Roger Marjoribanks Geological Methods in Mineral Exploration and Mining Springer
Preface This book is written as a practical field manual to be used by geologists engaged in mineral exploration.It is also hoped that it will serve as a text and refere nce for students in Applied Geology courses of universities and colleges.The book aims to outline e of the ctical skills that t eologist int an expl ather thar n as a text on it theory. is a professional,usually a geologist,who searches for ore bodies in a scientific and structured way.Mineral exploration professionals include a range of people:business people involved in financial and entrepreneurial activ- ities in the mining industry,board members and company management no longer involved in day to day exploration but often with past hands-on experience.tech- nical assistants.tenement managers.environmental and safety personnel,drillers vey s IT ge chemists ore ecialists,va ious types of on geologists. explor ts ar the jack all-trade with proje Au0a即1吧pu吧PICAYME1M3uosE1 stuopeojdxa43 noV_ available word to describe the totality of the skills that are needed to locate and define economic mineralization.Even the mine geologist,attempting to define ore blocks ahead of the mining crews,is an explorationist.The most fundamental and cost-effective skills of the explorationist relate to the acquisition.recording and pre- eological knowledge so that it can be used to predi sence of ore- these a the subiect of this book. Practical field techni ught at u ndergra aduate level are often forgotten and ometimes are not rei rced by that the explortionist needs may never bead cad.om ic envi ronment of universities.Special techniques and skills-or example,identifying prospective ground for acquisition,detailed prospect mapping or logging drill core Throughout the book.the rules of English grammar compel me.from time to time,to ascribe a sex now seems to me an awkward circumlo
Preface This book is written as a practical field manual to be used by geologists engaged in mineral exploration. It is also hoped that it will serve as a text and reference for students in Applied Geology courses of universities and colleges. The book aims to outline some of the practical skills that turn the graduate geologist into an explorationist. It is intended as a practical “how to” book, rather than as a text on geological or ore deposit theory. An explorationist1 is a professional, usually a geologist, who searches for ore bodies in a scientific and structured way. Mineral exploration professionals include a range of people: business people involved in financial and entrepreneurial activities in the mining industry, board members and company management no longer involved in day to day exploration but often with past hands-on experience, technical assistants, tenement managers, environmental and safety personnel, drillers, surveyors, IT specialists, geophysicists and geochemists, ore reserve specialists, various types of consultants, and the exploration geologists. Typically the exploration geologists are the jacks-of-all-trades with an overview of the team and the project. Although explorationist is a somewhat awkward and artificial term, this is the only available word to describe the totality of the skills that are needed to locate and define economic mineralization. Even the mine geologist, attempting to define ore blocks ahead of the mining crews, is an explorationist. The most fundamental and cost-effective skills of the explorationist relate to the acquisition, recording and presentation of geological knowledge so that it can be used to predict the presence of ore – these are the skills that are the subject of this book. Practical field techniques taught at undergraduate level are often forgotten and sometimes, although taught, are not reinforced by subsequent practice; some skills that the explorationist needs may never be adequately taught in the academic environment of universities. Special techniques and skills – or example, identifying prospective ground for acquisition, detailed prospect mapping or logging drill core 1 Throughout the book, the rules of English grammar compel me, from time to time, to ascribe a sex to my protagonist. In the first edition I got around this by using the expression “he or she”; but this now seems to me an awkward circumlocution. In this edition I simply ascribe gender alternately. v
