Deep deformation pattern from electrical anisotropy in an arched orogen (Betic Cordillera, western Mediterranean)

Ruíz-Constán, Ana; Galindo-Zaldı́var, Jesús; Pedrera, Antonio; Arzate, Jorge; Pous, J.; Anahnah, Farida; Heise, Wiebke; Santos, Fernando A. Monteiro; Marín‐Lechado, Carlos

doi:10.1130/g31144.1

Cited by 11 publications

(11 citation statements)

References 25 publications

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“…The northwesternmost mountain front remains active, featuring shallow seismicity associated with the northwestward propagation of NE-SW reverse faults (Ruiz-Constán et al, 2010). However, there is practically no surface evidence of Quaternary tectonic structures.…”

Section: Betic Cordilleramentioning

confidence: 99%

“…Seismic tomography reveals a high velocity slab dipping to the East from the Gibraltar Strait up to 600 km depth bellow the Alboran Sea (Wortel and Spakman, 2000;Spakman and Wortel, 2004). Seismic anisotropy (Buontempo et al, 2008) and dimensionality analysis of long-period magnetotelluric surveys (Ruiz-Constán et al, 2010) agree putting forward the deep crust and the mantle fabric that recorded deformation patterns associated to the east-dipping subduction and the westward emplacement of the Betic-Rif Cordilleras hinterland. Although most of the authors agree that the eastward subduction and the back-arc extension were mainly operating during the Early and Middle Miocene, their continuity since the Upper Miocene and the present-day activity/inactivity is under a vigorous debate (Platt and Houseman, 2003).…”

Section: Introductionmentioning

confidence: 97%

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Is there an active subduction beneath the Gibraltar orogenic arc? Constraints from Pliocene to present-day stress field

Pedrera

Ruíz-Constán

Galindo-Zaldı́var

et al. 2011

Journal of Geodynamics

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Section: Betic Cordilleramentioning

confidence: 99%

Section: Introductionmentioning

confidence: 97%

Is there an active subduction beneath the Gibraltar orogenic arc? Constraints from Pliocene to present-day stress field

Pedrera

Ruíz-Constán

Galindo-Zaldı́var

et al. 2011

Journal of Geodynamics

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“…SKS splitting [ Buontempo et al , 2008; Diaz et al , 2010] and Pn data [ Serrano et al , 2005] reveal that seismic anisotropy directions are tangential to the geological trend of the arc, as a consequence of a subduction‐induced toroidal flow during slab roll‐back. Electrical anisotropy directions between the Betic Cordillera and the foreland Iberian Massif show orthogonal trends and decreasing magnitude, reflecting higher deformation toward the axis of the Eurasian‐African plate boundary due to the westward emplacement of the Internal Zones of the cordillera [ Ruiz‐Constán et al , 2010].…”

Section: Geological and Geophysical Settingmentioning

confidence: 99%

Stress distribution at the transition from subduction to continental collision (northwestern and central Betic Cordillera)

Ruíz-Constán

Galindo-Zaldı́var

Pedrera

et al. 2011

Geochem. Geophys. Geosyst.

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[1] We analyze focal mechanisms of shallow-intermediate earthquakes in a NW-SE transect along the western Betic Cordillera and Alboran Sea, and deep earthquakes located in the central Betics to constrain the state of stress at the Gibraltar Arc slow convergence area. Shallow earthquakes (<40 km) are preferably clustered at the mountain front. A general NW-SE horizontal compression is compatible with the convergence, and NW plunging compression axes are in agreement with frontal thrust activity. Toward the Alboran Sea the earthquakes are progressively deeper, reaching intermediate depths (40-120 km) near the coast and supporting the present-day activity of subduction only in this area. The Iberian continental crust concentrates most of the intermediate seismicity and is forced to partially sink into the mantle, probably through the pull of the oceanic slab. This downdip pull together with the buoyancy of the Iberian continental crust produces the slab curvature, downdip extension in the external arc of the continental slab, and downdip compression in the inner arc. T axes highly dipping to the southeast at 90-120 km depth occur at the oceanic/ continental transition. Deep earthquakes (>620 km) show very similar focal mechanisms, fitting the general slab behavior of resistance to further descent at the 660 km discontinuity. Seismicity features evidence the present-day stress distribution in a context of transition from subduction to continental collision.

