CaltechAUTHORS
  A Caltech Library Service

Geochronology and geochemistry of subducted Cadomian continental basement in central Iran: Decompressional anatexis along the Jurassic Neotethys margin

Ashtiani, Rezvaneh Jamali and Hassanzadeh, Jamshid and Schmitt, Axel K. and Sudo, Masafumi and Timmerman, Martin and Günter, Christina and Sobel, Edward (2020) Geochronology and geochemistry of subducted Cadomian continental basement in central Iran: Decompressional anatexis along the Jurassic Neotethys margin. Gondwana Research, 82 . pp. 354-366. ISSN 1342-937X. https://resolver.caltech.edu/CaltechAUTHORS:20200220-140842000

Full text is not posted in this repository. Consult Related URLs below.

Use this Persistent URL to link to this item: https://resolver.caltech.edu/CaltechAUTHORS:20200220-140842000

Abstract

Late Neoproterozoic-Early Cambrian calc-alkaline granitoids are ubiquitous in the continental basement of Iran and indicate formation within a Cadomian arc system at the northern margin of Gondwana. A basement complex comprising mainly mica schist, paragneisses, and metagranite along with metabasite and rare pegmatite is exposed in the Zayanderud region north of Shahrekord located in the hinterland of the Zagros mountain range. This complex is unique in the Neotethyan realm because it includes eclogites with Jurassic metamorphic ages implying involvement of continental crust at the onset of subduction. Ion microprobe U Pb zircon dating along with trace element and oxygen isotope analyses for metagranites define two zircon age clusters of ca. 552 and 565 Ma confirming connection with the other Ediacaran age basement arc plutons in the belt. Zircon geochronology for pegmatite, by contrast, yielded a concordant age population averaging 176.5 ± 3.3 (2σ) Ma. Zircon crystals from the pegmatite also have unusually low rare earth element (REE) abundances with sharp increases towards the heavy REE. Along with an absence of a negative Eu anomaly, this indicates a high-grade metamorphic origin of zircon crystallizing from a pegmatite which was formed by melting of mica schist and possibly amphibole eclogite during decompression where incipient garnet breakdown released Zr and HREE to form zircon, and LREE were retained in stable apatite and titanite. Corresponding ⁴⁰Ar/³⁹Ar phengite dates from the pegmatite and the mica schist country-rock are overlapping with or only slightly postdate the U Pb zircon ages, indicating rapid cooling after reaching maximum metamorphic pressure in the Early Jurassic. The Zayanderud basement complex is thus potentially a rare example of deep burial of continental crust and rapid exhumation due to buoyant escape during the incipient stages of subduction, well before the ultimate closing of the Neotethys ocean basin between Arabia and Eurasia in the mid-Tertiary.


Item Type:Article
Related URLs:
URLURL TypeDescription
https://doi.org/10.1016/j.gr.2020.01.005DOIArticle
Additional Information:© 2020 Published by Elsevier B.V. on behalf of International Association for Gondwana Research. Received 9 October 2019, Revised 4 December 2019, Accepted 6 January 2020, Available online 19 February 2020.
Funders:
Funding AgencyGrant Number
Universität PotsdamUNSPECIFIED
Deutscher Akademischer Austauschdienst (DAAD)UNSPECIFIED
Shahid Beheshti UniversityUNSPECIFIED
Subject Keywords:Neotethys Ocean; Jurassic subduction; High-pressure metamorphism; Eclogite; Partial melting
Record Number:CaltechAUTHORS:20200220-140842000
Persistent URL:https://resolver.caltech.edu/CaltechAUTHORS:20200220-140842000
Official Citation:Rezvaneh Jamali Ashtiani, Jamshid Hassanzadeh, Axel K. Schmitt, Masafumi Sudo, Martin Timmerman, Christina Günter, Edward Sobel, Geochronology and geochemistry of subducted Cadomian continental basement in central Iran: Decompressional anatexis along the Jurassic Neotethys margin, Gondwana Research, Volume 82, 2020, Pages 354-366, ISSN 1342-937X, https://doi.org/10.1016/j.gr.2020.01.005. (http://www.sciencedirect.com/science/article/pii/S1342937X20300538)
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:101428
Collection:CaltechAUTHORS
Deposited By: Tony Diaz
Deposited On:20 Feb 2020 22:24
Last Modified:09 Mar 2020 19:38

Repository Staff Only: item control page