Mg/Ca temperature calibration for the benthic foraminifer Cibicidoides pachyderma

[ 1] The recent development of foraminiferal Mg/Ca as a paleotemperature proxy has enabled the extraction of global ice volume and local salinity from the more traditional paleotemperature proxy delta(18)O. The benthic foraminiferal genus Cibicidoides is widely used in paleoceanographic reconstructions because of its epifaunal habitat and cosmopolitan distribution, and it has received early attention in Mg/Ca work. However, existing temperature calibrations for Cibicidoides rely heavily on C. pachyderma core top data from one location, Little Bahamas Bank, where authigenic processes and/or reworking may result in elevated warm water Mg/Ca values. Here we present new C. pachyderma Mg/Ca data from a series of 29 high-quality multicore tops collected in the Florida Straits, spanning a temperature range of 5.8 - 18.6 degrees C. In contrast to previous calibrations, we find no evidence for a strongly exponential response to temperature. The data are best explained by a linear relationship, with a sensitivity of 0.12 mmol mol(-1) per degrees C.