Towards the Calibration of the Globigerinoides ruber (white) paleothermometer ...
The use of planktonic foraminiferal Mg/Ca ratios to reconstruct past sea surface temperatures (SST) is prevalent in the literature. The perceived simplicity of the underlying chemistry and ease of measurements are alluring. Canonically, temperature is thought to be the primary control on the shell M...
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Columbia University
2011
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| Online Access: | https://dx.doi.org/10.7916/d8ks744b https://academiccommons.columbia.edu/doi/10.7916/D8KS744B |
| Summary: | The use of planktonic foraminiferal Mg/Ca ratios to reconstruct past sea surface temperatures (SST) is prevalent in the literature. The perceived simplicity of the underlying chemistry and ease of measurements are alluring. Canonically, temperature is thought to be the primary control on the shell Mg/Ca values. Additionally, an appeal of this proxy is that it can be combined with shell ä18O values to reconstruct changes in the local ä18O of seawater, a proxy for salinity. However, we have identified a salinity effect on the Mg/Ca signal recorded in planktonic foraminifera influencing samples from open ocean locations. This effect causes excess Mg incorporation, higher than predicted by theory, in high salinity regions for the planktonic foraminiferal species, Globigerinoides ruber (white). The shell "excess Mg/Ca" resides within the primary calcite lattice of the shell itself and may be related to the observed cyclic banding of high and low Mg/Ca calcite with the foraminiferal shells. We derive new equations ... |
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