Preface or cuttings-seldom figure in basic training courses.Although no book can substi- tute for hands-on experience and demonstration,this manual aims to address some of the ot offer a set of standard rules that must be invariably followed.It describes practical skills and techniques that,through the ce of many geol ogists.have been found to be effective.However.it is not the author's intention to be prescriptive;each geologist has to develop their own techniques and will ultimately be judged on results,not the process by which these results were reached.In mineral exploration,the only"right"way of doing anything is the way that locates ore in the quickest and most cost-effective manner.It is preferable,however,for an individual to develop their own method of operation after having tried.and become aware of has shown to work well and which are generally a good exploration ractice New and techn ques are constantly nerging and no book such as this can be regarded as being a final statement.To make this a useful document and to keep it up to date and relevant,geologists should use it critically. The chapters of the book approximately follow the steps that a typical explo ration programme would go through.In Chap.1,the generation of new projects and prospects and the nature of the exploration process are described.In Chaps.2 and 3 are descriptions of the various techniques employed in making geological ap s from re surfa op and min Chapter qu ed by he exp onist to cre new ro ure -trenc g,pitting,strppi g and undergr und developn .CI (supported by several Appendices)cover all aspects of dril pters 5.6 ing.These chapter constitute a major part of this book,reflecting the supreme importance of drilling to the explorationist.In Chap.8 is a detailed description of the remote sensed images provided by Land observation satellites-a modern day boon to explorationists Although this book is primarily concerned with geological methods,in Chap.9 a brief overview is given of the more commonly used techniques of exploration geo physics and geochemistry finally chan 10 d sses digital exploration data bas the se of geographical info s(GIS)and explorati rthe storage.manipulation and presentation of digital exploratio mining data n and This second edition has been greatly expanded from the original 1997 edition to reflect changes that have taken place in exploration methods over last 10 years Basic geological field techniques still constitute the core skill for the explorationis and are the subject of a significant part of the book.However new technological advances have expanded the range of tools available to her.In diamond drilling faster and more reliable systems for orienting core have made this procedure almos routine and have led to an ing on the value to b fro titative structura Satellite na tems have b e much qua accurate thus ex ing the role t GPS can play in providing su vey contro iled mapping.and the of geochemical and geophysi data.New,very high resolution,commercial land observation satellites increasingly offer imagery that rival the best of air photography both in resolution and price
vi Preface or cuttings – seldom figure in basic training courses. Although no book can substitute for hands-on experience and demonstration, this manual aims to address some of these deficiencies. The book does not offer a set of standard rules that must be invariably followed. It describes practical skills and techniques that, through the experience of many geologists, have been found to be effective. However, it is not the author’s intention to be prescriptive; each geologist has to develop their own techniques and will ultimately be judged on results, not the process by which these results were reached. In mineral exploration, the only “right” way of doing anything is the way that locates ore in the quickest and most cost-effective manner. It is