Structural Geology

Preface
About the Book
Contents
About the Author
Part I: Fundamental Concepts
1: Introduction to Structural Geology
1.1 What Is Structural Geology?
1.2 What Are Structures?
1.2.1 Tectonic Structure
1.2.2 Nontectonic Structure
1.3 The Ultimate Cause of Deformation
1.4 What if We Fail to Do Structural Work!
1.5 Methodology of Structural Geology
1.5.1 Field Studies
1.5.2 Laboratory Studies
1.5.3 Experimental Modelling/Simulation
1.5.4 Numerical Modelling
1.5.5 Geophysical Studies
1.5.6 Remote Sensing
1.6 Where Is Structural Geology Today?
Box 1.1 Advent of Modern Structural Geology
1.7 Significance of Structural Geology
1.7.1 Academic Significance
1.7.2 Economic Significance
1.7.3 Societal Significance
1.7.4 Environmental Significance
1.8 Summary
2: Attitudes of Structures
2.1 Introduction
2.2 What Is `Direction´?
2.3 The Direction System
2.3.1 The Conventional System
2.3.2 The Azimuth System
2.4 Attitude of Planar Structures
2.4.1 True Dip and Apparent Dip
2.5 Attitude of Linear Structures
2.5.1 Plunge
2.5.2 Pitch
2.6 Common Field Instrument
2.6.1 Why Are E and W Interchanged in a Geological Compass?
Box 2.1 Measurement of Attitude by Clinometer Compass
2.7 Bearing and Back-Bearing
2.8 Summary
3: Stress
3.1 Introduction
3.2 Force
3.3 Types of Force
3.4 Stress
3.5 Units of Stress
3.6 Tensile Stress and Compressive Stress
3.7 Principal Stress Axes
3.8 Uniaxial Stress
3.9 Stress Ellipse
3.10 Biaxial Stress
3.11 Biaxial Stress on a Plane
3.12 Mohr Two-Dimensional Stress Diagram
3.13 Three-Dimensional Stress
3.13.1 Stress Ellipsoid
3.13.2 Three-Dimensional Stress at a Point
3.14 States of Stress
3.14.1 Hydrostatic Stress
3.14.2 Differential Stress
3.14.3 Deviatoric Stress
Box 3.1 What Is a Tensor?
Box 3.2 Concept of Traction
3.14.4 Lithostatic Stress
3.15 Palaeostress
3.15.1 Nature of Palaeostress
3.15.2 Estimation of Palaeostress
3.15.2.1 Faults
3.15.2.2 Grain Size
3.15.2.3 Calcite Twins
3.15.2.4 Veins
3.16 Stress Tensor
3.17 Stress Field
3.18 Stress History
3.19 Stress Inside the Earth
3.19.1 Nature of Stress Inside the Earth
3.19.2 Basic Stress Types Inside the Earth
3.19.3 Causes of Stress Inside the Earth
3.19.3.1 Overburden
3.19.3.2 Pore Fluid Pressure
3.19.3.3 Thermal Stresses
3.19.3.4 Plate Motion
3.19.3.5 Burial
3.20 Significance of Stress
3.20.1 Academic Significance
3.20.2 Engineering and Economic Significance
3.21 Summary
4: Strain
4.1 Introduction
4.2 Components of Strain
4.3 Homogeneous and Inhomogeneous Strain
4.4 Measures of Strain
4.4.1 Linear Strain
4.4.1.1 Extension
4.4.1.2 Stretch
4.4.1.3 Quadratic Elongation
4.4.1.4 Natural or Logarithmic Strain
4.4.2 Shear Strain
4.5 Volumetric Strain
4.6 Strain Ellipse
4.7 Strain Ellipsoid
4.7.1 Principal Strain Axes
4.7.2 Equation of Strain Ellipsoid
4.7.3 Shape and Ellipticity
4.8 Representation of Strain States
4.9 Pure Shear and Simple Shear
4.10 Coaxial and Noncoaxial Deformation
4.11 Strain Path
4.11.1 Coaxial Strain Path
4.11.2 Noncoaxial Strain Path
4.12 Progressive Deformation
4.13 Vorticity
Box 4.1 Strain Tensor in the Context of Structural Geology
4.14 Mohr Strain Diagram
4.15 Strain History
4.16 Significance of Strain
4.17 Summary
5: Estimation of Strain
