Surface Bottom Sediments of the North Atlantic on the Transect along 59.5° N

Abstract

An analysis of the lithological, isotope-geochemical, and micropaleontological parameters of the surface layer of bottom sediments in the North Atlantic was made at 26 stations on the profile along 59.5° N. The distribution of humidity and granulometric composition of sediments reflects vertical/circumcontinental zonality, since fine-grained and water-saturated material accumulates in the deepest parts of the Iceland Basin and the Labrador and Irminger seas, which are farthest from land. Larger masses of calcium carbonate are also formed there, but organic carbon is unevenly distributed. Both vertical/circumcontinental and climatic (circulation of the warm North Atlantic water) zonalities affect the mineral composition of the sediment fraction 0.063 mm. The accumulation of diatoms, radiolarians, and planktic foraminifers in sediments reflects both vertical/circumcontinental and, to a greater extent, climatic zonality. Variations in the isotopic oxygen and carbon ratios in the shells of benthic and planktic foraminifers require a complex interpretation involving data on the parameters of various surface and bottom water masses. The distribution of planktic microfossil assemblages according to cluster analysis shows areas of distribution of different water masses with a clear boundary along the eastern margin of the Subpolar Gyre. The distribution of “cluster” assemblages of benthic foraminifers does not correspond much to that of planktic microfossils, reflecting the division of the water area into abyssal and shallow water areas.