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Initial analyses showed that asteroid Ryugu's composition is close to CI (Ivuna-like) carbonaceous chondrites (CCs) - the chemically most primitive meteorites, characterized by near-solar abundances for most elements. However, some isotopic signatures (for example, Ti, Cr) overlap with other CC groups, so the details of the link between Ryugu and the CI chondrites are not yet fully clear. Here we show that Ryugu and CI chondrites have the same zinc and copper isotopic composition. As the various chondrite groups have very distinct Zn and Cu isotopic signatures, our results point at a common genetic heritage between Ryugu and CI chondrites, ruling out any affinity with other CC groups. Since Ryugu's pristine samples match the solar elemental composition for many elements, their Zn and Cu isotopic compositions likely represent the best estimates of the solar composition. Earth's mass-independent Zn isotopic composition is intermediate between Ryugu/CC and non-carbonaceous chondrites (NCs), suggesting a contribution of Ryugu-like material to Earth's budgets of Zn and other moderately volatile elements.

Correction to: Nature Astronomy https://doi.org/10.1038/s41550-022-01846-1. Published online 12 December 2022.

Carbonaceous meteorites are thought to be fragments of C-type (carbonaceous) asteroids. Samples of the C-type asteroid (162173) Ryugu were retrieved by the Hayabusa2 spacecraft. We measured the mineralogy and bulk chemical and isotopic compositions of Ryugu samples. The samples are mainly composed of materials similar to those of carbonaceous chondrite meteorites, particularly the CI (Ivuna-type) group. The samples consist predominantly of minerals formed in aqueous fluid on a parent planetesimal. The primary minerals were altered by fluids at a temperature of 37° ± 10°C, about 5.2 − 0.7 + 0.8 million (statistical) or 5.2 − 2.1 + 1.6 million (systematic) years after the formation of the first solids in the Solar System. After aqueous alteration, the Ryugu samples were likely never heated above ~100°C. The samples have a chemical composition that more closely resembles that of the Sun’s photosphere than other natural samples do.

To investigate the chemical effect on the muon capture process through a muon transfer reaction from a muonic hydrogen atom, the formation rate of muonic carbon atoms is measured for benzene and cyclohexane molecules in liquid samples. The muon transfer rate to carbon atoms of the benzene molecule is higher than that to the carbon atoms of the cyclohexane molecule. Such a deviation has never been observed among those molecules for gas samples. This may be because the transfers occur from the excited states of muonic hydrogen atoms in the liquid system, whereas in the gas system, all the transfers occur from the 1s (ground) state of muon hydrogen atoms. The muonic hydrogen atoms in the excited states have a larger radius than those in the 1s state and are therefore considered to be affected by the steric hindrance of the molecular structure. This indicates that the excited states of muonic hydrogen atoms contribute significantly to the chemical effects on the muon transfer reaction.

Attempts to improve the accuracy in measuring diamagnetic susceptibility χDIA of a small particle are conducted by measuring its magnetic translation. In this study, accuracy improvement was pursued by two different experiments. First, translation of a particle was observed the under microgravity ( $\mu$ ɡ ) conditions produced by a simple double-capsule system that was developed to sufficiently reduce the residual gravity. In particular, gravity ( ɡ ) was reduced to a value below 2 × 10−3 times the value of ɡ at sea level for 0.5 s by selecting the optimum material for the outer capsule. Furthermore, a simple technique to produce a time lag between the drop of the inner capsule considering the outer capsule was effective in minimizing the initial ɡ -vibration of the inner capsule. Preliminary experiments using this double-capsule system indicated that the typical error of χDIA was reduced by 80% (i.e., δχDIA a 2 × 10−7 emu/g) when compared to that obtained in a previous study under $\mu$ ɡ conditions. Many phenomena studied in condensed matter physics are measured at time scales below 0.1 s, and the new $\mu$ ɡ system is effective when complete isolation of the sample from the measuring device is required, as realized in the χDIA measurements experiment reported in this letter. In another experiment, horizontal parabolic translation was conducted under normal gravity; here, translation was induced by a field-gradient force produced by a Nd-Fe-B magnetic circuit. The accuracy of χDIA obtained by field-induced translation was significantly improved by optimizing the field distribution of the magnetic circuit; a typical error of χDIA remained at a level of 5 × 10−7 emu/g. Compared to the aforementioned double-capsule system, the compact apparatus operated under normal ɡ can be easily transported to various sites of material exploration to conduct preliminary χDIA measurement of test samples.

