Statistics and Data Analysis in Geochemical Prospecting

417 Pages·1983·17.944 MB·English

by  R.J. Howarth (Eds.)

HANDBOOK OF EXPLORATION GEOCHEMISTRY
G.J.S. GOVETT (Editor)
1. ANALYTICAL METHODS IN GEOCHEMICAL PROSPECTING
2. STATISTICS AND DATA ANALYSIS IN GEOCHEMICAL PROSPECTING
3. ROCK GEOCHEMISTRY IN MINERAL EXPLORATION
4. DRAINAGE GEOCHEMISTRY IN MINERAL EXPLORATION
5. SOIL GEOCHEMISTRY IN MINERAL EXPLORATION
6. BIOGEOCHEMISTRY AND GEOBOTANY IN MINERAL EXPLORATION
7. VOLATILE ELEMENTS IN MINERAL EXPLORATION
Handbook of Exploration Geochemistry
VOLUME 2
Statistics and Data Analysis
in Geochemical Prospecting
Edited by
R.J. HOWARTH
Reader in Mathematical Geology,
Department of Geology,
Imperial College of Science and Technology, London, U.K.
ELSEVIER SCIENTIFIC PUBLISHING COMPANY
Amsterdam - Oxford - New York 1983
ELSEVIER SCIENTIFIC PUBLISHING COMPANY
Molenwerf 1
P.O. Box 211,1000 AE Amsterdam, The Netherlands
Distributors for the United States and Canada:
ELSEVIER SCIENCE PUBLISHING COMPANY INC.
52, Vanderbilt Avenue
New York, N.Y. 10017
Library of Congress Cataloging in Publication Data
Main entry under title:
Statistics and data analysis in geochemical prospecting,
(Handbook of exploration geochemistry ; v. 2)
Bibliography: p„
Includes index.
1. Geochemical prospecting--Data processing.
2. Geochemical prospecting—Statistical methods.
I. Howarth, R. J0 II. Series.
TN270.S787 622'.13'0285^ 8I-19627
ISBN 0-W+-U2038-X AACR2
ISBN 0-444-42038-x (Vol. 2)
ISBN 0-444-41932-2 (Series)
© Elsevier Scientific Publishing Company, 1983
All rights reserved. No part of this publication may be reproduced, stored in a retrieval system or
transmitted in any form or by any means, electronic, mechanical, photocopying, recording or other­
wise, without the prior written permission of the publisher, Elsevier Scientific Publishing Company,
P.O. Box 330, 1000 AH Amsterdam, The Netherlands
Printed in The Netherlands
EDITOR'S FOREWORD
The objective of the Handbook of Exploration Geochemistry series is to
present specific aspects of exploration geochemistry in separate volumes in a
form that will be immediately useful to the field geologist practising geo­
chemistry and, at the same time, to provide a comprehensive review of the
subject that will be a source of reference for research workers. Other titles in
the series presently being prepared are: Rock Geochemistry in Mineral
Exploration; Drainage Geochemistry in Mineral Exploration; Soil Geo­
chemistry in Mineral Exploration; Biogeochemistry and Geobotany in
Mineral Exploration; and Volatile Elements in Mineral Exploration.
In the editor's foreword to the first volume of the Handbook of Explo
ration Geochemistry — Analytical Methods in Geochemical Prospecting — I
stated that the greatest impetus for the progress of exploration geochemistry
had come from the contemporaneous development of rapid, cheap, and
reliable multi-element analytical techniques, coupled with the ready avail­
ability of computers to handle the vastly increased flow of analytical data.
This, the second volume in the series, is devoted entirely to exploration
geochemical data processing and interpretation.
The processing and the interpretation of geochemical data is one of the
most difficult — and one of the most important — stages in the successful
application of exploration geochemistry. Although there are a bewildering
variety of statistical texts that catalogue a vast range of data treatment
techniques, the non-specialist is faced with making a decision concerning
which procedures are appropriate to an individual geochemical problem.
Furthermore, specific geochemical papers in various journals often assume
specialist knowledge, and detailed explanations of actual procedures are
limited. This volume — the only English language book specifically dealing
with exploration geochemical data processing and interpretation — is
intended to overcome these problems. I am pleased that Dr. Richard
Howarth agreed to undertake the rather awesome task of producing this
book, and I am delighted with his success in bringing together so many well-
known experts in the field.
Adequate space is provided in this volume to digress upon procedures. The
chapters are necessarily of varying degrees of mathematical difficulty, but
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the book as a whole should be comprehensible to the modestly numerate
geologist. The step-by-step approach adopted in many chapters, with
extensive illustrations of the effects of various statistical treatments of data,
should allow the exploration geologist to choose an appropriate technique
for most situations.
The organization in Part I takes the reader logically and sequentially
through the normal data handling procedures — from data storage and
retrieval, through control procedures in analysis, univariate analysis, sam­
pling procedures, and mapping techniques — to the most complicated aspects
of multivariate analysis. Part II consists of reviews of specific techniques and
procedures currently used in various parts of the world. The use of the
computer, an essential practical aid to large data sets and complex statistical
manipulations, is described in detail, but simpler techniques are also
discussed. The graphical aids in the Appendix are unique.
