Stratigraphy and sedimentology of Neogene mammal bearing deposits in the Akkaşdağı area, Turkey

The Akkaşdağı area, situated in the southern margin of the Tertiary ÇankırıÇorum Basin, Central Anatolia, Turkey, includes a 280 m thick, mostly continental sediment sequence that overlies either marine Palaeogene transgressive deposits or metamorphic rocks of Kırșehir Massif. From bottom to top the sequence can be divided into units of Deliceırmak Fm. (alluvial fan deposits) and Ceritkale member (marine fan-delta and shelf carbonates) of mid-upper Eocene, Güvendik Fm. (gypsum) of Oligocene, and Akkaşdağı Fm. (fine to coarse-grained alluvial clastics and lacustrine limestone) of upper Miocene-lower Pliocene. A granitic intrusion was emplaced into the basin after late Eocene. The Neogene succession includes mammalian fossils and the lithological composition of the succession is rather different from its equivalences in other parts of the basin. By facies analysis the Neogene infill could be categorised into alluvial fan deposits (facies association I), fluvial deposits (facies association II), lacustrine deposits (facies association III) and pyroclastic flow deposits (facies association IV). Facies association I is dominant and the others are observed inside as alternating sequences. The facies architecture and facies associations suggest that a structural depression existed in the area and was filled with sediments of distal alluvial fans, flood plains and lakes receiving deposits of distal or terminal alluvial fans and flood plains, and occupied partly by lakes.