Principles of Geochemical Prospecting. Techniques of Prospecting for Non-Ferrous Ores and Rare Metals

324 Pages·1960·9.763 MB·English

by  I. I. Ginzburg and Earl Ingerson (Auth.)

OTHER TITLES IN THIS SERIES
Vol. 1. Contributions in Geophysics.
Edited by BENIOFF ET AL.
Vol. 2. Clays and Clay Minerals.
Edited by SWINEFORD
Principles of
Geochemical Prospecting
TECHNIQUES OF PROSPECTING
FOR NON-FERROUS ORES AND
RARE METALS
I. I. GINZBURG
Translated from the original Russian by
V. P. SOKOLOFF
PERGAMON PRESS
LONDON · OXFORD · NEW YORK · PARIS
1960
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First published in the Russian language by
The State Scientific-Technical Publishing House for Literature
in Geology and Conservation of Mineral Resources
in Moscow, 1957
Copyright
©
1960
Pergamon Press Inc.
Library of Congress Card No. 59-9834
PRINTED IN GREAT BRITAIN BY
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FOREWORD
The wide application of geochemical prospecting methods at all stages of the
geologic service raises the need for developing some theoretical premises of
such prospecting, as well as to the need for a summation of the bulky data
accumulated empirically by geologic reconnaissance, geologic prospecting,
and geophysical field parties.
The author has endeavoured to throw as much light as possible on problems
originating in geochemical prospecting, to evaluate the relative importance
of different prospecting methods, and to give a generalized view of prospect­
ing work in different geologic, pedologic, climatic, and orographic environ­
ments, as well as to approach a clarification and an explanation of certain
regularities which could serve as the basis of a rational orientation of geo­
chemical prospecting.
This work is based on field data collected by the author and his co-workers,
and by several other persons engaged in this field, and also on the materials
of the All-Union Conference on Geochemical Prospecting in 1956.
The author expresses his sincere thanks to the personnel of the Labora­
tory of Weathering Processes and Geochemical Prospecting Methods, IGEM,
Academy of Sciences, U.S.S.R., for their help; to I. A. Rukavishni-
kova ; I. V. Vitovskaia ; V. V. Borodin ; Yu. Yu. Bugel'skii; Ę. M.
Mukanov ; L. D. German ; A. I. Pokrovskaia, Analytical Chemist; N. P.
Sechina, Spectrographic Laboratory Analyst, who performed a vast number
of the analyses. Moreover, the author is indebted to S. D. Miller, I. P.
Benevalenskii and G. I. Rossman, for much valuable data they placed at his
disposal; and also to A. G. Betekhtin, whose advice and remarks he has
followed; to 0. D. Levitzkii, F. I. Vol'fson and V. M. Kreiter, who very
kindly examined this work and made a number of valuable comments ; and
to V. I. Smirnov, who undertook the labor of editing the manuscript.
The present work is the first experiment of its kind in developing the
theoretical premises of geochemical prospecting on the basis of the existing
theories of endogenic and exogenic ore-formation, and the author would be
extremely grateful for any indication of errors, omissions, or shortcomings
of any of his theses.
Institute of Ore Deposits, Mineralogy,
Petrography, and Geochemistry,
Academy of Sciences, U.S.S.R.
" There must be a fundamental change in prospecting methods, for, unless the
new ideas of geochemistry are assimilated, we will be unable to respond quickly
enough to the growing needs of socialist economy." " The problem of pros­
pecting for mineral resources is in substance a geochemical problem." [A. E.
FERSMAN, Geochemical and Mineralogical Methods of Prospecting for Mineral
Resources (1940), pp. 17 and 20.]
INTRODUCTION
The problem of application of geochemical methods in prospecting for metals
has become progressively more urgent in recent years. Credit ought to be
given to our geophysicists, who were the first to raise this problem and also
the first to undertake its solution.
First trials of geochemical surveys in the petroleum industry of the U.S.S.R.
were carried out more than twenty-five years ago. In 1932, gas surveys in the
exploration for petroleum were developed and applied for the first time (V. I.
Sokolov). In 1935, there appeared in the press reports on stannometric
surveys of tin and gold lodes (B. L. Flerov) and on cuprometric surveys
(M. F. Zenin). A report on applications of spectrographic analysis in pros­
pecting and reconnaissance for deposits of tin was published in the same year
(Í. I. Sofronov and A. P. Solovov).
