Geochronology, geochemistry and tectonic setting of the Cadomian (Ediacaran–Cambrian) magmatism in the Istranca (Strandja) Massif: new insights into magmatism along the northern margin of Gondwana in NW Turkey

ABSTRACT

Cadomian (Ediacaran–Cambrian) magmatic rocks have been reported in the eastern (e.g. the Çatalca and İhsaniye plutons) and western (e.g. the Binkılıç and Safaalan plutons) parts of the Istranca (Strandja) Massif. This paper aims to investigate the tectonic setting and the magma evolution history of the Cadomian magmatic rocks using both new and previously existing geochemical and geochronological data. The meta-granitoid rocks with intermediate to felsic composition are the main magmatic activity in the region. They intrude into metamorphic basement rocks composed of gneiss, schist, amphibolite, calc-schist, and quartzites (the Tekedere group). These plutons show strong foliation and traces of the polyphase metamorphism. All plutons are peraluminous and slightly metaluminous, mostly calc-alkaline and high-K calc-alkaline, and plot into the volcanic arc granites (VAG) field on the tectono-magmatic discrimination diagrams. The zircon U–Pb crystallization ages of the plutons are between 525.3 ± 3.5 Ma and 548.7 ± 2.3 Ma. Initial εNd values vary from −0.02 to 1.86. Nd-T_DM model ages range between 1.08 and 1.24 Ga and indicate that the primitive magmas were originated and/or assimilated by the remelting of Neoproterozoic juvenile crustal rocks. New geochemical and geochronological data suggest a magma generation within a subduction-related magmatic arc setting in response to the southward subduction of the Proto-Tethys Ocean during the Late Precambrian-Early Palaeozoic period in the Istranca Massif.

KEYWORDS:

• Cadomian orogeny
• peri-gondwanan terranes
• subduction-related magmatism
• proto-tethys

Research highlights

Cadomian magmatic activity in the Istranca Massif consists of intermediate-felsic plutons.

Zircon U–Pb crystallization ages of the plutons are between 525.3±3.5 Ma and 548.7±2.3 Ma.

These plutons were generated in a subduction-related magmatic arc setting in response to the southward subduction of the Proto-Tethys Ocean.

Acknowledgments

This work has been supported by the Research Funds of the İstanbul University-Cerrahpasa, Project Numbers: 435/13092005, FYL-2019-33796, and FYL-2019-33797. We thank the Editor Prof. Dr Robert Stern, Prof. Dr Gültekin Topuz, and two anonymous referees for helpful comments that have significantly improved this manuscript. We would also like to thank Dr Zeynep Öner Baran from South Dakota Mines (USA) for some corrections and comments on the English of manuscript.

Disclosure statement

No potential conflict of interest was reported by the authors.

Supplementary material

Supplemental data for this article can be accessed here.

Additional information

Funding

This work was supported by the istanbul universitesi-Cerrahpaşa Bilimsel Araştırma Projeleri [435/13092005,FYL-2019-33796,FYL-2019-33797].