地球化学的手法を用いた考古学的資料の元素・同位体比分析による履歴と起源の解明
キーワード：考古学的資料、同位体比分析
2017.02.

白金族元素とオスミウム同位体組成を用いたマントル物質循環の解明
キーワード：白金族元素、オスミウム同位体比、マントル
2017.02.

Oman Drilling Project
2016.10～2019.05, 代表者：Prof. Peter Kelemen , Columbia University, International Continental Scientific Drilling Programme
(国際学術機関、加盟国：オーストリア、ベルギー、カナダ、中国、チェコ、フィンランド、フランス、ドイツ、アイスランド、インド、イスラエル、イタリア、日本、ニュージーランド、ノルウェー、ポーランド、韓国、スペイン、スウェーデン、スイス、オランダ、イギリス、アメリカ)
The overarching goal of scientific drilling in the Samail ophiolite is to understand the full spectrum of processes that create and modify oceanic crust and shallow mantle, involving mass and energy transfer between the mantle, the crust, the hydrosphere, the atmosphere and the biosphere over a range of temperatures from ~ 1350 to 20°C, depths from the surface to 10 or 20 km below the paleo-seafloor, and tectonic settings from spreading ridges to the deep ocean to surficial weathering to subduction zones..

主要原著論文

1.

Ryoko Senda, Kenji Shimizu, Katsuhiko Suzuki, Ancient depleted mantle as a source of boninites in the Izu-Bonin-Mariana arc Evidence from Os isotopes in Cr-spinel and magnetite, Chemical Geology, 10.1016/j.chemgeo.2016.06.018, 439, 110-119, 2016.11, [URL], Boninite is a volcanic rock derived from shallow melting of highly depleted hydrous mantle, fluxed with water from subducted slabs. The eruption of boninite early in the history of the Izu-Bonin-Mariana (IBM) arc (~ 48–45 Ma), suggests generation by melting of upper mantle material that was relatively unmodified by subducted components. Thus, the boninite composition should largely reflect that of the sub-arc mantle. For better understanding of the mantle sources of nascent arc settings and the contributions of different components to arc melts, we analyzed Os isotope ratios (187Os/188Os) of bulk rocks and mineral separates (euhedral Cr-spinel from boninites and euhedral Cr-spinel/magnetite mixtures from tholeiites younger than 45 Ma that erupted after boninites) from the Bonin Islands and Guam. The age-corrected (initial) Os isotope ratios of the whole-rock samples (0.1179–0.2050) were more radiogenic and variable than those of the mineral separates, possibly because of contamination with crustal materials during magma ascent or alteration after emplacement. The age-corrected Os isotope ratios of euhedral Cr-spinel in boninite from the Bonin Islands (0.1187–0.1254) and from Guam (0.1220–0.1269) are unradiogenic relative to primitive mantle, and those of the Cr-spinel/magnetite mixtures from the tholeiites from the Bonin Islands are similar to or slightly more radiogenic (0.1224–0.1382). The most depleted Os isotope ratio of the Cr-spinel from boninite yielded a model Re depletion (TRD) age of 1.4 Ga, suggesting that the mantle source of the boninite experienced melt extraction prior to 1.4 Ga. The source of the boninites is interpreted to be mostly highly depleted mantle with a small contribution of slab flux arising from altered oceanic crust that has radiogenic Os components, with or without contributions from components with relatively unradiogenic Os such as volcaniclastics of oceanic island basalt affiliation or very young mid-ocean ridge basalt..

主要総説, 論評, 解説, 書評, 報告書等

主要学会発表等

所属学会名

学術論文等の審査

海外渡航状況, 海外での教育研究歴