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a)
b)
X'
X'
C
0
500
Metres
0
500
Metres
B
A
C
C
C
X
X
0-100 m
100-200 m
200-300 m
300-400 m
400-500 m
A
X
X'
Observed
Calculated
c)
200 nT
B
0
1.0
0.1
0.01
0.001
Susceptibility
(SI)
0
500
200
400
600
800
1000
Metres
Modelled source
0.065 SI, strike length = 600 m
0.008 SI, strike length = 300 m
1200
1400
d)
Observed
Unconstrained
Constrained
Y'
Y'
Y'
0
250
Metres
0
250
Metres
0
250
Metres
Y
Y
Y
Figure 3.71
Aeromagnetic data from the Wallaby Au deposit, Western Australia, and the results of forward and inverse modelling.
(a) Reduced-to-pole TMI data. The letters refer to features discussed in the text. X
X
0
-
is the pro
le used for 2.5D modelling, and the
dashed-line rectangle de
nes the region used for 3D modelling. (b) Results from 3D Euler deconvolution applied to the data in (a) using an
11-point window and structural index (SI)
1.5. The grey rectangle is the surface projection of the 2.5D model shown in (c). (c) 2.5D dipping
prism model of the source of the magnetic anomaly drawn on the known subsurface susceptibility distribution. The dashed outline corresponds
to an alternative model compatible with the data. The starred values on the susceptibility scale correspond to the susceptibilities of the two
models. (d) Contours of the observed TMI and the TMI anomalies calculated from subsurface susceptibility distributions created by 3D inverse
modelling. Contour interval is 50 nT in all cases. Pro
ΒΌ
Y
0
X
0
) and the dashed outline show the locations of
le Y
-
(a subpro
le of pro
le X
-
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