Majerad Gabbrodiorites in the Southeast of Shahrood:  Evidence to Starting of Opening of the Supra-Subduction Basin of the Sabzevar Neotethyian Branch in the Middle Jurassic

Veiskarami, Marzieh; Sadeghian, Mahmoud; Payam Shahvali kohshori, Payam; Ghasemi, , Habibollah; Zhai, Minggou

doi:10.29252/gnf.5.2.293

Volume 5, Issue 2 (Autumn&Winter 2020) KJES 2020, 5(2): 293-314 | Back to browse issues page

‎ 10.29252/gnf.5.2.293

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Veiskarami M, Sadeghian M, Payam Shahvali kohshori P, Ghasemi , H, Zhai M. Majerad Gabbrodiorites in the Southeast of Shahrood: Evidence to Starting of Opening of the Supra-Subduction Basin of the Sabzevar Neotethyian Branch in the Middle Jurassic. KJES 2020; 5 (2) :293-314
URL: http://gnf.khu.ac.ir/article-1-2632-en.html

Majerad Gabbrodiorites in the Southeast of Shahrood: Evidence to Starting of Opening of the Supra-Subduction Basin of the Sabzevar Neotethyian Branch in the Middle Jurassic

Marzieh Veiskarami ^*

¹, Mahmoud Sadeghian²

, Payam Payam Shahvali kohshori²

, , Habibollah Ghasemi²

, Minggou Zhai³

1- Shahrood University of Technology , veiskaramim@gmail.com
2- Shahrood University of Technology
3- - State Key Laboratory of Lithospheric Evolution, Northwest University Xian

Abstract: (2709 Views)

Late Neoproterozoic Majerad igneous - metamorphic complex basement with NE-SW trend is located in the 150 km southeast of Shahrood and north edge of the Central Iran structural zone. Similar to the other complex basement of southeast Shahrood, in the north of Majerad- passage, this complex crosscut by several small scale gabbrodioritic intrusions and numerous diabasic dikes. Field evidences of fractionation from gabbro to tonalite are observed in these gabbrodiorite intrusions. These gabrrodiorites show granular, ophitic, subophitic and poikilitic textures and composed of augitic clinopyroxene, green hornblende, plagioclase and biotite (as an essential minerals). Magma forming of these rocks has calc-alkaline nature and is enriched in large ion lithophile elements (LILEs) and also light rare earth elements (LREEs) and depleted in high field strength elements (HFSEs) and heavy rare earth elements (HREEs). For the first time U-Pb age dating on zircons seperated from the gabbrodiorites, represented an average age around 166 million years (equivalent to middle Jurassic) for their formation. These magmas originated from the partial melting of the metasomatized subcontinental lithosoheric mantle source with spinel- lherzolithic primary nature in an extensional intracontinental back arc basin tectonic setting located on the subduction zone of the Zagros Neothetyan basin on the northern edge of Central Iran structural zone during the middle Jurassic.

Keywords: Gabbrodiorites, Middle Jurassic, Neothetys, Majerad, Shahrood.

Full-Text [PDF 1891 kb] (913 Downloads)

Subject: Petrology
Received: 2017/12/28 | Accepted: 2018/12/3 | Published: 2020/02/10