New U-Pb zircon geochronological data for Takestan magmatic rocks (Western Alborz) and their significance for the interpretation of Paleogene magmatism in Iran

ABSTRACT

The Takestan area is in the western part of the Alborz magmatic arc. Magmatic rocks of the area consist of plutonic rocks (e.g. granitoids), effusive volcanic, and pyroclastic rocks. Using U-Pb zircon LA ICP-MS dating, we conclude that major parts of Takestan plutonic rocks were emplaced at 41–39 Ma (Late Eocene, Bartonian), but a small part of these rocks have ages of ~37 Ma (Late Eocene, Priabonian). The dacitic rocks have an age of ~39 Ma (Late Eocene, Bartonian) and the rhyolitic rocks are the youngest part of the magmatic rocks of the region with ages of 37–35 Ma (Late Eocene, Priabonian). Old zircons are present in all of granitoid and volcanic samples, except for a dacitic sample. They are interpreted both as earlier components in a long-lived magma chamber and inherited zircons from older continental crust. The age of magmatic rocks in the western part of the Alborz magmatic arc decreases from east to west, but the ages of the majority of them are limited to Palaeogene. The studied rocks like other Palaeogene magmatic rocks of Iran were possibly formed in a subduction related tectonic environment. Indeed, the Palaeogene magmatism of Iran is akin to geodynamic events related to Neotethyan subduction beneath Iranian micro-continent at the southern part of Eurasia.

KEYWORDS:

• Alborz magmatic arc
• granitoid
• Iran
• Neotethyan ocean
• Palaeogene

Acknowledgements

We are thankful of Prof. Lorence G. Collins for editing former version of the manuscript. Also, we appreciate good reviews and comments by Federico Lucci and an anonymous reviewer which elevated the scientific level of the paper. Hamed Vahidpour has contribution in drawing and raising quality of Figures and formatting the primary version of the manuscript and therefore we kindly appreciate him.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Author contributions

A.A.S: Project administration; A.A.S: Conceptualization and Visualization; A.A.S, A.A, and B.N: Field work and petrography; A.A.S, C.R.M: Methodology and Geochronology; A.A.S, A.A and B.N: Investigations and Data curation; A.A.S Formal analysis; A.A.S, B.N and D.L: writing original manuscript, review and editing.

Data availability statement

Data generated or analysed during this study are provided in full within the published article.

Supplementary material

Supplemental data for this article can be accessed online at https://doi.org/10.1080/00206814.2023.2291779

Additional information

Funding

This work has been supported by grants awarded to Ali A. Sepahi by Bu-Ali Sina University in 2020 and by instrumental help of the University of New Brunswick in agreement by Chris McFarlane.