Sedimentology and stratigraphy of Cenozoic deposits in the KagA +/- zman-Tuzluca Basin, northeastern Turkey

The KagA +/- zman-Tuzluca Basin is located in the northeastern Anatolia, to the east of the intersection point (near KarlA +/- ova) of the major North and East Anatolian Fault systems. This intermontane basin displays a thick sequence (over 2000 m) of mostly terrestrial deposits represented by repetitive alternations of the lake and fluvial environments ranging from ?Late Eocene/Oligocene to Middle/? Late Miocene. A marine incursion only mappable in the southeastern margin of the basin deposited limestones and sandy limestones rich in marine mollusks and nummulites, in particular N. fichteli that constrain an Early Oligocene age for this marine unit (Kagan Fm). The terrestrial basin-fill deposits show different thicknesses throughout the basin due to irregular bottom topography and tectonic configuration of the basin margins. The thickest deposits were accumulated along the different margins of the basin, which received high quantities of siliciclastics from meandering river, alluvial and coastal fans, fan delta/Gilbert-type delta and wave-worked fluvial delta. Climate changes have also driven the development of lake environments during distinct depositional periods. Siliciclastic-dominated overfilled lakes (HalA +/- kA +/- AYlak and KA +/- zA +/- lkaya formations) and chemical-dominated underfilled lakes (Turabi and Tuzluca formations) were formed. They have been also classified as "Newark-type" and "Fundy-type" lakes, respectively. Fluvial systems evolved from high-energy meandering rivers deposited under humid climate (Gungoren Formation) to low-energy meandering rivers resulted from arid and semiarid climates (Cincavat Formation). The transitional intervals from ephemeral river-dry mudflat (Cincavat Formation) to saline pan/lake (Tuzluca Formation) indicate wadi-sand flat-playa fluvial systems. The chronostratigraphic constrains of the entire sequence remain poor and so far solely based on vertebrate fossil assemblages. The evaporitic Tuzluca Formation would be Middle Miocene in age due to its stratigraphic position over the Cincavat Formation.