Late Cenozoic and modern stress fields in the western Fars (Iran): Implications for the tectonic and kinematic evolution of central Zagros
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In this paper, the inversion of focal mechanisms from small and moderate earthquakes shows a consistent N020°-030° compression with a low ratio between differential stresses. But the authors do not consider the impact of small earthquakes on the stability of the strike-slip faults.Abstract:
[1] The Zagros (Iran) developed during Mio-Pliocene times in response to Arabia-Eurasia convergence. The western Fars highlights a major bend of the deformation front and displays a remarkable set of nearly N-S right-lateral strike-slip faults (the Kazerun-Borazjan/Karebass/Sabz-Pushan/Sarvestan faults) oblique at high angle to the belt. The region likely plays a major kinematic role by accommodating the change in shortening modes from partitioned in the western central Zagros to nonpartitioned in the eastern Zagros. The inversion of focal mechanisms from small and moderate earthquakes shows a consistent N020°–030° compression with a low ratio between differential stresses. This regime accounts for the combination of strike-slip and thrust-type mechanisms through likely σ2/σ3 permutations. Fault slip analysis reveals two successive late Cenozoic regional compressional trends, NE-SW then N020°. The latter is in good agreement with the present-day stress. The significance of the NE-SW compression is discussed alternatively in terms of stress deviations or block rotations in relation to the strike-slip fault system. Fieldwork and satellite imagery suggest that these faults behave first as transfer faults during folding of the cover and later as strike-slip faults, in agreement with the succession of stress regimes and the evolution of the dominant deformation style from thin-skinned to thick-skinned. The first-order stability of the collision-related state of stress since ∼5 Ma supports that the Arabia-Eurasia convergence did not give rise to partitioning in the western Fars but rather was (and is still) accommodated by distributed deformation involving both shortening and strike-slip motion throughout the cover and the basement.read more
Citations
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Zagros orogeny: a subduction-dominated process
Philippe Agard,Jafar Omrani,Laurent Jolivet,Hubert Whitechurch,Bruno Vrielynck,Wim Spakman,Patrick Monié,Bertrand Meyer,Rinus Wortel +8 more
TL;DR: In this paper, the authors presented a synthetic view of the geodynamic evolution of the Zagros orogen within the frame of the Arabia-Eurasia collision, and provided lithospheric-scale reconstructions of the zagros Orogen from ~ 150 to 0 Ma across two SW-NE transects.
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Building the Zagros collisional orogen: Timing, strain distribution and the dynamics of Arabia/Eurasia plate convergence
TL;DR: In this paper, the authors show that only 42% of the post-35 Ma convergence is partitioned by shortening within central Iran, and the current subduction dynamics can be explained by the original lateral difference in the buoyancy of the distal margin.
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Central Zagros fold‐thrust belt (Iran): New insights from seismic data, field observation, and sandbox modeling
TL;DR: In this paper, the authors present five generalized cross sections across the central Zagros fold-and-thrust belt (Iran) showing that the fold geometry varies significantly both horizontally and vertically.
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Comparisons of the kinematics and deep structures of the Zagros and Himalaya and of the Iranian and Tibetan plateaus and geodynamic implications
Denis Hatzfeld,Peter Molnar +1 more
TL;DR: In this paper, the authors compare the geologic histories, the deep structures, and the present-day kinematics of deformation of the Himalaya and the adjacent Tibetan Plateau with those of the Zagros and Iranian Plateau to test geodynamic processes of continental collision.
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Tertiary sequence of deformation in a thin‐skinned/thick‐skinned collision belt: The Zagros Folded Belt (Fars, Iran)
Frédéric Mouthereau,Julien Tensi,Nicolas Bellahsen,Olivier Lacombe,T. de Boisgrollier,S. Kargar +5 more
TL;DR: In this article, the authors describe how thin-skinned/thick-skinned deformation in the Zagros Folded Belt interacted in time and space, and estimate a total shortening of 65-78 km (16-19%).
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