Grain size effects on excess Thorium-230 of sediment cores from the Southern Ocean and the South East Atlantic ...
Excess Thorium-230 (230Thxs) as a constant flux tracer is an essential tool for paleoceanographic studies, but its limitations for flux normalization are still a matter of debate. In regions of rapid sediment accumulation, it has been an open question if 230Thxs-normalized fluxes are biased by parti...
| Main Authors: | , , , |
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| Format: | Article in Journal/Newspaper |
| Language: | English |
| Published: |
PANGAEA
2010
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| Subjects: | |
| Online Access: | https://dx.doi.org/10.1594/pangaea.753876 https://doi.pangaea.de/10.1594/PANGAEA.753876 |
| Summary: | Excess Thorium-230 (230Thxs) as a constant flux tracer is an essential tool for paleoceanographic studies, but its limitations for flux normalization are still a matter of debate. In regions of rapid sediment accumulation, it has been an open question if 230Thxs-normalized fluxes are biased by particle sorting effects during sediment redistribution. In order to study the sorting effect of sediment transport on 230Thxs, we analyzed the specific activity of 230Thxs in different particle size classes of carbonate-rich sediments from the South East Atlantic, and of opal-rich sediments from the Atlantic sector of the Southern Ocean. At both sites, we compare the 230Thxs distribution in neighboring high vs. low accumulation settings. Two grain-size fractionation methods are explored.We find that the 230Thxs distribution is strongly grain size dependent, and 50-90% of the total 230Thxs inventory is concentrated in fine material smaller than 10 µm, which is preferentially deposited at the high accumulation sites. ... : Supplement to: Kretschmer, Sven; Geibert, Walter; Rutgers van der Loeff, Michiel M; Mollenhauer, Gesine (2010): Grain size effects on Th-230 (xs) inventories in opal-rich and carbonate-rich marine sediments. Earth and Planetary Science Letters, 294(1-2), 131-142 ... |
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