5.1 Introduction
5.2 Strain Estimation from Deformed Rocks
5.3 Recent Advances in Strain Analysis
5.3.1 Extension of 2D to 3D Methods
5.3.2 Algebraic Method
5.3.3 Numerical Algorithm
5.3.4 Synthetic Strain Markers
5.3.5 Automation of Strain
5.3.6 Anisotropy of Magnetic Susceptibility (AMS)
5.3.7 SURFOR Method
5.3.8 Electron Backscatter Diffraction (EBSD)
5.3.9 X-Ray Computed Tomography
5.3.10 The Present Status
5.4 Two-Dimensional Strain
5.4.1 Axial Plots
5.4.2 Centre-to-Centre Method
5.4.3 Elliptical Objects
5.4.3.1 Fry Method
5.4.3.2 Rf/φ Method
5.4.4 Panozzo´s Projection Method
5.4.5 Hyperbolic Net Method
5.4.6 Theta Curves
5.4.7 Normalized Fry Method
5.4.8 Intercept Method
5.4.9 Mean Radial Length Method
5.4.10 SAPE Method
5.4.11 Method of Point Fabric Patterns
5.4.12 Gaussian Blur Technique
5.4.13 `Fitting the Void´ Method
5.4.14 ACF Method
5.4.15 Automated Image Analysis Technique
5.4.16 Strain from Deformed Fossils
5.4.16.1 Wellman Method
5.4.16.2 Breddin Graph
5.5 Three-Dimensional Strain
5.5.1 Background
5.5.2 Ellipsoidal Objects (Cloos Method)
5.5.3 Strain by Direct Measurement of Axes
5.5.4 Algebraic Method
5.5.5 Adjustment Ellipse Method
5.5.6 Autocorrelation Method
5.5.7 Strain by X-Ray Computed Tomography
5.5.8 Strain from the March Model
5.5.9 Strain Probe Method
5.5.10 Visualization Methods
Box 5.1 A General Appraisal of the Methods of Strain Analysis
5.6 Significance of Strain Estimation
5.7 Summary
6: Rheology
6.1 Introduction
6.2 Strain Rate
6.3 Steady-State Flow
6.4 Transient Flow
6.5 Isotropic and Anisotropic Materials
6.6 Constitutive Law
6.7 Constitutive Equations
6.7.1 What Is a Constitutive Equation?
6.7.2 Generalized Constitutive Equation
6.7.3 Constitutive Equations for Elastic Materials
6.7.4 Constitutive Equations for Plastic Materials
6.7.5 Constitutive Equations for Viscous Materials
6.8 Rheological Models
6.8.1 What Is a Rheological Model?
6.8.2 Elastic Model
Box 6.1 Poroelasticity and Thermoelasticity
6.8.3 Viscous Model
6.8.4 Plastic Model
6.9 Flow Laws
6.9.1 What Is a Flow Law?
6.9.2 Flow Laws for Single-Valued Grain Size
6.9.3 Flow Laws for Distributed Grain Size
6.9.4 Composite Flow Laws for Single-Valued Grain Size
6.9.5 Composite Flow Laws for Distributed Grain Size
6.10 Rheology of the Lithosphere
6.10.1 Background
6.10.2 Lithospheric Rheology in Relation to Temperature
6.10.3 Lithospheric Rheology in Relation to Rock Deformation
6.11 Summary
7: Concept of Deformation
7.1 Introduction
7.2 Kinematics of Deformation
7.2.1 Rigid Body Deformation
7.2.2 Non-rigid Body Deformation
7.3 Dynamics of Deformation
7.4 Modes of Deformation
7.4.1 Elastic Deformation
7.4.2 Brittle Deformation
7.4.3 Ductile Deformation
7.4.4 Plastic Deformation
7.4.5 Viscous Deformation
7.5 Brittle-Ductile Transition
7.6 Factors Controlling Deformation of Rocks
7.6.1 Composition
7.6.2 Temperature
7.6.3 Pressure
7.6.4 Rheology
7.6.5 Strain Rate
7.6.6 Planar Features
7.6.7 Orientation of Stress
7.6.8 Pore Fluids
Box 7.1 Deformation: Massive Versus Strongly Layered Rocks
7.7 Time-Dependent Deformation (Creep)
7.8 Deformation Mechanism Maps
7.9 Deformation and Continuum Mechanics
Box 7.2 What Is Continuum Mechanics?
