PARASOUND (3.5 kHz) subbottom echosounder profiles acquired on the southern Spitsbergenbanken, NW BarentsSea, show iceberg-keel scouring features which are buried by sediment that accumulated during the postLast Glacial Maximum (LGM) sea-level rise. Four acoustic units (Units 1 to 4 in stratigraphic order) were differentiated,based on the characterization of their acoustic facies and reflection surfaces. Unit 1 shows a chaotic internalstructure and is interpreted as a glacial till, whereas the laminated Units 2 to 4 accumulated by sedimentsettling fromsuspension clouds and bottomcurrents during the last deglaciation phase. The top of Unit 2was frequentlyincised by iceberg keels, resulting in up to 12mdeep ploughmarkswhichwere later filled and buried byUnit 3 and 4 sediments. Three main paleo-evironmental changes controlled the evolution of the facies succession:(1) The major shift from till formation (Unit 1) below grounded ice to the accumulation of laminated sediments(Unit 2) which are inferred to reflect ice lifting and meltwater release; (2) Iceberg-keel scouring aftersedimentation of Unit 2; (3) the probable abrupt termination of iceberg-keel scouring related to the glacio-eustaticsea-level rise. A linkage between these episodes of changes and short-lasting phases of rapid post LGMsea-level rise, such as meltwater pulses, is inferred, although further studies are needed to better understandthe temporal and genetic relationships between the sedimentary events recognized in the Barents Sea and climatechanges.

Buried iceberg-keel scouring on the southern Spitsbergenbanken, NW Barents Sea.

Zecchin M
;
Rebesco M;Lucchi RG;Caffau M;
2016

Abstract

PARASOUND (3.5 kHz) subbottom echosounder profiles acquired on the southern Spitsbergenbanken, NW BarentsSea, show iceberg-keel scouring features which are buried by sediment that accumulated during the postLast Glacial Maximum (LGM) sea-level rise. Four acoustic units (Units 1 to 4 in stratigraphic order) were differentiated,based on the characterization of their acoustic facies and reflection surfaces. Unit 1 shows a chaotic internalstructure and is interpreted as a glacial till, whereas the laminated Units 2 to 4 accumulated by sedimentsettling fromsuspension clouds and bottomcurrents during the last deglaciation phase. The top of Unit 2was frequentlyincised by iceberg keels, resulting in up to 12mdeep ploughmarkswhichwere later filled and buried byUnit 3 and 4 sediments. Three main paleo-evironmental changes controlled the evolution of the facies succession:(1) The major shift from till formation (Unit 1) below grounded ice to the accumulation of laminated sediments(Unit 2) which are inferred to reflect ice lifting and meltwater release; (2) Iceberg-keel scouring aftersedimentation of Unit 2; (3) the probable abrupt termination of iceberg-keel scouring related to the glacio-eustaticsea-level rise. A linkage between these episodes of changes and short-lasting phases of rapid post LGMsea-level rise, such as meltwater pulses, is inferred, although further studies are needed to better understandthe temporal and genetic relationships between the sedimentary events recognized in the Barents Sea and climatechanges.
Barents sea; sediment cores; Iceberg-keel scouring
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Utilizza questo identificativo per citare o creare un link a questo documento: http://hdl.handle.net/20.500.14083/88
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