Terada, K, Kikuchi, N, Burt, D, Voisin, S, and Nakazato, K. Full title: Low-load resistance training to volitional failure induces muscle hypertrophy similar to volume-matched, velocity fatigue. J Strength Cond Res 36(6): 1576-1581, 2022-We investigated how resistance training (RT) to failure at low load affects acute responses and chronic muscle adaptations compared with low-load RT to velocity fatigue at equal work volume. Twenty-seven subjects performed 8 weeks of bench press twice weekly. Subjects were randomly assigned to one of 3 groups: low-load volitional failure (LVoF, n = 9), low-load velocity fatigue (LVeF, n = 8), and high-load (HL, n = 10). Resistance training comprised 3 sets to failure at 40% one repetition maximum (1RM) in the LVoF group, 3 sets to velocity fatigue (20% lifting velocity loss) at 40% 1RM in the LVeF group, and 3 sets of 8 repetitions at 80% 1RM in the HL group. We measured muscle strength, hypertrophy, endurance, and power at baseline and after the RT program. We also measured muscle swelling and blood lactate after each RT bout to investigate the acute response. There were no differences in total work volume between the LVoF and LVeF groups. Responses to RT were similar between LVoF and LVeF, whether looking at acute muscle swelling, increase in blood lactate, chronic hypertrophy, and strength gain. However, LVoF and LVeF RT triggered different responses to muscle function in comparison with HL training: LVoF and LVeF showed enhanced acute responses and greater chronic endurance gains, but lower chronic strength gains than HL. In conclusion, low-load RT to volitional failure induces muscle hypertrophy similar to volume-matched velocity fatigue.

Magentic separation generally required strong magnetic forces induced in ferromagnetic or strong paramagnetic particles; in order to realize the separation in diamagnetic or weak paramagnetic particles, it was necessary to attach magnetic beads or magnetic ions to induce the strong magnetic force. A method to separate mixture of weak magnetic particles by its concentration of paramagnetic ferrous ion is newly proposed, which does not require the abovementioned magnetic attachments. The efficiently of the new method is experimentally examined using a pocketsize magnetic circuit (4.5 cm x2.0 cm x 1.0 cm) and a piece of cross sectional paper (5.0 cm x1.0cm). The separation is based on a principle that velocity of a translating particle, induced by a magnetic volume force in an area of monotonically decreasing field, is uniquely determined only by its magnetic susceptibility (per unit mass) of the particle; the velocity is independent to mass of particle. By examining the spectra of the separated particles recovered on the cross sectional paper, a histogram on Fe concentration is easily obtained for the particles without the need of consuming them.

Simultaneous ion counting and waveform averaging implemented on a field-programmable gate array compiled with a high-speed digitizer was applied to ultraperformance liquid chromatography-time-of-flight mass spectrometric analysis of sulfa drugs. Ion counting was carried out by a "Peak Detection" (PKD) function that works together with signal averaging (AVG). Sulfadimidine (SDD) and sulfadimethoxine (SDMX) were measured in human serum (HS) model sample matrix. By using simultaneous PKD and AVG acquisition, we observed a unified calibration curve for more than 3 orders of magnitude of sample amounts (0.010-100.0 pmol). The ion count rate for the "practical" sample amounts, such as less than 1 pmol, was below 30%, which is suitable for PKD-based ion counting for quantitative accuracy and excellent peak identification performance. Samples containing 200 fmol or less could not be identified from the AVG waveform. Adding HS treated with acetonitrile severely suppressed the SDMX ion to less than one-half (58.1%). However, a linear response was observed for chromatographic peak area for analytes calculated from PKD waveforms. Also, the mass-resolving power calculated from the peak on the PKD waveform was 24% better than the corresponding AVG waveform, which also improves performance for analyte identification.

In the last decade, non-destructive elemental analysis using negative muon beams advanced significantly. This method can be used to determine the elemental composition of bulk materials without causing damage. In this study, we performed a negative muon irradiation experiment for a Northwest Africa 482 lunar meteorite (NWA482), which was installed in a stainless steel analysis chamber. The analysis chamber was filled with helium gas to suppress the background signals caused by air-scattering muons. The muonic X-rays from Al, Fe, Ca, Mg, Si, and O in the samples were detected using six high-purity germanium semiconductor detectors arranged around the analysis chamber. To correct the X-ray self-absorption effect of the samples, a Monte-Carlo simulation using Geant4 toolkit was used. Based on the quantitative analysis for muonic X-ray measurement with the correction application from the simulation, we successfully investigated the analytical sensitivity of each element in meteorites based on the NWA482 data.

