Origin and geodynamic environments of the metamorphic sole rocks from the İzmir–Ankara–Erzincan suture zone (Tokat, northern Turkey)

ABSTRACT

The Late Cretaceous accretionary complex of the İzmir–Ankara–Erzincan suture zone, near Artova, is composed mainly of peridotites (variably serpentinized), amphibolite, garnet-micaschist, calc-schist, marble, basalt, sandstones, neritic limestones. The metamorphic rocks were interpreted as the metamorphic sole rocks occurring at the base of mantle tectonites, because: (i) amphibolites were observed together with the serpentinized peridotites suggesting their occurrences in the oceanic environment; (ii) foliation in amphibolites and serpentinized peridotites run subparallel to each other; (iii) all these metamorphic rocks and serpentinized peridotites are cross-cut by the unmetamorphosed dolerite dikes with island arc tholeiite-like chemistry. Geochemical characteristics of the amphibolites display enriched mid-ocean ridge basalt (E-MORB)- and ocean island basalt (OIB)-like signatures. The dolerite dikes, on the other hand, yield an island arc tholeiite-like composition. Geothermobarometric investigations of the metamorphic sole rocks suggest that the metamorphic temperature was ~650 ± 30°C and the pressure condition was less than 0.5 GPa. Dating of hornblende grains from amphibolite yielded age values ranging from 139 ± 11 to 157 ± 3.6 Ma (2σ). The oldest weighted average age value is regarded as approximating the timing of the intra-oceanic subduction. These cooling ages were interpreted to be the intra-oceanic subduction/thrusting time of the İzmir–Ankara–Erzincan oceanic domain.

KEYWORDS:

• accretionary complex
• geochemistry
• metamorphic sole
• İzmir–Ankara–Erzincan suture zone
• subduction zone

Acknowledgements

The authors thank geological engineering student Ömer Altınbaş for his assistance during the field study. Raul Carampin (Padova) is thanked for assistance during electron microprobe analyses. We thank the Editor Robert Stern and two anonymous reviewers for their constructive reviews on the manuscript.

Disclosure statement

No potential conflict of interest was reported by the authors.

Supplemental material

Supplemental data for this article can be accessed at http://dx.doi.org/10.1080/00206814.2016.1181991.

Additional information

Funding

The research presented in this article was supported by TÜBİTAK: project no: 112Y123.