Traditional and Emerging Geochemical Proxies in Foraminifera

Geochemical analyses of the carbonate tests calcified by foraminifera have provided much of the foundation for reconstructions of past ocean and climate conditions, and for chemostratigraphy. In particular, reconstructions of climate history (including temperature, salinity, and ice volume), ocean paleocirculation patterns, the carbon cycle, paleoproductivity, marine carbonate chemistry, and chemo-stratigraphy have relied on measurements of isotopic and trace element composition of foraminiferal calcium carbon-ate, and variations in these geochemical records through time and space. Substantial work has been done on details of traditional proxies (e.g., d18O, d13C) and on emerging proxies (e.g., d11B, eNd) in recent years; hence, a new overview of these proxies provides a timely reference and educational tool. We review the geochemical proxies that utilize foraminiferal carbonate tests, including potential uses of the proxies for reconstructions through time: d18O, d13C, trace elements (Mg, Cd, Ba, Zn, B, U), 87Sr/86Sr, d26Mg, d11B, and eNd. Both planktic and benthic foraminifera are included; planktic foraminifera provide information on the upper few hundred meters of the surface ocean, whereas benthic foraminifera provide information on conditions at the seafloor and in shallow porewaters, from shallow seas to deep ocean basins.