Not logged in
Data Publisher for Earth & Environmental Science

Raitzsch, Markus; Kuhnert, Henning; Groeneveld, Jeroen; Bickert, Torsten (2008): Magnesium/Calcium ratios in benthic foraminifera from surface sediments. PANGAEA,, Supplement to: Raitzsch, M et al. (2008): Benthic foraminifer Mg/Ca anomalies in South Atlantic core top sediments and their implications for paleothermometry. Geochemistry, Geophysics, Geosystems, 9(5), Q05010,

Always quote citation above when using data! You can download the citation in several formats below.

RIS CitationBibTeX CitationShow MapGoogle Earth

We used modern epibenthic foraminifer tests of Cibicidoides mundulus and Planulina wuellerstorfi from South Atlantic core top sediments in order to establish Mg/Ca-temperature relationships for the temperature range from 0 to 15°C. We obtained the following calibrations: Mg/Ca (mmol/mol) = 0.830*exp(0.145*BWT (°C)) for P. wuellerstorfi, and Mg/Ca (mmol/mol) = 0.627*exp(0.143*BWT (°C)) for C. mundulus. However, a number of tests, especially those bathed in North Atlantic Deep Water, revealed higher Mg/Ca ratios than predicted from the calibration. Our data suggest that d[CO3 2-] of bottom water exerts a significant control on dMg/Ca (temperature-corrected) of C. mundulus (dMg/Ca = 0.017*d[CO3 2-] -0.14), while dMg/Ca of P. wuellerstorfi is more likely to be governed by TCO2 (dMg/Ca = -0.007*TCO2 + 15). Since both d[CO3 2-] and TCO2 are closely linked to [CO3 2-], it is inferred that carbonate ion acts as secondary control, after temperature, on benthic shell Mg/Ca below -4°C. A drop in [CO3 2-] by 25 ?mol/kg at 4 km water depth, as suggested for the Last Glacial Maximum, would decrease Mg/Ca by up to 0.4 mmol/mol, which leads to an underestimation of bottom water temperature by -3.5°C. Therefore our results indicate that the Mg/Ca thermometer should be used cautiously for benthic foraminifers where changes in the carbonate chemistry are present in the paleoceanographic record.
Deutsche Forschungsgemeinschaft (DFG), grant/award no. 404421353: Iron manganese co-limitation – a potential driver of Southern Ocean phytoplankton ecology
German Science Foundation (DFG), grant/award no. 5472008: Priority Programme 1158 Antarctic Research with Comparable Investigations in Arctic Sea Ice Areas
Median Latitude: -28.834968 * Median Longitude: -19.330520 * South-bound Latitude: -48.013333 * West-bound Longitude: -58.518200 * North-bound Latitude: -1.665000 * East-bound Longitude: 17.755000
Date/Time Start: 1988-03-12T00:00:00 * Date/Time End: 2003-02-27T00:00:00
Minimum DEPTH, sediment/rock: 0.005 m * Maximum DEPTH, sediment/rock: 0.005 m
GeoB1041-1 * Latitude: -3.480000 * Longitude: -7.591667 * Date/Time: 1988-03-12T00:00:00 * Elevation: -4035.0 m * Penetration: 0.42 m * Location: Walvis Ridge * Campaign: M6/6 * Basis: Meteor (1986) * Method/Device: Giant box corer (GKG) * Comment: Karb.-schl., Forams
GeoB1105-3 * Latitude: -1.665000 * Longitude: -12.428330 * Date/Time: 1989-02-25T00:00:00 * Elevation: -3231.0 m * Penetration: 0.36 m * Recovery: 0.32 m * Location: Equatorial Atlantic * Campaign: M9/4 * Basis: Meteor (1986) * Method/Device: Giant box corer (GKG) * Comment: Karbonatschlamm
GeoB1113-7 * Latitude: -5.745000 * Longitude: -11.035000 * Date/Time: 1989-03-02T00:00:00 * Elevation: -2373.0 m * Penetration: 0.35 m * Recovery: 0.25 m * Location: Equatorial Atlantic * Campaign: M9/4 * Basis: Meteor (1986) * Method/Device: Giant box corer (GKG) * Comment: Foram.-sand, tonig
246 data points

Download Data

Download dataset as tab-delimited text — use the following character encoding:

View dataset as HTML