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This dataset contains grain size records from three Integrated Ocean Drilling Program core sites (U1345, U1343, and U1339) in the Bering Sea. These records are used to determine the effectiveness of different grain size parameters as proxies for sediment transport, current strength, and primary productivity in the Bering Sea during a past warm interval (Marine Isotope Stage 11, 424-374 thousand years ago (ka)). Grain size is measured using a laser diffraction particle size analyzer (Malvern Mastersizer 3000), and is reported for bulk sediments, and for the terrigenous fraction only. The raw dataset provided by the Malvern software includes the volume % of grains in 109 bin sizes, as well as the 10th (Dx10), 50th (Dx50) and 90th (Dx90) percentiles. We also provide the volume distribution of grains in the following size fractions: clay (less than 2 micrometers (μm)); silt (2-63 μm); sand (63-2000 μm); gravel (greater than 2000 μm); ice-rafted debris (greater than 150 μm; greater than 250 μm), and sortable silt (10-63 μm). Additional grain size parameters, including mean size, sorting and skewness, are calculated in GRADISTAT.
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Evaluating the paleoenvironmental significance of sediment grain size in Bering Sea sediments during Marine Isotope Stage 11
Grain size is an important textural property of sediments and is widely used in paleoenvironmental studies as a means to infer changes in the sedimentary environment. However, grain size parameters are not always easy to interpret without a full understanding of the factors that influence grain size. Here, we measure grain size in sediment cores from the Bering slope and the Umnak Plateau, and review the effectiveness of different grain size parameters as proxies for sediment transport, current strength, and primary productivity, during a past warm interval (Marine Isotope Stage 11, 424-374 ka). In general, sediments in the Bering Sea are hemipelagic, making them ideal deposits for paleoenvironmental reconstructions, but there is strong evidence in the grain size distribution for contourite deposits between ~408-400 ka at the slope sites, suggesting a change in bottom current transport at this time.We show that the grain size of coarse (>150 μm) terrigenous sediment can be used effectively as a proxy for ice rafting, although it is not possible to distinguish between iceberg and sea ice rafting processes, based on grain size alone.We find that the mean grain size of bulk sediments can be used to infer changes in productivity on glacial-interglacial timescales, but the size and preservation of diatom valves also exert a control on mean grain size. Lastly, we show that the mean size of sortable silt (10-63 μm) is not a valid proxy for bottom current strength in the Bering Sea, because the input of ice-rafted silt confounds the sortable silt signal.
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- Award ID(s):
- 2110923
- PAR ID:
- 10380106
- Date Published:
- Journal Name:
- Stratigraphy
- Volume:
- 19
- Issue:
- 2
- ISSN:
- 1027-6890
- Page Range / eLocation ID:
- 119-139
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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