P. Schmoldt, PhD - MTNet - DIAS

3D
N45W
3D-crust
TE Rho
TE Phi
Period (s)
Period (s)
TM Rho
TM Phi
Period (s)
Period (s)
10 -2
10 -1
10 0
10 1
10 2
10 3
10 4
10 5
10 -2
10 -1
10 0
10 1
10 2
10 3
10 4
10 5
10 -2
10 -1
10 0
10 1
10 2
10 3
10 4
10 5
10 -2
10 -1
10 0
10 1
10 2
10 3
10 4
10 5
syn020
syn019
syn017
syn015
syn013
syn011
syn009
syn007
syn006
syn005
syn004
syn003
syn002
syn001
0 50 100 150
Distance (Km)
10 -2
10 -1
10 0
10 1
10 2
10 3
10 4
10 5
Ohm.m
794
533
358
240
161
108
73
49
10 -2
10 -1
10 0
10 1
10 2
10 3
10 4
10 5
10 -2
10 -1
10 0
10 1
10 2
10 3
10 4
10 5
Ohm.m
1585
970
594
364
223
136
83
51
10 -2
10 -1
10 0
10 1
10 2
10 3
10 4
10 5
Degrees
Degrees
90
80
70
60
50
40
30
20
10
90
80
70
60
50
40
30
20
10
8.2. Generating synthetic 3D model data
3D
N45E
3D-mantle
TE Rho
Period (s)
TE Phi
Period (s)
TM Rho
Period (s)
TM Phi
Period (s)
10 -2
10 -1
10 0
10 1
10 2
10 3
10 4
10 5
10 -2
10 -1
10 0
10 1
10 2
10 3
10 4
10 5
10 -2
10 -1
10 0
10 1
10 2
10 3
10 4
10 5
10 -2
10 -1
10 0
10 1
10 2
10 3
10 4
10 5
syn020
syn019
syn017
syn015
syn013
syn011
syn009
syn007
syn006
0 50 100
Distance (Km)
Fig. 8.7.: Pseudosections of the profiles 3D-crust (left-hand side) and 3D-mantle (right-hand side) with stations representing the MT
recording sites of the PICASSO Phase I investigation; see Figures 8.4 and 8.5 for the location of stations and profiles. The northern
end of the profile (NE for 3D-crust profile, and NW for 3D-mantle profile) is shown to the right.
model (1000 Ωm in the northwestern half, and 500 Ωm in the southeastern half), however,
ρyx values are significantly different. YX data at long periods exhibit significant distortion
effects, originating from crustal structures and the oblique strike directions between the
two depth regions. Among other, ρyx data of the southern quadrant are higher than for
the northern quadrant resulting in an issue concerning, in particular, profiles using the
pic-stations (pic001 - pic020, denoted by stars in Figure 8.4). The circumstance that YX
responses of the southern mantle region are significantly more resistive than responses in
the northern mantle region is reflected in TM mode data of the crustal strike direction and
TE data of the mantle strike direction (see also Figure 8.7).
Forward response data can be displayed using so-called pseudosections, i.e. gridded
resistivity–period values beneath the profile, in which period is used as a depth proxy.
The pseudosection for the pic-line (stations syn001 – syn020 in Figure 8.7) is displayed
here because these stations form the most challenging combination by containing stations
from each resistivity region of the synthetic 3D model, and, moreover, because the station
locations are representations of the PICASSO Phase I recording sites (cf. Sec. 9.1).
Due to the characteristics of the 3D model, two profiles are created with data arranged
according to the geoelectric strike directions at crustal depth (N45W, left-hand side plot
in Figure 8.7) and mantle depth (N45E, right-hand side plot in Figure 8.7); see Figure
syn005
syn004
syn003
syn002
syn001
10 -2
10 -1
10 0
10 1
10 2
10 3
10 4
10 5
10 -2
10 -1
10 0
10 1
10 2
10 3
10 4
10 5
10 -2
10 -1
10 0
10 1
10 2
10 3
10 4
10 5
10 -2
10 -1
10 0
10 1
10 2
10 3
10 4
10 5
Ohm.m
Degrees
Ohm.m
Degrees
1585
970
594
364
223
136
83
51
90
80
70
60
50
40
30
20
10
794
533
358
240
161
108
73
49
90
80
70
60
50
40
30
20
10
177