An elemental analysis method utilizing muons has been demonstrated to be effective for non-destructive and quantitative analysis of precious bulk materials. In muon capture process, molecular structure dependence was known, and this property has the potential to be used to identify chemical structure in addition to elemental composition. Before these potential applications, fundamental studies examining the muon capture process are necessary. In this study, muon capture ratios for two iron oxide compounds, which are both important in earth science, γ-Fe2O3 (maghemite) and Fe3O4 (magnetite), were measured. The measured muon capture ratios were A(Fe/O) = 2.34 ± 0.03 and A(Fe/O) = 2.77 ± 0.03 for γ-Fe2O3 and Fe3O4, respectively.

Variations in isotopic abundance provide useful information for various scientific fields. Herein we performed a feasibility study by non-destructive isotopic analysis of negative muons. We irradiated two lead plate samples, one with the natural isotopic composition and one enriched with 208Pb, with negative muons and observed the gamma rays from 208Tl with a half-life of 3 min generated via muon absorption by 208Pb during muon irradiation. The isotopic abundance of 208Pb in natPb was successfully determined without sample destruction from the gamma ray intensity to be 69%, which agreed well with the mass spectrometry results.

Elemental isotopic ratios are measured in various research fields and provide useful information regarding age, origin, geological and biological activities, ancient climate, etc. Here, we report a new isotopic analysis method without sample destruction using muon-induced characteristic X-rays. We demonstrated this method by conducting muon-beam irradiation experiments on two Pb plates with different isotopic ratios: natural isotopic composition and artificially enriched 208Pb. The observed broad X-ray peaks of the Pb Kα line around 6 MeV were deconvolved with 206Pb, 207Pb, and 208Pb isotopes, giving the isotopic ratios. The resulting isotopic ratios were consistent with those obtained from mass spectrometry.

Meteoroid bombardment of the Earth-Moon system must have caused catastrophic damage to the terrestrial ecosphere. However, ancient meteoroid impacts and their relations to environmental changes are not well understood because of erosion and/or resurfacing processes on Earth. Here, we investigate the formation ages of 59 lunar craters with fresh morphologies and diameters greater than approximately 20 km and first find that 8 of 59 craters were formed simultaneously. Considering the radiometric ages of ejecta from Copernicus crater and impact glass spherules from various Apollo landing sites, we conclude that sporadic meteoroid bombardment occurred across the whole Moon at approximately 800 Ma. Based on crater scaling laws and collision probabilities with the Earth and Moon, we suggest that at least (4–5) × 1016 kg of meteoroids, approximately 30–60 times more than the Chicxulub impact, must have plunged into the Earth-Moon system immediately before the Cryogenian, which was an era of great environmental changes., Ancient impact events on Earth are not well characterized due to continuous re-surfacing of Earth. Here, the authors study impact craters on the Moon with ages up to 800 million years ago and present a cross correlation to Earth, linking up to mass extinction events throughout Earth’s history.

KAGUYA observed global emissions of carbon ions from the Moon, which have possibly existed since its birth., Carbon is a volatile element that has a considerable influence on the formation and evolution of planetary bodies, although it was previously believed to be depleted in the Moon. We present observations by the lunar orbiter KAGUYA of carbon ions emitted from the Moon. These emissions were distributed over almost the total lunar surface, but amounts were differed with respect to lunar geographical areas. The estimated emission fluxes to space were ~5.0 × 104 per square centimeter per second, which is greater than possible ongoing supplies from the solar wind and micrometeoroids. Our estimates demonstrate that indigenous carbon exists over the entire Moon, supporting the hypothesis of a carbon-containing Moon, where the carbon was embedded at its formation and/or was transported billions of years ago.