Far too little attention has been devoted in the past to the interpretation
of the geochemical data produced during exploration surveys. This book
should overcome one of the major reasons for this deficiency — the geol­
ogist's lack of the requisite knowledge to use the data. Its publication at a
time when microcomputers are becoming widely available should result in a
major increase in the scope and success of geochemical data interpretation,
hopefully with a consequent increase in the discovery rate of mineral
deposits through the use of exploration geochemistry.
G. J. S. GOVETT
Sydney, N.S.W., Australia
PREFACE
In the last 40 years, the use of geochemistry as a tool for mineral pros­
pecting has changed from a novel approach which was initially regarded with
some scepticism, to a routine method of prospection used in combination
with other geological and geophysical techniques. At the same time, the
increasing potential for multi-element analysis has meant that the volume of
data which could be produced in the course of a project is now very large, a
set of 30 elements determined on 5000 samples would not be unusual. The
basis of geochemical exploration is the measurement of element concen­
tration values in a wide variety of sampling media, and the identification of
unusual concentrations (usually enhanced rather than depleted concen­
tration levels) indicative of potential mineralization, or a region worthy of
more detailed investigation.
In the past, the volume of data collection has often been sufficiently low
that numerical description, analysis, and plotting of the data could be carried
out by manual methods. This is still possible where the number of elements
involved is small, although the opportunity of reanalysing the data and
replotting if the initial geochemical maps are not entirely satisfactory is
difficult to come by if manual methods have to be used. The use of com­
puters is now relatively common in larger organisations, and the widespread
introduction of mini- and micro-computers is helping to make routine
geochemical calculations possible at low cost, even if final plotting of data
onto maps still has to be carried out by hand in some cases.
The aim of this book is to survey the techniques available for the quality
control of laboratory data, the subsequent storage and retrieval of field and
laboratory information; the statistical analysis of single- and multi-element
data; and the presentation of geochemical data as maps. More advanced
multivariate methods of data analysis are also discussed. The aim throughout
is to enable the reader to assimilate the concepts involved in data analysis
with mathematical or statistical methods without becoming too embroiled in
algebraic notation. Each chapter aims to be self-contained. It is hoped that
exploration management will find it of interest as an overview of current
thinking in methods of geochemical data analysis, as well as the specialist
geochemist. While the examples are drawn from the use of sampling media
Vili
most familiar to those engaged in geochemical prospecting for ore deposits
(rocks, soils, stream and lake sediments), the principles apply equally well to
those engaged in geochemical studies from the point of view of igneous
petrology or mining geology, and even sedimentary geochemistry. So it is
hoped that all those engaged in geochemical studies will find something of
benefit to them within this volume.
The latter part of the book contains some surveys of the type of work
being carried out in various parts of the world. While it was not possible, in
the end, to have an exhaustive survey on a world-wide basis, it is apparent
that modern cartographic and statistical techniques are now being actively
used in most parts of the world in an effort to improve exploration geo­
chemical data interpretation. With the study of multi-element data now
becoming routine, it is to be hoped that intelligent data interpretation will
assist geochemists to arrive at a better understanding of the fundamental
geochemical processes operating in nature. This should, in its turn, sharpen
our perception of areas within which there is an enhanced probability of
encountering economic mineralization.
The compilation of this volume took a great deal longer than anyone
involved in its inception imagined and some chapters have been through a
number of lengthy revisions. The contributors are thanked for their patience
in awaiting the final outcome. Miss J. Nielsen and Mrs. P. A. Mill are thanked
for their assistance in typing this volume, and Miss A. F. Leech for her help
with the compilation of the indexes.
R. J. HOWARTH
London
LIST OF CONTRIBUTORS
R. I. Dubov. B.Sc. (geology and geophysics) University of Kiev, Ph.D. (geophysics)
Leningrad Institute of Mines, Dr.Sc. (geochemistry) Siberian Branch of the U.S.S.R.
Academy of Sciences. Following a period in geophysical and geochemical exploration,
Dr. Dubov worked at the Siberian Institute of Geochemistry (Academy of Sciences) as
head of the Laboratory of Physico-Mathematical Modelling. Then he headed the labora­
tory of mathematical methods for investigation and rational use of the natural resources
at the Siberian Institute of Energy (Academy of Sciences). Since 1979 Dr. Dubov holds
the Chair of Applied Mathematics at the Vladimir Polytechnic Institute, Vladimir,
U.S.S.R. He is engaged in the utilization of mathematics in various aspects, especially in
geochemistry.
Robert G. Garrett B.Sc. (geology), A.R.S.M., D.I.C., Ph.D. (applied geochemistry)
University of London. Following a N.A.S.A. Post-Doctoral Research Fellowship at North­
western University in 1966, Dr. Garrett joined the Geological Survey of Canada. Since
1967 he has been involved in developing improved methodologies for geochemical surveys
and data management and interpretation. In 1979 he was appointed Head of the Method
Development Section of the Resource Geochemistry Subdivision.
