Description
STRUCTURAL ANALYSIS & SYNTHESIS
STRUCTURAL ANALYSIS & SYNTHESIS A LABORATORY COURSE IN STRUCTURAL GEOLOGY
Structural Analysis and Synthesis is the best-selling laboratory manual of its kind. Specifically designed to support the laboratory work of undergraduates in structural geology courses, the book helps students analyze the various aspects of geological structures, and to combine their analyses into an overarching synthesis.
This book is intended for use in the laboratory portion of a first course in structural geology. As is explicit in the book’s title, it is concerned with both the analysis and synthesis of structural features. In this fourth edition, the has been broadened to include a range of new content and features, including:
Structural Analysis and Synthesis is a renowned and widely recognized aid to students in grasping and mastering the techniques required in structural geology, and will find a home wherever the principles and practices of structural geology are taught.
Table of Contents
Preface vii
About the Companion Website ix
1 Attitudes of Lines and Planes 1
Objectives 1
Definitions 2
Structural Elements 4
Structural Grain 5
2 Outcrop Patterns and Structure Contours 9
Objectives 9
Structure Contours 12
The Three‐Point Problem 13
Drawing a Topographic Profile 14
Drawing Cross Sections of Structure Contour Maps 15
Determining Outcrop Patterns with Structure Contours 15
Gently Bent Layers 17
Determining Exact Attitudes from Outcrop Patterns 18
Determining Stratigraphic Thickness in Flat Terrain 19
Determining Stratigraphic Thickness on Slopes 20
Determining Stratigraphic Thickness by Orthographic Projection 20
3 Stereographic Projection 31
Objective 31
Plotting a Plane 33
Plotting a Line 33
Plotting the Pole to a Plane 34
Line of Intersection of Two Planes 35
Angles of Lines within a Plane 36
Determining True Dip from Strike and Apparent Dip 37
Determining Strike and Dip from Two Apparent Dips 38
4 Folds and Cross Sections 43
Objectives 43
Glossary of Fold Terms 43
Classification by Shape 45
Classification by Orientation 45
Fold Classification Based on Dip Isogons 47
Outcrop Patterns of Folds 48
Cross or Structure Sections of Folded Layers 49
The Arc Method 50
Down‐Plunge Projection 50
5 Stereographic Analysis of Folded Rocks 67
Objectives 67
Beta (β) Diagrams 67
Pi (π) Diagrams 68
Pole Plotter 68
Determining the Orientation of the Axial Plane Using Fold Trace 69
Constructing the Profile of a Fold Exposed in Flat Terrain 69
Determining the Orientation of the Axial Plane Without a Fold Trace 70
Simple Equal‐Area Diagrams of Fold Orientation 71
Contour Diagrams 71
Determining the Fold Style and Interlimb Angle from Contoured Pi Diagrams 75
6 Rotations and Determining Original Directions in Folded Rocks 87
Objectives 87
Rotation of Lines 87
The Two‐Tilt Problem 89
Cones: The Drill‐Hole Problem 90
Unfolding Folds 93
7 Foliations, Parasitic Folds, and Superposed Folds 95
Objectives 95
Foliations 95
Parasitic Folds 97
Superposed Folds 99
8 Strain Measurements in Ductile Rocks 107
Objectives 107
Longitudinal Strain 107
Shear Strain 108
The Strain Ellipse 108
Strain Fields 108
The Coaxial Total Strain Ellipse 109
Measuring Strain in Deformed Objects 110
Strain in Folds 111
Deformed Fossils as Strain Indicators 111
Mohr Circle for Sheared Fossils 112
Mohr Circle for Boudinage 113
9 Advanced Strain Measurements 125
Objectives 125
Fry Method 126
Rf/φ Method 127
10 Brittle Failure 131
Objective 131
Quantifying Two‐Dimensional Stress 131
The Mohr Diagram 133
The Mohr Circle of Stress 134
Rules for Going Between Mohr Space and Real Space 135
The Failure Envelope 135
The Importance of Pore Pressure 138
11 Analysis of Fracture Systems 147
Objectives 147
Data Collection 148
Rose Diagram 148
Length vs Strike Graphs 149
Interpreting Joint Strike Diagrams 150
Contouring Joint Density 150
Accounting for Dip in Joints 152
12 Faults 157
Objectives 157
Measuring Slip 159
Rotational (Scissor) Faulting 161
Map Patterns of Faults 162
Timing of Faults 163
13 Dynamic and Kinematic Analysis of Faults 169
Objectives 169
Dynamic Analysis 169
Kinematic Analysis 174
14 Structural Synthesis 191
Objective 191
Structural Synthesis 191
Some Suggestions for Writing Style 193
Common Errors in Geologic Reports 193
15 Deformation Mechanisms in Mylonites 197
Objectives 197
Deformation Mechanisms 197
Fault Rocks 200
Kinematic Indicators 202
S‐C Fabrics 202
Asymmetric Porphyroclasts 202
Oblique Grain Shapes in Recrystallized Quartz Aggregates 203
Antithetic Shears 203
Strain and Offset in Shear Zones 204
Potential Sources of Error 205
16 Construction of Balanced Cross Sections 213
Objectives 213
Thrust‐Belt “Rules” 213
Recognizing Ramps and Flats 214
Relations Between Folds and Thrusts 215
Requirements of a Balanced Cross Section 218
Constructing a Restored Cross Section 219
Constructing a Balanced Cross Section 220
17 Introduction to Plate Tectonics 233
Objectives 233
Fundamental Principles 233
Plate Boundaries 234
Triple Junctions 235
Focal‐Mechanism Solutions (“Beach‐Ball” Diagrams) 236
Earth Magnetism 240
Apparent Polar Wander 242
18 Virtual Field Trip 253
Objective 253
Newfoundland Folds Field Trip 254
Ramapo Fault Field Trip 255
References 257
Further Reading 259
Index 265
