Geology and Structural Evolution of the Tokat Massif (Eastern Pontides, Turkey)

Authors: ALİ YILMAZ, HÜSEYİN YILMAZ

Abstract: The Tokat Massif consists of a pre-Jurassic metamorphic complex that crops out widely between Amasya and Reşadiye in the western part of eastern Pontides, and which can be correlated with the Karakaya Complex of the western Pontides. This complex is named the Tokat Group, and is divided into two main units, namely, the Turhal Metamorphics and Devecidağ Mélange. The Turhal Metamorphics form a volcano-sedimentary sequence in the northern part of the Tokat Massif. The lower level of the formation is made up of gneiss, amphibolite and mica schists, whereas the upper part is represented by an alternation of mica schist, phyllite, metaclastic rocks, metabasite and marble, which probably reflects an arc association. The Devecidağ Mélange is characterised by a metavolcano-sedimentary olistostrome, which forms the southern part of the massif. This unit is quite heterogeneous and reflects, in places, a subduction mélange and/or a fore-arc sequence. The Devecidağ Mélange may have formed in a setting between a subduction zone and a fore-arc. The units of the Tokat Massif can be traced along the eastern Pontides and also along the North Anatolian Ophiolitic Belt. These units have been accreted to the mélange prism as tectonic slices along the North Anatolian Ophiolite Belt before the Campanian. Some of Late Cretaceous ophiolitic mélange slices also crop out in the Tokat Group as E-W-trending tectonic slices. The ophiolites and ophiolitic mélange are believed to have been emplaced both to the north and to the south during the Late Cretaceous. The north-vergent thrusts have been later realigned into south-dipping thrusts during a neotectonic phase.

Keywords: Tokat Group, Karakaya Complex, structural evolution, eastern Pontides

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