Increased fluxes of ice-rafted detritus (IRD) from European ice sheets have been documented some ... more Increased fluxes of ice-rafted detritus (IRD) from European ice sheets have been documented some 1000-1500 years before the arrival of Laurentide Ice Sheet (LIS)-sourced IRD during Heinrich (H) events. These early fluxes have become known as 'precursor events', 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-Irish Ice Sheet (BIIS) IRD fluxes occur only as precursors before H layers. IRD characterization and planktonic foraminiferal d 18 O 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.
Supplementary tables for "New magnetostratigraphic insights from Iceberg Alley on the rhythm... more Supplementary tables for "New magnetostratigraphic insights from Iceberg Alley on the rhythms of Antarctic climate during the Plio-Pleistocene" Includes stratigraphic data for International Ocean Discovery Program (IODP) Expedition 382 Sites U1536 and U1537. <strong>Table Captions:</strong> <strong>Table S1.</strong> Splice table and additional appended cores for Site U1536 used in this study. <strong>Table S2.</strong> Splice table and additional appended cores for Site U1537 used in this study. <strong>Table S3.</strong> Correlation table for creation of correlated equivalent depth (ced) scale between Sites U1536 and U1537. <strong>Table S4.</strong> Uncertainty estimates for Site U1536 natural gamma radiation (NGR) correlation to Site U1537 on mcd depth scale using Undatable (Lougheed & Obrochta, 2019). <strong>Table S5.</strong> Site U1536 inclination, natural gamma radiation (NGR), gamma ray atten...
Increased fluxes of ice-rafted detritus (IRD) from European ice sheets have been documented some ... more Increased fluxes of ice-rafted detritus (IRD) from European ice sheets have been documented some 1000-1500 years before the arrival of Laurentide Ice Sheet (LIS)-sourced IRD during Heinrich (H) events. These early fluxes have become known as 'precursor events', 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-Irish Ice Sheet (BIIS) IRD fluxes occur only as precursors before H layers. IRD characterization and planktonic foraminiferal d 18 O 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.
Supplementary tables for "New magnetostratigraphic insights from Iceberg Alley on the rhythm... more Supplementary tables for "New magnetostratigraphic insights from Iceberg Alley on the rhythms of Antarctic climate during the Plio-Pleistocene" Includes stratigraphic data for International Ocean Discovery Program (IODP) Expedition 382 Sites U1536 and U1537. <strong>Table Captions:</strong> <strong>Table S1.</strong> Splice table and additional appended cores for Site U1536 used in this study. <strong>Table S2.</strong> Splice table and additional appended cores for Site U1537 used in this study. <strong>Table S3.</strong> Correlation table for creation of correlated equivalent depth (ced) scale between Sites U1536 and U1537. <strong>Table S4.</strong> Uncertainty estimates for Site U1536 natural gamma radiation (NGR) correlation to Site U1537 on mcd depth scale using Undatable (Lougheed & Obrochta, 2019). <strong>Table S5.</strong> Site U1536 inclination, natural gamma radiation (NGR), gamma ray atten...
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