preferable, however, for an individual to develop their own method of operation after having tried, and become aware of, those procedures that experience has shown to work well and which are generally accepted in industry as good exploration practice. New ideas and techniques are constantly emerging and no book such as this can be regarded as being a final statement. To make this a useful document and to keep it up to date and relevant, geologists should use it critically. The chapters of the book approximately follow the steps that a typical exploration programme would go through. In Chap. 1, the generation of new projects and prospects and the nature of the exploration process are described. In Chaps. 2 and 3 are descriptions of the various techniques employed in making geological maps from remote sensed reflectance imagery, surface outcrop and mine openings. Chapter 4 covers techniques employed by the explorationist to create new rock exposure – trenching, pitting, stripping and underground development. Chapters 5, 6 and 7 (supported by several Appendices) cover all aspects of drilling. These chapters constitute a major part of this book, reflecting the supreme importance of drilling to the explorationist. In Chap. 8 is a detailed description of the remote sensed images provided by Land observation satellites – a modern day boon to explorationists. Although this book is primarily concerned with geological methods, in Chap. 9 a brief overview is given of the more commonly used techniques of exploration geophysics and geochemistry. Finally, Chap. 10 discusses digital exploration data bases and outlines the use of geographical information systems (GIS) and exploration software for the storage, manipulation and presentation of digital exploration and mining data. This second edition has been greatly expanded from the original 1997 edition to reflect changes that have taken place in exploration methods over last 10 years. Basic geological field techniques still constitute the core skill for the explorationist and are the subject of a significant part of the book. However new technological advances have expanded the range of tools available to her. In diamond drilling, faster and more reliable systems for orienting core have made this procedure almost routine and have led to an increased awareness on the value to be got from quantitative structural logging. Satellite navigation systems have become much more accurate thus expanding the role that GPS can play in providing survey controls for detailed geological mapping, and the collection of geochemical and geophysical data. New, very high resolution, commercial land observation satellites increasingly offer imagery that rival the best of air photography both in resolution and price
Preface The desk top and laptop computers of today offer an almost exponential increase in processing power,memory capacity and graphics ability which,combined with new powerful software packages and sophisticated instrumentation,have revolutionised traditional geophysical and geochemical techniques. cessed and analysed,and this leads to a tendency for the ent day exploratio me in f nt of a mo hanin the field. ged a colour 3-D e from the reality it is supposed to represent. There is an increasin g danger that by focussing on data handling the explorationist loses sight of the need for quality data acquisition.The underlying philosophy behind much of this book is that,if geolog ical data is to be of value in finding ore bodies,ideas and insights must be used in a structured way to control all stages of data handling from field collection through to final presentation.In these days of electronic storage and processing of mass data. it is worth remembering the well-known quote2: Data is not information Information is not knowledge The book outlines some geological techniques for acquiring knowledge.The rest is up to the reader. kn