In 1936, Sofronov published his article on dispersion halos where he
stated their classification as well as the physico-chemical premises of the
prospecting methods. In the same year, E. A. Sergeev published a paper on
spot-plate analysis. In 1937 there appeared the first manual on electrical,
magnetic, and physico-chemical investigations prepared by S. D. Miller. In
the same year, V. I. Nikolaev proposed the use of geochemical surveys in
outlining boundaries of districts, the rock of which is enriched by potassium,
bromine, iodine and boron. In 1938, M. F. Zenin published a report on
cuprometric surveys.
Beginning with 1937, there were individual articles by S. D. Miller, E. A.
Sergeev, A. P. Solovov, V. A. Yukeev, Á. V. Korolev, and others, on metallo-
metric (geochemical) problems in prospecting for ore deposits. The 1940
article by V. M. Kreiter, " Prospecting and Reconnaissance for Mineral
Resources ", listed procedures for the following elements in its concluding
chapter on metallometric and other surveys : copper, lead, tin, gold, tungsten,
molybdenum and mercury. In the same year, A. E. Fersman published his
work entitled, Geochemical and Mineralogical Methods of Prospecting for
Mineral Resources.
Beginning with 1948-9, geochemical mapping on detailed and intermediate
scales was first begun in Central Kazakhstan (S. D. Miller).
Geochemical prospecting methods were first applied in Eastern Siberia in a
search for tin and molybdenum ores. Later on they became particularly
widely employed in Central Kazkhstan.
Xii PRINCIPLES OF GEOCHEMICAL PROSPECTING
These studies were not interrupted by the war. After the end of the war
they were intensified progressively, passing from the experimental to the
practical stage, involving large-scale operations and extensive areas in
Kazakhstan, Trans-Baikalia, Altai, and the east of the Soviet Union.
Soil-botanical investigations in prospecting for hydrosilicates of nickel
were conducted by D. P. Maliuga, beginning in 1937, in order to develop
methods of geochemical surveys. Studies of biochemical and botanical
methods were begun for the same reason by Í. N. Sochevanov (1935), S. M.
Tkalich (1938) and E. F. Epshtein (1948).
In 1950, a detailed study was published, by A. P. Vinogradov, on geo­
chemistry of the rare and the dispersed elements in soils of U.S.S.R. and in
foreign soils.* Investigations of biochemical methods were summarized by the
same author in 1955, in his special report, " Prospecting for Ore Deposits
with the Aid of Plants and Soils ".
A separate division was devoted to metallometric surveys in V. I. Smirnov's
book, Geologic Principles of Prospecting and Reconnaissance for Ore Deposits.
Hydrochemical methods began to be used with us in the 1930s, at first
for gold and later for other mineral resources.
In 1941, V. N. Florovskaia proposed the bitumen-luminescence method of
surveying. The first applications of the luminescent method were in the
logging of cores. Recently, I. S. Tzigel'man (1953) and Ć. N. Sverdlov pro­
posed to employ this method also in the exploration for metals. Since 1945,
V. A. Kovda and P. S. Slavin (1953) have been developing the soil-geo-
chemical mapping methods as an aid in the discovery of petroleum fields.
Botanists, S. V. Viktorov and N. G. Nesvetailova (1955), and others, have
become interested in the botanical method of geologic indications, in connec­
tion with aerial surveys.
In recent years there is developing a tendency among Soviet petrographers
toward geochemical surveys, particularly in some aspects of the granitization
problems.
In 1953, A. P. Vinogradov, A. B. Ronov and V. M. Rotynskii published
some of their very interesting conclusions, based on the geochemical
surveys of the carbonate rock of the Russian platform. The methodology of
quantitative lithologic geochemical maps was presented by Ronov (1953).
In 1951, a new and a highly detailed and circumstantial provisional manual
was published, with reference to A. P. Solovov's metallometric surveys. This
manual was prepared by Í. I. Sofronov, S. D. Miller, E. A. Sergeev and A. P.
Solovov on the basis of a large body of experimental materials and data.
* A second edition has recently appeared which has been translated into English by the
Geochemical Society, and published by the Consultants Bureau, New York, (1959).
INTBODuCTION xiii
The manual recommends a combination between metallometric surveys and
mineralogical, geophysical and geologic-prospecting investigations so as to
increase productivity of the exploration while reducing its costs.
A number of geochemical maps are available at present, on scales from
1:10,000 to 1:200,000, for the non-ferrous, the minor, and the rare metals in
different districts of the Soviet Union. These maps were prepared by geo­
physical field parties. They are a subject not only of a practical but also of a
basic scientific interest.
In the course of only the last seven years, 160,000 km2 of the territory in
Kazakhstan, Trans-Baikalia, the Far East Maritime Area, Khabarovsk Area,
and other parts of our country, were covered by geochemical mapping on
different scales.
