Neogloboquadrina pachyderma LA-ICP-MS spectral files and stable isotope data from: Geochemical differences between alive, uncrusted and dead, crusted shells of Neogloboquadrina pachyderma: Implications for paleoreconstruction

Planktic foraminiferal-based trace element-calcium ratios (TE/Ca) are a
cornerstone in paleoceanographic reconstructions. While TE-environment
calibrations are often established through culturing experiments, shell
growth in culture is not always consistent with growth in a natural
setting. For example, many species of planktic foraminifera thicken their
shell at the end of their life cycle, producing a distinct ‘gametogenic’
crust. Crust is common in fossil foraminifers, however, shells grown in
culture do not often develop a thick crust. Here we investigate potential
vital effects associated with the crusting process by comparing the trace
element (Mg/Ca, Na/Ca, Ba/Ca, Sr/Ca, Mn/Ca, Zn/Ca) and stable isotope
(δ13C, δ18O) composition of alive, fully mature, uncrusted shells to
recently deceased, crusted shells of Neogloboquadrina pachyderma collected
from the same plankton tows off the Oregon (USA) coast. We find that
uncrusted (N = 55) shells yield significantly higher Ba/Ca, Na/Ca, Mn/Ca,
and Sr/Ca than crusted (N = 66) shells, and crust calcite records
significantly lower TE/Ca values for all elements examined. Isotopic
mixing models suggest that the crust calcite accounts for ~40 to 70% of
crusted shell volume. Comparison of foraminiferal and seawater isotopes
indicate that N. pachyderma lives in the upper 90 m of the water column,
and that crust formation occurs slightly deeper than their average living
depth habitat. Results highlight the necessity to establish calibrations
from crusted shells, as application of calibrations from TE-enriched
uncrusted shells may yield attenuated or misleading paleoceanographic
reconstructions.