Volume 3, Issue 2 (Autumn&Winter 2017)                   KJES 2017, 3(2): 161-182 | Back to browse issues page


XML Persian Abstract Print


Download citation:
BibTeX | RIS | EndNote | Medlars | ProCite | Reference Manager | RefWorks
Send citation to:

Fazlnia A. Geochemical and Tectonomagmatic Evolution of the Alkali-syenite-syenite from the North and West Sardasht, Iran. KJES 2017; 3 (2) :161-182
URL: http://gnf.khu.ac.ir/article-1-2579-en.html
Urmia University , a.fazlnia@urmia.ac.ir
Abstract:   (2311 Views)

Ring-type Eocene-Miocene alkali syenite-syenite intrusions of the North and West Sardasht are part of north Sanandaj–Sirjan zone. The syenitic rocks are located in the central part of the complex near the appinite-gabbro outcrops. Field and microscopic evidences indicate that magma mingling between alkali syenite and appinite-gabbro magmas has occurred to form intermediate parts as syenite in some outcrops. Felsic outcrops are mainly composed of alkali feldspar in the form of perthite. Enclaves of olivine, clinopyroxene, plagioclase, and amphibole along with a few opaque minerals and apatite were formed in the syenites. The main textures of the rocks are granular and lamination. The high ratios of (La/Sm)n and (La/Yb)n, high levels of K, Rb, and less Ba, and low concentrations of Hf, Nb, Zr, and Ta indicate the interference of an arc-related setting for the formation of the rocks. Geochemical and tectonic setting evidences show that the intrusions  wereresulted by partial melting of the continental crust base of submature-mature (evolved) island arc or active continental margin formed as a result of hydrous-mafic magma injection of the mantle wedge upper supra subduction zone to the base. Geothermal gradient was high in the base of the subduction. By injecting the hydrous-mafic magma, widespread melting occurred, and the alkali syenites were formed. These tectonomagmatic conditions are confirmed by large-scale ring-shaped outcrops of the intrusions and mafic micro-granular enclaves. Finally subduction of Neotethyan oceanic crust under the other part of the crust or active continental crust, caused to form the Sardasht crust and then evolve this area over time to Oligocene. As a result of the continuity of the subduction, different rock types were formed around Sardasht

Full-Text [PDF 1608 kb]   (1402 Downloads)    
Subject: Petrology
Received: 2017/01/26 | Accepted: 2017/12/11 | Published: 2017/12/26

Add your comments about this article : Your username or Email:
CAPTCHA

Send email to the article author


Rights and permissions
Creative Commons License This work is licensed under a Creative Commons Attribution-NonCommercial 4.0 International License.

© 2024 CC BY-NC 4.0 | Kharazmi Journal of Earth Sciences

Designed & Developed by : Yektaweb