A5066975615- Astro and Planetary Science
- High-pressure geophysics and materials
- Geological and Geochemical Analysis
- Planetary Science and Exploration
- earthquake and tectonic studies
- Geology and Paleoclimatology Research
- Space Exploration and Technology
- Isotope Analysis in Ecology
- Spacecraft and Cryogenic Technologies
- Clay minerals and soil interactions
- Nuclear Physics and Applications
- Mineralogy and Gemology Studies
- Astronomical and nuclear sciences
- Energetic Materials and Combustion
- Minerals Flotation and Separation Techniques
- Metallurgical Processes and Thermodynamics
- Geochemistry and Geologic Mapping
- Metallurgy and Cultural Artifacts
- Crystal Structures and Properties
- Methane Hydrates and Related Phenomena
- Iron and Steelmaking Processes
- Crystallization and Solubility Studies
- Archaeology and ancient environmental studies
- Hydrocarbon exploration and reservoir analysis
- Landslides and related hazards
Hiroshima University
2016-2025
Tohoku University
2010-2020
Planetary Systems (United States)
2001-2017
Graduate School USA
2016-2017
Okayama Prefecture
2017
University of Niigata Prefecture
2017
Institute of Mineralogy
2007-2010
National Defense Academy of Japan
1987
Abstract Heavily shocked meteorites contain various types of high‐pressure polymorphs major minerals (olivine, pyroxene, feldspar, and quartz) accessory (chromite Ca phosphate). These are micron to submicron sized occur within in the vicinity shock‐induced melt veins pockets chondrites lunar, howardite–eucrite–diogenite ( HED ), Martian meteorites. Their occurrence suggests two formation mechanisms (1) solid‐state transformation host‐rock into monomineralic polycrystalline aggregates, (2)...
Without a protective atmosphere, space-exposed surfaces of airless Solar System bodies gradually experience an alteration in composition, structure and optical properties through collective process called space weathering. The return samples from near-Earth asteroid (162173) Ryugu by Hayabusa2 provides the first opportunity for laboratory study space-weathering signatures on most abundant type inner solar system body: C-type asteroid, composed materials largely unchanged since formation...
Abstract Transmission electron microscopy analyses of Hayabusa2 samples show that Ryugu organic matter exhibits a range morphologies, elemental compositions, and carbon functional chemistries consistent with those carbonaceous chondrites have experienced low‐temperature aqueous alteration. Both nanoglobules diffuse are abundant. Non‐globular particles also present, including some contain nanodiamond clusters. Diffuse is finely distributed in around phyllosilicates, forms coatings on other...
Experiments to investigate the partitioning of oxygen between liquid iron and (Mg,Fe)O magnesiowüstite were conducted at 30–70 GPa 2800–3500 K using a laser‐heated diamond anvil cell. A thin foil was prepared from reacted regions in recovered samples focused ion beam. The compositions coexisting quenched measured transmission electron microscope equipped with energy dispersive X‐ray spectroscopy energy‐loss spectroscopy. In order understand model results, additional experiments performed...
Abstract A dense magnesium iron silicate polymorph with a structure intermediate between olivine, ringwoodite, and wadsleyite was theoretically predicted about four decades ago. As this group of minerals constitute the major component shocked meteorites, constraining their transitional forms behaviour is potential importance for understanding impact events on parent bodies. Here we use high-resolution transmission electron microscopy techniques single-crystal X-ray diffraction analyses to...
Abstract Two petrographic settings of carbonaceous components, mainly filling open fractures and occasionally enclosed in shock‐melt veins, were found the recently fallen Tissint Martian meteorite. The presence veins deuterium enrichments (δD up to +1183‰) these components clearly indicate a pristine origin. are kerogen‐like, based on micro‐Raman spectra multielemental ratios, probably deposited from fluids shock‐induced parent rock Tissint. After precipitation organic matter, experienced...
A high-pressure phase is discovered in a shocked, stony meteorite.
Abstract Micrometeorites, a possible major source of Earth’s water, are thought to form from explosive dispersal hydrated chondritic materials during impact events on their parental asteroids. However, this provenance and formation mechanism have yet be directly confirmed using asteroid returned samples. Here, we report evidence mild shock metamorphism in the surface particles Ryugu based electron microscopy. All dominated by phyllosilicates but lack dehydration textures, which indicative...
