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Nares Strait, a major connection between the Arctic Ocean and Baffin Bay, was blocked by coalescent Innuitian and Greenland ice sheets during the last glaciation. This paper focuses on the events and processes leading to the opening of the strait and the environmental response to establishment of the Arctic‐Atlantic throughflow. The study is based on sedimentological, mineralogical and foraminiferal analyses of radiocarbon‐dated cores 2001LSSL‐0014PCandTCfrom northern Baffin Bay. Radiocarbon dates on benthic foraminifera were calibrated with ΔR = 220±20 years. Basal compact pebbly mud is interpreted as a subglacial deposit formed by glacial overriding of unconsolidated marine sediments. It is overlain by ice‐proximal (red/grey laminated, ice‐proximal glaciomarine unit barren of foraminifera and containing >2 mm clasts interpreted as ice‐rafted debris) to ice‐distal (calcareous, grey pebbly mud with foraminifera indicative of a stratified water column with chilled Atlantic Water fauna and species associated with perennial and then seasonal sea ice cover) glacial marine sediment units. The age model indicates ice retreat into Smith Sound as early asc. 11.7 and as late asc. 11.2 cal. kaBPfollowed by progressively more distal glaciomarine conditions as the ice margin retreated toward the Kennedy Channel. We hypothesize that a distinctIRDlayer deposited between 9.3 and 9 (9.4–8.9 1σ) cal. kaBPmarks the break‐up of ice in Kennedy Channel resulting in the opening of Nares Strait as an Arctic‐Atlantic throughflow. Overlying foraminiferal assemblages indicate enhanced marine productivity consistent with entry of nutrient‐rich Arctic Surface Water. A pronounced rise in agglutinated foraminifers and sand‐sized diatoms, and loss of detrital calcite characterize the uppermost bioturbated mud, which was deposited after 4.8 (3.67–5.55 1σ) cal. kaBP. The timing of the transition is poorly resolved as it coincides with the slow sedimentation rates that ensued after the ice margins retreated onto land.
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This content will become publicly available on December 9, 2025
Utility of Allochthonous ForaminiferaFaunas in SubmarinePaleoseismology Studies
Submarine paleoseismology hinges on analyzing stratigraphic records to learn about past earthquakes. Marine microfossils, such as foraminifera, can reveal critical details about the water depth of the sediment remobilized during earthquakes.Although allochthonous foraminifera are typically excluded from age control studies, these faunas are useful in providing insight into the water depth from which a sediment transport deposit originated. As an example, we describe a ~16 m thick Holocene sedimentary deposit first defined by Kioka et al. (2019) and later dated to 1.77 (+0.49/−0.31) ka by Usami et al. (2021) and Schwestermann et al. (2021) based on bulk OC, C-14. Strasser et al. (InPress) identified the event at IODP Expedition 386 Sites M0084, M0086, and M0088, located at hadal depths in the northern Japan Trench. Each site features a basal 1 to2 m thick, fining-upward medium sand to silt with well-defined planar and ripple lamination. The sequence has been interpreted as a turbidite composed of basalsand grading into silty clay that is overlain by a mass transport deposit. Calcareous foraminifera occur in the deposit despite being well below the CCD. Foraminiferal abundance decreases from the basal sand to the fi ne silty clay due to gravitational size sorting. Most displaced foraminifera, including thin-shelled taxa, are moderatelyt o well-preserved, likely due rapid burial, high alkalinity, and low internal friction within the flow. The foraminiferal assemblages are consistent across the three sites. The sandy portion of the deposit is dominated by Elphidium batialis, Uvigerina akitaensis, Nonionellina labradorica, Chilostomellina fi mbriata, and species of Bulimina, indicative of upper to middle bathyal depths (200 to 1000 m). In contrast, the silty clay contains smaller foraminifera like Bolivina, Cassidulina, Stainforthia and Epistominella, suggesting outer neritic to upper bathyal depths (100 to 600 m). Radiocarbon dating of the foraminifers within the basal sand from each site reveals that M0086 (16750 to 16200 cal BP) and M0088 (16650 to 16050 cal BP) have younger source ages compared to M0084 (19350 to 18800 cal BP). These findings indicate that the ~1.77 ka sediment transport event entrained much older strata that had originated in upper to middle bathyal depths and outer neritic to upper bathyal depths.
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- Award ID(s):
- 2044915
- PAR ID:
- 10599019
- Publisher / Repository:
- age.confex.com
- Date Published:
- Format(s):
- Medium: X
- Location:
- American Geophysical Union Fall 2024, Washington D.C., USA
- Sponsoring Org:
- National Science Foundation
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