Magnesium/Calcium ratios in benthic foraminifera from surface sediments ...

• Main Authors: Raitzsch, Markus, Kuhnert, Henning, Groeneveld, Jeroen, Bickert, Torsten
• Format: Dataset
• Language: English
• Published: PANGAEA 2008
• Subjects: Event label; DEPTH, sediment/rock; Depth, top/min; Depth, bottom/max; Planulina wuellerstorfi, Magnesium/Calcium ratio; Planulina wuellerstorfi, Magnesium/Calcium ratio, standard deviation; Cibicidoides mundulus, Magnesium/Calcium ratio; Cibicidoides mundulus, Magnesium/Calcium ratio, standard deviation; Giant box corer; MultiCorer; Bottom lander; Gravity corer Kiel type; LA-ICP-MS Thermo Finnigan Element 2; M6/6; M9/4; M12/1; M20/2; M23/2; M29/1; M34/1; M34/3; M46/2; M46/3; M57/2; Meteor 1986; Priority Programme 1158 Antarctic Research with Comparable Investigations in Arctic Sea Ice Areas SPP1158; Arctic; Antarctic; Antarc*; Foraminifera*; North Atlantic Deep Water; North Atlantic; Sea ice
• Online Access: https://dx.doi.org/10.1594/pangaea.759564; https://doi.pangaea.de/10.1594/PANGAEA.759564

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 ... : Supplement to: Raitzsch, Markus; Kuhnert, Henning; Groeneveld, Jeroen; Bickert, Torsten (2008): Benthic foraminifer Mg/Ca anomalies in South Atlantic core top sediments and their implications for paleothermometry. Geochemistry, Geophysics, Geosystems, 9(5), Q05010 ...