P. Schmoldt, PhD - MTNet - DIAS

11. Summary and conclusions
11.2.2. Suggestion for future work
MT investigations are, like most geophysical studies, limited by availability and quality
of the acquired data. Additional, target-oriented, recordings that could improve specific
aspects are:
• Broad-band recordings along the ‘Variscan Spain’ – ‘Alpine Spain’ boundary in the
Tajo Basin region, inferred from seismic tomography, appraising seismic findings
and confirming the proposed correlation between seismic velocity and electric resistivity
interfaces. These measurements could proved the basis for revising the
Iberian Massif outline beneath the Tajo Basin, which is currently based mainly on
surface geology mapping.
• An array of broad-band recordings in the Campo de Montiel region, to the west
of stations pic017 – pic020, that further investigates properties and extent of the
electrically conductive and seismically slow anomaly in the middle and lower crust.
Particularly assessing the inferred contribution of a hydrous phase to the response of
the proposed asthenospheric remnants and providing additional information about
whether the hydrous phase originates from percolation or slab dehydration processes.
• Long-period recordings in the centre of the Tajo Basin to enhance knowledge of the
low electric resistivity – low seismic velocity anomaly in the lithospheric-mantle.
Further, determining electrical properties of the inferred HIMU-like reservoir and
its impact on the local geology.
Future fieldwork campaigns should be scheduled for periods of increased solar activity
and recording sites installed an adequate distance from DC railway lines in order to increase
the signal-to-noise ratio, hence the quality of the impedance estimates. Since the
study area is situated sufficiently far away from equatorial as well as the polar regions,
recordings are considerably less affected by equatorial and polar electrojets that are amplified
during high solar activity periods. Thus, presuming a continuation of the 11 year
solar cycle, recordings during the years 2011–2016, 2022–2027, etc. are expected to yield
high-quality results 1 .
MT results should be supplemented by additional surface heat flow and seismic measurements,
particularly in the Campo de Montiel region where the electrically conductive
and seismically slow anomaly is determined. Moreover, advances in combining results
of different geophysical methods and understanding of relations between corresponding
parameters will significantly enhance understanding of the geological settings by ultimately
yielding a petrophysical model of the subsurface. Approaches that seek to provide
petrological models of the Earth’s mantle have been presented by Afonso et al. [2008]
1 It should be noted that the current solar cycle exhibits an elongated minimum, which may result in a shift
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of subsequent maxima and minima.