TY - JOUR
AU - Anna Haapaniemi
AU - James Scourse
AU - Victoria Peck
AU - Hilary Kennedy
AU - Paul Kennedy
AU - Sidney Hemming
AU - Mark Furze
AU - Anna nKowski
AU - William Austin
AU - John Walden
AU - Emilie Wadsworth
AU - Ian Hall
AB - Increased fluxes of ice-rafted detritus (IRD) from European ice sheets have been documented some 1000\textendash1500 years before the arrival of Laurentide Ice Sheet (LIS)-sourced IRD during Heinrich (H) events. These early fluxes have become known as \textquoteleftprecursor events\textquoteright, and it has been suggested that they have mechanistic significance in the propagation of H events. Here we present a re-analysis of one of the main cores used to generate the precursor concept, OMEX-2K from the Goban Spur covering the last 30 ka, in order to identify whether the British\textendashIrish Ice Sheet (BIIS) IRD fluxes occur only as precursors before H layers. IRD characterization and planktonic foraminiferal δ18O measurements constrained by a new age model have enabled the generation of a continuous record of IRD sources, timing, frequency and flux, and of local contemporary hydrographic conditions. The evidence indicates that BIIS IRD precursors are not uniquely, or mechanistically, linked to H events, but are part of the pervasive millennial-scale cyclicity. Our results support an LIS source for the IRD comprising H layers, but the ambient glacial sections are dominated by assemblages typical of the Irish Sea Ice Stream. Light isotope excursions associated with H events are interpreted as resulting from the melting of the BIIS, with ice-sheet destabilization attributed to eustatic jumps generated by LIS discharge during H events. This positive-feedback mechanism probably caused similar responses in all circum-Atlantic ice-sheet margins, and the resulting gross freshwater flux contributed to the perturbation of the Atlantic Meridional Overturning Circulation during H events.
BT - Boreas
M1 - 3
N2 - Increased fluxes of ice-rafted detritus (IRD) from European ice sheets have been documented some 1000\textendash1500 years before the arrival of Laurentide Ice Sheet (LIS)-sourced IRD during Heinrich (H) events. These early fluxes have become known as \textquoteleftprecursor events\textquoteright, and it has been suggested that they have mechanistic significance in the propagation of H events. Here we present a re-analysis of one of the main cores used to generate the precursor concept, OMEX-2K from the Goban Spur covering the last 30 ka, in order to identify whether the British\textendashIrish Ice Sheet (BIIS) IRD fluxes occur only as precursors before H layers. IRD characterization and planktonic foraminiferal δ18O measurements constrained by a new age model have enabled the generation of a continuous record of IRD sources, timing, frequency and flux, and of local contemporary hydrographic conditions. The evidence indicates that BIIS IRD precursors are not uniquely, or mechanistically, linked to H events, but are part of the pervasive millennial-scale cyclicity. Our results support an LIS source for the IRD comprising H layers, but the ambient glacial sections are dominated by assemblages typical of the Irish Sea Ice Stream. Light isotope excursions associated with H events are interpreted as resulting from the melting of the BIIS, with ice-sheet destabilization attributed to eustatic jumps generated by LIS discharge during H events. This positive-feedback mechanism probably caused similar responses in all circum-Atlantic ice-sheet margins, and the resulting gross freshwater flux contributed to the perturbation of the Atlantic Meridional Overturning Circulation during H events.
PB - Blackwell Publishing Ltd
PY - 2010
SN - 1502-3885
SP - 576
EP - 591
T2 - Boreas
TI - Source, timing, frequency and flux of ice-rafted detritus to the Northeast Atlantic margin, 30\textendash12 ka: testing the Heinrich precursor hypothesis
UR - http://dx.doi.org/10.1111/j.1502-3885.2010.00141.x
VL - 39
ER -