Preface vii The desk top and laptop computers of today offer an almost exponential increase in processing power, memory capacity and graphics ability which, combined with new powerful software packages and sophisticated instrumentation, have revolutionised traditional geophysical and geochemical techniques. New software programs available today allow vast amounts of data to be processed and analysed, and this leads to a tendency for the present day explorationist to spend more time in front of a monitor than in the field. Digital data, massaged and presented as multi colour 3-D surfaces can acquire a life of its own, quite divorced from the reality it is supposed to represent. There is an increasing danger that by focussing on data handling the explorationist loses sight of the need for quality data acquisition. The underlying philosophy behind much of this book is that, if geological data is to be of value in finding ore bodies, ideas and insights must be used in a structured way to control all stages of data handling from field collection through to final presentation. In these days of electronic storage and processing of mass data, it is worth remembering the well-known quote2: Data is not information Information is not knowledge Knowledge is not understanding Understanding is not wisdom The book outlines some geological techniques for acquiring knowledge. The rest is up to the reader. 2 Anonymous, but almost certainly adapted from: “Where is the wisdom we have lost in knowledge? Where is the knowledge we have lost in information” (T.S. Eliot)
Acknowledgments to work ove he marid hom the years and from whom ave geological ideas,techniques and procedures that are deseribed here.Among these are:Ray Crawford,Neville George,Don Bowes,Frank Hughes,Dave McKenzie Don Berkman,Mike Rickard,Ilmars Gemuts,Doug Dunnet,John Thoms,Dick Sillitoe and Gary Arnold. The Australian Institute of Geoscientists kindly gave their permission to reproduce a number of diagrams that previously appeared in AIG Handbook 5-Structural logging of drill core-that I authored in 2001 (2nd Edition 2007) The dia agrams in C.3.The pern 9 1ae61,6.6,6.9.6.10.614B.5,B.7,B.13.C1,C2a f Ivanhoe Mi ing Limited and Ne wcrest Limi acknowl edged to pub e descriptions of some of their exploration projects that appear at the end of Chap.4. Geological maps and sections appearing in the book are based on actual projects that the author has worked on.They have been re-drafted.modified and re-named to make them suitable for this publication and to preserve their anonymity. Gary Arnold kindly undertook to read a draft of the text and the book has ben- from his many constructive comm His input Sect.9.2 .10.3(GIS and digital da es)is gratefull say,I ac ccept full responsibility for all biases and errors that migh still remain in this work
Acknowledgments I am indebted to the many skilled field geologists with whom I have been privileged to work over the years and from whom I have acquired many of the exploration and geological ideas, techniques and procedures that are described here. Among these are: Ray Crawford, Neville George, Don Bowes, Frank Hughes, Dave McKenzie, Don Berkman, Mike Rickard, Ilmars Gemuts, Doug Dunnet, John Thoms, Dick Sillitoe and Gary Arnold. The Australian Institute of Geoscientists kindly gave their permission to reproduce a number of diagrams that previously appeared in AIG Handbook 5 – Structural logging of drill core – that I authored in 2001 (2nd Edition 2007). The diagrams in question are 6.1, 6.6, 6.9, 6.10, 6.14, B.5, B.7, B.13, C.1, C.2 and C.3. The permission of Ivanhoe Mining Limited and Newcrest Limited is acknowledged to publish the descriptions of some of their exploration projects that appear at the end of Chap. 4. Geological maps and sections appearing in the book are based on actual projects that the author has worked on. They have been re-drafted, modified and re-named to make them suitable for this publication and to preserve their anonymity. Gary Arnold kindly undertook to read a draft of the text and the book has benefited greatly from his many constructive comments. His input particularly into Sect. 9.2 (magnetic surveys) and Sect. 10.3 (GIS and digital databases) is gratefully acknowledged. Needless to say, I accept full responsibility for all biases and errors that might still remain in this work. ix
