Electromagnetic imaging of a transpressional tectonics in SW Iberia

Almeida, Eugénio P.; Pous, J.; Santos, Fernando A. Monteiro; Fonseca, Paulo E.; Marcuello, Álex; Queralt, Pilar; Nolasco, Rita; Mendes-Victor, L.

doi:10.1029/2000gl012037

Cited by 31 publications

(33 citation statements)

References 11 publications

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“…Research in SW Iberia (Santos et al, 1999(Santos et al, , 2002Almeida et al 2001Almeida et al , 2005Pous et al 2004;Muńoz et al 2005Muńoz et al , 2006 has investigated electrical properties of the South Portuguese Zone, SPZ (Variscan Rhenohercynian affinity), the Ossa Morena Zone, OMZ (Saxothuringian affinity) and the Central Iberian Zone, CIZ, which form the three tectonostratigraphic terranes of southern Iberian Variscan Massif. Of particular interest have been the properties of the terrane boundaries (suture zones) and the internal structure of the Ossa Morena Zone.…”

Section: Magnetotelluric Studies In the Alpine Fold Belt And Variscidesmentioning

confidence: 97%

How is the European Lithosphere Imaged by Magnetotellurics?

Korja

2007

Surv Geophys

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I review recent investigations on the electrical conductivity of the lithosphere and asthenosphere in Europe. The principal method in the reviewed studies is the magnetotelluric method, but in many cases other electromagnetic methods (e.g., magnetovariational profilings and geomagnetic depth soundings) have provided additional information on subsurface conductivity or have been the primary method. The review shows that the magnetotelluric method has been used, and is being used, in all kinds of environments and for many different processes shaping the crust and lithosphere. The crust is very heterogeneous, both with respect to the scale of conductive/resistive features and interpretations: research targets vary from Archaean palaeostructures to ongoing processes. The European database of the depth to the lithosphere-asthenosphere boundary (LAB) in Europe is updated, and a new map showing lateral variations of the depth of LAB is provided. The compilation shows that (1) the Phanerozoic European lithosphere, with considerable variations (45-150 km), is much thinner than the Precambrian European lithosphere, (2) the Trans-European Suture Zone is a major electrical border in Europe separating electrically (as well as geophysically and geologically in general) two quite different settings, (3) the thinnest lithosphere is found under the extensional Pannonian Basin (45-90 km), (4) in most of the East European Craton there are no indications of a high conductivity zone in upper mantle. In many regions there is no information at all on upper mantle conductivity, which calls for pan-European projects to operate arrays of simultaneously recording instruments with long recording periods (2-8 months) and dense spatial sampling (20-50 km).

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Section: Magnetotelluric Studies In the Alpine Fold Belt And Variscidesmentioning

confidence: 97%

How is the European Lithosphere Imaged by Magnetotellurics?

Korja

2007

Surv Geophys

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“…The OMZ involves a complex tectonic scenario with the development and closure of an ophiolitic complex -the socalled Beja-Acebuches Ophiolitic Complex (BAOC; Fonseca et al 1999;Mateus et al 1999;Figueiras et al 2002). Moreover, the OMZ southern border comprises highly deformed exotic terranes of an oceanic nature (including the "Pulo do Lobo" Accretionary Terrane (PLAT) and the BAOC), as complex tectonic melanges (Almeida et al 2001;Araújo et al 2005;Booth-Rea et al 2006). These formations are rimming an early main Variscan suture in the southwest of the Iberian Massif and they accreted to the Iberian Autochthon before the Middle/Late Devonian times Fonseca et al 1999).…”

Section: Geotectonic Settingmentioning

confidence: 99%

The Odivelas Limestone: evidence for a Middle Devonian reef system in western Ossa-Morena Zone (Portugal)

Machado¹,

Hladil²,

Koptíková³

et al. 2009

Geologica Carpathica

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Abstract:The Odivelas Limestone constitutes one of the few records of Middle Devonian sedimentation in the western Ossa-Morena Zone. Although deformed and metamorphosed the limestones have an abundant fossil content which allows their positioning as late Eifelian/early Givetian in age and to relate the reef fauna with the typical Rhenish facies for the same time period. Magnetic susceptibility analysis was attempted and is in agreement with the biostratigraphy, but the limited extent of sections and the metamorphism precludes firm correlations. The field evidence, petrographic and geochemical analysis point to a close paleogeographical relation and dependence of the reef system on volcanic structures which are included in the Beja Igneous Complex. The age of part of the volcanic and sub-volcanic suite of this complex is thus constrained.

