Master of Science (M.S.)
Degree Granting Department
Brad E. Rosenheim, Ph.D.
Julie N. Richey, Ph.D.
Amelia E. Shevenell, Ph.D.
Globorotalia truncatulinoides, Gulf of Mexico, Laser ablation, Mg/Ca, Planktic foraminifer, Sediment trap
Modern observations of planktic foraminifera from sediment trap studies help to constrain the regional ecology of paleoceanographically valuable species. Results from a weekly-resolved sediment trap time series (2008–2014) in the northern Gulf of Mexico demonstrate that 92% of Globorotalia truncatulinoides flux occurs in winter (January, February, and March), and that encrusted and non-encrusted individuals represent calcification in distinct depth habitats. We use individual foraminiferal analysis (IFA) of G. truncatulinoides tests to investigate differences in the elemental (Mg/Ca) and isotopic composition (18O and 13C) of the encrusted and non-encrusted ontogenetic forms of G. truncatulinoides, and to estimate their calcification depth in the northern Gulf of Mexico. We estimate that non-encrusted and encrusted G. truncatulinoides have mean calcification depths of 66 ± 9 meters and 379 ± 76 meters, respectively. We validate the Mg/Ca-calcification temperature relationship for G. truncatulinoides and demonstrate that the 18O and Mg/Ca of the non-encrusted form is a suitable proxy for winter surface mixed layer conditions in the Gulf of Mexico. Care should be taken not to combine encrusted and non-encrusted individuals of G. truncatulinoides for down core paleoceanographic studies.
Scholar Commons Citation
Reynolds, Caitlin Elizabeth, "Environmental controls on the geochemistry of Globorotalia truncatulinoides in the Gulf of Mexico: Implications for paleoceanographic reconstructions" (2018). Graduate Theses and Dissertations.