We designed an improved apparatus to separate and identify volatile solid particles at temperatures around 200 K using short-duration microgravity. Separation is based on the difference in diamagnetism of the mixed particles released in a region of monotonically decreasing magnetic field. The velocity of the translating particles in the microgravity region is considerably enhanced, which yields improved accuracy in measurement of the terminal velocity of the particles outside the magnetic field region. We achieved separation of a mixture of heterogeneous particles, including solid CO2, with high resolution. A particle's composition can be estimated from the value of magnetic susceptibility obtained from the terminal velocity because the particle's acceleration induced by the magnetic volume force is independent of particle mass. It is expected that material abundances of heterogeneous, volatile, solid particles, such as hexagonal ice, dry ice, ethane, methane, and CO, can be determined in this simple manner in cold regions on Earth and in the outer regions of the solar system.

The enriched basaltic (martian) shergottite Ksar Ghilane (KG) 002, discovered in 2010, is exceptionally rich in coexisting but discrete apatite and merrillite crystals. It has been selected to better constrain the formation conditions and post-crystallization processes, and thus the evolution of martian rocks based on Ca-phosphates. A petrological, chemical, chronological and microstructural approach using a series of high-spatial resolution techniques including Raman spectroscopy, electron microscopy (SEM, EPMA, CL-imaging) and secondary ion mass spectrometry (SIMS) analysis has been applied to a representative number of Ca-phosphate grains. Analytical results for apatite and merrillite reveal: (i) zoning in F, Cl, Br and I concentrations, (ii) elevated Cl concentrations in the range of ∼11,900–35,300 µg/g and halogen ratios, i.e., Cl/Br and Cl/I, as well as stable chlorine isotope composition, reported as δ37Cl values rel. to Standard Mean Ocean Chloride (SMOC, defined as 0‰) with a value of +0.67 ± 0.14‰ (1σ), distinguishing KG 002 phosphates from that of other enriched and depleted shergottites. The halogen and heavier δ37Cl record indicate a slightly higher degree of ∼3.5% assimilation of Cl-rich and isotopically heavier crustal reservoir on Mars when compared to other enriched shergottites. (iii) Structural investigations together with the chemical and petrological context of the grains confirm the occurrence of hydroxyl-poor merrillite, indicate weak if any alteration effects induced by metamictization, only minor structural modifications due to shock metamorphism, and absence of replacement reactions. Therefore, igneous crystallization of Ca-phosphates from a fractionated, hydrous and ferrous mantle source, rich in volatiles including the halogens and Na and lithophile rare earth-elements, and absence of interaction with crustal fluids/brines of the sample is deduced. (iv) The Pb isotopic composition of six apatite and three merrillite grains is highly unradiogenic and the 238U-206Pb record yields a phosphate crystallization time at 395 ± 240 Ma (2σ), which is similar to those of other enriched shergottites.

Two different types of data acquisition methods, "averaging mode" and "ion-counting mode", have been used in a time-of-flight (TOF) mass spectrometry. The most common method is an averaging mode that sums waveform signals obtained from each flight cycle. While it is possible to process many ions arriving at the same TOF in one flight cycle, low-abundance ions are difficult to measure because ion signals are overwhelmed by noises from the detection system. An ion-counting mode is suitable for the detection of such low-concentration ions, but counting loss occurs when two or more ions arrive at the detector within the dead time of the acquisition system. In this study, we introduce a technique that combines two methods to measure target ions with a high concentration difference, i.e., averaging mode and ion-counting mode are used simultaneously for high abundant and trace ions, respectively. By processing waveforms concurrently during data acquisition, one can choose to analyze either or both types of data to achieve a highly quantitative mass spectrum over a wide range of sample concentrations. The result of the argon isotope analysis shows that this method provides a more accurate determination of the isotope ratio compared to averaging mode alone at one-twentieth of the analysis time required by ion-counting alone. Graphical Abstract ᅟ.

