Origin of sediment pellets from the Arctic seafloor: sea ice or icebergs?

Abstract

Sediment cores from the Norwegian and Greenland Seas and the Nansen Basin were studied to determine the origin of sediment pellets, centimetre-sized aggregations of clay to sandsized sediment occurring in the cores. By comparing the grain size, grain shape and composition of the pellet sediments to sediments collected directly from the surfaces of sea ice in the Nansen Basin and from icebergs in the Barents Sea, the pelleted sediment was found to be more similar to that in the icebergs than that on the sea ice. The pellets may be formed on, in or under a glacier or during transport on/in an iceberg. When icebergs overturn or melt, the pellets fall out and are consolidated enough to survive a drop of up to 4 km to the ocean bottom and to retain their integrity even after burial on the seafloor.