Abstract The petrologic and mineralogical characteristics alteration processes of the nakhlites NWA 6148 10153 were studied. Both consist augite, olivine, mesostasis. Based on each volume fraction components chemical composition olivine pyroxene, correspond to lava units crystallized at 1346–1391 Ma in nakhlite body. position body is unclear. Iron oxides/hydroxides, barite, calcite fill fractures 6148, which are terrestrial weathering products. In 10153, grains replaced by goethite,...
The new mineral kushiroite, belonging to the pyroxene group, was first discovered in a refractory inclusion CH group carbonaceous chondrite ALH 85085. chemical formula is Ca1.008(Mg0.094Fe0.034Al0.878)(Al0.921Si1.079)O6, containing 88% CaAlAlSiO6 and 12% diopside components. We identified exact nature of kushiroite by micro-Raman spectroscopy electron backscatter diffraction (EBSD) analyses. results are consistent with those obtained from synthetic pyroxene, thus indicating monoclinic...
Peace River is one of the few shocked members L-chondrites clan that contains both high-pressure polymorphs olivine, ringwoodite and wadsleyite, in diverse textures settings fragments entrained shock-melt veins. Among these are complete olivine porphyritic chondrules. We encountered squeezed flattened chondrules veins this meteorite with novel composition. The former chemically unzoned (Fa(24-26)) crystals heavily display a concentric intergrowth Mg-rich wadsleyite very narrow compositional...
Microcrystals of coesite and stishovite were discovered as inclusions in amorphous silica grains shocked melt pockets a lunar meteorite Asuka-881757 by micro-Raman spectrometry, scanning electron microscopy, back-scatter diffraction, transmission microscopy. These high-pressure polymorphs SiO 2 indicate that the experienced an equilibrium shock-pressure at least 8–30 GPa. Secondary quartz are also observed separate meteorite. The estimated age reported 39 Ar/ 40 Ar chronology indicates...
We report evidence for the natural dissociation of olivine in a shergottite at high-pressure and high-temperature conditions induced by dynamic event on Mars. Olivine (Fa 34-41 ) adjacent to or entrained shock melt vein pockets Martian meteorite olivine-phyric Dar al Gani 735 dissociated into (Mg,Fe)SiO 3 perovskite (Pv)+magnesiowüstite (Mw), whereby partially vitrified during decompression. Transmission electron microscopy observations reveal that microtexture products evolves from lamellar...
The Chelyabinsk asteroid impact is the second largest airburst in our recorded history. To prepare for a potential threat from impacts, it important to understand nature and formational history of Near-Earth Objects (NEOs) like asteroid. In orbital evolution an asteroid, collision with other asteroids key process. Here, we show existence high-pressure mineral jadeite shock-melt veins meteorite. Based on assemblage calculated solidification time veins, equilibrium shock pressure its duration...
Abstract Mineral inventories of enstatite chondrites; ( EH and EL ) are strictly dictated by combined parameters mainly very low dual oxygen f O 2 sulfur S fugacities. They best preserved in the Almahata Sitta MS ‐17, ‐177 fragments, ALHA 77295 MAC 88136 Antarctic meteorites. These conditions induce a stark change geochemical behavior nominally lithophile elements to chalcophile or even siderophile changes elemental partitioning thus leading formation unusual mineral assemblages with high...
Abstract Hypervelocity impacts are among the fundamental phenomena occurring during evolution of solar system and characterized by instantaneous ultrahigh pressure temperature. Varied physicochemical changes have occurred in building blocks celestial bodies under such extreme conditions. The constituent material has transformed into a denser form, high-pressure polymorph. polymorph is also thought to be deep Earth’s interior. Hence, experiments using temperature generating apparatus been...
Fe-Mg partitioning between perovskite and ferropericlase in the MgO-FeO-SiO2 system has been studied up to about 100 GPa at around 2000 K using a laser-heated diamond anvil cell (LHDAC). The compositions of both phases were determined by analytical transmission electron microscopy (ATEM) on recovered samples. Present results reveal that apparent partition coefficient [KDPv/Fp = (XFePv XMgFp)/(XMgPv XFeFp)] decreases with increasing pressure for constant FeO system, it content ferropericlase....
Abstract— The high‐pressure polymorphs of olivine, pyroxene, and plagioclase in or adjacent to shock melt veins (SMVs) two L6 chondrites (Sahara 98222 Yamato 74445) were investigated clarify the related transformation mechanisms estimate pressure‐temperature conditions events. Wadsleyite jadeite identified Sahara 98222. Wadsleyite, ringwoodite, majorite, akimotoite, jadeite, lingunite (NaAlSi 3 O 8 ‐hollandite) 74445. nucleated along grain boundaries fractures original olivine. nucleation...