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Accommodation of transpressional strain in the Arabia-Eurasia collision zone: new constraints from (U-Th)/He thermochronology in the Alborz mountains, north Iran

Ballato, Paolo and Stockli, Daniel F. and Ghassemi, Mohammad R. and Landgraf, Angela and Strecker, Manfred R. and Hassanzadeh, Jamshid and Friedrich, Anke and Tabatabaei, Saeid H. (2013) Accommodation of transpressional strain in the Arabia-Eurasia collision zone: new constraints from (U-Th)/He thermochronology in the Alborz mountains, north Iran. Tectonics, 32 (1). pp. 1-18. ISSN 0278-7407. https://resolver.caltech.edu/CaltechAUTHORS:20130522-162514020

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Abstract

The Alborz range of N Iran provides key information on the spatiotemporal evolution and characteristics of the Arabia-Eurasia continental collision zone. The southwestern Alborz range constitutes a transpressional duplex, which accommodates oblique shortening between Central Iran and the South Caspian Basin. The duplex comprises NW-striking frontal ramps that are kinematically linked to inherited E-W-striking, right-stepping lateral to obliquely oriented ramps. New zircon and apatite (U-Th)/He data provide a high-resolution framework to unravel the evolution of collisional tectonics in this region. Our data record two pulses of fast cooling associated with SW-directed thrusting across the frontal ramps at ~ 18–14 and 9.5-7.5 Ma, resulting in the tectonic repetition of a fossil zircon partial retention zone and a cooling pattern with a half U-shaped geometry. Uniform cooling ages of ~ 7–6 Ma along the southernmost E-W striking oblique ramp and across its associated NW-striking frontal ramps suggests that the ramp was reactivated as a master throughgoing, N-dipping thrust. We interpret this major change in fault kinematics and deformation style to be related to a change in the shortening direction from NE to N/NNE. The reduction in the obliquity of thrusting may indicate the termination of strike-slip faulting (and possibly thrusting) across the Iranian Plateau, which could have been triggered by an increase in elevation. Furthermore, we suggest that ~ 7-6-m.y.-old S-directed thrusting predated inception of the westward motion of the South Caspian Basin.


Item Type:Article
Related URLs:
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http://dx.doi.org/10.1029/2012TC003159DOIUNSPECIFIED
http://onlinelibrary.wiley.com/doi/10.1029/2012TC003159/abstractPublisherUNSPECIFIED
Additional Information:© 2013 American Geophysical Union. Received 18 May 2012; accepted 20 November 2012; published 28 January 2013. This research was funded by the German Science Foundation (DFG) with the Leibniz Award to M.R.S. (STR 373/16-1) and grant (STR 373/19-1) to M.R.S. and A.F., the graduate-school program of Potsdam University (GRK1364), the U.S. National Science Foundation (EAR-9902932 to Gary Axen), and the University of Tehran Research Council (651/1/328 to J.H.). We are indebted to the Tehran Building and Housing Research Center and the Geological Survey of Iran for logistical support. T. Roeper is thanked for help with sample preparation. We are grateful to B. Ghorbal, R. Kislitsyn, S. Brichau and students of the (U–Th)/He laboratory at the University of Kansas for providing technical support. E. Kirby, E. Macaulay, R. Sobel, R. Thiede and J. Zamagni are thanked for discussions and suggestions. T. Schildgen is thanked for her help with the text and constructive comments. We also acknowledge Tectonics editor O. Oncken, the associate editor, J. Spotila, and an anonymous reviewer for their constructive reviews. P.B. thanks A. Moeller, B. Mocek and the Stockli family for their hospitality while staying at the University of Kansas. This work is dedicated to the late B. Mocek.
Funders:
Funding AgencyGrant Number
German Science Foundation (DFG)STR 373/16-1
German Science Foundation (DFG)STR 373/19-1
Potsdam UniversityGRK1364
NSFEAR-9902932
University of Tehran Research Council651/1/328
Subject Keywords:transpressional duplex; U-Th/He thermochronology; Arabia Eurasia collision zone; fault reactivation; Alborz range; Iran
Issue or Number:1
Record Number:CaltechAUTHORS:20130522-162514020
Persistent URL:https://resolver.caltech.edu/CaltechAUTHORS:20130522-162514020
Official Citation:Ballato, P., D. F. Stockli, M. R. Ghassemi, A. Landgraf, M. R. Strecker, J. Hassanzadeh, A. Friedrich, and S. H. Tabatabaei (2012), Accommodation of transpressional strain in the Arabia-Eurasia collision zone: new constraints from (U-Th)/He thermochronology in the Alborz mountains, N Iran, Tectonics, 32, 1–18, doi: 10.1029/2012TC003159.
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:38642
Collection:CaltechAUTHORS
Deposited By: Jason Perez
Deposited On:23 May 2013 17:39
Last Modified:03 Oct 2019 04:59

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