Page 40 - Geochemical Remote Sensing of The Sub-Surface

Geochemical Remote Sensing of the Subsurface
Edited by M. Hale
Handbook of Exploration Geochemistry, VoL 7 (G.J.S. Govett, Editor)
9 Elsevier Science B.V. All rights reserved 17
Chapter 2

GEOELECTROCHEMISTRY AND STREAM DISPERSION

O. F. PUTIKOV and B. WEN

INTRODUCTION

In conventional geochemical methods, geochemical signatures are the dispersion
halos of elements in mineral form, but the geochemistry of the ground surface does not
reflect the actual chemical content of the sources in the subsurface. In conventional
geophysical methods, geophysical fields are directly related to the physical properties of
rocks, but indirectly to their chemical compositions. The ambiguity of interpretation of
conventional geophysical and geochemical data led, in Russia, to research into
geoelectrochemistry, which was begun in the 1960s by Y.S. Ryss and his colleagues (I.S.
Goldberg, V.P. Korostin, S.G. Alekseev and others). Some geoelectrochemical methods
and the general physico-mathematical theory of the geoelectrochemical methods were
developed in the St. Petersburg State Mining Institute by O.F. Putikov, N.N. Uvarov and
others. The results are essentially a family of physico-chemical methods, in which the
physical fields of the rocks are utilised, but their chemical compositions rather than their
physical properties are studied. In this chapter these methods are divided into: (1)
prospecting methods (aimed at finding undiscovered deposits); and (2) exploration
methods (investigating poorly characterised deposits).

GEOELECTROCHEMICAL PROSPECTING

Physico-chemical basis

According to Antropova (1975) and Antropova et al. (1992), the forms in which
heavy metals are present in rocks and their weathering products are: (1) in mineral
lattices; (2) dissolved in groundwater; (3) dissolved in capillary moisture; (4) sorbed on
solid surfaces; (5) co-precipitated by iron-manganese hydroxides; (6) as metallo-organic
compounds; and (7) in the gaseous and quasi-gaseous states. In mineral lattices heavy
metals are constituents of ore minerals (oxides, sulphides, sulphates, arsenates and
others) and to a lesser extent of rock-forming minerals. In groundwater, heavy metals