P. Schmoldt, PhD - MTNet - DIAS

7. Geology of the Iberian Peninsula
Fig. 7.12.: Main morphostructural units of the south submeseta and their location in the Iberian Peninsula; modified after Gutierrez-
Elorza et al. [2002] (note: Cuenca = Basin, Montes = Mountains, Sierra = Mountain range, Llanura = Plain, Rio = River); the location
of map B is indicated by the red area in map A in the top-right of this figure.
Iberian Range experienced intense deformation during the Middle Miocene, initiated by
the Iberian – Internal Betics collision [e.g. Andeweg, 2002].
To the west of the Iberian Range, bordering the Tajo Basin to the northwest, the Spanish
Central System (SCS; also referred to as Central Range or in Spanish as Sistema Central)
forms a NE-SW trending mountain range branch. Outcrops of Variscan basement, associated
with the Iberian Massif, contain mainly metamorphic and igneous rocks with granitic
rocks dominating in the west and metamorphic rocks in the east [Tejero and Ruiz, 2002].
Details of the SCS formation process are not known at present, but several models have
been proposed, describing the SCS as pop-up structure [Warburton and Alvarez, 1989;
de Vicente et al., 1996; Tejero et al., 1996; Andeweg, 2002; Alonso-Zarza et al., 2002;
Tejero and Ruiz, 2002, and references within], or as a flower structure [Portero and Aznar,
1984; Tejero et al., 1996] and attributing it to simultaneous strike-slip faulting and block
rotation [Vegas et al., 1990]. The start of the SCS configuration is dated at the Eocene –
Oligocene boundary, with sedimentation in the Loranca and Madrid Basin (Cuenca de
Loranca and Cuenca de Madrid in Fig. 7.12) as well as in the Iberian Range evidencing
that at least the northeastern region of the SCS was constructed at that time [Andeweg,
2002]. The Moho deepens beneath the SCS, reaching a depth of 34 km, primarily due to
thickening of the lower crust [ILIHA DSS Group, 1993], which was attributed by Surinach
and Vegas [1998] to Cretaceous – Miocene shear zone activity of the SCS comprising rotation
of brittle upper crust segments, together with ductile deformation and thickening of
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