Geology Reference
In-Depth Information
130
120
110
100
90
80
70
30
20
10
0
10
20
30
real
430E
434
438
450
456E
imaginary
Slingram, 1760 Hz
1.6
1.4
1.2
1.0
0.8
0.6
24 °
16
ratio
°
8
0
Turam, 660 Hz
°
-8 °
-16
440E
444
450
456E
phase
difference
°
-24
°
1.4
1.2
1.0
0.8
0.6
16
Ratio
°
8
0 °
-8
Turam, 220 Hz
440E
444
450
456E
°
-16
phase
difference
°
300
200
100
0
-100
-200
-300
Self-potential
430E
434
438
444
448
452
456E
0
200 m
442E
446
450
454E
Apparent
resistivity
( Ω m)
Induced
polarization
Hematitic
quartz breccia
Quartzite
Black shale
Brecciated banded
ironstone
442E
446
450
454E
Percentage
frequency
effect (%)
5
10
Weathered zone in
conducting shale
Tremolitic siltstone
Limestone
Diamond-drill hole
438
442
446
450
454E
Fig. 9.13 Comparison of various geophysical
methods over the same profile as shown in Fig.
9.12 near Mount Minza, Northern Territory,
Australia. (After Duckworth 1968.)
Undifferentiated
shale
Conducting shale
instrument is used in which the transmitter and receiver,
which usually take the form of vertical coplanar coils, are
separate, so that their spacing is variable. Constant sepa-
ration traversing (CST) can be performed with the
subsurface energized to a desired depth, while vertical
electrical sounding (see Section 8.2.3) can be under-
taken by progressively increasing the transmitter-receiv-
er separation.
A widely used instrument based on the above princi-
ples is the Geonics EM31.
 
Search WWH ::




Custom Search