Modern Sedimentation in the Kara Sea: Evidence from the Lithological–Geochemical Investigation of Surface Bottom Sediments

Аннотация

In this paper, we report new data on the lithological and chemical compositions of the surface layer (0–2 cm) of bottom sediments from various zone of the Kara Sea: the estuaries of the Ob and Yenisei rivers, open part of the shelf, Eastern Novaya Zemlya Trough, Voronin Trough, and Novaya Zemlya bays. The sediments were collected during five cruises of the R/V Akademik Boris Petrov (2000, 2001, and 2003) and the R/V Akademik Mstislav Keldysh (2015 and 2016). Based on the statistical analysis of the obtained data array, all the bottom sediments were divided into cluster groups comprising their lithological and geochemical types. The obtained clusters and REE + Y systematics were used to distinguish facies genetic types of the bottom sediments and determine the accumulation zones of Holocene sequences. They are bounded by river estuaries, a shallow marine zone adjoining the southeastern coast of the sea, and deep troughs. The main sources of Holocene sediments in the Kara Sea are the suspended particulate materials of the Ob and Yenisei and materials transported by glacial meltwater from the Novaya Zemlya and Severnaya Zemlya archipelagoes. The dispersion of fine suspensions is controlled by the circulation of surface sea currents. The accumulation of suspended materials on the bottom is complicated by wave effects and circulation of bottom sea currents, which remove fine sediment fractions from the shallow regions of the sea and transport them into the deepest hydrodynamically calm parts of troughs.