The relationship of Heinrich events and their European precursors over the past 60 ka BP: a multi-proxy ice-rafted debris provenance study in the North East Atlantic |
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| Institution: | 1. Divisão de Geologia e Georecursos Marinhos, Instituto Português do Mar e da Atmosfera (IPMA), Avenida de Brasília 6, 1449-006 Lisboa, Portugal;2. Department of Earth Science, University of Bergen, and the Bjerknes Centre for Climate Research, University of Bergen, Allégaten 41 P.O. Box 7803, 5020 Bergen Norway;1. Department of Earth Sciences, University of New Brunswick, 2 Bailey Drive, Fredericton, NB, Canada;2. Centre for Past Climate Studies, Arctic Research Centre, iClimate, Department of Geoscience, Aarhus University, Høegh-Guldbergs Gade 2, DK-8000 Aarhus C, Denmark;3. Center for Geomicrobiology, Department of Bioscience, Aarhus University, Ny Munkegade 116, DK-8000 Aarhus C, Denmark;1. Institute of Meteorology and Climate Research, Karlsruhe Institute of Technology, Karlsruhe, Germany;2. Institute for Geophysics and Meteorology, University of Cologne, Cologne, Germany;3. Institute of Geography, University of Cologne, Cologne, Germany;4. Neanderthal Museum, Mettmann, Germany;2. Department of Earth Sciences, Royal Holloway University of London, Egham, UK;3. Godwin Laboratory for Palaeoclimate Research, Department of Earth Sciences, University of Cambridge, Cambridge, UK |
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| Abstract: | High resolution, multi-proxy records of ice-rafted debris (IRD) flux and provenance in the NE Atlantic detail the development, variability and decline of marine margins of the last glacial circum-North Atlantic ice sheets. Coupled lithological identification, Sr and Nd isotopic composition and 40Ar/39Ar ages of individual hornblende grains reduce ambiguity as to IRD potential source region, allowing clear differentiation between Laurentide (LIS), Icelandic and British (BIS) ice sheet sources (the Icelandic and BIS are collectively referred to as the NW European ice sheet, NWEIS). A step-wise increase in the flux of IRD to the core site at ～26.5 ka BP documents BIS advance and glaciation of Ireland. Millennial-scale variability of the BIS at a ～2 ka periodicity is inferred through clusters of pulsed IRD fluxes throughout the late glacial (26.5–10 ka BP). Combination of these European IRD events and the ～7 ka periodicity of LIS instability is thought to account for quasi-synchronicity of the NWEIS and LIS IRD pulses at Heinrich event (H) 2 and H1, previously suggested to represent the possible involvement of the NWEIS in the initiation of H events. Furthermore, the lack of extensive NWEIS marine margin is inferred prior to H3 (31.5 ka BP), such that no ‘European precursor’ event is associated with either H5 or H4. This suggests that ‘precursor events’ were not directly implicated in the collapse of the LIS, and the persistent instabilities of the BIS that are clustered at a 2 ka periodicity are incompatible with the concept that both H events and their ‘precursors’ are independent responses to a common underlying trigger. |
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