Hastarian/Ivorian (Tournaisian) boundary based on conodont biostratigraphy in the eastern Taurides, Turkey

•Detailed conodont biostratigraphy of the Lower Carboniferous, Hastarian-Ivorian boundary succession in Turkey.•Based on the stratigraphical distribution of conodont species, two zones have been defined in the eastern Taurides.•The Hastarian-Ivorian boundary in the eastern Taurides delineated by the first appearance of Gnathodus cuneiformis.•The first study to document the distribution and importance of conodonts across the Hastarian-Ivorian boundary in Turkey.

Tournaisian successions in Taurides (Turkey) maintain uniform lithologies, particularly alternations of limestone and shale. In the light of bioevents of biostratigraphically significant species in the section, two zones have been established across the Tournaisian succession in the eastern Taurides: the Polygnathus inornatus Zone (Hastarian–Lower Tournaisian) and the Gnathodus cuneiformis–Polygnathus communis communis Zone (Ivorian–Upper Tournaisian). Based on conodont assemblages, the Hastarian–Ivorian boundary has been delineated by the first occurrence of Gnathodus cuneiformis, an index taxon for the basal part of the Ivorian.