OCE-RIG: Improving Climate Records Through a Mechanistic Understanding of Sub-Micron Proxy Heterogeneity in Spinose Foraminifera

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Calcite shells of planktonic and benthic foraminifera incorporate minerals and stable isotopes from the surrounding water into their shells as they grow, so the shells provide records of the environmental conditions in which the organisms lived. These shells are often preserved in sediments and are used to provide estimates of paleoclimates. However, many basic questions still remain about the relationship between foraminiferal shell composition and environmental conditions. A better understanding of foraminiferal biocalcification, in particular the relation between changing environmental conditions and the incorporation of trace and minor elements in the carbonate shells, will allow scientists to interpret paleoceanographic records more accurately. This award will support the work of the PI and a graduate student who will investigate biomineralization of foraminiferal shells at a sub-micron scale. The student will also participate in the University of Washington's Project COOL: Chemical Oceanography Outside the Laboratory, a science outreach program for middle school students. This research on the basic mechanics of biomineralization may also be useful for the field of material sciences and for medical applications related to bone growth. Researchers will use new in situ analytical approaches such as SIMS, nanoSIMS, laser-ablation ICP-MS, and new-generation EPMA with advanced element-mapping capabilities to investigate heterogeneous biomineralization of foraminiferal shells at a submicron scale, including apparent diurnal cycles in the Mg/Ca and Na/Ca banding within foraminifera tests. A mechanistic understanding of submicron-spatial scale elemental partitioning within foraminifera should improve our ability to interpret these elemental proxies in the context of paleoceanographic reconstruction.