Stratigraphy and palaeoenvironment of the Lower-“middle” Oligocene units in the northern part of the Western Taurides (İncesu area, Isparta, Turkey)

This study describes the stratigraphic and palaeoenvironmental significance of the Lower-“middle” Oligocene sediments based on the fauna from the Delikarkası Formation and the microflora from the İncesu Formation of the İncesu area (northern part of the western Taurides, Isparta province, Turkey). In the area, the Oligocene sediments show a regressive succession, which begins with the limestones of the Delikarkası Formation indicating marine conditions followed by conglomerates, sandstones and coaly mudstones of alluvial and fluvial (shallow marine-continental) origin. A well preserved foraminiferal assemblage including Nummulitesintermedius, Nummulitesvascus and Halkyardiamaxima proves an Early Oligocene age for the Delikarkası Formation. Due to palynological markers such as Boehlensipollishohli, Slowakipollishippophaëoides, Dicolpopolliskockelii, Magnolipollisneogenicus ssp. minor, Plicapollispseudoexcelsus, Caryapollenitessimplex and Intratriporopollenitesinstructus the İncesu Formation, which concordantly rests on the Delikarkası Formation, may be assigned to the Early-“middle” Oligocene. From the palynomorph assemblage, three zones have been recognised according to abundance of species. Zone 1 is characterized by predominance of C.simplex and Momipitespunctatus and rarely presence of tricolpate and tricolporate pollen. Zone 2 consists mainly of Inaperturopollenitesdubius, Leiotriletesmaxoides ssp. maximus, Verrucatosporitesfavus,Verrucatosporitesalienus and infrequently marine dinoflagellate cysts. Zone 3 is characterized by a high percentage of ferns such as Echinatisporis?chattensis and Polypodiaceoisporitessaxonicus. The presence of marine dinoflagellate cysts like Apectodinium sp. and Cleistosphaeridium sp., back-mangrove elements such as Acrostichumaureum and lepidocaryoid palms (e.g. Longapertitesdiscordis, Longapertitespunctatus and Longapertitespsilatus) in the sediments of the İncesu Formation imply coastal or near-coastal conditions. Terrestrial palynomorphs in more inland settings were transported by running water towards the sea. Conifers are represented by poorly preserved and rare pollen grains of Pityosporites, Cathayapollis and Piceapollis which may have been transported by wind. In this study, the terrestrial climate of the İncesu Formation is also discussed on the basis of the Coexistence Approach method. The climate was warm at the coast (over 20 °C), as evidenced by A.aureum and lepidocaryoid palms, whereas there was a mean annual temperature of 17.2–17.4 °C must be assumed for the upland environment(s).

Research highlights
► Paper presents biostratigraphical and palaeoenvironmental significance of Oligocene palynomorphs and foraminifera.
► Paper also describes the stratigraphy of Cenozoic units in the northern part of the Western Taurides, Turkey.
► Foraminifera, marine dinoflagellate cysts and back-mangrove elements in the Oligocene units imply coastal or near-coastal conditions.
► The climatic evolution is compared with changes in vegetation and palaeogeography.