Active surface deformation and sub-lithospheric processes in the western Mediterranean constrained by numerical models
Summary (1 min read)
INTRODUCTION
- The authors modeling studies demonstrate the need for sub-crustal or sub-lithospheric, southwestward-directed forcing to account for observed southwestward motion of the Rif and Betic domains.
- The authors then discuss the implications of these model results in light of previous geodynamic models of the plate boundary zone.
TECTONIC SETTING OF THE WESTERN MEDITERRANEAN
- In the western Mediterranean, the Alboran Sea is a thinned continental domain (15 km thickness; Lonergan and White 1997) surrounded by the Internal Rif and Internal Betics , which are the westernmost limit of the Alpine mountain belt (Fig. 1).
- Three factors are likely to infl uence the spatial distribution of the interseismic strain 1) lateral plate driving forces due to long term Nubia-Eurasia oblique convergence, 2) low rigidity of the diffuse plate boundary zone, and 3) deep traction beneath the plate boundary due to upper mantle drag or slab traction.
- The RMSs for the entire zone and for the Rif-Betics region are summarized in Table 1.
- Depending on the thermal regime, the effective elastic thickness of continental plates varies from 3 to 80 km (Watts and Burov, 2003).
DISCUSSION AND GEODYNAMIC IMPLICATIONS
- The authors modeling experiments include no a priori information on sub-lithospheric geometry and are designed to determine whether sublithospheric processes are needed to account for observed deformation of the western Mediterranean region.
- Geodynamic models of the zone involving still active westward rollback of the western Mediterra- nean narrow slab (Gutscher et al., 2002) cannot generate such a small coupling zone confi ned to the External Rif. Spakman and Wortel (2004) suggested that the western Mediterranean slab is detached under the Betics.
- The authors further suggest that the horizontal traction patch could represent the remaining coupling zone between the slab and the overlying continental lithosphere.
- According to their delamination model (Fig. 3) the traction zone is expected to move to the south-southwest following propagation of the delamination front.
- During the Pliocene-Quaternary, eastward subduction has died out, as suggested by the accretionary wedge sealed by undeformed sediments (Zitellini et al., 2009).
ACKNOWLEDGMENTS
- The authors thank G. Bokelmann, S. Lallemand and J.L. Bodinier for their fruitful discussions, and to C. Faccenna and fi ve anonymous reviewers for their constructive comments on this manuscript.
- Reilinger benefi ted from a Visiting Researcher Fellowship from the Observatoire de Recherche Méditerranéen en Environnement of Montpellier while engaged in this study.
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Cites background from "Active surface deformation and sub-..."
...There are GPS and paleomagnetic evidences of active radial motion of the Betic and Riff nappes (Cifelli et al., 2008; Pérouse et al., 2010) and the tomography would also suggest an E-ward dipping slab (Gutscher et al., 2002; Spakman and Wortel, 2004)....
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...There are GPS and paleomagnetic evidences of active radial motion of the Betic and Riff nappes (Cifelli et al., 2008; Pérouse et al., 2010) and the tomography would also suggest an E-ward dipping slab (Gutscher et al....
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References
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121 citations
"Active surface deformation and sub-..." refers background in this paper
...…1997; Gutscher et al., 2002; Faccenna et al., 2004), which passively falls in the mantle driven by its own weight (subduction without convergence, Jolivet et al. 2008) ; (2) break-off of a subducting lithospheric slab (Blanco and Spakman, 1993); (3) crustal extrusion due to forces transmitted…...
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...Slab rollback, that has already been proposed for the overall formation of the Alboran Sea (e.g., Jolivet et al., 2008), may be involved....
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114 citations
101 citations
"Active surface deformation and sub-..." refers background in this paper
...The mechanism responsible for the continental and oceanic nature of the slab (delamination or continental subduction) is still debated (Faccenna et al. 2004; Duggen et al. 2008)....
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...…modeling experiments do not allow us to constrain the depth of the delamination processes, which could be inside the continental lithospheric mantle (Duggen et al., 2008), at the Moho interface, or confi ned to the crust at the brittle-ductile transition of the lower crust (Gueydan et al., 2003)....
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...According to geochemical studies of igneous rocks of the zone, beneath the Alboran Basin the slab is a remnant part of the Tethys oceanic lithosphere, but beneath the External Betics and Rif it consists of delaminated (or subducted) continental lithosphere (Duggen et al. 2008)....
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57 citations
"Active surface deformation and sub-..." refers background in this paper
...This effective elastic thickness difference is equivalent to an elastic plate of constant thickness with a factor of 10 difference in rigidity contrast (Chéry, 2008)....
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