P. Schmoldt, PhD - MTNet - DIAS

Layer Density Thermal conductivity
7.3. Tajo Basin and central Spain
Thickness Heat production
North South North South
(kg m −3 ) (W m −1 K −1 ) (km) (µW m −3 )
Sediment layer 2400 2.5 2 1 2.5 2.5
Upper crust 2700 2.5 12 13 3.3 2.5
Middle crust 2850 2.5 9
Lower crust 2900 2.1 8 0.8
Tab. 7.4.: Parameters of the thermal model for the Tajo Basin, assuming the thermal conductivity of the lithospheric-mantle to be
3.4 Wm −1 K −1 ; after Tejero and Ruiz [2002].
Fig. 7.27.: Geotherms of the Tajo Basin calculated for the parameters given in Table 7.4; modified from Tejero and Ruiz [2002].
the lower crust acting as an incompetent layer (Fig. 7.28). The concept of a weak
lower crust, as proposed by Tejero and Ruiz [2002], is in agreement with the observed
seismicity in this region, exhibiting no events in the lower crust of central Spain [Instituto
Geografico Nacional, 2010] (cf. earthquake locations depict in Figure 7.22). The
seismic–aseismic boundary is accordingly related to the brittle–ductile boundary of the
crust; observed events are assumed to be transmitted through inherit fault zones and flexural
bounding stresses from regional compression [Tejero and Ruiz, 2002]. However, the
assumption of an exponential decay of heat production with depth used by the authors
for the calculation of their model is questionable (cf. Vilà et al. [2010]), and the obtained
thermal structure could be significantly different for the case of a constant heat production
within each layer.
Recently European scale models of the lithosphere’s thermal and rheological proper-
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