P. Schmoldt, PhD - MTNet - DIAS

Log Period
Log Period
2.5
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1.5
1
RMS Misfit
10.1. Inversion for crustal structures
0.5
pic020 pic019 pic017 pic015 pic013 pic011 pic009 pic007 pic005 pic004 pic003 pic002 pic001
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TE Apparent Resistivity
20 17 13 09 05 03 01
TE Phase
20 17 13 09 05 03 01
Stations
40
30
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5
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TM Apparent Resistivity
20 17 13 09 05 03 01
TM Phase
20 17 13 09 05 03 01
Stations
Fig. 10.8.: Misfit of the final Tajo Basin crust model, individually broken down into an average for each station (top), as well as for
apparent resistivity and phase of the two modes (bottom); due to space restriction only a selection of station indices is given at the
bottom of apparent resistivity and phase plots. The colour scale is set to a range of two times the error floor used in the inversion.
Features of the crustal model
Close to the surface, down to a depth of around 3 km, a highly conductive structure (labelled
‘a’ in Figure 10.6, highlighted by thick dashed white lines) is present throughout
the whole length of the profile. This surficial conductor is likely to be caused by accumulation
of saline fluid or an increase of fluid salinity at the bottom of the Tertiary and
Mesozoic sedimentary layer. Along the profile, the location of this conductor is displaced
downwards by two more resistive regions (b1) and (b2). The horizontal limits of region
‘b1’, located in the centre of the profile (around station pic011), coincide with two faults
intersecting the PICASSO profile in the proximity of stations pic009 and pic013 (see
Figure 7.15 for course and location of the two faults in a map of the Tajo Basin). The
northern downwards displacement of conductor ‘a’ (labelled ‘b2’) coincides with the location
of a fault between stations pic004 and pic005. An additional fault is located to the
north of the PICASSO Phase I and may coincide with the northern limit of the downward
displacement ‘b2’; however, since this fault is outside the PICASSO Phase I profile no reliable
correlations can be given regarding a correlation between fault and northern extent
of feature ‘b2’.
Besides the two conductors ‘a’ and ‘c’, a relatively homogeneous region of around
100 Ωm is observed in the upper and intermediate crust of the northern region of the
profile, whereas the southern region exhibits a highly different behaviour. The upper
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15
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