Page 43 - Geochemical Remote Sensing of The Sub-Surface

20 O.F. Putikov and B. Wen

Pb, ~g/ml

10 /a
c
50 m
5

0
AB
0 iiiili:~i~ii~i~ii!ii~i::~ii!::i~i~!::~ ilili ~ii~i:. ~iiiiiiiiii~iiiiiiiiii~iiiiii

I00-

200
\,, "x,
300

~il [x~ w 14

Fig. 2-2. Jet halo of lead, over a blind polymetallic ore body, overlain by allochthonous clays of
thickness 30 to 100 m with different intervals between measurement points (a- 50 m, b- 20 m, c- 5
m). Schematic geological section: 1- silts, 2- clays, 3- clay-siliceous siltstones, 4- quartzites, 5-
mudstone with pyrite, 6- mudstones, siltstones, 7- pyrite-polymetallic ore (reproduced with
permission from Ryss et al., 1987b).

9 the shape of anomalies in profile is more variable
9 anomaly amplitude, Cm~x, and width, b, are only loosely related to the depth of the
source, h
9 the halo extends nearly vertically from the source, so that the halo width, b,
corresponds to the vertical projection of the source to the surface

These features of the jet halo enhance the prospecting depth of the
geoelectrochemical methods. A number of field experiments have verified that the
prospecting depth for an ore body attains some hundred metres and for oil and gas
reservoirs several kilometres. Similar results have been obtained with data for relatively-
confined forms of metals, although the widths of halos are greater than those for mobile
and weakly-conf'med forms of metals.
Detailed studies of the distributions of concentrations of metals in jet halos reveal
apparent non-uniformity of anomaly structure (Fig. 2-2). Maximum concentrations of
anomalies on the diumal surface correspond to the zones of enhanced concentrations of
mobile fo~ms of metals at depth, which extend almost vertically and have a complicated