Structural Geology An Introduction to Geometrical Techniques

622 Pages·2009·7.51 MB·English

by  Donal M. Ragan

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STRUCTURAL GEOLOGY
AnIntroductiontoGeometricalTechniques
fourth edition
Many textbooks describe information and theories about the Earth without training
studentstoutilizerealdatatoanswerbasicgeologicalquestions.Thisvolume–acombi-
nationoftextandlabbook–presentsanentirelydifferentapproachtostructuralgeology.
Designedforundergraduatelaboratoryclasses,itisdedicatedtohelpingstudentssolve
manyofthegeometricalproblemsthatarisefromfieldobservations.Thebasicapproach
is to supply step-by-step instructions to guide students through the methods, which
includewell-establishedtechniquesaswellasmorecutting-edgeapproaches.Particular
emphasisisgiventographicalmethodsandvisualizationtechniques,intendedtosupport
studentsintacklingtraditionallychallengingtwo-andthree-dimensionalproblems.Exer-
cises at the end of each chapter provide students with practice in using the techniques,
and demonstrate how observations and measurements from the field can be converted
into useful information about geological structures and the processes responsible for
creatingthem.
Building on the success of previous editions, this fourth edition has been brought
fully up-to-date and incorporates new material on stress, deformation, strain and flow.
Also new to this edition are a chapter on the underlying mathematics and discussions
of uncertainties associated with particular types of measurement. With stereonet plots
and full solutions to the exercises available online at www.cambridge.org/ragan, this
bookisakeyresourceforundergraduatestudentsaswellasmoreadvancedstudentsand
researcherswantingtoimprovetheirpracticalskillsinstructuralgeology.
Don Ragan waseducatedatOccidentalCollege,UniversityofSouthernCalifornia
andattheUniversityofWashingtoninSeattle,receivinghisPh.D.in1960.Hespenta
yearasaFulbrightScholarattheUniversityofInnsbruck,andlater,withaNationalSci-
enceFoundationFellowship,atImperialCollege,London,wherehereceivedaDiploma
ofMembershipinGeology(DIC).HisteachingcareerattheUniversityofAlaska,Fair-
banks,andatArizonaStateUniversityhasspannedatotalof34years,andhasfocused
onimbuingstudentswithathoroughunderstandingofgeometricalandanalyticaltech-
niquesinstructuralgeology.Hisresearchinterestscenterontheroleofstructuralsettings
in structure-making processes, including studies of Alpine peridotites, glacial ice and
weldedtuffs.

STRUCTURAL GEOLOGY
An Introduction to Geometrical Techniques
fourth edition
donal m. ragan
ArizonaStateUniversity,USA
CAMBRIDGE UNIVERSITY PRESS
Cambridge, New York, Melbourne, Madrid, Cape Town, Singapore,
São Paulo, Delhi, Dubai, Tokyo
Cambridge University Press
The Edinburgh Building, Cambridge CB2 8RU, UK
Published in the United States of America by Cambridge University Press, New York
www.cambridge.org
Information on this title: www.cambridge.org/9780521897587
© D. M. Ragan 2009
This publication is in copyright. Subject to statutory exception and to the
provision of relevant collective licensing agreements, no reproduction of any part
may take place without the written permission of Cambridge University Press.
First published in print format 2009
ISBN-13 978-0-511-64137-4 eBook (NetLibrary)
ISBN-13 978-0-521-89758-7 Hardback
ISBN-13 978-0-521-74583-3 Paperback
Cambridge University Press has no responsibility for the persistence or accuracy
of urls for external or third-party internet websites referred to in this publication,
and does not guarantee that any content on such websites is, or will remain,
accurate or appropriate.
For
Janne,AnnelieseandA´sta

Contents
Preface pagexv
Acknowledgements xvii
1 Structuralplanes 1
1.1 Introduction 1
1.2 Definitions 1
1.3 Dipandstrike 2
1.4 Accuracyofanglemeasurements 5
1.5 Graphicmethods 10
1.6 Findingapparentdip 13
1.7 Analyticalsolutions 15
1.8 Cotangentmethod 17
1.9 Truedipandstrike 18
1.10 Dipvectors 20
1.11 Three-pointproblem 24
1.12 Observedapparentdips 25
1.13 Exercises 27
2 Thicknessanddepth 30
2.1 Definitions 30
2.2 Thicknessdetermination 31
2.3 Thicknessbydirectmeasurement 31
2.4 Thicknessfromindirectmeasurements 32
2.5 Apparentthickness 36
2.6 Thicknessbetweennon-parallelplanes 39
2.7 Thicknessindrillholes 41
2.8 Depthtoaplane 43
2.9 Distancetoaplane 44
2.10 Errorpropagation 46
2.11 Exercises 54
vii
viii Contents
3 Linesandintersectingplanes 57
3.1 Definitions 57
3.2 Linearstructures 57
3.3 Plungeofaline 59
3.4 Pitchofaline 61
3.5 Intersectingplanes 64
3.6 Cotangentmethod 65
3.7 Structurecontours 66
3.8 Linevectors 67
3.9 Accuracyoftrenddeterminations 69
3.10 Exercises 71
4 Planesandtopography 72
4.1 Exposuresonhorizontalsurfaces 72
4.2 Effectoftopography 74
4.3 Dipandstrikefromageologicalmap 76
4.4 Linearinterpolation 77
4.5 Parallellines 79
4.6 Three-pointproblem 80
4.7 Structurecontours 82
4.8 Predictingoutcroppatterns 84
4.9 Exercises 87
5 Stereographicprojection 88
5.1 Introduction 88
5.2 Stereogram 88
5.3 Stereonet 92
5.4 Plottingtechniques 93
5.5 Measuringangles 99
5.6 Attitudeproblems 101
5.7 Polarnet 104
5.8 Dipandstrikeerrors 105
5.9 Intersectionerrors 106
5.10 Exercises 107
6 Rotations 109
6.1 Introduction 109
6.2 Basictechniques 109
6.3 Sequentialrotations 114
6.4 Rotationsaboutinclinedaxes 116
6.5 Rotationalproblems 118
6.6 Tiltingproblems 119