Nils E. Gustausson. M.Sc. (mathematics) Âbo Akademi, Turku. He joined the Geological
Survey of Finland in 1971, and has since been responsible for the processing of regional'
geochemical data, with statistical applications, in the geochemistry department.
Richard J. Howarth. B.Sc, Ph.D. (geology) University of Bristol. Following a period in
the oil industry, Dr. Howarth joined the Applied Geochemistry Research Group at the
Imperial College of Science and Technology in 1968, and was appointed Reader in
Mathematical Geology in 1978. He has been a Council member of the International
Association for Mathematical Geology since 1977, and a regional editor of Computers
& Geosciences since 1975.
Pierre Ley marie. Ing. (geology), E.N.S. Geology, Nancy; D.Sc. (geology) University of
Nancy. Following work for the Compagnie Générale de Géophysiques, Dr. Leymarie
worked at the Centre de Recherches Pétrographiques et Géochimiques of the Centre
Nationale de la Recherche Scientifique from 1960 to 1978, first as head of the laboratory
of crystallography, then of the Department of Computer Applications. He is now Maitre
de Recherches in the Ecole Nationale Supérieure des Mines de Paris at Sophia Antipolis,
where he works on new display techniques for geochemical data.
Trevor Mattiske. B.Sc. (applied mathematics) University of Adelaide. Mr. Mattiske was
analyst/programmer, responsible for geochemical data processing with Amax Exploration
X
(Australia), Inc. in 1971—1973. Subsequently, he became responsible for all mine
planning and geological computing applications with the Minerals Exploration Division
of Amax Iron Ore Corporation. From 1979 to 1981 he was Senior Systems Analyst for
Hamersley Iron at their Tom Price mine site.
Vaclav Nëmec. RNDr. (geology) Charles University, Prague. Dr. Nëmec joined the
Geological Exploration Service in Prague in 1953, and has specialized in ore reserve com­
putations since 1955. He was a Visiting Research Scientist with the Kansas Geological
Survey in 1969-70, and following his return to Geoindustria in Prague in 1970 has been
employed as a Senior Research Scientist. Dr. Nëmec served as Eastern Treasurer of the
International Association for Mathematical Geology from 1968 to 1980, and has also
been the convenor of the international section on mathematical methods in geology of
the Mining Pribram Symposia, held in Czechoslovakia, for many years.
Sönke W. Rehder. Dipl.-Math, (mathematics, statistics, and computer science) Dortmund
University. Mr. Rehder joined the German Geological Survey (Federal Institute for Geo-
sciences and Natural Resources) in 1978. He is currently working with the Exploration
Research Group in the Geochemical Section.
Olle C. Selinus. B.Sc. (geology, geophysics and chemistry), Ph.D. (geochemistry) University
of Uppsala. Dr. Selinus joined the Geological Survey of Sweden in 1972, and is working
with the development of lithogeochemical methods. Prior to joining the Survey, he was
employed by the Stora Kopparberg mining company.
Alastair J. Sinclair. B.A.Sc. (applied geology), M.A.Sc. (economic geology) University of
Toronto; Ph.D. (economic geology) University of British Columbia. Dr. Sinclair is
Professor of Geology and Director of the Geological Engineering Program at the University
of British Columbia. Prior to joining the University of British Columbia in 1964, he spent
two years as Assistant Professor in the Department of Geology, University of Washington.
He consults for the mining industry in several countries.
Richard Sinding-Larsen. M.Sc, Ph.D. (economic geology) Norwegian Institute of Tech­
nology. Dr. Sinding-Larsen joined the Geological Survey of Norway in 1968, and was
Head of the Data and Systems Section from 1972 to 1978, when he was appointed
Associate Professor of Economic Geology at the Norwegia Institute of Technology. Since
1976 he has been Chairman of COGEODATA, the International Union of Geological
Sciences Commission on Storage, Automatic Processing, and Retrieval of Geological Data.
Michael Thompson. B.Sc. (chemistry), Ph.D. (analytical chemistry) University of London;
A.R.C.S., C.Chem., F.R.S.C. Dr. Thompson has been a Lecturer in the Applied Geo­
chemistry Research Group at the Imperial College of Science and Technology, London,
since 1969, after working in industry and the civil service. He directs the Group's
analytical facility, and is responsible for both routine and investigative aspects of the
work.
Gunter P. van den Boom. Dr. rer. nat. joined the Federal Institute of Geosciences and
Natural Resources in Hanover, Germany, in 1958. He is now working as a Senior Scientist
in the Exploration Research Group (Geochemistry), where his main task is the develop­
ment and application of new geochemical methods in mineral exploration.
Keith Viewing. B.Sc. (geology) University of Durham; Ph.D. (applied geochemistry)
XI
University of London. Professor Viewing is Director of the Institute of Mining Research
in the University of Zimbabwe. He was previously involved in mineral exploration and
mining geology with the Rhodesian Selection Trust Group of Companies, and contributed
to the development of multi-element geochemical drainage reconnaissance techniques in
Sierra Leone under Professor J. S. Webb at Imperial College.