Effects of antecedent topography on reefal carbonate deposition: Early-Middle Miocene of the Adana Basin, S Turkey

Early-Middle Miocene reefal limestones and other shallow marine sedimentary sequences were important components of Neogene Basins (especially the Adana Basin) in Southern Turkey. The most important controlling factors of sedimentation were antecedent topography and substratum type, clastic input and sea level changes of different scales. The effects of these factors can be observed on the southwest extension of the Adana Basin.Miocene sediments unconformably overlie the older limestones, ophiolite and ophiolitic melange. Lithological variations and structural properties of Pre-Miocene rocks caused an irregular sea floor topography development that was initially filled by local terrestrial conglomerates. During the Early Miocene transgression, these terrestrial clastics transitionally passed into shallow marine clastics, and also new pebbly conglomerate-sandstone bearing deposits observed in local depressions of Pre-Miocene topography. Remaining low lying areas were filled by claystones and sandy–clayey limestones. At the same time, reef limestone deposition developed over the higher areas where a hard-substratum was available for red algae and other reef builders. Large shelled organisms in the clastics created a suitable substratum for successive reef level development. The carbonate deposition shifted landwards due to continuous transgression (intermediate sea level changes) causing backstepping reef development. Small sea level changes in the study area controlled the energy of the environment, lithological variations in the clastics and lateral facies changes in each reef body.