2:00 PM - 2:15 PM
[BPT03-02] A more robust salinity proxy: towards a mechanistic understanding of sodium incorporation in foraminiferal calcite
Keywords:Biomineralization, Foraminifera, Salinity proxy
We cultured two foraminiferal species under a range of salinities and analyzed the newly formed calcite for their average Na/Ca and its distribution across chamber walls using Electron Probe Micro Analysis and Nanoscale Secondary Ion Mass Spectrometry. Obtained maps show that Na and other incorporated elements (Mg, K, S, and P) occur in distinct bands adjacent to the primary organic sheet. The width and intensity of these bands differ between elements and between the two species investigated. We evaluated the intensity of the high-Na, -Mg, -K, bands as a function of salinity. Together, these results are the basis of a new calcification model that explains incorporation of these elements as a function of 1) seawater chemistry and 2) biological control during calcification by the foraminifer. This framework will be applied to test recently obtained calibrations for incorporation of Na (and other elements) as a function of salinity.