Geochemical Prospecting - Retrospect and Prospect
The concept of using chemical methods in prospecting dates back at least to the middle of the 16th century. Modern methods of geochemical prospecting, however, based on secondary haloes and utilizing trace-element techniques, were first practised in the U.S.S.R. and the Scandinavian countries in the 1930's. After 1945, methods based on soils, stream sediments and vegetation were rapidly developed in the U.S.A., the United Kingdom, Canada, France and other countries. The modern methods of geochemical prospecting owe their rapid development in the 20th century to the following: !.-Recognition of the primary and secondary dispersion haloes and trains that are associated with ali mineral deposits. 2.~Development of accurate and rapid analytical methods utilizing the spectrograph and the various specifie sensitive colorimetrie reagents, especially dithizone. 3.-Development of polyethylene laboratory ware of ali types and the development of resins. This permitted greater freedom of field analyses and reduced the incidence of contamination. 4.-Development of gas chromatography. This permitted the rapid and accurate determination of hydrocarbons in petroleum prospecting. Future research in geochemical prospecting should be focused on the following tasks: !.-Definition of geochemical provinces and their r elation to mineral deposits. 2.-Development of methods for discovering large lowgrade deposits. 3.-Development of methods for discovering deeply buried deposits. 4.-Further development of methods to outline primary haloes. 5.-Eiucidation and formulation of techniques to relate the size and intensity of anomalies to the grade of the deposits. 6.-Development and refinement of biogeochemical methods, especially those based on indicator plants, chlorotic or toxic effects, and microbiological techniques. 7.-Definition of the types of primary and secondary haloes associated with accumulations of oil and gas.