Ocean surface and bottom water conditions, iceberg drift and sediment transport on the North Iceland margin during MIS 3 and 2
Radiocarbon dates and marine tephra suggest that the upper 10 m of core MD99-2274 off North Iceland extends from ~0 to ~65 ka BP. A multi-proxy sediment and biomarker study at a ~0.5 ky resolution is used to derive a paleoclimate scenario for this area of the southwestern Nordic Seas, which during t...
| Main Authors: | , , , , |
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| Format: | Dataset |
| Language: | English |
| Published: |
PANGAEA
2021
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| Subjects: | |
| Online Access: | https://doi.pangaea.de/10.1594/PANGAEA.931154 https://doi.org/10.1594/PANGAEA.931154 |
| Summary: | Radiocarbon dates and marine tephra suggest that the upper 10 m of core MD99-2274 off North Iceland extends from ~0 to ~65 ka BP. A multi-proxy sediment and biomarker study at a ~0.5 ky resolution is used to derive a paleoclimate scenario for this area of the southwestern Nordic Seas, which during the Holocene had intermittent excursions of icebergs and a seasonal cover of drifting sea ice across the site. The sortable silt mean size (S̅S̅) suggests a bottom current (1000 m depth) flow speed maximum to minimum range of ~8 cm/s during Marine Isotope Stages 2 to 3, but the data are unreliable for the Holocene. Slow-down in flow speeds may be associated with massive ice and water discharges linked to the Hudson Strait ice stream (H-events) and to melt of icebergs from Greenland in the Nordic seas where convection would have been suppressed. Five pulses of sediment with a distinct felsic component are associated with iceberg transport from E/NE Greenland. Sea ice, open water and sea surface temperature (SST) biomarker proxies (i.e. IP25, brassicasterol and alkenones) all point towards near-perennial sea ice cover during MIS 3 and 2, rather than seasonal sea ice or open water conditions. Indeed, our biomarker and sediment data require that the seas north of Iceland have a thick, nearly continuous cover of sea-ice through which icebergs, calved from ice stream termini, drift slowly southward. The cross-correlation of the quartz % records between MD99-2274 and the well-dated core PS2644 in Blosseville Basin indicates significant coherence in the records at a multi-millennial (~8 ky) timescale. A transition to open ocean conditions is evident from the early Holocene onwards, albeit with the occurrence of some drift ice and icebergs. |
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