Chrono-biostratigraphic analysis of the Lower Pleistocene paleotsunami deposits overlying the Late Pliocene Erosional Surface (LPES) at the Manavgat Subbasin (SW Türkiye) based on new nannofossil and fossil ascidian spicule data

In the Manavgat Subbasin, which is the eastern part of the Antalya Basin located at the Eastern Mediterranean marginal basins, an erosional surface that formed after the late Pliocene regression and erosion period was determined. This hiatus is overlain by Lower Pleistocene paleotsunami deposits that are probably the result of earthquakes below the Mediterranean that caused rapid and short-lived sea flooding of the coastal plain. Sedimentologic and biostratigraphic examination of rock samples, taken from 10 locations, provided evidences of this new regressive succession. The lower Pleistocene paleotsunamite zone extends in 2-3 m. thickness at the region. It consists of poorly sorted clastic sediments which are composed of sand to boulder-sized grains within a muddy matrix. The muddy matrix contains various macro- and microfossils data representing different environmental, sedimentological and stratigraphic origins. The sand to boulder components are composed of different aged marl, sandstone, conglomerate, and limestone fragments, which were reworked from extrabasinal sedimentary successions and coeval reef block or boulders that were removed from the intrabasin. Detected calcareous nannofossil data have brought out two different aged sedimentary sequences in the Karpuzçay Formation known as Miocene aged: (1) Early Pliocene aged clastic shelf deposits "Karpuzçay Formation" below and (2) Early Pleistocene aged "Manavgat Formation" contains shallow marine and coastal clastic deposits that begun with the paleotsunami deposits of "Manavgat Formation Tsunamite Member". The blue-grey marls of the Karpuzçay Formation have 45-60% synsedimentary nannofossil assemblage of NN15 - Reticulofenestra pseudoumbilica zone (late Early Pliocene), grey-brown mudstones of the Manavgat Formation include 5-15% synsedimentary nannofossil data NN19a - Gephyrocapsa caribbeanica subzone (Early Pleistocene). The nannofossil data of Manavgat Formation Tsunami Member deposits suggest that the tsunami event occurred between 1.81 Ma and 1,60Ma (Gelasian-Calabrian transition).