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Crustal thickness and images of the lithospheric discontinuities in the Gibraltar arc and surrounding areas

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Mancilla Pérez, Flor de Lis and Stich, Daniel and Morales, José and Martín, Rosa and Díaz, Jordi and Pazos, Antonio and Córdoba Barba, Diego and Pulgar, Javier A. and Ibarra, Pedro and Harnafi, Mimoun and González Lodeiro, Francisco (2015) Crustal thickness and images of the lithospheric discontinuities in the Gibraltar arc and surrounding areas. Geophysical Journal International, 2013 (3). pp. 1804-1820. ISSN 0956-540X

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Official URL: http://dx.doi.org/10.1093/gji/ggv390


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Abstract

The Gibraltar arc and surrounding areas are a complex tectonic region and its tectonic evolution.since Miocene is still under debate. Knowledge of its lithospheric structure will help to.understand the mechanisms that produced extension and westward motion of the Alboran domain,.simultaneously withNW–SE compression driven by Africa–Europe plates convergence..We perform a P-wave receiver function analysis in which we analyse new data recorded at.83 permanent and temporary seismic broad-band stations located in the South of the Iberian.peninsula. These data are stacked and combined with data from a previous study in northern.Morocco to build maps of thickness and average vP/vS ratio for the crust, and cross-sections.to image the lithospheric discontinuities beneath the Gibraltar arc, the Betic and Rif Ranges.and their Iberian and Moroccan forelands. Crustal thickness values show strong lateral variations.in the southern Iberia peninsula, ranging from ∼19 to ∼46 km. The Variscan foreland is.characterized by a relatively flat Moho at ∼31 km depth, and an average vP/vS ratio of ∼1.72,.similar to other Variscan terranes, which may indicate that part of the lower crustal orogenic.root was lost. The thickest crust is found at the contact between the Alboran domain and the.External Zones of the Betic Range, while crustal thinning is observed southeastern Iberia.(down to 19 km) and in the Guadalquivir basin where the thinning at the Iberian paleomargin.could be still preserved. In the cross-sections, we see a strong change between the eastern.Betics, where the Iberian crust underthrusts and couples to the Alboran crust, and the western.Betics, where the underthrusting Iberian crust becomes partially delaminated and enters into.the mantle. The structures largely mirror those on the Moroccan side where a similar detachment.was observed in northern Morocco. We attribute a relatively shallow strong negativepolarity.discontinuity to the lithosphere-asthenosphere boundary. This means relatively thin.lithosphere ranging from ∼50 km thickness in southeastern Iberia and northeastern Morocco.to ∼90–100 km beneath the western Betics and the Rif, with abrupt changes of ∼30 km under.the central Betics and northern Morocco. Our observations support a geodynamic scenario.where in western Betics oceanic subduction has developed into ongoing continental subduction/delamination while in eastern Betics this process is inactive.


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© The Authors 2015. Published by Oxford University Press on behalf of The Royal Astronomical Society.
We deeply acknowledge the comments and suggestions made by the editor S. Goes. The reviewers N. Piana Agostti and an anonymous helped to improve the manuscript.We are grateful to the staff of the permanent networks for providing relevant data and to all members of the TopoIberia Seismic Working Group for their hard work in the acquisition and processing of field data. This work is part of the Consolider- Ingenio 2010 project TOPO-IBERIA (CSD2006- 00041). Additional funding was provided by projects CGL2006- 01171, CGL2008-01830, P09-RNM-5100 and CGL2012-31472. We acknowledge work on free software SAC (Goldstein et al. 1999) and GMT (Wessel & Smith 1998).

Uncontrolled Keywords:Subduction zone processes; Continental margins: convergent; Neotectonics; Crustal structure
Subjects:Sciences > Physics > Geophysics
ID Code:36569
Deposited On:12 Apr 2016 16:02
Last Modified:20 Apr 2016 08:35

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