@article{oai:nagoya.repo.nii.ac.jp:00011011,
 author = {TAKAHASHI, Takafumi and TANAKA, Kazuya and KAWABE, Iwao},
 journal = {The Journal of Earth and Planetary Sciences, Nagoya University},
 month = {},
 note = {The Late Cretaceous (ca. 67 Ma) Naegi granite-pegmatite suite in Nakatsugawa City, Gifu Prefecture, central Japan, has been studied in view of the lanthanide tetrad effect in evolved felsic rocks. The pegmatite occurring sparsely in the granite body as small patches (<20 cm) and the matrix granite were sampled. REE including Y, major and some minor elements in the samples have been determined. The REE data for mineral separates (quartz, plagioclase, K-feldspar, biotite, and residual heavy minerals) from a granite sample have also been obtained. The chondrite-normalized REE patterns for pegmatite and granite commonly show convex tetrad effects and huge negative Eu anomalies of Eu/Eu^*=0.02-0.004 but no notable Y/Ho fractionation. The whole-rock sample of granite and its mineral separates show similar convex tetrad effects, suggesting the convex tetrad effect in the original magma before crystallization. The granite and pegmatite show no significant differences in major element chemistry and mineralogy except mineral size and texture, but the pegmatite is depleted in Eu, Sr, and Ba relative to the granite. In addition, the pegmatite exhibits a convex tetrad effect and a fairly large negative Eu anomaly, when normalized by the granite. The field occurrence of pegmatite suggests a heterogeneous distribution of aqueous fluid inside of the granitic magma, which is possibly related to the unmixing phenomenon of fluid and silicate melt. Here is proposed a simple model of fractional loss of fluid from hydrous felsic melt. Applying the model to the observed REE fractionation between pegmatite and host granite pairs, REE partition coefficients between aqueous fluid and melt, K_d(REE: fluid/melt), have been evaluated. The logK_d(REE: fluid/melt) values indeed exhibit small concave tetrad effects, positive Eu anomalies, and light REE enrichment trends. Fractional loss of fluid from a hydrous felsic melt system leaves residual silicates in which the small concave tetrad effect and positive Eu anomaly of logKd(REE: fluid/melt) can be exaggerated in reversed manners. As a result, the residual silicates acquire pronounced convex tetrad effects and huge negative Eu anomalies., 国立情報学研究所で電子化したコンテンツを使用している。},
 pages = {13--35},
 title = {Lanthanide tetrad effect of Naegi granite-pegmatite suite, central Japan : Convex tetrad effect by fractional loss of fluid from hydrous felsic melt},
 volume = {54},
 year = {2007}
}