The Meghalaya Plateau and the Mikir Hills constitute a northeastern extension of the Precambrian Indian Shield. They are dominantly composed of Proterozoic basement granite gneisses, granites, migmatites, granulites, the Shillong Group metasedimentary cover sequence, and Mesozoic-Tertiary igneous and sedimentary rocks. Medium to coarse grained, equigranular to porphyritic Cambrian granite plutons intrude the basement granite gneisses and the Shillong Group. U-Pb SHRIMP zircon geochronology and geochemistry of the granite gneisses and granites have been carried out in order to understand the nature and timing of granite magmatism, supercontinent cycles, and crustal growth of the Meghalaya Plateau and Mikir Hills. Zircons from the Rongjeng granite gneiss record the oldest magmatism at 1778 ± 37 Ma. An inherited zircon core has an age of 2566.4 ± 26.9 Ma, indicating the presence of recycled Neoarchaean crust in the basement granite gneisses. Zircons from the Sonsak granite have two ages: 523.4 ± 7.9 Ma and 1620.8 ± 9.2 Ma, which indicate partial assimilation of an older granite gneiss by a younger granite melt. Zircons from the Longavalli granite gneiss of the Mikir Hills has a crystallization age of 1430.4 ± 9.6 Ma and a metamorphic age of 514 ± 18.6 Ma. An inherited core of a zircon from Longavalli granite gneiss has an age of 1617.1 ± 14.5 Ma. Zircons from younger granite plutons have Cambrian mean ages of 528.7 ± 5.5 Ma (Kaziranga), 516 ± 9.0 Ma (South Khasi), 512.5 ± 8.7 Ma (Kyrdem), and 506.7 ± 7.1 Ma and 535 ± 11 Ma (Nongpoh). These plutons are products of the global Pan-African tectonothermal event, and their formation markedly coincides with the later stages of East Gondwana assembly (570–500 Ma, Kuunga orogen). The older inherited zircon cores (2566.4 ± 26.9 Ma, 1758.1 ± 54.3 Ma, 1617.1 ± 14 Ma) imply a significant role for recycled ancient crust in the generation of Cambrian granites. Thus the Meghalaya Plateau and Mikir Hills experienced major felsic magmatic episodes at ~ 1800 Ma, ~ 1600 Ma, ~ 1400 Ma, and ~ 500 Ma with recycling of Neoarchaean crust, and later contributions from Paleo-Mesoproterozoic granite gneiss sources. A 258 ± 20 Ma lower intercept age of the Rongjeng granite gneiss perhaps indicates a Permo-Triassic thermal imprint on the Meghalaya Plateau. The granite gneisses and granites have peraluminous to metaluminous compositions, and syn-orogenic to post-collisional affinities. We conclude that the orogenic history of the Meghalaya Plateau and the Mikir Hills records crustal growth of the Columbia and Gondwana supercontinents as noted in other Pan-African-Indian-Prydz-Brasiliano orogens.

Translation of binary-mixture particles composed of solid CO2 and graphite were observed in an area of static magnetic-field that monotonically decreased in one direction, and magnetic susceptibility χmix of individual particle was determined from the observed relationship between translating velocity and field intensity. Using the variance of χmix value, mixing ratio f of graphite was speedily estimated without consuming the particle; here published χ values of solid CO2 and graphite were used in the estimation, and mass measurement of particle was unnecessary. In the experiment, the translated particles were quietly released in an area of microgravity produced by a short shaft with a height of 180 m (duration< 0.5 s), and the magnetic field was supplied by a pair of small Nd magnetic plate. The detection of f was based on a principle which realized magnetic separation of ordinary diamagnetic and paramagnetic particles at low field intensity. The experimental results confirm the efficiency of the energy conservation law proposed for the field-induced translation at a reduced temperature of T∼200 K. By improving the present apparatus, binary-mixture particles can be magnetically separated according to the sequence of their f value, and a histogram of f is speedily obtained from the population of separated particles. Such histogram will provide direct information to estimate the formation process of the binary-mixture particles, especially in various onsite missions on the terrestrial surface as well in the outer solar system.

著者人数: 13名, Accepted: 2018-07-23, 資料番号: SA1180184000

Most solid particles, composed of diamagnetic or weak paramagnetic materials, cannot be extracted by a conventional magnetic separator. Here we report that an ensemble of heterogeneous particles, composed of bismuth, gold, graphite and rock forming minerals are separated into fractions of different materials by small NdFeB magnetic plates. It is based on a recent finding that acceleration of a translating particle, induced by magnetic volume force in an area of field gradient, is uniquely determined by intrinsic susceptibility of material; the acceleration is independent to particle mass. The setup will serve as an effective technique of pre-treatment in analysing mixture of heterogeneous particles; such a technique is desired in various research fields of science, and the magnetic separation may play a role of a “chromatography technique” conventionally used in the analysis of organic molecules. The portable and low-cost system could provide a breakthrough for on-site research in industrial and medical fields as well as in resource explorations in nature. Extraction of rare materials such as gold or platinum becomes possible in a hazardless manner.

