Japan Geoscience Union Meeting 2014

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Symbol S (Solid Earth Sciences) » S-RD Resources, Mineral Deposit & Resource Exploration

[S-RD45_28PM2] New progress of resource geology: global environmental change and element enrichment

Mon. Apr 28, 2014 4:15 PM - 5:00 PM 415 (4F)

Convener:*Mihoko Hoshino(National Institute of Advanced Industial Science and Technology), Kyoko Yamaoka(Geological Survey of Japan, National Institute of Advanced Industrial Science and Technology), Tatsuo Nozaki(Institute for Research on Earth Evolution, Japan Agency for Marine-Earth Science and Technology), Ryohei Takahashi(Graduate School of Engineering and Resource Science, Akita University), Chair:Tatsuo Nozaki(Institute for Research on Earth Evolution, Japan Agency for Marine-Earth Science and Technology), Kyoko Yamaoka(Geological Survey of Japan, National Institute of Advanced Industrial Science and Technology)

4:30 PM - 4:45 PM

[SRD45-08] Origin of Heavy-REE-rich apatite in deep-sea mud from Minami-Torishima area, southeastern Japan

*Yoshiaki KON1, Ki-cheoul SHIN2, Mihoko HOSHINO1, Kenzo SANEMATSU1, Nobuyuki OKAMOTO3, Nobuhiko YANO3, Mikiya TANAKA4, Tetsuichi TAKAGI1 (1.Geological Survey of Japan, AIST, 2.Research Institute for Humanity and Nature, 3.JOGMEC, 4.Research Institute for Environmental Management Technology, AIST)

Keywords:REE, deep-sea mud, apatite, Minami-Torishima, LA-ICPMS, Nd isotope

We have conducted geochemical and mineralogical investigations of the rare earth and yttrium (REY)-rich mud from Minami-Torishima area in the Pacific in order to clarify the concentration of REY and their host-phase in the mud. X-ray diffraction analysis shows that the mud is mainly composed of phillipsite, fluorapatite, quartz, albite, illite and montmorillonite. Whole-rock CaO, P2O5 and total REY contents of the mud are positively correlated. Relative abundance of apatite is also positively correlated to P2O5 and total REY contents. These correlations suggest that apatite is the main host of the P2O5 and REY in the mud. In order to quantitatively estimate the REY-host phase, we make in-situ compositional analyses of constituent minerals in the REY-mud. The result shows that the apatite is abundant in REY (9300 to 32000 ppm) and characterized by negative Ce-anomaly. In contrast, phillipsite is less abundant in REY (60 to 170 ppm). We conclude that the main REY host phase of the mud is apatite.