P. Schmoldt, PhD - MTNet - DIAS

9. Data collection and processing
0 km
10 km
30 km
100 km
300 km
Depth range
Depth: 12 – 30 km (intermediate and lower crust)
90
75
60
45
30
15
0
pic041
pic040
pic037
pic035
pic033
pic031
Betic Cordillera
pic029
pic027
pic025
pic023
CIZ
pic022
pic020
pic019
pic017
pic015
Multi-strike
(Av. RMS-misfit in brackets)
pic013
pic011
pic009
pic007
Tajo Basin
pic006
All stations Tajo Basin
19.3 (1.0) 49.1 (0.8)
Fig. 9.9.: RMS misfit for different geoelectric strike directions of stations recorded during PICASSO Phase I, using data in the Niblett-
Bostick depth range 12 – 30 km; shown in the inset. Empty spaces are due to lack of data for this depth range at the respective station.
Also shown in the top right corner is the optimal common geoelectric strike direction clockwise from North calculated for all stations
and for stations in the Tajo Basin only; indicated by dashed and dotted white lines in the main plot, respectively. Assignment of
stations to the different geological regions, displayed on the bottom of the plot, is based on their location in respect to geological units
of the USGS EnVision map for Europe (Fig. 9.1), CIZ: Central Iberian Zone, part of the Iberian Massif. See text for further details.
pic009, and pic013. Note that the geoelectric strike estimate has a 90 degrees ambiguity;
therefore calculated values of N50.5E and N47.8E imply that geoelectric strike directions
of N140.5E and N137.5E fit the data equally well. However, unlike station pic005, stations
pic009 and pic013 do not exhibit a strong 2D behaviour, indicating that the two
respective faults do not result in a significant vertical geoelectric interface.
Comparing RMS misfits of the Tajo Basin intermediate and lower crust with the region
associated with the Betic Cordillera reveals the different subsurface structures present
along the profile, i.e. no distinct strike direction observable for the Betic Cordillera. This
circumstance can be explained by the complex 3D structures below the mountain chain
originating from its intricate origin (cf. Sec. 7). This difference in dimensionality for Tajo
Basin and Betics region of the profile, also observed at mantle depth (shown in the next
paragraphs), suggests separate investigation of the two regions. Strike analysis results for
other depth ranges, shown in the following figures, support the concept of the complex
structure of the southern region.
Combined intermediate and lower crust
Given the similarities in optimal strike direction, as well as overall directional variation
of RMS misfit for intermediate and lower crust, strike analysis is conducted for the combined
depth range as well. Analysis for the combined depth range yields a directional
RMS misfit distribution that is similar to distributions of the individual depth ranges and
a multi-strike direction of N49.1E (0.8 av. RMS misfit) for the Tajo Basin region (Fig.
9.9). Northern-most stations (pic001 – 004) agree well with this strike direction, whereas
central stations (pic006 - 020) exhibit a considerable 1D structure. Results from seismic
studies in the Tajo Basin, indicating a geologic strike direction with an NW-SE orientation
(cf. Section 7.3.2), are used to solve the 90 degrees ambiguity. Accordingly, the
geoelectric strike direction chosen for this region is N40.9W (or N139.1E). RMS misfits
for stations associated with the Betic Cordillera is generally higher and no optimal strike
direction is observable.
214
pic005
pic004
pic003
pic002
pic001
RMS
misfit
4
3
2
1
0