Habitat differentiation and geographic separation of Isoetes velata populations in central Iberian Peninsula

Populations of Isoetes velata were studied in order to provide more information on their habitat and distribution in the Western and Northwestern Iberian Peninsula. Habitat together with morphology of megaspores were used as diagnostic features. The form I. velata subsp. velata f. lereschii is considered here as a synonym of I. velata subsp. asturicense and therefore only two taxa remain within the species: I. velata subsp. velata and I. velata subsp. asturicense. Intermediate individuals have been found in the Western Central System. The differentiation within the I. velata group appears to be the result of gradual genetic divergence after isolation. Palaeobotanical data confirm the presence of I. velata subsp. asturicense in Late Glacial lake sediments in northwestern Spain. Cluster classification of the soft-water vegetation with Isoetes velata subsp. asturicense revealed two main groups in the Spanish Central System. A single association, the Sparganio angustifolii-Callitrichetum fontqueri which includes Iberian Atlantic stands of Sparganium angustifolium and Isoetes velata subsp. asturicense, is here recognized. Besides, a variant of the association with Eleocharis acicularis is identified in shallow temporary waters in the Western Sierra de Gredos.

¿PUEDE HABER 5 FASES DE DEFORMACIÓN HERCÍNICA EN LA ZONA DE VALDEMORILLO (MADRID)?

This work aims to understand the processes that have taken part in the deformation, both on a small and large scale, of metamorphic materials in Valdemorillo area, located in the west of the Community of Madrid and within the Spanish Central System. The objective is to understand the kinematic evolution and the specific mechanical behaviour of igneous-metamorphic materials from the area, deformed by certain efforts developed throughout the Hercynian Orogeny. Therefore, a structural analysis has been carried out throughout a geological mapping scaled 1: 25000 and the analysis of various petrographic studies by microscope. Thus, a total of 5 different deformations have been identified, which have allowed us to better understand the reconstruction of the processes generated in these materials and that we see today.

Lithospheric image of the Central Iberian Zone (Iberian Massif) using global-phase seismic interferometry

The Spanish Central System is an intraplate mountain range that divides the Iberian Inner Plateau in two sectors – the northern Duero Basin and the Tajo Basin to the south. The topography of the area is highly variable with the Tajo Basin having an average altitude of 450–500 m and the Duero Basin having a higher average altitude of 750–800 m. The Spanish Central System is characterized by a thick-skin pop-up and pop-down configuration formed by the reactivation of Variscan structures during the Alpine orogeny. The high topography is, most probably, the response of a tectonically thickened crust that should be the response to (1) the geometry of the Moho discontinuity, (2) an imbricated crustal architecture, and/or (3) the rheological properties of the lithosphere. Shedding some light on these features is the main target of the current investigation. In this work, we present the lithospheric-scale model across this part of the Iberian Massif. We have used data from the Central Iberian Massif Deformation (CIMDEF) project, which consists of recordings of an almost-linear array of 69 short-period seismic stations, which define a 320 km long transect. We have applied the so-called global-phase seismic interferometry. The technique uses continuous recordings of global earthquakes (>120∘ epicentral distance) to extract global phases and their reverberations within the lithosphere. The processing provides an approximation of the zero-offset reflection response of a single station to a vertical source, sending (near)-vertical seismic energy. Results indeed reveal a clear thickening of the crust below the Central System, resulting, most probably, from an imbrication of the lower crust. Accordingly, the crust–mantle boundary is mapped as a relatively flat interface at approximately 10 s two-way travel time except in the Central System, where this feature deepens towards the NW reaching more than 12 s. The boundary between the upper and lower crust is well defined and is found at 5 s two-way travel time. The upper crust has a very distinctive signature depending on the region. Reflectivity at upper-mantle depths is scattered throughout the profile, located between 13 and 18 s, and probably related to the Hales discontinuity.

Cadalso de los Vidrios leucogranite ‘Blanco Cristal’: a widely used heritage stone from Spain

Cadalso de los Vidrios leucogranite is extracted from the Sierra de Guadarrama (Spanish Central System) under the trade name ‘Blanco Cristal’. It is a fine- to medium-grained, hypidiomorphic and equigranular building stone that has been used in many heritage buildings, such as the Villena Palace (1534). The current annual production of Cadalso de los Vidrios leucogranite is approximately 8000 m3, of which 40% is exported around the world. It has been used in places such as the Vieux-Port in Marseille (France), Cork International Airport (Ireland) and the Puri EXIM Bank of Jakarta (Indonesia) among others. It is currently being used in the construction of the iconic tower of Jesus Christ of the Sagrada Familia Basilica, in Barcelona (Spain). Cadalso de los Vidrios leucogranite Blanco Cristal has excellent petrophysical properties, a uniform colour and good resistance to thermal shock and freezing temperatures. These qualities make Blanco Cristal an ideal material for monuments and buildings.

Lithospheric image of the Central Iberian Zone (Iberian Massif) using Global-Phase Seismic Interferometry

The Spanish Central System is an intraplate mountain range that divides the Iberian Inner Plateau in two sectors – the northern Duero Basin and the Tajo Basin to the south. The topography of the area is highly variable with the Tajo Basin having an average altitude of 450–500 m while the Duero Basin presents a higher average altitude of 750–800 m. The Spanish Central System is characterized by a thick-skin pop-up and pop-down configuration formed by the reactivation of Variscan structures during the Alpine Orogeny. The high topography is, most probably, the response of a tectonically thickened crust that should be also identified by 1) the geometry of the Moho discontinuity 2) an imbricated crustal architecture and/or 3) the rheological properties of the lithosphere. Shedding some light about these features are the main targets of the current investigation. In this work, we present the lithospheric-scale model across this part of the Iberian Massif. We have used data from the CIMDEF project, which consists of recordings of an almost-linear array of 69 short-period seismic stations, which define a 320 km long transect. We have applied the so-called Global-Phase Seismic Interferometry. The technique uses continuous recordings of global-earthquakes (> 120º epicentral distance) to extract global phases and their reverberations within the lithosphere. The processing provides an approximation of the zero-offset reflection response of a single station to a vertical source, sending (near) vertical seismic energy. Results indeed reveal a clear thickening of the crust below the Central System resulting, most probably, from an imbrication of the lower crust. Accordingly, the crust-mantle boundary is mapped as a relative flat interface at approximately 10 s two-way travel time except in the Central System, where this feature deepens towards the NW reaching more than 12 s. The boundary between the upper and lower crust is well defined and is found at 5 s two-way travel. The upper crust has a very distinctive signature depending on the region. Reflectivity at upper-mantle depths is scattered throughout the profile, located between 13–18 s, and probably related with the Hales discontinuity.