Page 69 - Geochemical Remote Sensing of The Sub-Surface

46 O.F. Putikov and B. Wen

+ . ^, ^.+ +
,
i _ _ ;I" /. ..J
H- ' ~/~.." /. /- - /
lllot--~ole/~ V ) ~ [ '
r+ (^,//1^ + +
^'.
.
400
9 320
~ B
uo 240
~ 160 J
~ 80 i
0
Borehole 1 2 3 4

^
.~
~--m.... ~IW m. l T T
"~"s 9
',,+ I + ,+ +
+ ^ ",,. 4-[ + .~ + +
^+'~.~+ + "'., +
^
3 I'--12 -] 4 F'L-']' 5 [~z ~ ~ "
Fig. 2-24 9 Results obtained by the CHIM method over beryllium mineralisation in Byelorussia:
(A) plan of beryllium anomaly, and (B) distribution of beryllium along profile and schematic
geological section; 1- sands, clays; 2- diabases; 3- granites; 4- tectonic disjunctions; 5- ore bodies;
6- zones of mineralisation (reproduced with permission from Bensman et al., 1982).

The role of CHIM in oil prospecting is illustrated in Fig. 2-26. The perimeter of the
oil deposit at depth of about 2500 m is satisfactorily delineated by the contour of
maximum lead mass extracted by the CHIM method.

Diffusion extraction of metals (MDE)

The MDE method relies on an element-collector analogous to a simplified CHIM
element-collector, but without the inner metallic electrode. The application of MDE does
not involve an external current. These differences underlie the essentially different
physico-chemical basis of MDE. The transfer of the movable forms of elements
(generally ions) through the semi-permeable membrane occurs mainly because of two
processes, diffusion and migration in the electric field of the double electric layer of
membrane. In the absence of an external electric field, as in the MDE method, there is
increased diffusion of hydrogen ions through the membrane into the surrounding
environment, promoting dissolution of the solid phase. Dissolved elements pass through
the membrane into the element-collector but, in contrast to the CHIM method, the