Sedimentation rates (data on 210pb and 137cs radionuclides) in different facial-genetic types of the Kara sea bottom sediments

In the article original data on isotope composition of natural “excess” Pb-210 and artificial Cs-137 radionuclides in upper 25–50-cm layer of sea-bottom sediments at the Kara Sea (from Ob’ and Yenisei estuaries, Eastern-Novaya-Zemlya trough, Voronin trough, as well as Sedov bay (Novaya Zemlya)) are presented. The research results showed close tie between sedimentation rates and facial-genetic types of the sea-bottom sediments. Highest sedimentation rates are typical for the terrigenic-estuarine type. The type is divided on tractional load with sedimentation rate 0.4–0.7 cm per year and “mud bank” sediments with sedimentation rate 0.7–1.0 cm per year. The terrigenic-shallow-marine type is characterized by lowest sedimentation rate – 0.1–0.3 cm per year. The background terrigenic-marine type has a broadest spectrum of the sedimentation rates: on trough slope the rates are minimal (likely to terrigenic-shallow-marine type), within central parts of the trough (as a result of gravity creep) the rates may increase up to 0.9 cm per year. Single facial-genetic type is glacial sediments of Navaya Zemlya bays. Measured recent sedimentation rate within inner depression of the Sedov bay is 0.1–0.2 cm per year.