Late Devonian–Late Triassic sedimentary development of the central Taurides, S Turkey: Implications for the northern margin of Gondwana

The sedimentary development of the northern continental margin of Gondwana is illustrated here by a study of Devonian to Triassic facies in the Alpine-age Hadim and Bolkar nappes, which overlie the regionally autochthonous Geyik Dağ continental platform. Successions begin with Middle–Upper Devonian terrigenous sandstones, shales and limestones deposited on a shallow-marine, continental shelf. Regional thermal subsidence, crustal extension and glacioeustatic sea level changes exerted a significant influence. Overlying Carboniferous successions are subdivided into four facies associations in both nappes. Carboniferous sediments accumulated on a shallow-marine shelf, influenced by global sea-level change during a time of southern hemisphere glaciation. Lower Carboniferous dark shales, with localised phosphatic material, probably accumulated in a productive, transgressive shelf setting. Localised volcanism in an adjacent autochthonous unit (Sultan Dağ) is suggestive of tectonic instability during Late Tournasian–Early Visean time. Shallow-marine shelf carbonate deposition continued through the Permian, with an increase in sedimentation rate that probably reflects rift-related subsidence of the north-Gondwana margin. Further low energy, shallow-marine deposition took place during the Early–Middle Triassic, ranging from relatively proximal carbonates to more distal mudstones. The Devonian–Triassic sandstones and mudstones are terrigenous, probably derived from local basement highs and the Pan-African craton to the south. Thickness variations suggest the Tauride platform segmented into a several differentially subsiding sub-basins. There was a profound change to coarser grained, shallow-marine to alluvial sedimentation during Triassic-earliest Jurassic related to the evolution of the Neotethyan ocean to the north. The overall succession was, therefore, controlled by interplay of sea level change and tectonics.