Electron- or X-ray-induced characteristic X-ray analysis has been widely used to determine chemical compositions of materials in vast research fields. In recent years, analysis of characteristic X-rays from muonic atoms, in which a muon is captured, has attracted attention because both a muon beam and a muon-induced characteristic X-ray have high transmission abilities. Here we report the first non-destructive elemental analysis of a carbonaceous chondrite using one of the world-leading intense direct current muon beam source (MuSIC; MUon Science Innovative Channel). We successfully detected characteristic muonic X-rays of Mg, Si, Fe, O, S and C from Jbilet Winselwan CM chondrite, of which carbon content is about 2 wt percent, and the obtained elemental abundance pattern was consistent with that of CM chondrites., 電子やX線を用いた特性X線分析は基礎的化学分析手法として様々な分野で用いられている。近年、その高い透過性からミュオン捕獲特性X線を用いた分析手法が注目を集めている。我々はここに最新の強力なDCミュオン源であるMuSICを用いて行った炭素質コンドライトの分析結果について報告する。炭素を約2\%含むJbilet Winselwan隕石を測定した結果、Mg, Si, Fe, O, S, Cからのミュオン捕獲特性X線を検出し、元素存在度のパターンはCMコンドライトとして無矛盾であった。本非破壊分析手法は炭素に高い感度を持つことから、C型小惑星からのサンプルが持ち帰られた場合にも、それを分析する強力な新手法となりえる。

A comprehensive study of the organic chemistry and mineralogy of an ultracarbonaceous micrometeorite (UCAMM D05IB80) collected from near the Dome Fuji Station, Antarctica, was carried out to understand the genetic relationship among organic materials, silicates, and water. The micrometeorite is composed of a dense aggregate of ∼5 µm-sized hollow ellipsoidal organic material containing submicrometer-sized phases such as glass with embedded metal and sulfides (GEMS) and mineral grains. There is a wide area of organic material (∼15 × 15 μm) in its interior. Low-Ca pyroxene is much more abundant than olivine and shows various Mg/(Mg + Fe) ratios ranging from ∼1.0 to 0.78, which is common to previous works on UCAMMs. By contrast, GEMS grains in this UCAMM have unusual chemical compositions. They are depleted in both Mg and S, which suggests that these elements were leached out from the GEMS grains during very weak aqueous alteration, without the formation of phyllosilicates. The organic materials have two textures—smooth and globular with an irregular outline—and these are composed of imine, nitrile and/or aromatic nitrogen heterocycles, and amide. The ratio of nitrogen to carbon (N/C) in the smooth region of the organics is ∼0.15, which is five times higher than that of insoluble organic macromolecules in types 1 and 2 carbonaceous chondritic meteorites. In addition, the UCAMM organic materials are soluble in epoxy and are thus hydrophilic; this polar nature indicates that they are very primitive. The surface of the material is coated with an inorganic layer, a few nanometers thick, that consists of C, O, Si, S, and Fe. Sulfur is also contained in the interior, implying the presence of organosulfur moieties. There are no isotopic anomalies of D, 13C, or 15N in the organic material. Interstellar photochemistry alone would not be sufficient to explain the N/C ratio of the UCAMM organics; therefore, we suggest that a very small amount of fluid on a comet must have been necessary for the formation of the UCAMM. The GEMS grains depleted in Mg and S in the UCAMM prove a very weak degree of aqueous alteration; weaker than that of carbonaceous chondrites. Short-duration weak alteration probably caused by planetesimal shock locally melted cometary ice grains and released water that dissolved the organics; the fluid would likely have not mobilized because of the very low thermal conductivity of the porous icy body. This event allowed the formation of the large organic puddle of the UCAMM, as well as organic matter sulfurization, formation of thin membrane-like layers of minerals, and deformation of organic nanoglobules., アクセプト後にタイトル・アブストラクト等変更あり、著者最終稿は変更前のタイトル"Formation of an Ultracarbonaceous Antarctic Micrometeorite through Minimum Aqueous Alteration in a Small Porous Icy Body", This work was supported by a Grant-in-Aid for Scientific Research from the Japanese Ministry of Education, Culture, Sports, Science and Technology (No. 22224010, PI: H. Nagahara). The STXM facility at the beamline 5.3.2.2, ALS, is supported by the Department of Energy, Basic Energy Sciences Program.

