Late Quaternary climate and sea-level changes recorded in sediment composition off the Buyuk Menderes River delta (eastern Aegean Sea, Turkey)

Influences of Holocene climatic and sea level changes on sedimentation on the continental shelf off the Buyuk Menderes River delta, SW Turkey were investigated using grain size and X-ray clay mineralogical data on surficial and 14C-dated core sediments collected at 19-81 m water depths. Modern, fine-grained, siliciclastic sediments cover most of the seafloor of inner to mid-shelf areas. A narrow, relict belt extends from northwest to south (at 66-81 m water depths), where sediments are characterized by abundant sand and gravel (27-52%) and biogenic carbonate (16-44%) contents, and microscopic examination suggests an older origin. The radiocarbon ages of mid and lower sections in cores (3670-10,380 yr BP) reflect sedimentation under depositional conditions from early to late Holocene in the study area. Additionally, downcore changes of grain size toward coarser-grained sediments most probably record global climatic effects with sea level changes, specifically the transition from lowstand in early Holocene to highstand at mid-late Holocene. The presence of this relict belt in offshore waters can be attributed largely to active uplift tectonics. The coarser-grained relict belt, compared with available seismic profiles, corresponds to an lowstand unconformity of bottomset beds of the prograding Buyuk Menderes Delta