Clay-mineral and grain-size distributions in surface sediments of the White Sea (Arctic Ocean): indicators of sediment sources and transport processes |
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| Authors: | Cornelia Saukel Rüdiger Stein Christoph Vogt Vladimir P Shevchenko |
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| Institution: | (1) Alfred Wegener Institute for Polar and Marine Research, P.O. Box 120161, 27515 Bremerhaven, Germany;(2) Crystallography/ZEKAM, University of Bremen, FB Geowissenschaften/Geosciences, P.O. Box 330440, 28334 Bremen, Germany;(3) P.P. Shirshov Institute of Oceanology of the Russian Academy of Sciences, 36 Nahimovski prospect, 117997 Moscow, Russia |
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| Abstract: | In this study, the grain-size and clay-mineral compositions of 73 surface sediment samples collected in a variety of environmental
settings in the White Sea are presented to characterize recent sedimentation processes, reconstruct transport pathways, and
identify potential source areas of the terrigenous components. Areas >100 m deep are invariably characterized by silty clay,
whereas areas <100 m deep exhibit more heterogeneous grain-size compositions plausibly explained by coastal erosion and (re-)distribution
mechanisms, particularly tidal currents. The dominance of sand in the estuarine areas of the Onega and Dvina rivers as well
as toward the Gorlo Strait connecting the White Sea with the Barents Sea is attributed to increased current speeds. Illite
and smectite are the dominant clay minerals in recent sediments of the southwestern and eastern White Sea sectors, respectively.
Their distribution patterns largely depend on the geology of the source areas, and mirror surface circulation patterns, especially
in Dvina Bay. Smectite is a key clay mineral in White Sea surface sediments, as it reveals the dominating influence of the
Northern Dvina’s runoff on sedimentation and water circulation throughout the basin. In comparison to other Eurasian shelf
seas, the White Sea is characterized by a greater diversity of clay-mineral assemblages, which range from illite- to smectite-dominated
sectors containing variable amounts of chlorite and kaolinite. |
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