Geological Methods in Mineral Exploration and Mining

123 Pages·1997·4.859 MB·English

by  Roger W. Marjoribanks (auth.)

GEOLOGICAL METHODS IN
MINERAL EXPLORATION AND
MINING
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GEOLOGICAL
METHODSIN
MINERAL
EXPLORATION
ANDMINING
Written and illustrated by
Roger W. Marjoribanks
la
11
I
SPRINGER-SCIENCE+BUSINESS MEDIA, B.V
First edition 1997
© 1997 Springer Science+Business Media Dordrecht
Originally published by Chapman & Hali in 1997
Softcover reprint ofthe hardcover lst edition 1997
Typeset in 10/12pt Palatino by Saxon Graphics Ltd, Derby
ISBN 978-94-010-6459-0 ISBN 978-94-011-5822-0 (eBook)
DOI 10.1007/978-94-011-5822-0
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A catalogue record for this book is available from the British Library
Library of Congress Catalog Card Number: 96-71731
El
Printed on permanent acid-free text paper, manufactured in
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CONTENTS
Preface ix
Acknowledgements xi
1 PROSPECTING AND THE EXPLORATION PROCESS 1
1.1 DEFINITION OF TERMS 1
1.2 GENERATING NEW PROJECTS AND PROSPECTS 1
1.3 SOME WAYS OF GENERATING NEW EXPLORATION IDEAS 2
1.4 A CHECK-LIST OF NEGATIVE ASSUMPTIONS 2
1.5 STAGES IN PROSPECT EXPLORATION 3
1.5.1 Target Generation 3
1.5.2 Target Drilling 4
1.5.3 Resource Evaluation Drilling 4
1.5.4 Feasibility Study 4
1.6 MAXIMIZING SUCCESS IN EXPLORATION PROGRAMMES 4
1.7 DIFFERENT TYPES OF EXPLORATION STRATEGY 6
2 GEOLOGICAL MAPPING IN EXPLORATION 9
2.1 GENERAL CONSIDERATIONS 9
2.1.1 Why Make A Map? 9
2.1.2 The Nature Of A Geological Map 9
2.1.3 Smart Mapping 10
2.1.4 Choosing The Best Technique 12
2.1.5 Choosing The Best Scale 14
2.1.6 The Use of Satellite Navigation (GPS) 15
2.2 AIR PHOTO MAPPING 17
2.2.1 Geological Interpretation 17
2.2.2 Scales 18
2.2.3 Photo Handling Techniques 19
2.2.4 Working With Enlarged Air Photographs 21
2.2.5 Data Transfer To Base Map 21
2.3 MAPPING WITH A PLANE TABLE 22
2.4 MAPPING ON A PEGGED GRID 24
2.4.1 Requirements of the Grid 24
2.4.2 Making The Map 26
2.5 MAPPING WITH TAPE AND COMPASS 28
vi Contents
3 MINE MAPPING 31
3.1 General 31
3.2 Mapping In Open Cuts 31
3.3 Mapping Underground Openings 34
4 MINERAL EXPLORATION DRILLING 39
4.1 GENERAL 39
4.1.1 The Importance of Drilling 39
4.1.2 Types of Drilling 39
4.1.3 Choosing the Right Technique 41
4.1.4 Targeting Drill Holes 43
4.2 DIAMOND DRILLING 44
4.2.1 Preamble 44
4.2.2 Before You Begin 44
4.2.3 Setting Up A Diamond Hole 45
4.2.4 Geological Observation 45
4.2.5 Recognizing and Interpreting Structures in Core 46
4.2.6 Measuring and Recording Structures in Core 50
4.2.7 Core Logging Systems 52
4.2.8 Down-Hole Surveying 55
4.2.9 Using Down-Hole Survey Data to Plot Sections and Plans 56
4.2.10 Sampling and Assaying 58
4.2.11 Core Handling 59
4.3 REVERSE CIRCULATION (RC) DRILLING 63
4.3.1 Drilling Technique 63
4.3.2 Geological Logging 63
4.3.3 Display and Storage of Cuttings 65
4.3.4 Sampling 65
4.3.5 Sampling Below The Water Table 66
4.4 ROTARY AIR BLAST (RAB) DRILLING 67
4.4.1 Drilling Technique 67
4.4.2 Geological Logging 67
4.4.3 Sampling 68
4.5 AUGER DRILLING 69
5 PITTING, TRENCHING AND STRIPPING 71
5.1 PREAMBLE 71
5.2 SAFETY AND LOGISTICS 71
5.3 GEOLOGICAL MAPPING 72
5.4 GEOCHEMICAL SAMPLING 73
6 GEOPHYSICAL AND GEOCHEMICAL METHODS 77
6.1 GENERAL 77
6.2 A BRIEF OVERVIEW OF TECHNIQUES 78
6.2.1 Satellite Imagery 79
Contents vii
6.2.2 Magnetic Surveys 79
6.2.3 Gravity Surveys 80
6.2.4 Radiometric Surveys 81
6.2.5 Electromagnetic (EM) Surveys 81
6.2.6 Electrical Surveys 82
6.2.7 Stream Sediment Sampling 83
6.2.8 Soil Sampling 83
6.2.9 Heavy Mineral Concentrate Sampling 84
6.2.10 Laterite Sampling 84
7 GEOGRAPHICAL INFORMATION SYSTEMS 85
7.1 DEFINITION 85
7.2 THE NEED FOR GIS 85
7.3 GIS STORAGE OF MAP DATA 85
7.3.1 Digitized format 86
7.3.2 Polygon or Vector Format 86
7.3.3 Raster Format 86
7.3.4 Validation of electronically stored data 87
7.4 MANIPULATION OF GIS DATA 87
7.5 PRESENTATION OF GIS DATA 87
Appendix A NOTES ON THE USE OF THE GRAPHICAL SCALE DIAMOND
CORE LOGGING FORM 89
Appendix B MEASUREMENT OF STRUCTURES IN ORIENTED DRILL CORE 93
B.1 MECHANICAL ORIENTATION OF DRILL CORE 93
B.2 HOW TO HANDLE ORIENTED CORE 95
B.3 HOW TO MEASURE STRUCTURES IN ORIENTED CORE 96
B.3.1 General 96
B.3.2 Using a Stereo-net 96
B.3.3 Using Mathematics 100
B.3.4 Using a Core Frame 101
Appendix C PRACTICAL FIELD TECHNIQUES 105
C.1 CHOOSING THE RIGHT COMPASS 105
C.2 MEASURING THE STRIKE AND DIP OF PLANES 105
C.3 MEASURING LINEAR FEATURES 106
Appendix D SUGGESTED FURTHER READING 109
References 111
Index 113
PREFACE
This book is written as a practical field manual to effective. Each geolOgist has to develop his/her
