New evidence for the presence of the Inner Tauride Ocean: Lithological, geochronological and P-T correlations with the Tavs,anlı and Afyon zones of Central Anatolia (Türkiye)

The Tavs,anli and Afyon zones, which are well defined in western Turkiye, represent high pressure-low tem-perature (HP-LT) metamorphic rocks formed in a subduction zone. The Korumaz and Hinzir mountains (northeast of Kayseri) between the Central Anatolian Crystalline Complex and the Eastern Tauride Belt are represented by a HP-LT metamorphic sequence, which is thought to have formed between the Carboniferous and the Cretaceous. Here we present 40Ar/39Ar data from white micas within the Lower-Middle Triassic calc-phyllites from Korumaz Mountain, which yielded an age of 87 +/- 2 Ma. Therefore, based on new mineralogical and geochronological data we suggest that this low-grade (HP-LT) metasedimentary sequence correlates with the Afyon Zone. Tectonically emplaced on-top of the HP-LT metasedimentary units of the Korumaz and Hinzir mountains is a meta-accretionary complex consisting of serpentinite, listvenite, marble, phyllite, calc-phyllite, metabasite, and meta-plagiogranite. Petrographic and mineral chemical studies show that the meta-accretionary complex was subjected to metamorphism under the HP-LT conditions that are similar to those of the Tavs,anli Zone in western Turkiye. Zircon Hf isotopic compositions from the meta-plagiogranite in the Korumaz and Hinzir mountains exhibit a depleted mantle signature with positive epsilon Hf(t) values of +5.6 to +13.1, and yielded a U-Pb crystallization age of 101.14 +/- 0.84 Ma, which is the oldest age determined in oceanic crustal rocks of the ophiolites from the Tauride Belt. Geochemically, the metabasites and meta-plagiogranites from the meta-accretionary complex show subduction-related characteristics. White micas from phyllites and listvenite, which dominate the matrix of the meta-accretionary complex, yielded 40Ar/39Ar metamorphic ages ranging from 78 to 60 Ma. Our new geological and geochronological data suggest that metamorphic units of the Korumaz and Hinzir mountains are the eastern continuation of the Afyon and Tavs,anli zones. This indicates that the Inner Tauride Ocean, the existence of which has been controversial in the literature, was indeed present between the Central Anatolian Crystalline Complex and the Eastern Tauride Belt.

Automated summary

This article examines the high pressure-low temperature metamorphic rocks in Tavs, Anli, and Afyon regions of western Turkey and finds that the metamorphic units in Korumaz and Hinzir mountains are connected to the Afyon and Tavs,anli zones. It also confirms the existence of the Inner Tauride Ocean.