Abstract:
This data set consists of Globorotalia truncatulinoides (R) Mg/Ca to water
temperature calibrations from Indian Ocean core-top sediments and plankton
tows. G. truncatulinoides (R) is a deep dwelling species that provides a Mg
thermometer for the extremes of the permanent thermocline.
Abstract
Recent work has provided useful Mg/Ca to water temperature calibrations for
shallow-dwelling
... planktonic foraminifer species. Globorotalia
truncatulinoides (right coiling (R)) is a deep-dwelling species that can serve
as a source of information about the temporal variability in the water
characteristics of the thermocline. We present a temperature calibration for
the Mg/Ca in the shell of G. truncatulinoides (R) and examine some of the
practical issues associated with evaluating the usefulness of the technique.
The Mg/Ca in the primary and the secondary calcite of individual G.
truncatulinoides (R) correlates exponentially with water column temperatures,
showing a change of ~10% in the Mg/Ca per 1°C (R2 = 0.92). A limited
comparison with plankton tow samples demonstrates that the average Mg/Ca
temperature was offset +1°C from the average temperature calculated using the
D18O calibration of O'Neil et al. [1969], and the Mg/Ca temperatures have a
range similar to the d18O temperatures. Comparisons of the [Mg] in the core
top samples to water depth of deposition indicates that dissolution does not
alter the measured value of Mg in the primary calcite. 