7.10 Summary
Part II: Structures: Geometry and Genesis
8: Folds
8.1 Introduction
8.2 Parts of a Fold
8.3 Geometrical Parameters of Folds
Box 8.1 Wavelength-Amplitude Ratio: Use in Identifying Fold Generations
8.4 Fold Style
8.4.1 Cylindricity
8.4.2 Symmetry
8.4.3 Aspect Ratio
8.4.4 Tightness
8.4.5 Bluntness
Box 8.2 How Large a Buckle Fold Can Form in the Crust? Any Idea!
8.5 Classification of Folds
8.5.1 Classification Based on Interlimb Angle
8.5.2 Fleuty´s Classification
8.5.3 Classification Based on Plunge of Fold Axis
8.5.4 Classification Based on Limb Curvature
8.5.5 Classification Based on Fold Closure
8.5.6 Classification Based on Dip of Folded Strata
8.5.7 Classification Based on Angularity of Hinge
8.5.8 Classification Based on Symmetry of Folds
8.5.9 Classification Based on Order of Folds
8.5.10 Cylindrical Folds
8.5.11 Fold Systems
8.5.12 Folds Showing Two or More Axial Planes
8.5.13 Classification Based on Layer Thickness
8.5.14 Ramsay´s Classification
8.5.15 Hudleston´s Classification
8.5.16 Classification Based on Axial Angle
8.6 Special Types of Folds
Box 8.3 Growth Folds
8.7 Fold Mechanics
8.8 Buckling
8.8.1 Basic Ideas
8.8.2 Single-Layer Buckling
8.8.2.1 Stages of Buckling
8.8.2.2 Dominant Wavelength During Buckling
8.8.3 Multilayer Buckling
8.8.3.1 Nature of Multilayer Buckling
8.8.3.2 Role of Spacing in Multilayer Buckling
8.8.3.3 Dominant Wavelength of Multilayer Folds
8.8.3.4 Characteristics of Buckled Folds
8.9 Bending
8.10 Kinking
8.11 Passive Folding
8.12 Progressive Development of Fold Shapes
8.12.1 Model 1
8.12.2 Model 2
8.12.3 Model 3
8.12.4 Model 4
8.13 Significance of Folds
8.13.1 Academic Significance
8.13.2 Economic Significance
8.14 Summary
9: Faults
9.1 Introduction
9.2 Fault Geometry
9.2.1 Parts of a Fault
9.2.2 Geometrical Parameters of a Fault
Box 9.1 Relations Among Some Parameters of a Fault
9.2.3 Separation of a Fault
9.3 Classification of Faults
9.3.1 Classification 1: Based on Translational Movement
9.3.1.1 Based on Attitude of Fault Relative to Adjacent Beds
9.3.1.2 Based on Slip of Fault Plane
9.3.1.3 Based on Relative Movement of Beds
9.3.1.4 Based on Amount of Dip of Fault
9.3.2 Classification 2: Based on Rotational Movement
9.3.3 Classification 3: Based on Fault Association