Contents 1 Prospecting and the Exploration Process 1 11 Definition of Terms 1 1.2 New Prosp 1 13 enerating New Exploration Ideas. A Che egative Assumptions 4 1.5 Stages in Prospect Exploration. 5 1.5. larget Generation.。.。. 1.5.2 Target Drilling. 6 1.5.3 Resource Evaluation Drilling 6 1.5.4 Feasibility Study 6 16 Maximizing Succ ess in Exploration Programmes 7 17 s of Exploration Strategy 0 18 0 1.9 azor 10 References Geological Mapping in Exploration 3 2.1 。 3 21.1 Why Make a map? 13 2.1.2 The Nature of a Geological Map 2.13 Intelligent Mapping 214 Choosingthe Best Technique 215 Choosing the Best scale ng 2.2 Mapping Using Reflectance Imagery as a Map Base 。 2.2. General. 2.2.2 Acquiring Air Photographs. 22.3 Geological Interpretation 2.2.4 Determining Scale. 225 Stereoscopic Image pairs 3 236 age Handling Technig 2.2.7 Working with Enlarged d Ai r Photographs xi
Contents 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 . 3 1.4 A Check-List of Negative Assumptions . 4 1.5 Stages in Prospect Exploration . 5 1.5.1 Target Generation . . . 5 1.5.2 Target Drilling . 6 1.5.3 Resource Evaluation Drilling . . 6 1.5.4 Feasibility Study . . . 6 1.6 Maximizing Success in Exploration Programmes . 7 1.7 Different Types of Exploration Strategy . 9 1.8 Exploration Feedbacks . 9 1.9 Breaking Occam’s Razor . . . . . . . . . . . . . . . . . . . . . 10 References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11 2 Geological Mapping in Exploration . . . . . . . . . . . . . . . . . . 13 2.1 General Considerations . . . . . . . . . . . . . . . . . . . . . . 13 2.1.1 Why Make a Map? . . . . . . . . . . . . . . . . . . . 13 2.1.2 The Nature of a Geological Map . . . . . . . . . . . . 14 2.1.3 Intelligent Mapping . . . . . . . . . . . . . . . . . . . 15 2.1.4 Choosing the Best Technique . . . . . . . . . . . . . . 18 2.1.5 Choosing the Best Scale . . . . . . . . . . . . . . . . . 20 2.1.6 Measuring and Recording Structures . . . . . . . . . . 22 2.1.7 Using Satellite Navigation (GPS) . . . . . . . . . . . . 23 2.2 Mapping Using Reflectance Imagery as a Map Base . . . . . . 25 2.2.1 General . . . . . . . . . . . . . . . . . . . . . . . . . 25 2.2.2 Acquiring Air Photographs . . . . . . . . . . . . . . . 26 2.2.3 Geological Interpretation . . . . . . . . . . . . . . . . 26 2.2.4 Determining Scale . . . . . . . . . . . . . . . . . . . . 27 2.2.5 Stereoscopic Image Pairs . . . . . . . . . . . . . . . . 29 2.2.6 Image Handling Techniques . . . . . . . . . . . . . . 31 2.2.7 Working with Enlarged Air Photographs . . . . . . . . 34 xi
Contents 2.2.8 Data Transfer to Base Map 2.3 Mapping with a Plane Table 24 24 pping ona Pegged Grid ents of the 2.4.2 ing the Ma p 2.5 Mapping with Tape and Compass References. 49 3 Mine Mapping 3.1 General 5 3.2 Mapping in Open Cuts 33 Mapping Underground Openings 24 Safety in Mines 6 4 Trenching and Underground Development 6 Preambl 4.2 Pitting and Trenching 63 4.3 Underground Development 64 4.4 Safety and Logistics in Trenching 45 Geological Mapping 46 Geochemical sampling 47 Examples of Successful Exploration Programmes References 72 Drilling a general dis scussion the Importance of Drilling 3 T 52 Choosing the Right Technique 5.3 Targeting Holes,.,.,.,.,. 5.4 Drilling on Section.,.,.,.,., References 94 6 Rotary Percussion and Auger Drilling 。 6.1 Rotary Percussion Drilling 8 6.1.1 Reverse circulation drilling (RCy 6.12 Air Core drillins 93 6.1.3 ry Air Blast(RAB)Drilling Auger Drilling erences 。 09 7 Diamond Drilling 1. Preamble 99 7.2 Some Definitions 73 Before You Begin 102 74 Setting Up a Diamond Hole 102 7.5 Geol gical Observation 103 7.6 10g
