Comparison of Laser Ablation and Solution‐Based ICP‐MS Results for Individual Foraminifer Mg/Ca and Sr/Ca Analyses
Jennifer S. Fehrenbacher, Thomas M. Marchitto, Howard J. Spero
Abstract
Abstract The trace element and isotopic composition of foraminifera shells are widely used in paleoceanography to reconstruct past ocean conditions. Individual foraminifer analysis (IFA) is a rapidly expanding technique for obtaining trace element and/or isotope data from individual foraminifer specimens. IFA permits an assessment of population variability, which can be linked to environmental conditions at the time of calcification or can be used to assess postdepositional diagenesis. Uniform interpretation of IFA depends on the assumption that the data are not impacted by analytical technique. Here, we compare paired trace element (Mg/Ca and Sr/Ca) data for the same specimens analyzed first using laser ablation inductively coupled plasma‐mass spectrometry (ICP‐MS), followed by solution ICP‐MS. Foraminiferal trace element (TE) to calcium ratios compare well between the two methods for foraminifera of simple morphology ( Orbulina universa ), heavily calcified specimens with TE‐homogeneous outer calcite ( Pulleniatina obliquiloculata ), or when all chambers in multichambered species are analyzed by the laser and averaged together ( Trilobatus sacculifer and Neogloboquadrina dutertrei ). We highlight potential issues in interpreting and comparing studies that use different analytical techniques and recommend that the paleoceanographic community establish accepted protocols for generating IFA that would maximize our ability to cross‐compare paleoceanographic data and reconstructions when different analytical techniques are used.