9.3.4 Classification 4: Based on Orientation of Stress Axes
9.3.5 Classification 5: Based on Net-Slip
9.4 Recognition of Faults
9.4.1 Presence of Fault Rocks
Box 9.2 Active Faults
9.4.2 Features or Marks on Fault Surface
9.4.3 Structures Associated with Fault Surface
9.4.4 Secondary Crystallization
9.4.5 Behaviour of Strata
9.4.5.1 Abrupt Truncation of Strata
9.4.5.2 Abrupt Truncation of Structure
9.4.5.3 Juxtaposition of Contrasting Rocks
9.4.6 Change in Attitude of Strata
9.4.6.1 Sudden Steepening of Strata
9.4.6.2 Anomalous Dip and Strike of Strata
9.4.6.3 Abrupt Change in Dip of Strata
9.4.7 Geomorphologic Criteria
9.4.7.1 Scarps/Fault Scarps
9.4.7.2 Localization of Springs
9.4.7.3 Straightening of Stream Course
9.4.7.4 Sudden Change in Stream Profile
9.4.7.5 Truncation of a Mountain Front
9.5 Fault Damage Zone
9.6 Fault Zone Rocks
9.7 Growth of Faults
Box 9.3 Fault Chronology
9.8 Fault Mechanics
9.8.1 Coulomb Criterion of Failure
9.8.2 Anderson´s Theory
9.8.3 Hafner´s Theory
9.8.4 Seismic Faulting
9.8.5 Role of Friction in Fault Mechanics
Box 9.4 Friction in the Context of Faults
9.9 Significance of Faults
9.9.1 Academic Significance
9.9.2 Economic Significance
9.10 Summary
10: Extensional Regime and Normal Faults
10.1 Introduction
10.2 Extensional Regime
10.2.1 What Is Extensional Regime?
10.2.2 Mechanisms of Extensional Faulting
10.2.3 Geological Environments for Extensional Regime
10.2.4 Models of Extensional Tectonics
10.2.4.1 Crustal Thinning Model
10.2.4.2 Low-Angle Detachment Fault Model
10.2.5 Extensional Tectonics in the Himalaya
10.3 Normal Faults
Box 10.1 How to Identify the Downthrown Block of a Normal Fault?
10.4 Types of Normal Faults
10.4.1 Domino Faults
10.4.2 Detachment Faults
10.4.3 Growth Faults
10.4.4 Metamorphic Core Complexes
10.4.5 Rifts
10.4.6 Ring Faults and Calderas
10.5 Significance of Normal Faults
10.5.1 Academic Significance
10.5.2 Economic Significance
10.6 Summary
11: Contractional Regime and Thrust Faults
11.1 Introduction
11.2 Deformation Styles of Contractional Regime
11.2.1 Thick-Skinned Deformation
11.2.2 Thin-Skinned Deformation
11.3 Crystalline Thrusts
11.4 Thrust Faults
11.5 Thrust Terminology
11.6 Thrusts and Nappes
11.6.1 Definitions
Box 11.1 Rocks Travel! But How Long?
