is divided over six chapters, which are briefly
described below.
Chapter 1 summarizes current key concepts in fracture physics. It starts with a pres-
entation of the elastic theory of fracture, and concentrates on the results of linear elas-
tic fracture mechanics. The chapter touches also upon other fracture properties, e.g.,
crack nucleation, dynamic fracturing and slow fracturing processes. Nucleation is ad-
dressed by statistical mechanics methods incorporating modern approaches of ther-
mal and fiber bundle processes. The analyses of dynamic fracturing and slow fractur-
ing focus on the differences, as compared to the linear elastic approach. The contro-
versy in interpreting experimental dynamic results is highlighted, as are the surface
morphology patterns that emerge in fracturing and the non-Griffith crack extension
criterion in very slow fracturing processes.
Chapter 2 concentrates on basic topics in fracture geology. Fractography is applied
to improve the understanding of some intricacies, such as nucleation and fracture
growth in rocks. A review of fourteen lab experiments and a numerical experiment is
followed by a discussion on the properties of mirror planes and fringes on joint sur-
faces. These are exemplified on sedimentary and granitic rocks. Concepts of conjugate
hybrid joints and longitudinal splitting are re-evaluated in the light of recent experi-
ments. Various aspects of joint classification are reviewed. The chapter’s last section (2.4)
relates to mutual relationships of primary and secondary fractures, such as wing cracks,
pinnate joints and branching fractures.
Chapter 3 presents observations on sedimentary rocks in four fracture provinces:
Two in the USA, one in south Britain and one in south Israel. Although not represent-
ing all types and styles of fracturing, the combined data allow a synthesis of joint for-
mation in different tectonic settings.
Chapter 4 presents four fracture provinces in granites (in Germany, the Czech Re-
public and in California) that exhibit a wide spectrum of fracture settings. The
syntectonic, uplift and post-uplift joint features resemble their equivalents in sedimen-
tary rocks. However, granites also display unique fracture features that are associated
with late cooling stages of the pluton.
VI Preface
Chapter 5 deals with a new method of investigating embryonic stages of rock fail-
ure by measuring high-frequency electromagnetic radiation (EMR) from micro-cracks.
We review previous EMR investigations, present our new EMR model and show the
extracted EMR ‘fingerprints’ in rocks and other materials when strained. EMR sig-
nals from laboratory tests as well as from quarry blasting are analyzed. Underground
EMR preceding rock-bursts and gas outburst are studied, and some criteria for their
forecasting based on the obtained parameters are derived. The EMR results described
here are expected to lead to a novel forecasting method of earthquake nucleation.
Chapter 6 addresses some particular problems in fracture geology, including pro-
cedures for the study of joints. A discussion on previous paleostress studies in the
Middle East, particularly in the Israeli Negev, leads to a model on regional jointing in
the broad context of plate tectonics. This chapter contains a new approach in study-
ing joint length and a brief account of the procedure of estimating the fracture
paleostresses on a joint surface by a fractographic method. Also included is a detailed
characterization of the unique fracture geometry of a fault termination zone. Addi-
tional topics are, the description of a variety of fault-joint geometric and genetic rela-
tionships and a characterization of a new joint category, termed ‘surface joints’. We
also take account of hydro-geological research that relies on fracture distribution data
in the Beer Sheva syncline. Finally, we present here major features of a new mechani-
cal model of en echelon segmentation that differs from the more conventional ideas.
This book is a sequel to a previous volume in this series, ‘Tectonofractography’ (1991),
and many premises are not re-introduced here. Some terms are introduced in a special
section on nomenclature.