The quantitative accuracy and throughput performance for the newly developed hardware-based simultaneous ion counting and waveform averaging (AVG) in a time-of-flight (TOF) mass spectrometer was studied. The peak detection (PKD) algorithm was used for ion counting instead of voltage threshold detection method that is widely used in ion counting techniques. The silicon isotope abundance ratios were determined by the ion counting with ± 4 % uncertainties relative to the known isotope ratios. The measurements were carried out at relatively higher count rate condition (40 % which means that 0.4 ions arrived at the detector for each TOF trigger), but no systematic errors observed, which indicates the PKD algorithm was able to resolve two or more ions detected simultaneously compared to a simple voltage threshold detection algorithm. An excellent linear response was observed between PKD-based ion counts and the peak area determined by AVG waveform for 2 orders of magnitude. By using peak area based on AVG waveform for higher abundance ions and ion counting based on PKD for lower abundance ions, the silicon isotope abundance ratios were determined with the same analytical precision at one-tenth of the analysis time required for the ion counting alone.

Accepted: 2016-12-01, 資料番号: SA1160257000

Most existing solids are categorised as diamagnetic or weak paramagnetic materials. The possibility of magnetic motion has not been intensively considered for these materials. Here, we demonstrate for the first time that ensembles of heterogeneous particles (diamagnetic bismuth, diamond and graphite particles, as well as two paramagnetic olivines) can be dynamically separated into five fractions by the low field produced by neodymium (NdFeB) magnets during short-duration microgravity (μg). This result is in contrast to the generally accepted notion that ordinary solid materials are magnetically inert. The materials of the separated particles are identified by their magnetic susceptibility (χ), which is determined from the translating velocity. The potential of this approach as an analytical technique is comparable to that of chromatography separation because the extraction of new solid phases from a heterogeneous grain ensemble will lead to important discoveries about inorganic materials. The method is applicable for the separation of the precious samples such as lunar soils and/or the Hayabusa particles recovered from the asteroids, because even micron-order grains can be thoroughly separated without sample-loss.

Zircon U-Pb geochronology was applied to a migmatitic gneiss in the Busan gneiss complex, Gyeonggi massif, Korea. 207Pb/206Pb ages of concordant zircon grains reveal that overgrowth rims with Th/U ratios lower than 0.1 formed at 1937 ± 6 Ma during the migmatization and mantled the inherited cores of ca. 3500–2200 Ma. The 207Pb/206Pb age of the rims is consistent with the monazite Th-total Pb age (ca. 1938 Ma), suggesting that the rims are the product of Paleoproterozoic regional metamorphism. Our zircon age data are not sufficient for discerning the tectonic affinity of the Busan gneiss complex belonging to either Gyeonggi or Yeongnam massif. However, consistency of these ages with the ca. 1930 Ma Pb-Pb age reported from the Bagdalryeong gneiss complex, Gyeonggi massif, supports the tectonic model that the Busan gneiss complex is a part of the Gyeonggi massif. Discordant U-Pb data obtained from the zircon rims (293 ± 31 Ma) and the monazite Th-total Pb age (ca. 289 Ma) suggest that the Busan gneiss complex was affected by the Early Permian regional metamorphism during the Ogcheon (Okcheon) Orogeny. Therefore, we conclude that the Busan gneiss complex is a part of the Gyeonggi massif occurring as either a basement rock of the Ogcheon (Okcheon) metamorphic rocks, or a tectonically emplaced, exotic piece affected by the Early Permian Ogcheon (Okcheon) metamorphism. In addition, our U-Pb data suggest that the Busan complex is possibly linked with the Hida-Oki terrane in Japanese Islands.