11.6.2 The Himalaya: A Storehouse of Thrust and Nappe Structures
11.7 Thrust Geometry
11.8 Types of Thrust Geometry
11.8.1 Planar Thrust Geometry
11.8.2 Thrust Geometry as Related to Folds
11.8.3 Thrust Geometry as Related to Stratigraphic Sequence
11.9 Trishear
11.10 Models of Thrust Formation
11.10.1 Background
11.10.2 Compressional Models
11.10.3 Gravitational Models
11.10.3.1 Gravitational Gliding
11.10.3.2 Gravitational Collapse
11.10.3.3 Gravitational Extrusion
11.10.3.4 Gravitational Spreading
11.10.4 Mixed Models
11.10.5 Role of Detachment Geometries
11.11 Diapirs and Salt Domes
11.11.1 Background
11.11.2 Geographical Distribution of Salt Domes
11.11.3 Why Subsurface Salt Is Unstable?
11.11.4 Formation of Salt Domes
11.11.5 Salt Tectonics
11.11.5.1 Extensional Salt Tectonics
11.11.5.2 Contractional Salt Tectonics
11.11.6 Flow Mechanisms
11.12 Significance of Thrust Faults and Salt Diapirs
11.12.1 Academic Significance
11.12.2 Economic Significance
11.13 Summary
12: Strike-Slip Faults
12.1 Introduction
12.2 Motion of Strike-Slip Faults
12.3 Types of Strike-Slip Faults
12.3.1 Transform Fault
12.3.2 Transcurrent Fault
12.3.3 Wrench Fault and Tear Fault
12.3.4 Transfer Fault
12.4 Classes of Strike-Slip Faults
12.5 Transpression and Transtension
12.6 Structures Associated with Strike-Slip Faults
12.6.1 Fault Bend and Stepover
12.6.2 Flower Structure
12.6.3 Strike-Slip Duplex
12.6.4 Folds, Thrusts and Normal Faults
12.6.5 Termination
12.6.6 Riedel Shears
12.6.7 Pull-Apart Basins
12.7 Strike-Slip Faults on a Regional Perspective
Box 12.1 Strike-Slip System in a Craton
12.8 Significance of Strike-Slip Faults
12.8.1 Academic Significance
12.8.2 Applied Significance
12.9 Summary
13: Joints and Fractures
13.1 Introduction
13.2 Joints, Fractures and Shear Fractures
13.3 Understanding Joints and Fractures: From Laboratory Experiments
13.4 Types of Joints
13.5 Geometrical Parameters of Joints
13.5.1 Scale of Joints
13.5.2 Shape of Joints and Fractures
13.5.3 Joint Density and Joint Intensity
13.5.4 Fracture Spacing Index
13.6 Microcracks
Box 13.1 Recracking
13.7 Veins
13.8 Fracture Refraction
13.9 Surface Features of Joints
13.10 Joint Propagation
13.11 Joints as Related to Stresses
13.12 Joints on a Larger Perspective (Lineaments)
13.13 Joints as Related to the Present-Day Stress Field
13.14 Joint Mechanics
13.14.1 Fundamental Principles
13.14.2 Linear Elastic Fracture Mechanics (LEFM)
13.14.3 Joint-Driving Mechanisms
13.14.4 Joint-Driving Stress
13.14.5 Joint Loading Paths
13.14.6 Folding
13.14.6.1 Conceptual Models
13.14.6.2 Regional Studies
13.14.7 Example 1
13.14.8 Example 2
13.14.9 Example 3
13.14.10 Example 4
13.15 Causes of Joint Formation
13.15.1 Burial
13.15.2 Uplift and Erosion
13.15.3 Thermal Contraction
13.15.4 Sheeting
13.15.5 Tectonic Causes
13.16 Fracture Mechanics
13.16.1 What Is Fracture Mechanics?
13.16.2 Modes of Fracture Opening
13.16.3 Stress Intensity
13.16.4 Crack Extension Force
13.16.5 Crack Extension Laws
13.16.6 Microcracking by Process Zone
13.16.7 Dynamic Fracture
13.16.8 Shear Fracturing
13.16.9 Griffith´s Fracture Theory
13.17 Significance of Joints and Fractures
13.17.1 Academic Significance
13.17.2 Economic Significance
13.17.3 Engineering Significance
13.17.4 Environmental Significance
13.18 Summary
14: Foliation
14.1 Introduction
14.2 Foliation and Cleavage
14.3 Foliation in Hand Specimens
14.4 Foliation in Thin Sections
14.4.1 Some Common Forms of Foliation
14.4.2 Foliation in Some Common Rock Types
14.5 Classification of Cleavage
14.5.1 Continuous Cleavage
14.5.2 Spaced Cleavage
14.6 Relative Chronology of Foliations
14.7 Genesis of Foliation
14.7.1 Background
14.7.2 Role of Deformation
14.7.3 An Overview of Foliation Formation
14.8 Foliation-Forming Processes
14.8.1 Folding
14.8.1.1 Can Folding Develop Foliation?
14.8.1.2 Crenulation Foliation
14.8.1.3 Axial-Plane Foliation
14.8.2 Ductile Shearing
14.8.2.1 Background
14.8.2.2 Mylonitic Foliation
14.8.2.3 Transposition Foliation
14.8.3 Pressure Solution
14.8.4 Grain Rotation
14.8.5 Mineral Growth
14.8.6 Dynamic Recrystallization
14.8.7 Progressive Shear Deformation
14.8.8 Metamorphism
14.8.9 Metamorphic Differentiation
Box 14.1 Can Foliation Formation Reach a Steady-State Condition?
