Cinématique de l'Iran central et oriental : Morphotectonique et datations cosmogéniques et OSL

Abstract : This study presents the results of geomorphological analysis on faults kinematics in central and eastern Iran. According to GPS measurements, the right-lateral shear between central Iran and Afghan block amounts to 16 mm/yr (Vernant et al., 2004 ; Masson et al., 2007) and might be accommodated by strike-slip faulting limited to the western and eastern edges of the Lut block (Walker et al., 2004). However the geological slip-rate of these faults is poorly constrained as for the faults located within the Iranian plateau, where limited activity is inferred. We demonstrate the ongoing activity of the Anar and Deshir right-lateral strike-slip faults located on the plateau and establish their geological slip-rate averaged on several seismic cycles. We combined cumulative offset of alluvial fan surfaces measurements with their ages obtained by cosmic ray exposure dating (10Be et 36Cl) and optically stimulated luminescence dating (OSL). The comparison of surface and near-surfaces ages and concentrations reveals the occurrence of a variable and significant inheritance in the alluvial material and we suggest a method to estimate the minimum amount of inheritance. We derived minimum slip-rates of 0.8 mm/yr and 0.85-2 mm/an for the Anar and Deshir faults, respectively. These results suggest that the right-lateral shear between central and eastern Iran might affect a wider region than the Lut block and its boundaries and is accommodated by a larger number of faults than initially suggested. Geological and GPS data are in insufficient number to determine if there are incompatibilities between finite and instantaneous deformation.
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Submitted on : Thursday, June 24, 2010 - 1:46:18 PM
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Kristell Le Dortz. Cinématique de l'Iran central et oriental : Morphotectonique et datations cosmogéniques et OSL. Tectonique. Université Pierre et Marie Curie - Paris VI, 2010. Français. ⟨tel-00494966⟩

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