A5012283271- Geological and Geochemical Analysis
- earthquake and tectonic studies
- Geochemistry and Elemental Analysis
- Methane Hydrates and Related Phenomena
- Geology and Paleoclimatology Research
- High-pressure geophysics and materials
- Geological and Geophysical Studies
- Geochemistry and Geologic Mapping
- Paleontology and Stratigraphy of Fossils
- Geological Studies and Exploration
- Radioactive element chemistry and processing
- Underwater Acoustics Research
- Geomagnetism and Paleomagnetism Studies
- Seismic Imaging and Inversion Techniques
- Hydrocarbon exploration and reservoir analysis
- Earthquake and Disaster Impact Studies
- Geological formations and processes
- Reservoir Engineering and Simulation Methods
- Extraction and Separation Processes
- Astro and Planetary Science
- Therapeutic Uses of Natural Elements
- Underwater Vehicles and Communication Systems
- Bauxite Residue and Utilization
- Marine Biology and Ecology Research
- Seismic Waves and Analysis
Chiba Institute of Technology
2018-2024
The University of Tokyo
2014-2023
Waseda University
2011-2021
Japan Agency for Marine-Earth Science and Technology
2006-2018
Frontier Energy (United States)
2016
Japan Organization for Metals and Energy Security (Japan)
2008
University of Hawaii System
2006
Tokyo Institute of Technology
2006
Scripps Institution of Oceanography
2006
University of California, San Diego
2006
Volcanism on Earth is known to occur in three tectonic settings: divergent plate boundaries (such as mid-ocean ridges), convergent island arcs), and hot spots. We report volcanism the 135 million-year-old Pacific Plate not belonging any of these categories. Small alkalic volcanoes form from small percent melts originate asthenosphere, implied by their trace element geochemistry noble gas isotopic compositions. propose that erupt along lithospheric fractures response flexure during...
Initial subduction-related boninitic magmatism occurred between 48 and 44 Ma in the Izu–Bonin–Mariana (IBM) arc. High-Mg adakites low-Ca boninites have been dredged from Bonin Ridge fore-arc seamount. Whole-rock 40Ar/ 39Ar ages suggest that boninite (44·0 ± 1·4 Ma) adakite (43·1 1·0 40·8 0·8 overlapped, or slightly later than magmatism. The are high-Mg andesites exhibit U-shaped rare earth element (REE) patterns with an elevated average Mg# of 0·78 [Mg# = Mg/(Mg + Fe) molar ratio] Ni content...
We have discovered deep-sea mud that is extremely enriched in rare-earth elements and yttrium (together called REY) the Japanese Exclusive Economic Zone around Minamitorishima Island, western North Pacific Ocean. The maximum total REY concentration reaches approximately 7000 ppm, which much higher than reported for conventional deposits on land other known potential resources ocean. REY-rich characterized by abundant phillipsite biogenic calcium phosphate. In addition, stratigraphic layer...
A dense field of ferromanganese (Fe-Mn) nodules was discovered on a seamount approximately 300 km east Minamitorishima Island, in the Japanese Exclusive Economic Zone. To evaluate its potential as resource for critical metals, we describe results geological survey using SHINKAI 6500 submersible (dive No. 6K 1207) during cruise YK10-05 R/V Yokosuka 2010, and geochemical analyses collected samples. Submersible observations showed that spherical 5–10 cm diameter almost fully cover region high...
We analyzed 1338 deep-sea sediment samples from 19 Deep Sea Drilling Project/Ocean Program sites covering a large portion of the Indian Ocean, and constructed new comprehensive data set their bulk chemical compositions, including rare-earth, major, trace elements. The bulk-sediment rare-earth yttrium (REY) composition REY-enriched samples, characterized by relatively small negative Ce anomalies, almost no Y enrichment in heavy elements, can be interpreted as superposition REY compositions...
Seven piston cores were collected from the seafloor ~250 km south of Minamitorishima Island in western North Pacific Ocean during cruise KR13-02 R/V Kairei; some portions PC04 and PC05, total contents rare-earth elements yttrium (∑REY) exceeded 4,000 ppm. Microscopic observations showed that highly REY-enriched layers (∑REY > ~2,000 ppm) contained significant amounts calcium phosphate phillipsite. We conducted microscopic grain size distribution analyses bulk sediments distinctive components...
We report detailed lithological and chemical characteristics of deep-sea sediments, including rare-earth elements yttrium-rich mud (REY-rich mud), in the Japanese Exclusive Economic Zone (EEZ) around Minamitorishima Island. Three research cruises obtained fourteen sediment cores collected by piston coring. Based on visual descriptions geochemical analysis cores, we confirm presence REY-rich containing more than 400 ppm total REY (∑REY) southern northwestern areas EEZ. The layers are...