14.8.10 Crystal-Plastic Deformation
14.8.11 Mineral Nucleation
14.8.12 Mineral Growth
14.9 Significance of Foliation
14.9.1 Academic Significance
14.9.2 Economic Significance
14.10 Summary
15: Lineation
15.1 Introduction
15.2 Types of Lineation
15.3 Non-penetrative Lineation
15.3.1 Slickensides
15.3.2 Slickenlines
15.3.3 Slickenfibres
15.4 Penetrative Lineation
15.4.1 Mineral Lineation
15.4.2 Lineation Given by Pebbles, Etc.
15.4.3 Crenulation Lineation
15.4.4 Intersection Lineation
15.4.5 Mullions
15.4.6 Rods
15.4.7 Pencil Structure
15.4.8 Boudin
15.4.9 Stretching Lineation
15.4.10 Pressure Shadows
Box 15.1 Lineations in Three-Dimensional Space
15.5 Lineation as a Tectonic Fabric
15.6 Genesis of Lineation
15.6.1 Metamorphism-Dominated Processes
15.6.2 Deformation-Dominated Processes
15.6.2.1 Deformation of Pre-existing Constituents
15.6.2.2 Folding
15.6.2.3 Extensional Processes
15.6.2.4 Rotation
15.6.2.5 Shear Deformation
15.6.3 Geometrically Controlled Lineation
15.6.4 Lineation as a Consequence of Plate Motion?
15.7 Significance of Lineation
15.8 Summary
Part III: Wider Perspectives
16: Mechanisms of Rock Deformation
16.1 Introduction
16.2 Factors Controlling Mechanisms of Deformation
16.3 Classification of Mechanisms of Deformation
16.4 Mechanisms on Microscale
16.4.1 Recovery
16.4.2 Dynamic Recrystallization
16.4.3 Bulge Recrystallization
16.4.4 Grain-Boundary Sliding
16.4.5 Crystal Plastic Deformation
Box 16.1 Feldspar Recrystallization
16.4.6 Diffusion Creep
16.4.7 Dislocation Creep
16.4.8 Grain-Boundary Pinning
16.5 Mechanisms on Mesoscale
16.5.1 Brittle Deformation Mechanisms
16.5.2 Superplastic Deformation
16.5.3 Diffusive Mass Transfer
16.5.4 Pressure Solution
16.5.5 Strain Hardening and Strain Softening
16.5.6 Hydrolytic Weakening
16.5.7 Crack-Seal Mechanism
16.5.8 Seismic Faulting
16.6 Summary
17: Shear Zones
17.1 Introduction
17.2 Deformation Domains
Box 17.1 Ductile Shear Zone-Brittle Fault Analogy
17.3 Shear Zone and Finite Strain Axes
17.4 Strain Within a Shear Zone
Box 17.2 Strain Associated with Large Shear Zones
17.5 Classification of Shear Zones
17.5.1 On the Basis of Geometry of Shear Zones
17.5.2 On the Basis of Kinematics of Deformation
17.5.3 On the Basis of Microscale Deformation Mechanisms
17.5.4 On the Basis of Relative Displacement of Rocks
17.5.5 Shear Zones Under Plate Tectonic Settings
17.5.6 Ductile and Brittle Shear Zones
17.5.7 On the Basis of Progressive Deformation or Flow
17.5.8 Classification on the Basis of Shear Zone Profile
17.5.8.1 Shear Zone with Sigmoidal Foliation
17.5.8.2 Shear Zone with Planar Foliation
17.5.8.3 Asymptotic Shear Zones
17.5.8.4 Tapering Shear Zones
17.5.8.5 Convergent Shear Zones
17.5.8.6 Anastomosing Shear Zones
17.5.9 Single and Multiple Shear Zones
17.5.9.1 Single Shear Zone
17.5.9.2 Multiple Shear Zones
17.6 Shear Zone Rocks
17.7 Fabric Development in Shear Zones
17.8 Shear Zone Formation
17.8.1 Background
17.8.2 Initiation of a Shear Zone
17.8.3 Growth of a Shear Zone
17.8.4 Evolution of Shear Zone Thickness
17.8.5 Strain-Softening Mechanisms
17.8.5.1 Shear Heating
17.8.5.2 Geometric Softening
17.8.5.3 Effects of Quartz Dauphiné Twinning on Strain Localization
17.9 Shear Zones on a Lithospheric Perspective
17.10 Significance of Shear Zones
17.10.1 Academic Significance
17.10.2 Economic Significance
17.11 Summary
18: Shear-Sense Indicators
18.1 Introduction
18.2 Ductile Shear-Sense Indicators
