Search

Your search keyword '"Yoshikawa, Masako"' showing total 134 results
Start Over Author "Yoshikawa, Masako"
134 results on '"Yoshikawa, Masako"'

9. Application of Mass Spectrometry for Analysis of Cesium and Strontium in Environmental Samples Obtained in Fukushima Prefecture : Analysis of Cesium Isotope Compositions in Environmental Samples by Thermal Ionization Mass Spectrometry-2

Author

Shibahara, Yuji, Kubota, Takumi, Fukutani, Satoshi, Fujii, Toshiyuki, Takamiya, Koichi, Ohta, Tomoko, Shibata, Tomoyuki, Yoshikawa, Masako, Konno, Mitsuyuki, Mizuno, Satoshi, Yamana, Hajimu, and Takahashi, Tomoyuki, editor

Published
2016
Full Text
View/download PDF

34. Alkali basalt from the Seifu Seamount in the Sea of Japan: post-spreading magmatism in a back-arc setting.

Author

Morishita, Tomoaki, Hirano, Naoto, Sumino, Hirochika, Sato, Hiroshi, Shibata, Tomoyuki, Yoshikawa, Masako, Arai, Shoji, Nauchi, Rie, and Tamura, Akihiro

Subjects
BASALT, RARE earth metals, TRACE elements, YTTERBIUM, BACK-arc basins, MAGMATISM, MID-ocean ridges, PERIDOTITE
Abstract

We present geochemical and 40Ar/39Ar age data for a peridotite xenolith-bearing basalt dredged from the Seifu Seamount (SSM basalt) in the northeast Tsushima Basin, southwest Sea of Japan. An 40Ar/39Ar plateau age of 8.33±0.15 Ma (2 σ) was obtained for the SSM basalt, indicating that it erupted shortly after the termination of back-arc spreading in the Sea of Japan. The SSM basalt is a high-K to shoshonitic alkali basalt that is characterized by light rare earth element enrichment. The trace element features of the basalt are similar to those of ocean island basalt, although the Yb content is much higher, indicating formation by the low-degree partial melting of spinel peridotite. The Nd, Sr, and Pb isotopic compositions of the SSM basalt differ from those of back-arc basin basalts in the Sea of Japan. The Sr–Nd isotopic composition of the SSM basalt suggests its source was depleted mid-ocean ridge mantle containing an enriched mantle (EM1) component. The SSM basalt was formed in a post-back-arc extension setting by the low-degree partial melting of an upwelling asthenosphere that had previously been associated with the main phase of back-arc magmatism. [ABSTRACT FROM AUTHOR]

Published
2020
Full Text
View/download PDF

38. Slab-derived halogens and noble gases illuminate closed system processes controlling volatile element transport into the mantle wedge

Author

Kobayashi, Masahiro, Sumino, Hirochika, Nagao, Keisuke, Ishimaru, Satoko, Arai, Shoji, Yoshikawa, Masako, Kawamoto, Tatsuhiko, Kumagai, Yoshitaka, Kobayashi, Tetsuo, Burgess, Ray, and Ballentine, Chris J.

Subjects
noble gas, Geophysics, Space and Planetary Science, Geochemistry and Petrology, Earth and Planetary Sciences (miscellaneous), subduction zone, volatile recycling, slab fluids, halogen, mantle peridotite
Abstract

Halogen and noble gas systematics are powerful tracers of volatile recycling in subduction zones. We present halogen and noble gas compositions of mantle peridotites containing H2O-rich fluid inclusions collected at volcanic fronts from two contrasting subduction zones (the Avacha volcano of Kamchatka arc and the Pinatubo volcano of Luzon arcs) and orogenic peridotites from a peridotite massif (the Horoman massif, Hokkaido, Japan) which represents an exhumed portion of the mantle wedge. The aims are to determine how volatiles are carried into the mantle wedge and how the subducted fluids modify halogen and noble gas compositions in the mantle. The halogen and noble gas signatures in the H2O-rich fluids are similar to those of marine sedimentary pore fluids and forearc and seafloor serpentinites. This suggests that marine pore fluids in deep-sea sediments are carried by serpentine and supplied to the mantle wedge, preserving their original halogen and noble gas compositions. We suggest that the sedimentary pore fluid-derived water is incorporated into serpentine through hydration in a closed system along faults at the outer rise of the oceanic, preserving Cl/H2O and 36Ar/H2O values of sedimentary pore fluids. Dehydration–hydration process within the oceanic lithospheric mantle maintains the closed system until the final stage of serpentine dehydration. The sedimentary pore fluid-like halogen and noble gas signatures in fluids released at the final stage of serpentine dehydration are preserved due to highly channelized flow, whereas the original Cl/H2O and 36Ar/H2O ratios are fractionated by the higher incompatibility of halogens and noble gases in hydrous minerals.

Published
2016

40. A Mobile Asteroid Surface Scout (MASCOT) on board the Hayabusa 2 Mission to the near Earth asteroid (162173) Ryugu

Author

Jaumann, Ralf, Bibring, Jean-Pierre, Glassmeier, K.H., Grott, M., Ho, T.-M., Ulamec, Stephan, Schmitz, N., Auster, H. U., Biele, J., Kuninaka, H., Okada, Tatsuaki, Yoshikawa, Masako, Watanabe, S., Spohn, T., Koncz, Alexander, Hercik, David, Michaelis, Harald, and Fujimoto, M.

Subjects
Hayabusa 2, Planetengeologie, Planetenphysik, Asteroid 162173, MASCOT, Asteroid, Leitungsbereich PF, Systementwicklung und Projektbüro, Planetare Sensorsysteme, ryugu, Nutzerzentrum für Weltraumexperimente (MUSC)
Published
2016

Catalog

Books, media, physical & digital resources
See catalog results