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“…Other mid‐crustal conductive bodies correlated with the main thrust zones formed during Variscan shearing processes [ Monteiro Santos et al , 2002], as the contact between the South Portuguese and Ossa Morena Zones [ Almeida et al , 2001]. In the Betic Cordillera, MT studies have been traditionally focused on the crustal structure of its more active eastern part [ Pous et al , 1999; Martí et al , 2009; Pedrera et al , 2009, 2010], while west of the 4°W meridian they are scarce and mainly address the lithospheric structure and its implications for geodynamic models [ Ruiz‐Constán et al , 2010; Rosell et al , 2011].…”

Section: Previous Geophysical Researchmentioning

confidence: 99%

“…Since the 1970s, controlled‐source seismic experiments have been performed with the aim of determining the geometry of the Guadalquivir foreland basin in detail, as well as the main features of the crustal structure and Moho depth below the Betic Cordillera and its foreland [ Banda and Ansorge , 1980; Medialdea et al , 1986]. More recently, magnetotelluric studies have been applied, but traditionally focusing on the crustal structure of the eastern Betics and the southwestern Iberian Massif [ Pous et al , 1999, 2004; Martí et al , 2004, 2009; Pedrera et al , 2009, 2010], or regional deep crustal and lithospheric structures [ Ruiz‐Constán et al , 2010; Rosell et al , 2011]. West of the 4°W meridian there is a lack of resistivity data focused on shallow crustal structures.…”

Section: Introductionmentioning

confidence: 99%

Constraints on the frontal crustal structure of a continental collision from an integrated geophysical research: The central‐western Betic Cordillera (SW Spain)

Ruíz-Constán¹,

Pedrera²,

Galindo-Zaldı́var³

et al. 2012

Geochem Geophys Geosyst

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Mélange rocks outcrop widely in the central and western frontal sectors of the Betic Cordillera, as in many other collisional orogens where they form part of the accretionary wedges. Extrusion of Triassic plastic clays and evaporites was favored by the progressive accretion of the Betic External Zones, mixing rocks of different provenance and forming a synorogenic frontal mélange unit. MT data coupled with gravity data are a valid combined methodology to characterize the geometry of these mélange units, since the characterization of plastic rocks geometry is usually uncertain using seismic techniques. The results correlate well with known geological features (sedimentary basins, calcareous ranges, evaporitic rocks) and reveal the deep geometry. A resistive body, slightly dipping toward the SE, points to the continuity of the Iberian Massif below the Guadalquivir basin (2°) and the External Zones (6–8°). To the south, gravity models show the Iberian continental crust subducting below the Internal Zones with a roughly 20–35° slope. The main conductive bodies are related to the location of evaporitic rocks involved in the frontal mélange. They overlie the Iberian Massif and, southwards, the frontal Jurassic and Cretaceous limestone sequences of the External and Median Subbetics. In this setting, thick plastic rock units placed above the foreland could act as a lubricant facilitating continental subduction, and being progressively accreted toward a frontal mélange.

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Deep deformation pattern from electrical anisotropy in an arched orogen (Betic Cordillera, western Mediterranean)

Cited by 11 publications

References 25 publications

Is there an active subduction beneath the Gibraltar orogenic arc? Constraints from Pliocene to present-day stress field

Is there an active subduction beneath the Gibraltar orogenic arc? Constraints from Pliocene to present-day stress field

Stress distribution at the transition from subduction to continental collision (northwestern and central Betic Cordillera)

Constraints on the frontal crustal structure of a continental collision from an integrated geophysical research: The central‐western Betic Cordillera (SW Spain)

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