2019 年 53 巻 2 号 p. 139-150
The practical partition coefficients of rare earth elements (REEs) between limestone and seawater were examined by comparing the data of some young limestones, present-day biogenic carbonates, and those experimentally obtained. The plausible REE partition coefficients for the limestone studies were obtained from the REE data of Quaternary limestones and modern seawaters. The inferred partition coefficients range from 214 for La to 327 for Ce, and show a nearly flat REE pattern. These REE partition coefficients were applied to some Carboniferous to Quaternary limestone samples that have been considered to involve a lesser amount of non-carbonate materials (i.e., clay, apatite, and Fe-Mn oxyhydroxide). The estimated REE patterns of the paleoseawaters show various sizes of negative Ce anomalies and LREE depletions, and these features are similar to those seen in modern seawaters regardless of the limestone ages.