Geophysical Research Letters · 2009 · 158 citations · 25 references
Natural SciencesEarth SciencesOceanographyOcean CirculationPhysical OceanographySedimentologyAtlantic Meridional Overturning Circulation HistoryCore DescriptionMarine Sediment ProxiesMeridional Overturning CirculationAtlantic Meridional Overturning CirculationHeinrich EventsPa RatiosParticle Composition EffectsParticulate Biogenic SilicaSediment Core InterpretationTh RatiosWater Mass Properties
Ocean circulation may have undergone reductions and reinvigorations in the past closely tied to regional climate changes. Measurements of 231 Pa/ 230 Th ratios in a sediment core from the Bermuda Rise have been interpreted as evidence that the Atlantic Meridional Overturning Circulation (AMOC) was weakened or completely eliminated during a period of catastrophic iceberg discharges (Heinrich‐Event 1, H1). Here we present new data from the Bermuda Rise that show further 231 Pa/ 230 Th peaks during Heinrich‐2 (H2) and Heinrich‐3 (H3). Additionally, a tight correlation between diatom abundances (biogenic silica) and 231 Pa/ 230 Th is discovered in this core. Our results redirect the interpretation of 231 Pa/ 230 Th from the Bermuda Rise as a proxy for ocean circulation towards a proxy that reacts highly sensitive to changes of particle composition and water mass properties.
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