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Radiometric methods of exploration
Geoexploration, 13 ( 1 9 7 5 ) 2 4 7 - - 2 4 8 © Elsevier" Scientific Publishing C o m p a n y , A m s t e r d a m - - P r i n t e d in The N e t h e r l a n d s
Book Review
Radiometric Methods of Exploration. V.L.S. Bhimasankaram. Centre of Exploration Geophysics, Osmania University, Hyderabad, 1974, 212 pp, U.S. $ 4.OO. This b o o k is directed especially to postgraduate students in geophysics and geology who want an introduction into theory and practice of radiometric methods for exploration purposes. Emphasis has been laid on the physical point of view, and the theoretical parts assume only basic knowledge of mathematics and physics. The b o o k has a handy format and is written in a condensed straightforward way. It tells of the practical details of field operation and gives a lot of experience, especially valuable for radiometric ore prospecting. After a short review of the historical development of radiometry, the basic concepts of the disintegration of natural radioactive elements are presented. The practical importance of different types of equilibrium encountered in nature between members of a radioactive series is emphasized. Then the radioactive emissions and their interaction with matter is reviewed with special attention paid to the different cases of gamma ray attenuation: total, narrow beam, broad beam and self-absorption cases. The last case is subdivided into thin, intermediate and thick layer types of attenuation and absorption. In this connection the old units of quantity, activity, concentration and dose are carefully explained. Their equivalence in the cgs-unit-system is also given. It is surprising that the SI-units have still n o t been adopted in this field of physics. The radioactivity of c o m m o n rocks, soils and waters is presented, together with a discussion of the influence of geological and meteorological conditions. Some occurrences of uranium and thorium in India are described. A rather extensive exposition is given of ordinary measuring devices and of techniques for small-scale surveying with emphasis laid on the practical things a prospector has to k n o w a b o u t instruments and a b o u t the kind of information he may obtain with them. Next, the author carefully and instructively leads the reader into the field of processing and interpretation of radiometric data. For clarity some specific concepts are introduced, for example the perspectivity of an anomaly (its significance for a certain goal) and the saturation ratio used in the estimation of thinner ore layers. In the theoretical calculation of gamma intensity anomalies from model ore bodies, the author starts with the formula for a b o d y shaped like a truncated cone and then extends the b o d y to such limiting cases as the semi-in-
248
finite medium, the thin infinite layer and so on. In the formulas the author often refers to the so called King's function. It is a pity that this function is not tabulated in the book, since it is recommended that interpreters should be familiar with it. It is of fundamental importance for the application of height corrections and for the understanding of overburden attenuation. Several examples of radiometric field studies, taken from the Russian literature, are presented and c o m m e n t e d upon. The last parts of the b o o k are devoted to laboratory radiometric analysis and dating. The b o o k is warmly recommended to all interested in the practice and the interpretation of radiometric measurements. L. G R A N A R
(Stockholm)
Book Review
Radiometric Methods of Exploration. V.L.S. Bhimasankaram. Centre of Exploration Geophysics, Osmania University, Hyderabad, 1974, 212 pp, U.S. $ 4.OO. This b o o k is directed especially to postgraduate students in geophysics and geology who want an introduction into theory and practice of radiometric methods for exploration purposes. Emphasis has been laid on the physical point of view, and the theoretical parts assume only basic knowledge of mathematics and physics. The b o o k has a handy format and is written in a condensed straightforward way. It tells of the practical details of field operation and gives a lot of experience, especially valuable for radiometric ore prospecting. After a short review of the historical development of radiometry, the basic concepts of the disintegration of natural radioactive elements are presented. The practical importance of different types of equilibrium encountered in nature between members of a radioactive series is emphasized. Then the radioactive emissions and their interaction with matter is reviewed with special attention paid to the different cases of gamma ray attenuation: total, narrow beam, broad beam and self-absorption cases. The last case is subdivided into thin, intermediate and thick layer types of attenuation and absorption. In this connection the old units of quantity, activity, concentration and dose are carefully explained. Their equivalence in the cgs-unit-system is also given. It is surprising that the SI-units have still n o t been adopted in this field of physics. The radioactivity of c o m m o n rocks, soils and waters is presented, together with a discussion of the influence of geological and meteorological conditions. Some occurrences of uranium and thorium in India are described. A rather extensive exposition is given of ordinary measuring devices and of techniques for small-scale surveying with emphasis laid on the practical things a prospector has to k n o w a b o u t instruments and a b o u t the kind of information he may obtain with them. Next, the author carefully and instructively leads the reader into the field of processing and interpretation of radiometric data. For clarity some specific concepts are introduced, for example the perspectivity of an anomaly (its significance for a certain goal) and the saturation ratio used in the estimation of thinner ore layers. In the theoretical calculation of gamma intensity anomalies from model ore bodies, the author starts with the formula for a b o d y shaped like a truncated cone and then extends the b o d y to such limiting cases as the semi-in-
248
finite medium, the thin infinite layer and so on. In the formulas the author often refers to the so called King's function. It is a pity that this function is not tabulated in the book, since it is recommended that interpreters should be familiar with it. It is of fundamental importance for the application of height corrections and for the understanding of overburden attenuation. Several examples of radiometric field studies, taken from the Russian literature, are presented and c o m m e n t e d upon. The last parts of the b o o k are devoted to laboratory radiometric analysis and dating. The b o o k is warmly recommended to all interested in the practice and the interpretation of radiometric measurements. L. G R A N A R
(Stockholm)