Geochemistry and zircon U–Pb dating of amphibolite in the Menderes Massif (western Türkiye): first record of Late Devonian extension

ABSTRACT

The timing of extensional events in northern Gondwana remains elusive. In relations to this event, a new zircon U-Pb age and Hf isotopic compositions, and whole-rock geochemistry provided here for the amphibolites in the basement unit of the Menderes Massif (MM) within the Anatolide-Tauride Block (ATB). LA-ICP-MS U-Pb zircon dating of one sample yielded a crystallization age of 367.0 ± 2.5 Ma, providing the first record of Late Devonian (Famennian) mafic magmatism in the Menderes Massif. This sample contains inherited zircon grains with ages spanning from 588 Ma to 541 Ma, likely sourced from late Neoproterozoic country rocks. Chondrite-normalized rare earth element patterns exhibit enrichment in light rare earth elements and flat patterns for heavy rare earth elements, suggesting affinities with tholeiitic EMORB and ocean island basalt. The geochemical data, coupled with the positive εHf(t) values ranging from 0.5 to 7.8, indicate that the amphibolite likely originated from juvenile melts generated by partial melting of the asthenospheric mantle. This melt was subsequently modified by crustal contamination and fractional crystallization. Contemporaneous EMORB- and OIB-like mafic rocks are identified in the eastern Taurides and Iran, respectively. Both regional geological and geochemical evidence proposes that Late Devonian magmatism in the Anatolide-Tauride Block occurred in a within-plate tectonic setting. This magmatic activity might have been triggered by the northward subduction of the Paleotethys beneath the Pontides during the Devonian, a process that would produce a slab-pull force, creating an extensional tectonic regime along the northern margin of Gondwana.

KEYWORDS:

• Mafic intrusion
• within-plate magmatism
• extension
• Menderes Massif
• Anatolide
• Gondwana

Acknowledgments

I would like to thank Osman Candan, Gültekin Topuz, and E.Yalçın Ersoy for their valuable contributions and comments. Special thanks to Alan S. Collins for providing access to the Adelaide Microscopy and for his valuable, help at the Department of Earth Sciences, University of Adelaide, during the Turkish Higher Education Council grant. Special thanks to Aoife McFadden and Benjamin Wade from the Adelaide Microscopy for their help with the measurements. I am grateful to Fukun Chen and Ping Xiao for their support for the Sr-Nd-Hf isotopic analyses. I would like to thank the editor-in-chief, Robert Stern, and the reviewers Timur Ustaömer, Alastair, H.F. Robertson, and Osman Parlak, for their review and constructive comments, which contributed the improvement of this paper.

Disclosure statement

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

Supplementary material

Supplemental data for this article can be accessed online at https://doi.org/10.1080/00206814.2023.2273376

Additional information

Funding

This study was supported by scientific research projects of Dokuz Eylül University (2007-KB-FEN-046) and TÜBİTAK research grant (No: 112Y380).