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“…Moreover, the S-wave velocity structure obtained in this study for the south-eastern part of Iberia will complement previous geophysical studies performed in this area such as: geodynamic evolution (Galindo-Zaldívar et al 1999;Andeweg 2002;Braga et al 2003;Galindo-Zaldívar et al 2003;Sanz de Galdeano and Alfaro 2004), seismic refraction and gravity data analysis (Suriñach and Vegas 1988;Banda et al 1993), seismic reflection (García- Dueñas et al 1994;Carbonell et al 1998), studies performed with magnetotelluric and deep seismic data (Pous et al 1999(Pous et al , 2004Almeida et al 2001;Carbonell et al 2003;Simancas et al 2003), seismic tomography (Blanco and Spakman 1993;Dañobeitia et al 1998;Serrano et al 1998;Gurría and Mezcua 2000;Serrano et al 2002) and seismic velocity structure (Calvert et al 2000;Serrano et al 2005).…”

Section: Introductionmentioning

confidence: 58%

Shear-wave velocity structure of the south-eastern part of the Iberian Peninsula from Rayleigh wave analysis

Corchete

Chourak²

2010

Int J Earth Sci (Geol Rundsch)

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In this study, we present the lithospheric structure of the south-eastern part of the Iberian Peninsula by means of a set of 2D images of shear velocity, for depths ranging from 0 to 50 km. This goal will be attained by means of the inversion of the Rayleigh wave dispersion. For it, the traces of 25 earthquakes occurred on the neighbouring of the study area, from 2001 to 2003, will be considered. These earthquakes have been registered by 11 broadband stations located on Iberia. All seismic events have been grouped in source zones to get an average dispersion curve for each source-station path. The dispersion curves have been measured for periods between 2 and 45 s, by combination of two digital filtering techniques: Multiple Filter Technique and Time Variable Filtering. The resulting set of source-station averaged dispersion curves has been inverted according to the generalized inversion theory, to get S-wave velocity models for each source-station path. Later, these models have been interpolated using the method of kriging, to obtain a 2D mapping of the S-wave velocity structure for the south-eastern part of Iberia. The results presented in this paper show that the techniques used here are a powerful tool to investigate the crust and upper mantle structure, through the dispersion analysis and its inversion to obtain shear velocity distributions with depth. By means of this analysis, principal structural features of the south-eastern part of Iberia, such as the existence of lateral and vertical heterogeneity in the whole study area, or the location of the Moho discontinuity at 30 km of depth (with an average S-velocity of uppermost mantle of 4.7 km/s), have been revealed. Other important structural features revealed by this analysis have been that the uppermost of Iberian massif shows higher velocity values than the uppermost of the Alpine domain, indicating that the massif is old and tectonically stable. The average velocity of the crust in Betic cordillera is of 3.5 km/s, while in the Iberian massif is 3.7 km/s. All these features are in agreement with the geology and other previous geophysical studies.

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Electromagnetic imaging of a transpressional tectonics in SW Iberia

Cited by 31 publications

References 11 publications

How is the European Lithosphere Imaged by Magnetotellurics?

How is the European Lithosphere Imaged by Magnetotellurics?

The Odivelas Limestone: evidence for a Middle Devonian reef system in western Ossa-Morena Zone (Portugal)

Shear-wave velocity structure of the south-eastern part of the Iberian Peninsula from Rayleigh wave analysis

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