Sedimentation rates in the Sea of Marmara: a comparison of results based on organic carbon—primary productivity and 210Pb dating

Abstract

A large number of surficial sediment samples (75 grab samples, one boomerang core, four ☐ cores) as well as primary productivity measurements have been used to estimate the rates of sediment accumulation in the Sea of Marmara; using an empirical expression for the relationship between surface productivity and organic carbon content of the sediment ( Müller-Suess formula). It was found that calculated low sedimentation rates occurred on the inner southern Marmara shelf (ave. 8 cm 1000 y −1) where the primary production was relatively high (ave. 161 gC m −2 y −1); and vice versa, high sedimentation rates were calculated for the southwestern shelf (123 cm 1000 y −1), an area with very low primary productivity (64 gCm −2 y −1). This discrepancy among the values, is probably due to the combined effects of the distinctive and peculiar oceanography of the Sea of Marmara (well stratified flow, strong horizontal transport, and varying conditions for mineralization of organic matter etc.). Utilizing the 210Pb method, sediment accumulation rates have been determined of approximately 190 cm 1000 y −1 on the northeastern shelf, 120 cm 1000 y −1 in the eastern depression, 260 cm 1000 y −1 in the central depression, 100 cm 1000 y −1 in the western depression and 280 cm 1000 y −1 on the southwestern shelf of this sea. These generally high rates of sedimentation using this method further support the conclusion that the amount of primary produced organic carbon preserved in the recent bottom deposits of the Sea of Marmara seems not to be universally related to the rate of sedimentation.