During the last twenty years, 25 million sampling points were examined
(of which 11 million were in Central Kazakhstan). In 1948-1953, about 9
million samples were collected, by geophysical organizations alone, and in
1954-5 up to 10 million samples.
In 1955, by the Order of the Ministry of Geology and Conservation, geo­
chemical investigations were made mandatory in the practice of all geologic
agencies of the Ministry in all stages of geologic field studies.
A number of interesting papers dealing chiefly with experimentation on
methods of geochemical prospecting, dispersion halos, chemical techniques,
and some regularities in the distribution of individual elements in relatively
small areas, were published abroad since the war (in U.S.A., Canada, Sweden,
England, Finland and Germany). Some of these were republished by the
Foreign Literature Press, by V. I. Smirnov (Editor), in the Collection entitled
Geochemical Methods of Prospecting for Ore Deposit. These studies were based
on the premises, the methods, and the experience reported in articles by
Soviet geochemists and geophysicists (seeHawkes, 1948).
Judging by the recent literature, the foreign studies now in progress have
different orientations. Articles published in the foreign press show a pre­
ponderant interest in geochemical surveys of areas in a direct proximity to
already existing mines or of ore districts already known, while employing
mass-quantitative colorimetric methods of analysis for small quantitites
(traces) of individual metals. However, more recently, there has appeared
some information about decisions to undertake a geochemical survey of the
entire continent of Australia and about some large-scale undertakings in
South and Central Africa, etc.
The following metallometric surveys are in use in U.S.S.R. : the recon­
naissance on the 1:1,000,000-1:200,000 scale; the prospecting on the
1:100,000-1:25,000 scale; and the detailed on the 1:10,000-1:5000
and even 1:2000 scale. The small-scale survey embraces considerable areas
Xiv PRINCIPLES OF GEOCHEMICAL PROSPECTING
in poorly known and even entirely unknown terrains. Only after some
interesting areas are detected by the small-scale survey, are they surveyed
on the large scale (1:10,000-1:5000), whereupon the results are verified by
geophysical and geologic-prospecting methods.
Geologists and chemists perform the fundamental work in geochemical
prospecting abroad, while with us it is done by geophysicists. However, our
geologists, too, are beginning to show more interest in such studies in recent
times. Our geochemical surveys are especially extensive in districts contain­
ing outcrops of bedrock and in areas covered by loose materials of small thick­
ness (Central Kazakhstan and parts of Trans-Baikalia).
Nevertheless, the scale of geochemical prospecting still does not correspond
to the growing needs of our country. One of the causes by which the expan­
sion of geochemical methods was impeded was the absence of exact methods of
routine analysis for traces of metals—and also the inadequate preparedness
of most of the geologists for this type of work. The previously developed
methods of mineral analysis were better suited to geologists, and it was on
these methods that their attention came to be concentrated. However, the
mineral survey could not be entirely satisfactory to geologists because of its
high labor requirements in prospecting and because of its suitability only to
heavy minerals and to minerals stable in the oxidized zone (cassiterite, zircon,
monazite, gold, platinum, etc.). It was not applicable to the finely dissemi­
nated easily oxidized sulfides and other compounds, for minerals of low speci­
fic gravity and for the finely dispersed minerals. Geochemical surveys have
no such defects.
The spectrographic and modern chemical analyses permit detection of
individual elements with practically any mineralogical composition of rocks
and ores, and they are capable of determining the percentage content of
individual elements more or less exactly, depending on the method used
(semi-quantitative or quantitative spectrographic analysis).
Semi-quantitative spectrographic analysis for metals is used by us exten­
sively because it is very rapid and, moreover, because it is applicable in
routine mass-analysis for a large number of chemical elements simultaneously
determined.
The use of spectrographic analysis assured the significant successes of
geochemical surveys for the non-ferrous and the rare metals, particularly for
lead, zinc and molybdenum, and, to a lesser extent, for copper, mercury,
arsenic and antimony. Spectrographic analysis proved to be unsuited, how­
ever, for routine determinations of the noble metals (Au, Pt).
Metallometrics was developed on the premises of the spectrographic analysis
and many people refer to prospecting by spectrography as the spectro-
metallometric method (Bedrov, 1956).
INTRODUCTION XV
The successes of recent years obtained by applications of colorimetric pro­
cedures to determinations of the traces of metals permit us to pose the prob­
lem of their more extensive use in mines and by field parties in the near
future, inasmuch as the colorimetric methods are extremely sensitive, yielding
nothing, in this respect, to spectrographic methods, when it comes to most of
the non-ferrous metals.
