Delamination in the Betic Range: Deep structure, seismicity, and GPS motion

Mancilla, Flor de Lis; Stich, Daniel; Berrocoso, Manuel; Martín, Ricardo Muñoz; Morales, J.; Fernández-Ros, A.; Páez, R.; Pérez-Peña, Alejandro

doi:10.1130/g33733.1

Cited by 74 publications

(86 citation statements)

References 26 publications

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“…This active shortening is manifested by the concentration of shallow seismicity in the mountain front (Ruiz-Constan et al 2009; Supporting Information Fig. SM1b) with predominant reverse-faulting mechanisms (Stich et al 2003(Stich et al , 2006(Stich et al , 2010, and the GPS velocity field measurements (Stich et al 2006;Mancilla et al 2013). These observations support a current geodynamic scenario where oceanic subduction has developed into a continental subduction/delamination process in western Betics.…”

Section: Active Underthrusting In the Western Betics With The Observasupporting

confidence: 64%

“…On both sides of the Alboran Sea, these reflectors have an apparent eastward dip and reach depths of 60-70 km near ∼3.5 • W in central Betics and ∼50 km under the east edge of the Rif. These subcrustal reflectors coincide with areas of GPS motion on both sides of the Alboran sea significantly deviates from the current African-Iberian convergence direction (Fadil et al 2006;Koulali et al 2011;Mancilla et al 2013). These anomalies are stronger in Northern Morocco (Fadil et al 2006;Koulali et al 2011) and provide evidence for the important role of active subcrustal tectonics in the Iberia-Maghreb plate boundary zone (Fadil et al 2006;Koulali et al 2011;Mancilla et al 2013).…”

Section: Comparison Between the Betic And The Rif Domainsmentioning

confidence: 81%

“…The relatively dense coverage of seismic stations resulted in an average inter-station distance of ∼60 km for the TopoIberia consortium network and ∼30 km for the INDALO experiment. To complement our analysis, we included the PRF obtained by Mancilla et al (2013) from 26 stations located in North Morocco (black triangle in Fig. 1).…”

Section: Geological Setting and Previous Analysismentioning

confidence: 99%

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

Mancilla

Stich

Morales

et al. 2015

Geophysical Journal International

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S U M M A R YThe 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 with NW-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 v P /v S 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 v P /v S 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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Section: Active Underthrusting In the Western Betics With The Observasupporting

confidence: 64%

Section: Comparison Between the Betic And The Rif Domainsmentioning

confidence: 81%

Section: Geological Setting and Previous Analysismentioning

confidence: 99%

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

Mancilla

Stich

Morales

et al. 2015

Geophysical Journal International

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“…16 an anomalously thick crust (> 50 km) in the westernmost Gibraltar arc (Mancilla et al, 2013), where topography is relatively low.…”

Section: Accepted M Manuscriptmentioning

confidence: 99%

“…Mancilla et al, 2013;Mancilla et al, 2012). To fill the gaps, we have computed receiver functions at other stations with available waveform data for which we determined the Moho depth.…”

Section: Accepted M Manuscriptmentioning

confidence: 99%

Subduction and volcanism in the Iberia–North Africa collision zone from tomographic images of the upper mantle

et al. 2015

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Subduction and volcanism in the Iberia-North Africa collision zone from tomographic images of the upper mantle, Tectonophysics (2015Tectonophysics ( ), doi: 10.1016Tectonophysics ( /j.tecto.2015 This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.A C C E P T E D M A N U S C R I P T ACCEPTED MANUSCRIPT A C C E P T E D M A N U S C R I P T ACCEPTED MANUSCRIPT2 AbstractNew tomographic images of the upper mantle beneath the westernmost Mediterranean suggest that the evolution of the region experienced two subduction-related episodes. First subduction of oceanic and/or extended continental lithosphere s, now located mainly beneath the Betics at depths greater than 400 km, took place on a NW-SE oriented subduction zone. This was followed by a slab-tear process that initiated in the east and propagated to the west, leading to westward slab rollback and possibly lower crustal delamination. The current position of the slab tear is located approximately at 4W, and to the west of this location the subducted lithosphere is still attached to the surface along the Gibraltar arc. Our new P-wave velocity model is able to image the attached subducted lithosphere as a narrow high-velocity body extending to shallow depths, coinciding with the region of maximum curvature of the Gibraltar Arc, the occurrence of intermediate-depth earthquakes, and anomalously thick crust. This thick crust has a large influence in the measured teleseismic travel time residuals and therefore in the obtained Pwave tomographic model. We show that removing the effects of the thick crust significantly improves the shallow images of the slab and therefore the interpretations based on the seismic structure.

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A geodetic plate motion and Global Strain Rate Model

Kreemer

Blewitt

Klein

2014

Geochem. Geophys. Geosyst.

782

785

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We present a new global model of plate motions and strain rates in plate boundary zones constrained by horizontal geodetic velocities. This Global Strain Rate Model (GSRM v.2.1) is a vast improvement over its predecessor both in terms of amount of data input as in an increase in spatial model resolution by factor of $2.5 in areas with dense data coverage. We determined 6739 velocities from time series of (mostly) continuous GPS measurements; i.e., by far the largest global velocity solution to date. We transformed 15,772 velocities from 233 (mostly) published studies onto our core solution to obtain 22,511 velocities in the same reference frame. Care is taken to not use velocities from stations (or time periods) that are affected by transient phenomena; i.e., this data set consists of velocities best representing the interseismic plate velocity. About 14% of the Earth is allowed to deform in 145,086 deforming grid cells (0.25 longitude by 0.2 latitude in dimension). The remainder of the Earth's surface is modeled as rigid spherical caps representing 50 tectonic plates. For 36 plates we present new GPS-derived angular velocities. For all the plates that can be compared with the most recent geologic plate motion model, we find that the difference in angular velocity is significant. The rigid-body rotations are used as boundary conditions in the strain rate calculations. The strain rate field is modeled using the Haines and Holt method, which uses splines to obtain an self-consistent interpolated velocity gradient tensor field, from which strain rates, vorticity rates, and expected velocities are derived. We also present expected faulting orientations in areas with significant vorticity, and update the no-net rotation reference frame associated with our global velocity gradient field.Finally, we present a global map of recurrence times for M w 57.5 characteristic earthquakes.

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Delamination in the Betic Range: Deep structure, seismicity, and GPS motion

Cited by 74 publications

References 26 publications

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

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

Subduction and volcanism in the Iberia–North Africa collision zone from tomographic images of the upper mantle

A geodetic plate motion and Global Strain Rate Model

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