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2026
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| Online Access: | https://doi.org/10.5281/zenodo.20311500 |
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| author | Wang, Jiakai Xiong, Zhifang Li, Tiegang |
| author_facet | Wang, Jiakai Xiong, Zhifang Li, Tiegang |
| contents | <p><span>The Antarctic Slope Front (ASF) and Antarctic Slope Current (ASC) regulate exchange across the continental slope and the influence of warm Circumpolar Deep Water (CDW) along the West Antarctic margin, but the long-term variability of this Amundsen Sea slope setting remains poorly constrained. Here we present a ~25 kyr record from core ANT39/A3-02, supported by a Bacon age model and sedimentological and geochemical proxy groups interpreted as relative changes in surface productivity, bottom current strength, and coarse detrital enrichment. Bottom current strength and coarse detrital enrichment vary together through much of the record, indicating repeated sediment reworking close to the seafloor on the upper slope. Surface productivity shows a different pattern. During Heinrich Stadial 1 and the interval from the Antarctic Cold Reversal to the early Holocene, bottom current strength and coarse detrital enrichment remained high. In contrast, productivity was muted or only modestly enhanced, with Mn/Ti and U/Ti providing constraints on concurrent near-bottom redox and ventilation changes. This mismatch suggests that upper-ocean conditions, including sea ice and stratification linked to meltwater input, limited light availability and nutrient entrainment into the photic zone, even when CDW-bearing waters were likely present near the slope front or on the shelf. In the late Holocene, productivity more often increased together with bottom current strength and coarse detrital enrichment. Together with published regional sea ice evidence, this pattern is best explained by more frequent seasonal sea ice opening and weaker meltwater stratification related to ice sheet retreat, rather than by maximum CDW heat delivery. These results show that the Amundsen Sea upper-slope record does not preserve a single persistent CDW-driven signal. Instead, it records alternating coupled and decoupled states between surface productivity and near-bottom hydrodynamic activity. This distinction is important for interpreting sedimentary records from the West Antarctic Ice Sheet-adjacent margin, because meltwater-related stratification may allow CDW-related slope-front exchange and near-bottom winnowing to remain active even when the surface-productivity response is muted.</span></p> |
| format | Recurso digital |
| id | zenodo_https___doi_org_10_5281_zenodo_20311500 |
| institution | Zenodo |
| language | |
| publishDate | 2026 |
| publisher | Zenodo |
| record_format | zenodo |
| spellingShingle | Surface-bottom coupling on the Amundsen Sea upper slope over the past 25 kyr: evidence for changes in slope-front dynamics Wang, Jiakai Xiong, Zhifang Li, Tiegang <p><span>The Antarctic Slope Front (ASF) and Antarctic Slope Current (ASC) regulate exchange across the continental slope and the influence of warm Circumpolar Deep Water (CDW) along the West Antarctic margin, but the long-term variability of this Amundsen Sea slope setting remains poorly constrained. Here we present a ~25 kyr record from core ANT39/A3-02, supported by a Bacon age model and sedimentological and geochemical proxy groups interpreted as relative changes in surface productivity, bottom current strength, and coarse detrital enrichment. Bottom current strength and coarse detrital enrichment vary together through much of the record, indicating repeated sediment reworking close to the seafloor on the upper slope. Surface productivity shows a different pattern. During Heinrich Stadial 1 and the interval from the Antarctic Cold Reversal to the early Holocene, bottom current strength and coarse detrital enrichment remained high. In contrast, productivity was muted or only modestly enhanced, with Mn/Ti and U/Ti providing constraints on concurrent near-bottom redox and ventilation changes. This mismatch suggests that upper-ocean conditions, including sea ice and stratification linked to meltwater input, limited light availability and nutrient entrainment into the photic zone, even when CDW-bearing waters were likely present near the slope front or on the shelf. In the late Holocene, productivity more often increased together with bottom current strength and coarse detrital enrichment. Together with published regional sea ice evidence, this pattern is best explained by more frequent seasonal sea ice opening and weaker meltwater stratification related to ice sheet retreat, rather than by maximum CDW heat delivery. These results show that the Amundsen Sea upper-slope record does not preserve a single persistent CDW-driven signal. Instead, it records alternating coupled and decoupled states between surface productivity and near-bottom hydrodynamic activity. This distinction is important for interpreting sedimentary records from the West Antarctic Ice Sheet-adjacent margin, because meltwater-related stratification may allow CDW-related slope-front exchange and near-bottom winnowing to remain active even when the surface-productivity response is muted.</span></p> |
| title | Surface-bottom coupling on the Amundsen Sea upper slope over the past 25 kyr: evidence for changes in slope-front dynamics |
| url | https://doi.org/10.5281/zenodo.20311500 |