Raitzsch, Markus; Kuhnert, Henning; Groeneveld, Jeroen; Bickert, Torsten (2008): Magnesium/Calcium ratios in benthic foraminifera from surface sediments [dataset]. PANGAEA, https://doi.org/10.1594/PANGAEA.759564, 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, https://doi.org/10.1029/2007GC001788
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Abstract:
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.
Project(s):
Funding:
German Research Foundation (DFG), grant/award no. 5472008: Priority Programme 1158 Antarctic Research with Comparable Investigations in Arctic Sea Ice Areas
Coverage:
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
Event(s):
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
Parameter(s):
| # | Name | Short Name | Unit | Principal Investigator | Method/Device | Comment |
|---|---|---|---|---|---|---|
| 1 | Event label | Event | ||||
| 2 | DEPTH, sediment/rock | Depth sed | m | Geocode | ||
| 3 | Depth, top/min | Depth top | m | |||
| 4 | Depth, bottom/max | Depth bot | m | |||
| 5 | Planulina wuellerstorfi, Magnesium/Calcium ratio | P. wuellerstorfi Mg/Ca | mmol/mol | Raitzsch, Markus | LA-ICP-MS Thermo Finnigan Element 2 | |
| 6 | Planulina wuellerstorfi, Magnesium/Calcium ratio, standard deviation | P. wuellerstorfi Mg/Ca std dev | ± | Raitzsch, Markus | ||
| 7 | Cibicidoides mundulus, Magnesium/Calcium ratio | C. mundulus Mg/Ca | mmol/mol | Raitzsch, Markus | LA-ICP-MS Thermo Finnigan Element 2 | |
| 8 | Cibicidoides mundulus, Magnesium/Calcium ratio, standard deviation | C. mundulus Mg/Ca std dev | ± | Raitzsch, Markus |
License:
Creative Commons Attribution 3.0 Unported (CC-BY-3.0)
Size:
246 data points