xii Contents 2.2.8 Data Transfer to Base Map . . . . . . . . . . . . . . . 37 2.3 Mapping with a Plane Table . . . . . . . . . . . . . . . . . . . 38 2.4 Mapping on a Pegged Grid . . . . . . . . . . . . . . . . . . . . 41 2.4.1 Requirements of the Grid . . . . . . . . . . . . . . . . 41 2.4.2 Making the Map . . . . . . . . . . . . . . . . . . . . . 43 2.5 Mapping with Tape and Compass . . . . . . . . . . . . . . . . 47 References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 49 3 Mine Mapping . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 51 3.1 General . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 51 3.2 Mapping in Open Cuts . . . . . . . . . . . . . . . . . . . . . . 51 3.3 Mapping Underground Openings . . . . . . . . . . . . . . . . 56 3.4 Safety in Mines . . . . . . . . . . . . . . . . . . . . . . . . . . 60 References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 61 4 Trenching and Underground Development . . . . . . . . . . . . . . 63 4.1 Preamble . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 63 4.2 Pitting and Trenching . . . . . . . . . . . . . . . . . . . . . . . 63 4.3 Underground Development . . . . . . . . . . . . . . . . . . . . 64 4.4 Safety and Logistics in Trenching . . . . . . . . . . . . . . . . 65 4.5 Geological Mapping . . . . . . . . . . . . . . . . . . . . . . . 66 4.6 Geochemical Sampling . . . . . . . . . . . . . . . . . . . . . . 69 4.7 Examples of Successful Exploration Programmes . . . . . . . . 71 References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 72 5 Drilling: A General Discussion the Importance of Drilling . . . . . 75 5.1 Types of Drilling . . . . . . . . . . . . . . . . . . . . . . . . . 75 5.2 Choosing the Right Technique . . . . . . . . . . . . . . . . . . 76 5.3 Targeting Holes . . . . . . . . . . . . . . . . . . . . . . . . . . 79 5.4 Drilling on Section . . . . . . . . . . . . . . . . . . . . . . . . 83 References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 84 6 Rotary Percussion and Auger Drilling . . . . . . . . . . . . . . . . 85 6.1 Rotary Percussion Drilling . . . . . . . . . . . . . . . . . . . . 85 6.1.1 Reverse Circulation Drilling (RC) . . . . . . . . . . . 85 6.1.2 Air Core Drilling . . . . . . . . . . . . . . . . . . . . 93 6.1.3 Rotary Air Blast (RAB) Drilling . . . . . . . . . . . . 93 6.2 Auger Drilling . . . . . . . . . . . . . . . . . . . . . . . . . . 96 References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 97 7 Diamond Drilling . . . . . . . . . . . . . . . . . . . . . . . . . . . . 99 7.1 Preamble . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 99 7.2 Some Definitions . . . . . . . . . . . . . . . . . . . . . . . . . 100 7.3 Before You Begin . . . . . . . . . . . . . . . . . . . . . . . . . 102 7.4 Setting Up a Diamond Hole . . . . . . . . . . . . . . . . . . . 102 7.5 Geological Observation . . . . . . . . . . . . . . . . . . . . . 103 7.6 Recognizing and Interpreting Structures in Core . . . . . . . . . 104
Contents xii 7.6.1 Statement of the Problem,···,·····,··· 7.6.1 Planar Structures 104 7.6.3 Faults 105 764 Linear Structures 107 765 Folds 109 766 The Scale Problem 110 767 e 112 77 Measuring and Recording Structures in Core 7.8 Core Logging Systems 7.8. Prose Logging 6 7.8.2 Graphical Scale Logging. 1 7.8.3 Analytical Spreadsheet Logging 119 7.9 Down-Hole Surveying 123 701 Procedure 123 7.9.2 Using Down-Hole Survey Data to Plot Sections nd Plan 124 7.10 When Should Core Be Oriented? 127 Sampl 7.12 and Assaying· Core Handling 7.13 Core Photography 135 References 136 8 Satellite Imagery 。 137 81 General discussion 137 82 How Earth Observation Satellites Work 139 83 140 84 Display of Analysis of R 9 Geophysical and Geochemical Methods 143 9.1 9.2 Magnetic Surveys 。 93 Gravity surveys. 149 04 Radiometric surveys 150 9.5 Electromagnetic(EM)Surveys 150 9.6 9 Hybrid and Ma agnetic Su 152 Advance s in Instrumentation and g Stream Sediment Sampling. 9.10 Soil Sampling s55 9.11 Heavy Mineral Concentrate (HMC)Sampling. 158 9.12 Rock Chip Sampling 160 9.13 Laterite Sampling 161 References 162
Contents xiii 7.6.1 Statement of the Problem . . . . . . . . . . . . . . . . 104 7.6.2 Planar Structures . . . . . . . . . . . . . . . . . . . . 104 7.6.3 Faults . . . . . . . . . . . . . . . . . . . . . . . . . . 105 7.6.4 Linear Structures . . . . . . . . . . . . . . . . . . . . 107 7.6.5 Folds . . . . . . . . . . . . . . . . . . . . . . . . . . . 109 7.6.6 The Scale Problem . . . . . . . . . . . . . . . . . . . 110 7.6.7 Vergence . . . . . . . . . . . . . . . . . . . . . . . . . 112 7.7 Measuring and Recording Structures in Core . . . . . . . . . . 113 7.8 Core Logging Systems . . . . . . . . . . . . . . . . . . . . . . 