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| Titel |
A comparison of benthic foraminiferal Mn / Ca and sedimentary Mn / Al as proxies of relative bottom-water oxygenation in the low-latitude NE Atlantic upwelling system |
| VerfasserIn |
C. L. McKay, J. Groeneveld, H. L. Filipsson, D. Gallego-Torres, M. J. Whitehouse, T. Toyofuku, O. E. Romero |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1726-4170
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| Digitales Dokument |
URL |
| Erschienen |
In: Biogeosciences ; 12, no. 18 ; Nr. 12, no. 18 (2015-09-18), S.5415-5428 |
| Datensatznummer |
250118097
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| Publikation (Nr.) |
 copernicus.org/bg-12-5415-2015.pdf |
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| Zusammenfassung |
| Trace element incorporation into foraminiferal shells (tests) is governed by
physical and chemical conditions of the surrounding marine environment, and
therefore foraminiferal geochemistry provides a means of palaeo-oceanographic
reconstructions. With the availability of high-spatial-resolution
instrumentation with high precision, foraminiferal geochemistry has become a
major research topic over recent years. However, reconstructions of past
bottom-water oxygenation using foraminiferal tests remain in their infancy.
In this study we explore the potential of using Mn / Ca determined by
secondary ion mass spectrometry (SIMS) as well as by flow-through inductively
coupled plasma optical emission spectroscopy (FT-ICP-OES) in the benthic
foraminiferal species Eubuliminella exilis as a proxy for recording
changes in bottom-water oxygen conditions in the low-latitude NE Atlantic
upwelling system. Furthermore, we compare the SIMS and FT-ICP-OES results
with published Mn sediment bulk measurements from the same sediment core.
This is the first time that benthic foraminiferal Mn / Ca is directly
compared with Mn bulk measurements, which largely agree on the former oxygen
conditions. Samples were selected to include different productivity regimes
related to Marine Isotope Stage 3 (35–28 ka), the Last Glacial Maximum
(28–19 ka), Heinrich Event 1 (18–15.5 ka), Bølling Allerød
(15.5–13.5 ka) and the Younger Dryas (13.5–11.5 ka). Foraminiferal
Mn / Ca determined by SIMS and FT-ICP-OES is comparable. Mn / Ca was
higher during periods with high primary productivity, such as during the
Younger Dryas, which indicates low-oxygen conditions. This is further
supported by the benthic foraminiferal faunal composition. Our results
highlight the proxy potential of Mn / Ca in benthic foraminifera from
upwelling systems for reconstructing past variations in oxygen conditions of
the sea floor environment as well as the need to use it in combination with
other proxy records such as faunal assemblage data. |
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