18.2.1 Sigmoidal Foliation
18.2.2 Oblique Foliation
18.2.3 Asymmetric Folds
18.2.4 Intrafolial Folds
18.2.5 Oblique Lenses
18.2.6 S-C Structures
18.2.7 Shear Band Foliation
18.2.8 Asymmetric Porphyroclasts
18.2.9 Quarter Structures
18.2.9.1 Quarter Folds
18.2.9.2 Quarter Mats
18.2.9.3 Asymmetric Myrmekite
18.2.10 Grain-Shape Foliation
18.2.11 Mica Fish and Foliation Fish
18.2.12 Asymmetry of Boudins
18.2.13 Flanking Structures
18.2.14 Mantled Structures Under Stick-and-Slip Conditions
18.2.15 Quartz CPO
18.2.15.1 Quartz c-Axis Fabric
18.2.15.2 Quartz a-Axis Fabric
Box 18.1 Strain-Insensitive Fabric
18.3 Brittle Shear-Sense Indicators
18.3.1 `V´- Pull-Apart Structures
18.3.2 Tension Gashes
18.3.3 Sheared Joints
18.3.4 Duplex
18.3.5 Domino Structure
18.4 Opposite Shear Sense
18.5 Summary
19: Deformation and Metamorphism
19.1 Introduction
19.2 Deformation and Metamorphism Are Interactive
19.3 Deformation Structures in Metamorphic Perspectives
19.3.1 Foliation
19.3.2 Pressure Shadows
19.3.3 Crenulation Foliation
19.3.4 Mineral Segregation
19.3.5 Veins
19.4 Porphyroblasts
19.5 Formation of Curved Trails in Porphyroblasts
19.5.1 Model 1
19.5.2 Model 2
19.5.3 Model 3
19.6 Relative Timing of Deformation
Box 19.1 Porphyroblasts that Lack Inclusions
19.6.1 Pre-tectonic Crystallization
19.6.2 Inter-tectonic Crystallization
19.6.3 Syntectonic Crystallization
19.6.4 Post-tectonic Crystallization
19.7 Summary
20: Superposed Folds
20.1 Introduction
20.2 Early Concepts on Superposed Folds
20.2.1 Crossing Orogenic Belts
20.2.2 Successive Deformations in a Single Orogenic Cycle
20.2.3 Successive Folding During a Single Progressive Deformation
20.2.4 Synchronous Folding in Different Directions During One Deformation
Box 20.1 How to Identify Superposed Folds?
20.3 Types of Superposed Folds
20.3.1 Type 0: Redundant Superposition
20.3.2 Type 1: Dome-Basin Pattern
20.3.3 Type 2: Dome-Crescent-Mushroom Pattern
20.3.4 Type 3: Convergent-Divergent Pattern
20.4 Geometric Changes in Superposed Folds
20.5 Buckling of Superposed Folds
20.5.1 Single-Layer Superposed Buckling
20.5.1.1 First Mode of Superposed Buckling
20.5.1.2 Second Mode of Superposed Buckling
20.5.1.3 Third Mode of Superposed Buckling
20.5.1.4 Fourth Mode of Superposed Buckling
20.5.2 Multilayer Superposed Buckling
20.6 Classification of Thiessen and Means
20.7 Classification of Grasemann and Others
20.8 Reorientation of Lineations and Cleavages
20.9 Deformation Phase
20.10 D-Numbers
20.11 Summary
Appendix A: Stereographic Projection
Appendix B: Effect of Faults on Outcrops
Effect of Vertical Fault on Horizontal Strata
Effect of Inclined Fault on Horizontal Strata
Effect of Strike-Slip Fault
Effect of Vertical Strike-Slip Fault on Horizontal Strata
Effect of Inclined Strike-Slip Fault on Horizontal Strata
Effect of Inclined Strike-Slip Fault on Inclined Strata
Effect of Fault on Folded Strata
Effect of Fault on Anticline
Effect of Fault on Syncline
Effect of Strike-Slip Fault on Anticline
Effect of Strike-Slip Fault on Syncline
Concluding Remarks
Appendix C: Section Balancing
Introduction
Some Generalizations
Assumptions
Methods of Balancing
Equal-Area Balancing
Combination of Equal-Area and Key-Bed Balancing
Combination of Key Bed and Area Restoration
Line-Length Balancing
Summary
Glossary
A
C
D
E
F
G
H
I
L
M
O
P
R
S
T
U
Z
References
A
B
C
D
E
F
G
H
I
J
K
L
M
N
O
P
R
S
T
U
V
W
Y
Z
Author Index
Subject Index