@article{7d33b60cebb145fc9d4f5b8bd18245e0,
title = "Late Miocene Deformation Kinematics Along the NW Zagros Fold-Thrust Belt, Kurdistan Region of Iraq: Constraints From Apatite (U-Th)/He Thermochronometry and Balanced Cross Sections",
abstract = "Apatite (U-Th)/He (AHe) thermochronometric results are integrated with geologic cross sections, structural relationships, and stratigraphic data to reconstruct the growth of the NW Zagros orogenic belt in the Kurdistan region of Iraq. Prolonged exhumation is documented across the belt with deformation advances and retreats from ~14 Ma onward. After in-sequence propagation of deformation during middle to late Miocene times, preserved growth strata and AHe data show a deformation retreat by latest Miocene time (~5 Ma). In the NW Zagros, the Phanerozoic succession contains two principal d{\'e}collements in Lower Triassic and middle Miocene units. The Triassic strata are interpreted as the main d{\'e}collement for a thin-skinned system that was dominant during most of the Cenozoic. By ~8–5 Ma, the fold-thrust belt shifted to basement-involved deformation in association with growth of the mountain front flexure and reactivation of frontal structures. The shift from thin-skinned to a hybrid thin- and thick-skinned mode of shortening may reflect variations in the mechanical behavior of the upper crust and the presence of inherited basement discontinuities. On the basis of two NE-SW balanced cross sections spanning the NW Zagros, the estimated total minimum horizontal shortening is ~18.2 km (6%) in the central and ~16 km (7%) in the southern sectors of the Kurdistan region of Iraq. These findings suggest that the evolution of the NW Zagros orogenic belt was likely driven by the mechanical stratigraphy of the sedimentary cover, inherited basement discontinuities, and the dynamic and thermomechanical effects of potential slab breakoff and lithospheric mantle delamination events.",
keywords = "fold-thrust belt, out-of-sequence, slab breakoff, thermochronology, thin-skinned versus thick-skinned, Zagros",
author = "Koshnaw, {Renas I.} and Stockli, {Daniel F.} and Horton, {Brian K.} and Antonio Teixell and Barber, {Douglas E.} and Kendall, {Jerome J.}",
note = "Funding Information: This research was supported by an industry research grant awarded to PI Brian K. Horton and Co‐PI Daniel F. Stockli, and Geological Society of America Graduate Student Research Grants, the Jackson School of Geosciences Ronald K. DeFord Field Scholarship, and the American Ph.D. scholarship from the Iraq Scholars and Leaders Program awarded to Renas I. Koshnaw. We thank Mjahid M. Zebari, Bahroz G. Abdullah, Halo A. Fateh, Hajar R. Abdul Qadr, Mahdi K. Aswad, Bawar S. Ahmed, Rebwar A. Farman, and Rojgar H. Ali for providing logistical support and field assistance. We express gratitude to George A. Yacu at the Ministry of Natural Resources, Kurdistan Regional Government, Iraq, for facilitating the subsurface data sharing agreement. The Structural Geology group at the University of Bern, Switzerland, and the Structural Geology and Geodynamic group at the University of G{\"o}ttingen enabled use of Move software through academic licenses provided by Midland Valley‐Petex. We also thank Desmond B. Patterson, Lisa G. Stockli, Yomayra Roman, Michael G. Prior, and Spencer Seman for analytical assistance in the laboratory, and Jonas Kley and Martin R. Correa for scientific discussions. We extend gratitude to Nadine McQuarrie, Mark Allen, Jamshid Hassanzadeh, and the Editor Laurent Jolivet for their constructive criticism on an earlier version of the manuscript. Publisher Copyright: {\textcopyright}2020. American Geophysical Union. All Rights Reserved. Copyright: Copyright 2020 Elsevier B.V., All rights reserved.",
year = "2020",
month = dec,
doi = "10.1029/2019TC005865",
language = "English",
volume = "39",
journal = "Tectonics",
issn = "0278-7407",
number = "12",
}