Accommodation of Arabia-Eurasia convergence in the Zagros-Makran transfer zone, SE Iran: A transition between collision and subduction through a young deforming system

V. Regard (1) , O. Bellier (1) , J. -C. Thomas (2) , M. R. Abbassi , J. Mercier (3) , E. Shabanian , K. Feghhi , S. Soleymani

1 CEREGE - Centre européen de recherche et d'enseignement des géosciences de l'environnement
2 LGIT - Laboratoire de Géophysique Interne et Tectonophysique
3 UP11 - Université Paris-Sud - Paris 11

At Iranian longitude, the Arabian plate is moving northward relative to Eurasia (∼20 mm yr^-1 according to GPS). To the east, this relative motion is accommodated by northward subduction under the E-W Makran emerged accretionary prism. To the west, it is accommodated partly by the Zagros fold-and-thrust belt and partly by the Alborz/Kopet Dagh deforming zones further north. This work investigates the NNW striking transition zone that connects Zagros and Makran: the Minab-Zendan fault system. Satellite images, and structural and geomorphic field observations show a distributed deformation pattern covering a wide domain. Five north to NW trending major faults were identified. They exhibit evidence for late Quaternary reverse right-lateral slip, and correspond to two distinct fault systems: the western one transferring the Zagros deformation to the Makran prism, and the eastern one northward transferring the deformation to the Alborz/Kopet Dagh. Tectonic study and fault slip vector analyses indicate that two distinct tectonic regimes have occurred successively since the Miocene within a consistent regional NE trending compression: (1) an upper Miocene to Pliocene tectonic regime characterized by partitioned deformation, between reverse faulting and en echelon folding; (2) a NE trending σ₁ axis transpressional regime homogeneously affecting the region since upper Pliocene. The change is contemporaneous with major tectonic reorganization regionally recorded. Therefore this study provides evidence for active deformation that is not localized, but distributed across a wide zone. It accommodates the convergence and transfers it from collision to subduction by transpressional tectonics without any partitioning process in the present-day period.

Domaines: Planète et Univers [physics]

V. Regard, O. Bellier, J. -C. Thomas, M. R. Abbassi, J. Mercier, et al.. Accommodation of Arabia-Eurasia convergence in the Zagros-Makran transfer zone, SE Iran: A transition between collision and subduction through a young deforming system. Tectonics, 2004, 23, ⟨10.1029/2003TC001599⟩. ⟨insu-03607128⟩