Origin and geodynamic implications of basaltic rocks intercalated with Miocene turbidites around the İskenderun Basin (Eastern Mediterranean / Turkey)

We report a detailed investigation and the geodynamic implications of a basaltic lava flow that is intercalated with the early–middle Miocene turbiditic sedimentary rocks (Karataş Formation) that are exposed near the İskenderun Basin in southern Turkey. In order to reveal the age and origin of the basaltic rocks, we systematically sampled clastic samples from measured sedimentary sections, which include the basaltic lava flow, from around Ceyhan (east of Adana city). Forty different species belonging to 14 calcareous nannoplankton genera were identified in the samples, representing the Langhian–Tortonian (middle–late Miocene) time interval. Considering the stratigraphic distribution of the calcareous nannoplankton species in the section, the age of the basaltic lava flow is determined to be Serravallian (middle Miocene). The basaltic rocks experienced only minor magmatic evolution and have a restricted compositional range. Analysed in situ major element contents (from electron microprobe analysis, EMPA) for minerals (plagioclase, olivine and clinopyroxene) hosted by the late Miocene basaltic rocks show that they originated in an intraplate setting. Geochemical analysis indicates that olivine have Fo (forsterite) compositions between 57.81% and 83.83%. The EMPA contents (primarily based on pyroxenes) suggests that the late Miocene volcanism was related to the Pleistocene Delihalil–Turunçlu basaltic volcanism. The studied late Miocene volcanism could have originated in two possible tectono-magmatic environments: 1) one involving collisional tectonics (e.g., folding) combined with a change from regional compression to strike-slip; or 2) an intraplate setting. We propose that the tectonic setting of the late Miocene basaltic lava flow was similar to that of the extensive Pleistocene Delihalil volcanism in the same region. This would extend the onset of the regional basaltic volcanism back to the middle–late Miocene, rather than being restricted to the Pleistocene–Quaternary. •Basaltic volcanic rocks were observed intercalated in the Miocene turbidites.•The basaltic rocks includes subordinate pillow lavas and exhibit slightly erosive and chilled margin at the base.•Geochemical analyses and clinopyroxene–olivine discrimination diagrams exhibit that the basaltic rocks should be originated in an intra–plate geodynamic environment.•Calcareous nannoplankton paleontology indicates that the age of the volcanic rocks should be about Serravallian.•The beginning of the r