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The dynamics of forearc - back-arc vertical motion: numerical models and observations from the Mediterranean
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  • Attila Balazs,
  • Claudio Faccena,
  • Taras V. Gerya,
  • Kosuke Ueda,
  • Francesca Funiciello
Attila Balazs
ETH Zurich

Corresponding Author:attila.balazs@erdw.ethz.ch

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Claudio Faccena
Universita Roma TRE
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Taras V. Gerya
Swiss Federal Institute of Technology (ETH-Zurich)
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Kosuke Ueda
ETH Zürich
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Francesca Funiciello
Università Degli Studi Roma Tre (Rome, Italy)
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The evolution of subduction zones influences the rise and demise of forearc and back-arc basins on the overriding plate. We conducted 2D elasto-visco-plastic numerical models of oceanic subduction and subsequent continental collision which include erosion, sedimentation, and hydration processes. The models show the evolution of wedge-top and retro-forearc basins in the continental overriding plate, separated by a forearc high. These forearc regions are affected by repeated compression and extension phases. Higher subsidence rates are recorded in the syncline structure of the retro-forearc basin when the slab dip angle is higher and the subduction interface is stronger and before the slab reaches the 660 km upper-lower mantle discontinuity. The 3-4 km negative residual topographic signal is produced by the gradually steepening slab, which drags down the overlying upper plate. Extensional back-arc basins are either formed along inherited crustal or lithospheric weak zones at large distance from the arc region or are created above the hydrated mantle wedge originating from arc rifting. Back-arc subsidence is primarily governed by crustal thinning controlled by slab roll-back. Onset of collision and continental subduction is linked to the rapid uplift of the forearc basins; however, the back-arc region records ongoing extension during the initial phase of soft collision. Finally, during subsequent hard collision both the forearc and back-arc basins are ultimately affected by compression. Our modelling results provide insights into the evolution of Mediterranean subduction zones and propose that the Western-Eastern Alboran, Paola-Tyrrhenian, Transylvanian-Pannonian Basins should be considered as genetically connected forearc –back-arc basins, respectively.