The Laptev Sea belongs to the polar climate region, characterized by minimal influence on geochemical weathering processes. The dominant role in the formation of sedimentary rocks in high latitudes is played by mechanical sorting of sedimentary material. Using 15 sediment cores located along 120–130° E from the Lena Delta to the continental slope and in the Sadko Trough as an example, a close relationship between the grain-size and geochemical composition of marine sediments was revealed. The results of the study showed that shelf sedimentation occurs in at least two stages: (I) accumulation of sediments in coastal area, the area directly adjacent to the sources of sediments, and (II) the subsequent mechanical sorting of sedimentary material on the shelf itself. At the first stage, the finest clay fraction is partially separated from the primary terrestrial sedimentary material. At the second stage, as one move away from the coastal area, the sand and silt fractions are separated. This sedimentation pattern is determined by the combination of the Lena Delta morphology and the Siberian Coastal Current. In conditions of an unstable hydrodynamic regime of the shallow shelf, predominantly sandy sediments (SiO/AlO 4.5) accumulate at a rate of 0.5 g cm yr. These sediments differ from the sediments of the terrestrial area by a higher content of Si and a lower content of Ti, Mg, Fe and Ni. In conditions of a calm hydrodynamic environment of the Sadko Trough, predominantly silty sediments (SiO/AlO 4.5) accumulate at a rate of 0.5 g cm yr, characterized by a higher content of Ti, Mg, Fe and Ni and a lower content of Si. The contents of K, Rb, Cr and Ca in shelf sediments do not show a clear correlation with grain-size distribution and are thus not informative for reconstructing sedimentation patterns.
VYu. Rusakov (Wed,) studied this question.