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A Paleogene extensional arc flare-up in Iran

Verdel, Charles and Wernicke, Brian P. and Hassanzadeh, Jamshid and Guest, Bernard (2011) A Paleogene extensional arc flare-up in Iran. Tectonics, 30 . Art. No. TC3008 . ISSN 0278-7407. http://resolver.caltech.edu/CaltechAUTHORS:20110712-132640320

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Abstract

Arc volcanism across Iran is dominated by a Paleogene pulse, despite protracted and presumably continuous subduction along the northern margin of the Neotethyan ocean for most of Mesozoic and Cenozoic time. New U-Pb and ^(40)Ar/^(39)Ar data from volcanic arcs in central and northern Iran constrain the duration of the pulse to ~17 Myr, roughly 10% of the total duration of arc magmatism. Late Paleocene-Eocene volcanic rocks erupted during this flare-up have major and trace element characteristics that are typical of continental arc magmatism, whereas the chemical composition of limited Oligocene basalts in the Urumieh-Dokhtar belt and the Alborz Mountains which were erupted after the flare-up ended are more consistent with derivation from the asthenosphere. Together with the recent recognition of Eocene metamorphic core complexes in central and east central Iran, stratigraphic evidence of Eocene subsidence, and descriptions of Paleogene normal faulting, these geochemical and geochronological data suggest that the late Paleocene-Eocene magmatic flare-up was extension related. We propose a tectonic model that attributes the flare-up to decompression melting of lithospheric mantle hydrated by slab-derived fluids, followed by Oligocene upwelling and melting of enriched mantle that was less extensively modified by hydrous fluids. We suggest that Paleogene magmatism and extension was driven by an episode of slab retreat or slab rollback following a Cretaceous period of flat slab subduction, analogous to the Laramide and post-Laramide evolution of the western United States.


Item Type:Article
Related URLs:
URLURL TypeDescription
http://dx.doi.org/10.1029/2010TC002809DOIArticle
ORCID:
AuthorORCID
Wernicke, Brian P.0000-0002-7659-8358
Additional Information:© 2011 American Geophysical Union. Received 8 October 2010; revised 16 February 2011; accepted 2 March 2011; published 22 June 2011. We acknowledge analytical assistance from Axel Schmitt of the UCLA Keck ion microprobe facility, Terry Spell of the Nevada Isotope Geochronology Lab, and Mike Rhodes of the University of Massachusetts. This research was supported by NSF grant EAR‐0511054 awarded to B. Wernicke, grant EAR‐0337775 awarded to G. Axen and B. Horton, and the Gordon and Betty Moore Foundation. The ion microprobe facility at UCLA is partly supported by a grant from the Instrumentation and Facilities Program, Division of Earth Sciences, National Science Foundation. Discussions with Gary Axen, John Eiler, Jahandar Ramezani, and Danny Stockli contributed significantly to the development of ideas in this paper. We appreciate constructive reviews from Philippe Agard, Mihai Ducea, Robert Miller, Chris Morley, and an anonymous reviewer. This is Caltech Tectonics Observatory contribution 148.
Group:Caltech Tectonics Observatory
Funders:
Funding AgencyGrant Number
NSFEAR-0511054
NSFEAR-0337775
Gordon and Betty Moore FoundationUNSPECIFIED
Subject Keywords:arc volcanism; extension-related volcanism; extensional tectonics
Other Numbering System:
Other Numbering System NameOther Numbering System ID
Caltech Tectonics Observatory 148
Record Number:CaltechAUTHORS:20110712-132640320
Persistent URL:http://resolver.caltech.edu/CaltechAUTHORS:20110712-132640320
Official Citation:Verdel, C., B. P. Wernicke, J. Hassanzadeh, and B. Guest (2011), A Paleogene extensional arc flare‐up in Iran, Tectonics, 30, TC3008, doi:10.1029/2010TC002809
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:24386
Collection:CaltechAUTHORS
Deposited By: Tony Diaz
Deposited On:13 Jul 2011 22:23
Last Modified:01 Feb 2017 00:46

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