In the eastern part of the Pasinler-Horasan Neogene basin, the lowermost section consists generally of tuffs, andesites and basalts. This association is nomenclated as "Karakurt volcanics" They are underlain by an ophiolitic melange of Lower Cretaceous age which is unconformably overlain by the Oligocene Çayarası formation consisting of clastic rocks. The basin is bounded by sinistral strike-slip faults controlling sedimentation of various continental detritic rocks. These are distinguished as Aras and Horasan formations, both Pliocene in age, representing respectively marls and claystones of deep lagoonal environment, conformably overlain by fine grained sediments. Terrace gravels, alluvial fans and colluvium represent the Quaternary sedimentation.