Acknowledgements
The authors wish to thank all those who contributed to the writing of this book. Sev-
eral persons contributed immensely to the field work and data collection. These in-
clude Peter and Elfriede Bankwitz who collaborated in the study of fracturing in gran-
ites in central Europe, particularly, the pre-uplift fracture during the cooling of the
pluton. Jointing in sandstone (Zion National Park, Utah) and in granites (the Sierra
Nevada Batholith, California) was studied in cooperation with Ken Grossenbacher and
Kenzi Karasaki. Some of the initial observations that were made with them on post-
uplift joints and oblique fractures during my (DB) Sabbatical year at LBNL matured
during the years to concrete data, and they should share the credit for it. Section 4.12
was mostly contributed by Ken Grossenbacher. Important help was also given by Paul
Witherspoon and Sally Benson. This book contains numerous citations from works by
Terry Engelder and his associates that contributed greatly to the understanding of
jointing. Working with Tsafrir Levi on his thesis has been a delight for one of us (DB).
Julia Goldbaum enriched considerably our understanding of EMR phenomena. We also
acknowledge the important contributions by Yoav Avni and Menachem Friedman, and
instructive field trips with Yehuda Eyal and Ram Weinberger. Charles Howard contrib-
uted greatly to the writing of Sect. 6.8.
Special thanks are due to colleagues who critically reviewed chapters in draft: Chap-
ter 2, Ram Weinberger; Chapter 3, Ithamar Perath; Chapter 4, Reginald Shagam; Chap-
ter 6, Meir Abelson and Ronit Nativ.
Figures 2.35e and 3.35c were donated by Ran Kagan and Alon Raviv, respectively, and
Fig. 2.69b and 3.10e were photographed during inspections of quarries with Peter and
Elfriede Bankwitz.
Most of our experiments were conducted in the Ruth and Horst Deichmann Rock
Mechanics Laboratory of the Negev, the Department of Geological and Environmental
Sciences, the Ben Gurion University of the Negev.
For important technical help, we owe thanks to Vyacheslav Palchik, Dina, Isaak
and Michael Frid, Julia and Boris Goldbaum, Avi Sharon, Leonid Baluashvili, Eli
Shimshilashvili, Rivka Eini, Ran Novitsky, Hagit Lev, Ania Arbel, Daniela Vida, Michal
Barima, Ronen Shavit from BGU, and Pascual Benito from LBNL. We also owe thanks
to H. Hertrich from Solnhofer Bodenplatten-Industrie GmbH and Co KG for help in
our experiments.
The help extended by members of the department of the Geological and Environ-
mental Sciences was crucial to the completion of this book. Financial assistance was
received from the Earth Sciences Administration (Ministry of Energy and Infrastruc-
VIII Acknowledgements
ture), and thanks are due to Yosef Bartov for his interest and assistance. Support was
also given by the Israel Science Foundation, the Ezvonot Committee of the Israeli Gov-
ernment Estate Distributions and by the Vatat and NRCN funds.
Many authors and publishers contributed valuable photographs and diagrams upon
our request, enabling us to fundamentally upgrade our book. All readers are invited to
write to us about errors that they find in the book.
The ideas presented in this book were beginning to crystallize when a sudden dete-
rioration in my (DB) wife Hanna’s health overshadowed all literary thinking. Dan and
Merav, Zvi and Jonathan were with us during her last months of suffering. This book is
dedicated to her memory.