116 7.8.1 Prose Logging . . . . . . . . . . . . . . . . . . . . . . 116 7.8.2 Graphical Scale Logging . . . . . . . . . . . . . . . . 117 7.8.3 Analytical Spreadsheet Logging . . . . . . . . . . . . 119 7.9 Down-Hole Surveying . . . . . . . . . . . . . . . . . . . . . . 123 7.9.1 Procedure . . . . . . . . . . . . . . . . . . . . . . . . 123 7.9.2 Using Down-Hole Survey Data to Plot Sections and Plans . . . . . . . . . . . . . . . . . . . . . . . . 124 7.10 When Should Core Be Oriented? . . . . . . . . . . . . . . . . . 127 7.11 Sampling and Assaying . . . . . . . . . . . . . . . . . . . . . . 127 7.12 Core Handling . . . . . . . . . . . . . . . . . . . . . . . . . . 130 7.13 Core Photography . . . . . . . . . . . . . . . . . . . . . . . . 135 References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 136 8 Satellite Imagery . . . . . . . . . . . . . . . . . . . . . . . . . . . . 137 8.1 General Discussion . . . . . . . . . . . . . . . . . . . . . . . . 137 8.2 How Earth Observation Satellites Work . . . . . . . . . . . . . 139 8.3 Display of Satellite Images . . . . . . . . . . . . . . . . . . . . 140 8.4 Geological Interpretation . . . . . . . . . . . . . . . . . . . . . 140 8.5 Analysis of Reflectance Data . . . . . . . . . . . . . . . . . . . 142 References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 142 9 Geophysical and Geochemical Methods . . . . . . . . . . . . . . . 143 9.1 General Discussion . . . . . . . . . . . . . . . . . . . . . . . . 143 9.2 Magnetic Surveys . . . . . . . . . . . . . . . . . . . . . . . . . 146 9.3 Gravity Surveys . . . . . . . . . . . . . . . . . . . . . . . . . . 149 9.4 Radiometric Surveys . . . . . . . . . . . . . . . . . . . . . . . 150 9.5 Electromagnetic (EM) Surveys . . . . . . . . . . . . . . . . . . 150 9.6 Electrical Surveys . . . . . . . . . . . . . . . . . . . . . . . . 151 9.7 Hybrid Electrical and Magnetic Surveys . . . . . . . . . . . . . 152 9.8 Advances in Instrumentation and Data Modelling . . . . . . . . 153 9.9 Stream Sediment Sampling . . . . . . . . . . . . . . . . . . . . 155 9.10 Soil Sampling . . . . . . . . . . . . . . . . . . . . . . . . . . . 157 9.11 Heavy Mineral Concentrate (HMC) Sampling . . . . . . . . . . 158 9.12 Rock Chip Sampling . . . . . . . . . . . . . . . . . . . . . . . 160 9.13 Laterite Sampling . . . . . . . . . . . . . . . . . . . . . . . . . 161 References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 162
xiv Contents 10 Geographical Information Systems and Exploration Databases 165 10.1 Definition 102 165 10.3 prage of M ap Da Digitise e Format 10.32 Polygon or Vector Format. 10.3.3 Raster Format,.。.,. 170 10.4 170 10.5 Georeferencing 171 10.5.1 Geographical Coordinates 171 10.5.2 Cartesian Coordinates 10.5.3 Map Datums 17 10.5.4 Map Re 173 10.6 Manipu 173 10.7 Presentation of GIS Data 174 Appendix A Notes on the Use of Graphical Scale Logging. A.I Column 1(Hole Depth) 180 A2 Column 2 (Core Recovery) 180 A3 Column 3(Core Ouality) 180 AA Column 4(Sample No.) 180 Column5(Assay Results) 180 Columr apping L gs lumn A.8 Column 8 (Geology Notes). W88 A.9 Column 9(Summary Log) 。 182 A.10 Remarks Area. 182 Appendix B Oriented Drill Core:Techniques and Procedures 183 B.1 Techniques for Orienting Drill Core 183 R11 Non-mechanical means 183 B12 Mechanical Means How to Handle Oriented Core B.3 asure Structures in Oriented Core 8 B3. Before You Measure 0 B.3.2 How Many Measurements Are Needed?. B.3.3 Using a Core Frame. 192 B.3.4 Using Internal Core Angles. 195 B.3.5 Discussion on the Best Measuring Technique 201 B.3.6 Plotting Structure Measurements on Drill Section 202 App endix c Calculating Strike 205 int Problem.······· 205
