Wilson, Lindsay J. and Austin, William E. N. (2002): Millennial and sub-millennial-scale variability in sediment colour from the Barra Fan, NW Scotland; implications for British ice sheet dynamics

Leg/Site/Hole:
Identifier:
2003-068261
georefid

Creator:
Wilson, Lindsay J.
University of Saint Andrews, School of Geography and Geosciences, Saint Andrews, United Kingdom
author

Austin, William E. N.
author

Identification:
Millennial and sub-millennial-scale variability in sediment colour from the Barra Fan, NW Scotland; implications for British ice sheet dynamics
2002
In: Dowdeswell, Julian A. (editor), O Cofaigh, Colm (editor), Glacier-influenced sedimentation on high-latitude continental margins
Geological Society of London, London, United Kingdom
203
349-365
Sediment colour, together with other proxy data, provides a novel, rapid and non-destructive tool in the investigation of glacier-influenced sedimentation on the Barra Fan, NW Scotland. Lightness (L (super *) ) and reflectance (400-700 nm) measurements at this site provide a quantitative estimate of changes in calcium carbonate and clay content. Interstadials are carbonate-rich/clay-poor (higher L (super *) and reflectivity), whereas stadials are carbonate-poor/clay-rich (lower L (super *) and reflectivity). Detailed sedimentological investigations suggest that the last British Ice Sheet (BIS) extended to the outer continental shelf-break shortly after 30 ka BP. This climatic response of the BIS to global cooling at the Marine Isotope Stage (MIS) 3-2 transition marks a significant increase in sediment delivery to the Barra Fan. Prior to 30 ka BP, strong Dansgaard/Oeschger (D/O) cyclicity dominates the record. After 30 ka BP, shorter periodicities prevailed as the BIS reached its maximum extent. Glacier dynamics plays a significant role in the delivery of ice-rafted debris (IRD) across this margin, highlighting the inherent difficulties of correlating millennial-scale IRD events when the IRD is derived from different ice sheets. An event stratigraphy based upon carbonate-rich interstadials provides a more robust means of amphi-Atlantic correlation during this interval.
English
Serial
Coverage:Geographic coordinates:
North:57.3000
West:-11.0000East: -9.0000
South:56.3000

Quaternary geology; Sedimentary petrology; absolute age; Atlantic Ocean; atomic absorption; Barra Fan; C-14; carbon; Cenozoic; chemical composition; chronostratigraphy; clastic sediments; clay; color; continental shelf; cores; dates; Foraminifera; glacial environment; glacial geology; glacial sedimentation; glaciers; glaciomarine environment; glaciomarine sedimentation; grain size; Holocene; ice sheets; Invertebrata; isotopes; lithostratigraphy; magnetic susceptibility; marine environment; marine sedimentation; microfossils; mineral composition; North Atlantic; Northeast Atlantic; Ocean Drilling Program; outer shelf; paleomagnetism; Protista; Quaternary; radioactive isotopes; reflectance; Rockall Trough; seasonal variations; sediment transport; sedimentation; sediments; sequence stratigraphy; spectra; spectroscopy; stratigraphic units; taxonomy;

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