Individual Foraminiferal Analyses: A Review of Current and Emerging Geochemical Techniques

Abstract

The trace element (TE) and isotopic composition of calcareous foraminifera has been invaluable in advancing our understanding of environmental change throughout the geological record. Whereas “bulk” geochemical techniques, typically requiring the dissolution of tens to hundreds of foraminiferal tests for a single analysis, have been used for decades to reconstruct past ocean-climate conditions, recent technological advances have increased our ability to investigate foraminiferal geochemistry from an individual test to a micron-scale domain level. Here we review current and emerging techniques and approaches to studying the trace element and stable isotope geochemistry of individual foraminifera (i.e., individual foraminiferal analyses or “IFA”), covering spatial scales including whole-test analysis, intratest spot analysis, and cross-sectional chemical mapping techniques. Our discussion of each technique provides an overview of how the specific analytical tool works, the history of its usage in foraminiferal studies, its applications, considerations, and limitations, and potential directions for future study. Lastly, we describe potential applications of combining multiple IFA techniques to resolve key questions related to paleoceanography, (paleo)ecology, and biomineralization, and provide recommendations for the storage, dissemination, and transparency of the vast amounts of data produced through these methods. This review serves as a resource for budding and experienced foraminiferal geochemists to explore the wide array of cutting-edge approaches being used to study the geochemical composition of modern and fossil foraminifera.