Restrictions in Mg/Ca-paleotemperature estimations in high latitude bottom waters : evidence from the Fram Strait and the Nordic Seas.

Werner, Kirstin, Marchitto, Thomas, Not, Christelle, Spielhagen, Robert and Husum, Katrine (2014) Restrictions in Mg/Ca-paleotemperature estimations in high latitude bottom waters : evidence from the Fram Strait and the Nordic Seas. [Poster] In: AGU Fall Meeting 2014. , 15.12.-19.12.2014, San Francisco, California, USA .

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Abstract

PP43B-1476
Mg to Ca ratios of the benthic foraminifer species Cibicidoides wuellerstorfi provide a great potential for reconstructing bottom water temperatures, especially from the lower end of the temperature range between 0 and 6°C (Tisserand et al., 2013). A set of core top samples from the Fram Strait and the Norwegian margin have been studied for Mg/Ca ratios in C. wuellerstorfi in order to establish a calibration relationship to the environmental conditions. In this part of the northern North Atlantic the bottom water temperature range between -0.5 and -1°C. For the calibration to modern water mass conditions, modern oceanographic data from both existing conductivity-temperature-depth (CTD) casts and the World Ocean Data Base 2013 (Boyer et al., 2013) have been used. Benthic Mg/Ca ratios are relatively high suggesting a preference of C. wuellerstorfi to incorporate Mg below 0°C. Although no correlation has been found to existing temperature calibrations, the data are in line with earlier Mg/Ca data from C. wuellerstorfi in the area (Martin et al., 2002; Elderfield et al., 2006). The carbonate ion effect is most likely a main cause for the relatively high Mg/Ca ratios found in core top samples from the Fram Strait and the Nordic Seas, however, other factors may influence the values as well. Holocene records of benthic trace metal/Ca ratios from the eastern Fram Strait display trends similar to those found in other proxy indicators, despite the difficulties to constrain a temperature calibration for this low temperature range. In particular, the benthic B/Ca and Li/Ca records resemble trends in Holocene planktic foraminifer assemblages, suggesting to be influenced by environmental factors such as the carbonate ion effect consistent for the entire water column.

Document Type: Conference or Workshop Item (Poster)
Keywords: Paleotemperature; Arctic Ocean; Fram Strait; Nordic Seas; Foraminifera; Cibicidoides wuellerstorfi
Research affiliation: OceanRep > GEOMAR > FB1 Ocean Circulation and Climate Dynamics > FB1-P-OZ Paleo-Oceanography
Related URLs:
Projects: Laptev Sea System, Transdrift
Date Deposited: 08 Apr 2015 06:56
Last Modified: 08 Apr 2015 06:56
URI: http://oceanrep.geomar.de/id/eprint/27678

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