Contents
1 Fracture Physics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
1.1 The Griffith Criterion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2
1.1.1 Stress and Strain . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2
1.1.2 Energy Considerations and the Griffith Criterion . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
1.1.3 Fracture Modes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
1.2 Nucleation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
1.2.1 General . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
1.2.2 Stress Concentration Avenues to Microcrack Nucleation . . . . . . . . . . . . . . . . . 11
1.2.3 Thermal Nucleation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
1.2.4 Fiber Bundle Model . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26
1.3 Linear Elastic Fracture Mechanics (LEFM) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32
1.3.1 General . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32
1.3.2 Equations of Equilibrium and of Motion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33
1.3.3 Two-dimensional (2D) Problems and Stress Intensity Factors . . . . . . . . . . . 35
1.4 Dynamic Fracture . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43
1.4.1 Mott and Mott-like Approaches . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43
1.4.2 2D Dynamic Crack . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 46
1.4.3 Energy Calculations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 49
1.4.4 Fracture Pattern Analysis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 59
1.5 Subcritical Cracking . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 62
1.5.1 General . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 62
1.5.2 Creep . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 62
1.5.3 The Dependence of Jointing in Rock Layers Solely on Stress . . . . . . . . . . . . . 63
2 Elements of Fracture Geology . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 81
2.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 81
2.2 Fractography and Tectonofractography . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 81
2.2.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 81
2.2.2 The Origin: Crack Nucleation via Fractographic Techniques . . . . . . . . . . . . 83
2.2.3 Fractographic Experiments . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 96
2.2.4 Joint Mirror Planes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 125
2.2.5 Joint Fringes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 130
2.2.6 Mirror Boundaries . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 140
2.2.7 Recent Studies on En Echelon Fringes from the Beer Sheva Syncline . . 141
2.2.8 Straight Kinks and Curved Kinks . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 150
2.2.9 Recent Studies from the Appalachian Plateau . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 152
X Contents
2.2.10 On the En Echelon Fringe Terminology . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 157
2.2.11 Summary of Five Categories of Breakdown Styles . . . . . . . . . . . . . . . . . . . . . . . . 160
2.2.12 Recent Studies from the South Bohemian Pluton . . . . . . . . . . . . . . . . . . . . . . . . . 161
2.2.13 Oblique Extension Joints and Longitudinal Splits (or Splittings) . . . . . . 166
2.3 On Uplift, Post-Uplift, Neotectonic and Surface Joints . . . . . . . . . . . . . . . . . . . . . . . . . . . 177
2.3.1 Neotectonic Joints . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 177
2.3.2 Exfoliation Joints and Sheet Joints . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 180
2.3.3 Surface Joints . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 180
2.4 Primary and Secondary Fractures . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 182
2.4.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 182
2.4.2 The Wing Crack Model . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 183
2.4.3 Pinnate and Horsetail Fractures . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 186
2.4.4 Fracture Polarization in the Two Extensional Quadrants
along the Fault . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 188
2.4.5 Termination-Zone Joints . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 188
2.4.6 Fracture Branching . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 189
3 Four Fracture Provinces in Sedimentary Rocks . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 191
3.1 The Devonian Fracture Province of the Appalachian Plateau, New York . . . . . 191
3.1.1 General Geology . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 191
3.1.2 The Tectonic Problem . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 197
3.1.3 Sequence of the Dip Joint Development . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 199
3.1.4 Progressive Development of the Regional Stress Field . . . . . . . . . . . . . . . . . . . 201
3.1.5 Tectonic History of the Appalachian Plateau Detachment Sheet . . . . . . . 203
3.1.6 Three Main Concepts of Regional Cross-Fold Joint Patterns . . . . . . . . . . . 208
3.2 Fracturing in The Bristol Channel Basin . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 210
3.2.1 General Geology and Previous Investigation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 210
3.2.2 Fracture Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 214
3.2.3 Data Collection and Joint Identification . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 220
3.2.4 Joint Sets in the Blue Lias . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 222
3.2.5 Stresses in the South-Dipping Limestone Beds
during Alpine Inversion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 227
3.2.6 Conclusions by Engelder and Peacock (2001) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 231
3.2.7 Discussion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 231
3.3 Post-Uplift Exfoliation Joints and Arch Formation in Sandstone
at Zion National Park, Utah, USA . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 234
3.3.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 234
3.3.2 Fracture Characteristics at Zion National Park . . . . . . . . . . . . . . . . . . . . . . . . . . . 236
3.3.3 Fracture Mechanisms at Zion National Park . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 245
3.3.4 Discrimination between Sheeting and Exfoliation . . . . . . . . . . . . . . . . . . . . . . . 250
3.3.5 Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 250
3.4 Jointing and Faulting in Eocene Chalk Formations
in the Beer Sheva Syncline, Israel . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 251
3.4.1 The Beer Sheva Syncline . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 251
3.4.2 Fractures in the Beer Sheva Syncline . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 255
3.4.3 Fracture Diversity in the Beer Sheva Syncline . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 266