A pelagic Upper Devonian sequence in Sarıyer, İstanbul

Authors: ARAL I. OKAY, AYŞE ÖZDEMİR, NİLGÜN OKAY

Abstract: The Palaeozoic sequence in the İstanbul region is made up of a continuous transgressive sedimentary series extending from Ordovician continental clastic rocks to Lower Carboniferous turbidites. The middle part of this sequence consists predominantly of carbonates ranging from shallow marine Upper Silurian limestones to latest Devonian to earliest Carboniferous deep marine limestones and shales. Here, we describe a new Upper Devonian deep marine limestone-siltstone section from the Sarıyer region in the European part of İstanbul. The 37-m thick section located in the campus of the İstanbul Technical University consists at the base of dark micritic limestones interbedded with carbonate-rich siltstones, which pass up into siltstones with rare micritic limestone lenses and beds. Conodonts indicate a late Famennian (latest Devonian) age for the İTÜ campus section; 5 conodont biozones are documented; Pseudopolygnathus granulosus, Polygnathus styriacus, Palmatolepis gracilis manca, Palmatolepis gracilis expansa, and Bispathodus aculeatus aculeatus. The Late Devonian fauna from the İTÜ Campus section are dominated by the important marker species of Palmatolepis, Bispathodus and Polygnathus. There are also some Branmehla, Mehlina, and Icriodus elements within the succession. The conodont assemblages are representative of the palmatolepid-bispathodid biofacies, which indicate deposition on an outer shelf to slope environment.

Keywords: İstanbul Zone, Devonian, Famennian, conodont, Ayineburnu Formation

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