Neogene tectonic evolution of the Misis-Andırın-Engizek range: structural and sedimentary evidences from Bulgurkaya Sedimentary Mélange

Abstract

Sedimentary melanges represent submarine mass transport processes and tectonic events in related basins. Systematic examinations of melanges in orogenic belts provide significant markers for the geodynamical evolution of different tectonic and sedimentary processes, especially during subduction and continental plate collisions. Here, we present a combined analysis of Bulgurkaya Formation which is well exposed in the Misis-Andirin-Engizek mountain range in SE Anatolia (Turkey), focused mainly on the Andirin region, where it is best exposed. This NE-SW oriented range (approximately 200 km long) represents subduction and collision events between Afro-Arabian plates in the south and Tauride platform in the north after Cretaceous. Structural and sedimentological characteristics indicate that the Bulgurkaya Formation originated in a basin affected by different phases of compressional tectonics; however, the main process producing the melange with a block-in-matrix fabric is inferred to be sedimentary. After formation and emplacement of underlying ophiolite-related tectonic melanges (Dikenli and Meydan melanges), late-stage subduction and collision caused instability and destabilised the Tauride nappes in the north represented by Mesozoic carbonates of the Andirin Group. Inclined basin slopes transport debris-type material into the basin that accumulates along the edges while relatively steady fine-grained deposition occurs in the deeper central parts. We infer that the following compression in the region sustain the underthrusting of the Dikenli Fm. beneath the Andirin carbonate nappes and cause tectonic erosion and change the dynamic equilibrium of the northerly wedge-toe leading extensive gravitational mass-wasting deposition of the Bulgurkaya Formation as a polygenetic melange.