Stratigraphy of the metamorphic rocks of Niğde Massif and new evidence of Triassic rifting of the Inner Tauride Ocean (Central Anatolia, Türkiye)

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Özkan M. K., Beyazpirinç M., Akçay A. E., Çoban M., Candan O., Koralay O. E., ...More



Metamorphites of Niğde Massif, which form the basis of study area covering the Niğde vicinity

in Central Anatolia, are composed of Late Devonian Gümüşler, Carboniferous-early Permian

Kaleboynu late Permian Kızıldağ formation and unconformable Triassic-Late Cretaceous cover

units from bottom to the top, which are separated from each other with unconformities. The Triassic

succession (Söğütlüdere formation) of phyllite-marble-schist alternations with common amphibolite

levels is first distinguished in this study, unconformably overlies the Paleozoic succession.

Thick homogeneous marbles of Jurassic-Cretaceous period, is defined by quartzite at the bottom

representing the unconformity at the base, is defined as the Kırtepe formation. The succession

probably ends with the Late Cretaceous metaflysch (Kırkpınar formation) constituting metaophiolite

blocks with unconformable contact relationships. Amphibolite sample of the Söğütlüdere formation

gives 239 Ma (Middle Triassic) age, which is interpreted as the crystallization age of the primary

basic magmatism. The youngest detrital zircon ages (223-224 Ma) obtained from the metaclastics of

the same formation shows that the primary deposition age of the formation is probably Late Triassic,

which is consistent with this data. Geochemical data indicate an extensional environment of the

alkaline composition and anorogenic originated basic volcanism developed on the continental crust.

When these results evaluated together with the regional data, the metabasites of the Söğütlüdere

formation can be interpreted as the first phase products of rifting, which commenced with the rifting

process of the Tauride-Anatolide Platform in the Triassic period and resulted in the opening of the

Inner Tauride Ocean and the break off the Kırşehir Block.