Page 66 - Geochemical Remote Sensing of The Sub-Surface

Geoelectrochemistry and stream dispersion 43

m

II

(X2
m ,,. m w ..o

|
0 (Zl . T

'1;1
Fig. 2-21. Geoelectrochemical hodograph (metal accumulation, m, versus time, x) for a two-layer
medium.

Different types of equipment have been designed in Russia for the CHIM method.
The CHIM-k installation has a capacity of 10 Kw and allows the use of 40 element-
collectors with a current and voltage stabiliser. Another installation consists of two
modules and allows the use of 60-120 element-collectors simultaneously.
Ground mode CHIM is usually used for detailed investigations on the scale 1:10000
and larger. Observation spacing depends on width and inhomogeneity of the anomaly
targets and is usually is 20-25 m or less. It is necessary to place all element-collectors in
the same ground layer. Logging mode CHIM allows the determination of concentrations
of metals in ore with an error +100% at intervals that cannot be investigated by other
borehole logging methods (in the fractured zones, in cavities and so on). The time of
accumulation is 10-20 hours for the ground mode of CHIM and 1-2 hours for the logging
mode.
Ground mode CHIM can be applied under condition, in which conventional methods
of geochemical exploration are not effective, for example:

9 detection of deep-seated mineralisation, beneath as much as 500 m of unconsolidated
overburden or clay sediments;
9 evaluation of geophysical anomalies and indication of the material composition of
their sources;
9 more accurate determination of the position of sources of anomalies first detected by
other geoelectrochemical methods;
9 indication of the contours of oil-gas reservoirs.