Scandium is a critical element in state-of-the-art, green technologies. However, it also extremely expensive due to its scarcity. Recently, some deep-sea sediments that contain significant amounts of rare-earth elements are indispensable modern industries have been discovered the western North Pacific Ocean, and concentration Sc these comparable with land-based mines. A simple leaching experiment has demonstrated up 70% sediments, contained within biogenic calcium phosphate particles, can be...
Abstract. Petit-spot volcanoes, occurring due to plate flexure, have been reported globally. As the petit-spot melts ascend from asthenosphere, they provide crucial information of lithosphere–asthenosphere boundary. Herein, we examined lava outcrops six monogenetic volcanoes formed by volcanism in western Pacific. We then analyzed 40Ar/39Ar ages, major and trace element compositions, Sr, Nd, Pb isotopic ratios basalts. The ages two were ca. 2.6 Ma (million years ago) 0 Ma. compositions...
In 2009, petit-spot submarine volcanoes were discovered off the oceanward slope of central Chile trench, offshore from Valparaiso, Chile, at around 33°S. Ar-Ar dating mugearite and alkali-basalt yields ages 10.11 ± 0.22 Ma 6.69 0.88 Ma, respectively. Back-calculations plate motion along present absolute movement direction Nazca Plate, conducted using age data, indicate that eruption occurred above a zone flexure. The back-calculation results suggest was erupted flexural arch prior to arrival...
Abstract The source mantle of the basaltic ocean crust on western half Pacific Plate was examined using Pb‐Nd‐Hf isotopes. results showed that subducted Izanagi‐Pacific Ridge (IPR) formed from both (180–∼80 Ma) and Indian (∼80–70 mantles. becomes younger westward is thought to have IPR. ridge along Kurile‐Japan‐Nankai‐Ryukyu (KJNR) Trench at 60–55 Ma leading edge currently stagnated in transition zone. Conversely, entire eastern Plate, isotopically distinct East Rise Juan de Fuca Ridge,...
The deep carbon cycle plays an important role on the chemical differentiation and physical properties of Earth's mantle. Especially in asthenosphere, seismic low-velocity high electrical conductivity due to dioxide (CO2)-induced partial melting are expected but not directly observed. Here we discuss experimental results relevant genesis primitive CO2-rich alkali magma forming petit-spot volcanoes at deformation front outer rise northwestern Pacific plate. suggest that melt last equilibrated...
Detailed petrological and geochemical analyses of volcanic rocks from back‐arc en echelon seamounts, consisting four cross‐chains in the Izu‐Bonin back arc, provide insights into origin complex magma types for volcanism associated with spreading an oceanic arc environment. The sampled are classified three distinct rock suites on basis trace element characteristics: “Enriched Suite” enriched compositions high Nb/Zr (0.075–0.10); a “Less Enriched depleted high‐field‐strength elements (HFSEs),...
Sub-bottom profiling was conducted in the Japanese Exclusive Economic Zone (EEZ) around Minamitorishima Island, western Pacific Ocean, to investigate features and distribution of mud rich rare earth elements yttrium (REY-rich mud). Based on echogram records, we distinguished three acoustic facies: opaque (O), transparent (T), layered (L). The O-type facies is acoustically highly reflective, without visible structures beneath top surface. T-type transparent, with a basal reflector from...
Deep-sea sediments with total rare-earth elements and yttrium (ΣREY) concentrations exceeding 400 ppm, which are termed REY-rich mud, widely distributed in the world oceans. Specifically, deep-sea within Japanese exclusive economic zone (EEZ) surrounding Minamitorishima Island western North Pacific have attracted significant attention as a new REY resource, because they contain REY-enriched layers 2000 ppm of ΣREY. However, neither deeper than 15 m below seafloor (mbsf) nor those outside EEZ...
Abstract Petit-spot volcanoes provide a unique opportunity to directly examine the structure and geochemical composition of lithospheric asthenospheric mantle beneath subducting oceanic crust. Currently, petit-spot volcanos—formed in response flexure plates—are known exist off Japan, Java, Chile Mariana trenches, however, difficulties associated with detecting them leaves possibility that they may be more widespread along outer rise plates. Investigation lavas xenolithic material erupted...
The oceanic lithosphere cools as it spreads away from the mid-ocean ridges, and subducts into mantle at subduction zones. In context of Earth’s material cycle, quantitative chemical thermal state is desired to be estimated elucidate flux mantle. As a step toward reconstructing lithosphere, we present geochemical data set xenoliths petti-spots in northwestern Pacific, where no seismic anomaly imaged. petit-spot-borne provide us unique information avoiding modifications derived...