be used by geologists engaged in mineral explo own techniques and will ultimately be judged on
ration. It is also hoped that it will serve as a text results, not the process by which these results
and reference for students in Applied Geology were reached. In mineral exploration, the only
courses of universities and colleges. The book 'right' way of doing anything is the way that
aims to outline some of the practical skills that locates ore in the quickest and most cost-effective
turn the graduate geologist into an explo manner. It is preferable, however, for an individ
rationist:. It is intended as a practical 'how to' ual to develop his/her own method of operation
book, rather than as a text on geological or ore after having tried, and become aware of, those
deposit theory. procedures which experience has shown to work
An explorationist is a professional who search well and which are generally accepted in indus
es for ore bodies in a scientific and structured try as good exploration practice.
way. Although an awkward and artificial term, The chapters of the book approximately fol
this is the only available word to describe the low the steps which a typical exploration pro
totality of the skills which are needed to locate gramme would go through. In Chapter 1, the
and define economic mineralization. Even the generation of new projects and prospects and
mine geologist, attempting to define ore blocks the nature of the exploration process are
ahead of the mining crews, is an explorationist. described. In Chapters 2 and 3 are descriptions
The most fundamental and cost-effective skills of of the various techniques employed in making
the explorationist relate to the acquisition, record geological maps from surface outcrop and mine
ing and presentation of geological knowledge so openings. Chapter 4 deals with exploration
that it can be used to predict the presence of ore. drilling and presents methods for acquiring and
Practical field techniques taught at under presenting geological information from various
graduate level are often forgotten and some types of drill core and cuttings. Chapter 5
times, although taught, are not reinforced by describes the procedures involved in trenching
subsequent practice; some skills may never be and pitting. Although this book is primarily con
adequately taught in the academic environment cerned with geological methods, in Chapter 6 a
of universities. Special techniques needed by an brief overview is given of the more commonly
explorationist - for example, mapping on grids used techniques of exploration geophysics and
or logging drill core or cuttings - seldom figure geochemistry. Finally, Chapter 7 outlines the
in basic training courses. Although no book can use of geographical information systems (GIS)
substitute for hands-on experience and demon for the storage, manipulation and presentation
stration, this manual aims to address some of of map data.
these deficiencies. New ideas and techniques are constantly
The book does not offer a set of standard rules emerging and no book such as this can be
to be invariably followed. It describes practical regarded as being a final statement. To make this
skills and techniques that, through the experi a useful document and to keep it up to date and
ence of many geologists, have been found to be relevant, geologists should use it critically.
x Preface
The underlying philosophy behind much of Information is not knowledge
this book is that, if geological data is to be of Knowledge is not understanding
value in finding ore bodies, ideas and insights Understanding is not wisdom
must be used in a structured way to control all
The book outlines some geological techniques
stages of data handling from field collection
for acquiring knowledge. The rest is up to the
through to final presentation. In these days of
reader.
electronic storage and processing of mass data, it
is worth remembering the well-known quote!:
Roger W. Marjoribanks, Perth,
Data is not information Western Australia
I Possibly adapted from: 'Where is the wisdom we have lost
in knowledge? Where is the knowledge we have lost in infor
mation?' (T.S. Eliot).
ACKNOWLEDGEMENTS
I am inc.ebted to the many skilled field geologists here. The book has benefited from the construc
with whom I have been privileged to work over tive comments and suggestions of a number of
many years, and from whom I have acquired reviewers. However, all biases and errors that
many of the exploration and geological ideas, might be found in this text are the author's own,
techniques and procedures which are described and he takes full responsibility for them.