The following is the lowest metal-content determinable colorimetrically
in the field, as against the spectrographically determinable content at the
IGEM Laboratory of the Academy of Sciences, U.S.S.R. (A), and according
to the data by Solovov (B) (1955) :
Spectrographic Spectrographic
Element Colorimetric A Â Element Colorimetric A Â
(%) (%) (%) (%) (%) (%)
Zn 0.001 0.01 0.03 Pb 0.001 0.002 0.001
Ni 0.0015 0.001 0.001 Ag 0.00002 0.0001 —
Cu 0.0010 0.0005 0.001 W 0.001 0.01 0.01 to 0.03
Co 0.0010 0.001 0.003 Mo 0.0001 0.0005 0.003
In addition to these methods, there are both chemical (colorimetric and
physico-chemical) and spectrographic highly sensitive methods for determin­
ing Co, Sn, Bi, In, Te, Mn, Se, K, Na, Al, Hg, As, Sb, Â and F. Some of these
methods are suited for routine analysis. Technical improvements in colori-
metry and spectrography permit us to hope that extremely high sensitivity,
as well as suitability for routine tests, may be attained also for the remaining
elements in the near future. Developments in photometry, mechanized
sample-feeding (Nedler, 1955), application of step-filters (Kler, 1954), flame
photometry, aids in the spectrographic analysis for easily volatile consti­
tuents : Hg, As, Sb (Stepanov and Sergeev, 1956 ; Rusanov, 1956), and
others, may help us appreciably in this respect.
The highly productive methods of spot-analysis (Tananaev, 1934, 1952 ;
Maiorov, 1955 ; Voznesenskii, 1955) will undoubtedly find their applications
in the near future, in dealings with polymetallic materials, and so will the
luminescent and the isotopic methods. Chromatographic methods, with the
use of ion-exchangers, may be developed for a number of chemical elements.
Some of these methods may be suited for use in the field, and some in stationary
base laboratories servicing the closest field parties.
The extensive territory of the U.S.S.R. is a favorable environment for
establishment of stationary spectrographic and chemical laboratories, in
connection with geologic prospecting and survey works, to remain in opera­
tion for several years, so as to serve the field parties in the laboratory's area.
However, some chemical analyses must be done in the field, in some types of
XVÍ PRINCIPLES OF GEOCHEMICAL PROSPECTING
geologic surveying and prospecting parties, for, the sooner the analytical data
are made available the more efficient and economic is the work of a pros­
pecting geologist in the field.
So far, biochemical methods have not been used very extensively because
of their complexity with respect to the preparation of test materials for the
analysis (the necessity of the preliminary drying and combustion) and be­
cause of their high sensitivity to climatic variations, microrelief, hydro-
geologic environments, etc. They are essential, however, in some instances,
especially in closed districts, where other and more efficient methods are
poorly suited, for some reason, or are insufficiently sensitive.
A skeptical attitude toward geochemical prospecting methods has been
observed in certain geologists, and, conversely, certain workers in geo­
chemical (metallometric) methods underestimate the value of geologic re­
search in geochemical prospecting. The not uncommonly observed detach­
ment of geochemical (metallometric) from geological investigations is not
permissible in either case. Geochemical prospecting may be crowned with
success and may yield valuable data for the orientation of the geologic ex­
ploration and for the prognoses only when it is related closely to geologic
studies of the prospected district, to its structure, tectonics, stratigraphy,
lithology, pedogenesis and geomorphology.
Geochemical prospecting methods are based on the analysis of solid, liquid
and gaseous substances of which the Earth's crust is composed. Hence we
distinguish the geochemical proper (for the solid phase) from the hydro-
chemical (for the liquid phase) and from the gas methods. We shall be dealing
in our further discussion with the geochemical and the hydrochemical
methods, while omitting the gas methods. The latter are developed particu­
larly extensively in petroleum geology but only weakly in prospecting for
metals, if we do not count the emanation surveys in prospecting for radio­
active ores.
It is not enough, however, to have highly productive analytical methods at
one's disposal. One must also know how to apply them and how to interpret
the results correctly. One must know what particular elements must be
determined, how and on what grid to take the samples in order correctly to
interpret the results obtained. One must know also in what particular
associations of minerals this or that determined element is generally
present.
The analytical results must be mapped on different scales (depending on the
test grid). The resulting analytical survey findings must be harmonized with
the geologic and mineralogic data and it must be correctly treated statisti­
cally.
Thus geochemical prospecting, like any other geologic study, needs to be