Rare earth elements, Sr, Ba, Fe, and major cation concentrations in some living foraminiferal tests collected from Iriomote Island, Japan: An exploration for trace element behavior during biogenic calcium carbonate formation

Research on living foraminiferal tests from Iriomote Island, Japan, reveals that rare earth elements (REEs), strontium (Sr), and magnesium (Mg) incorporate into biogenic calcium carbonate following patterns consistent with crystal structure and ionic radius control. The study found that the sample/seawater concentration ratios of these elements align with theoretical models predicting cation incorporation based on size compatibility. However, iron (Fe) and barium (Ba) exhibited higher-than-expected ratios, suggesting the presence of insoluble precipitates like Fe-hydroxides and barite. Notably, REE concentrations correlated with Fe, implying coprecipitation during seawater exposure or intracellular digestion before CaCO3 crystallization. This study provides insights into trace element behavior in biogenic calcium carbonate formation, offering a deeper understanding of geochemical processes in marine environments.

TERAKADO, Y., OFUKA, Y., & TADA, N. (2010). Rare earth elements, Sr, Ba, Fe, and major cation concentrations in some living foraminiferal tests collected from Iriomote Island, Japan: An exploration for trace element behavior during biogenic calcium carbonate formation. Geochemical Journal, 44(4), 315–322. https://doi.org/10.2343/geochemj.1.0068