xiv Contents 10 Geographical Information Systems and Exploration Databases . . 165 10.1 Definition . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 165 10.2 The Need for Digital Exploration Databases . . . . . . . . . . . 165 10.3 GIS Storage of Map Data . . . . . . . . . . . . . . . . . . . . . 168 10.3.1 Digitised Line Format . . . . . . . . . . . . . . . . . . 168 10.3.2 Polygon or Vector Format . . . . . . . . . . . . . . . . 170 10.3.3 Raster Format . . . . . . . . . . . . . . . . . . . . . . 170 10.4 Validation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 170 10.5 Georeferencing . . . . . . . . . . . . . . . . . . . . . . . . . . 171 10.5.1 Geographical Coordinates . . . . . . . . . . . . . . . . 171 10.5.2 Cartesian Coordinates . . . . . . . . . . . . . . . . . . 171 10.5.3 Map Datums . . . . . . . . . . . . . . . . . . . . . . . 172 10.5.4 Map Registering . . . . . . . . . . . . . . . . . . . . . 173 10.6 Manipulation of GIS Data . . . . . . . . . . . . . . . . . . . . 173 10.7 Presentation of GIS Data . . . . . . . . . . . . . . . . . . . . . 174 Appendix A Notes on the Use of Graphical Scale Logging . . . . . . . . . . . . . 179 A.1 Column 1 (Hole Depth) . . . . . . . . . . . . . . . . . . . . . 180 A.2 Column 2 (Core Recovery) . . . . . . . . . . . . . . . . . . . . 180 A.3 Column 3 (Core Quality) . . . . . . . . . . . . . . . . . . . . . 180 A.4 Column 4 (Sample No.) . . . . . . . . . . . . . . . . . . . . . 180 A.5 Column 5 (Assay Results) . . . . . . . . . . . . . . . . . . . . 180 A.6 Column 6 (Mapping Logs) . . . . . . . . . . . . . . . . . . . . 180 A.7 Column 7 (Histogram Logs) . . . . . . . . . . . . . . . . . . . 181 A.8 Column 8 (Geology Notes) . . . . . . . . . . . . . . . . . . . . 182 A.9 Column 9 (Summary Log) . . . . . . . . . . . . . . . . . . . . 182 A.10 Remarks Area . . . . . . . . . . . . . . . . . . . . . . . . . . . 182 Appendix B Oriented Drill Core: Techniques and Procedures . . . . . . . . . . 183 B.1 Techniques for Orienting Drill Core . . . . . . . . . . . . . . . 183 B.1.1 Non-mechanical Means . . . . . . . . . . . . . . . . 183 B.1.2 Mechanical Means . . . . . . . . . . . . . . . . . . . 183 B.2 How to Handle Oriented Core . . . . . . . . . . . . . . . . . . 188 B.3 How to Measure Structures in Oriented Core . . . . . . . . . . 190 B.3.1 Before You Measure . . . . . . . . . . . . . . . . . . 190 B.3.2 How Many Measurements Are Needed? . . . . . . . . 191 B.3.3 Using a Core Frame . . . . . . . . . . . . . . . . . . . 192 B.3.4 Using Internal Core Angles . . . . . . . . . . . . . . . 195 B.3.5 Discussion on the Best Measuring Technique . . . . . 201 B.3.6 Plotting Structure Measurements on Drill Section . . . 202 Appendix C Calculating Strike and Dip from Multiple Diamond Drill Holes . . 205 C.1 The Three Point Problem . . . . . . . . . . . . . . . . . . . . . 205
Contents C.2 Solution Using Structure Contours,······,·,···· 205 C.3 Solution Using a Stereonet. 206 C.4 An Elegant Solution to Determining the Attitude of Planes in Non-oriented Core 208 Appendix D How to Use a Stereo Net to Convert Internal Core Angles dinate Structure The Solution for Linear Structures Appendix E Practical Field Techniques.··.····· 。 215 E.I Choosing the Right Compass. 215 B.2 Understanding Your Compass 215 E.3 Measuring the Strike and Dip of Planes 217 E.4 Measuring the Trend and Plunge of Lineations 218 Appendix F Suggested Further Reading 223 Acronyms and Abbreviations 229 Index 233
Contents xv C.2 Solution Using Structure Contours . . . . . . . . . . . . . . . . 205 C.3 Solution Using a Stereonet . . . . . . . . . . . . . . . . . . . . 206 C.4 An Elegant Solution to Determining the Attitude of Planes in Non-oriented Core . . . . . . . . . . . . . . . . . . . 208 Appendix D How to Use a Stereo Net to Convert Internal Core Angles to Geographic Coordinates . . . . . . . . . . . . . . . . . . . . . . 211 D.1 The Solution for Planar Structures . . . . . . . . . . . . . . . . 211 D.2 The Solution for Linear Structures . . . . . . . . . . . . . . . . 213 Appendix E Practical Field Techniques . . . . . . . . . . . . . . . . . . . . . . . 215 E.1 Choosing the Right Compass . . . . . . . . . . . . . . . . . . . 215 E.2 Understanding Your Compass . . . . . . . . . . . . . . . . . . 215 E.3 Measuring the Strike and Dip of Planes . . . . . . . . . . . . . 217 E.4 Measuring the Trend and Plunge of Lineations . . . . . . . . . 218 Appendix F Suggested Further Reading . . . . . . . . . . . . . . . . . . . . . . 223 Acronyms and Abbreviations . . . . . . . . . . . . . . . . . . . . . . . . 229 Index . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 233