Constraining the timescales for the evolution of planetary bodies in our solar system is essential for a complete understanding of planet-forming processes. However, frequent collisions between planetesimals in the early solar system obscured and destroyed much of the primitive features of the old, first-generation planetary bodies. The presence of differentiated, achondritic clasts in brecciated chondrites and of chondritic fragments in achondritic breccias clearly witness multiple processes such as metamorphism, magmatism, fragmentation, mixing, and reaccretion. Here, we report the results of ion microprobe Pb-Pb dating of a granite-like fragment found in a meteorite, the LL3-6 ordinary chondrite regolith breccia Adzhi-Bogdo. Eight spot analyses of two phosphate grains and other co-genetic phases of the granitoid give a Pb-Pb isochron age of 4.48 ± 0.12 billion years (95% confidence) and a model age of 4.53 ± 0.03 billion years (1σ), respectively. These ages represent the crystallization age of a parental granite-like magma that is significantly older than those of terrestrial (4.00-4.40 Gyr) and lunar granites (3.88-4.32 Gyr) indicating that the clast in Adzhi-Bogdo is the oldest known granitoid in the solar system. This is the first evidence that granite-like formation is not only a common process on Earth, but also occurred on primitive asteroids in the early solar system 4.53 Gyr ago. Thus, the discovery of granite magmatism recorded in a brecciated meteorite provides an innovative idea within the framework of scenarios for the formation and evolution of planetary bodies and possibly exoplanetary bodies.

We report SHRIMP U–Pb age of zircons in four samples of eclogite and one sample of orthogneiss from Sulu ultrahigh-pressure (UHP) zone in Yangkou area, eastern China. UHP rocks are distributed along the Sulu orogenic belt suturing North China Block with South China Block. In Yangkou area, UHP unit is well exposed for about 200 m along Yangkou beach section and consists mainly of blocks or lenses of ultramafic rocks and eclogite together with para- and orthogneiss which are highly sheared partly. Zircon grains examined in this study from eclogite show oscillatory zoning and overgrowth texture in CL images, and most of the grains have high Th/U ratio ranging from 0.8 to 2.1 indicating an igneous origin. The weighted mean 206Pb/238U ages of zircons from the four samples range from 690 to 734 Ma. These ages can be correlated to the magmatic stage of the protoliths. In rare cases, zircon grains possess a narrow rim with very low Th/U ratio (< 0.02). EPMA U–Th-total Pb dating of such rim yields younger ages that range from 240 to 405 Ma marking the metamorphic stage. On the other hand, zircons from the orthogneiss show irregular shape and zoning with inclusion-rich core and inclusion-free rim. These grains of zircon yield U–Pb discordia intercept ages of 226 ± 63 Ma and 714 ± 110 Ma (MSWD 0.78). Bulk of the areas of the rims rim of the zircons demonstrate younger 206Pb/238U ages close to the upper intercept, with low Th/U ratio (< 0.20) indicating their metamorphic origin. In contrast, the cores show older 206Pb/238U ages close to lower intercept and high Th/U ratio of (0.14–5.25) indicating their igneous origin. The upper intercept age is also commonly noted in zircons from eclogite. Our results suggest a bimodal igneous activity along this zone during the Neoproterozoic, probably related to the rifting of the Rodinia supercontinent.

The Maizuru terrane, distributed in the Inner Zone of southwest Japan, is divided into three subzones (Northern, Central and Southern), each with distinct lithological associations. In clear contrast with the Southern zone consisting of the Yakuno ophiolite, the Northern zone is subdivided into the western and eastern bodies by a high-angle fault, recognized mainly by the presence of deformed granitic rocks and pelitic gneiss. This association suggests an affinity with a mature continental block; this is supported by the mode of occurrence, and petrological and isotopic data. Newly obtained sensitive high mass-resolution ion microprobe (SHRIMP) zircon U–Pb ages reveal the intrusion ages of 424 ± 16 and 405 ± 18 Ma (Siluro–Devonian) for the granites from the western body, and 249 ± 10 and 243 ± 19 Ma (Permo–Triassic) for the granodiorites from the eastern body. The granites in the western body also show inherited zircon ages of around 580 and 765 Ma. In addition, electron probe microanalysis (EPMA) monazite U–Th–total Pb dating gives around 475–460 Ma. The age of intrusion, inherited ages, mode of occurrence, and geological setting of the Siluro–Devonian granites of the Northern zone all show similarities with those of the Khanka Massif, southern Primoye, Russia, and the Hikami granitic rocks of the South Kitakami terrane, Northeast Japan. We propose that both the Siluro–Devonian and Permo–Triassic granitic rocks of the Northern zone are likely to have been juxtaposed through the Triassic–Late Jurassic dextral strike-slip movement, and to have originated from the Khanka Massif and the Hida terrane, respectively. This study strongly supports the importance of the strike-slip movement as a mechanism causing the structural rearrangement of the Paleozoic–Mesozoic terranes in the Japanese Islands, as well as in East Asia.

ARTICLE I NFO Dhofar 287 is a lunar meteorite found in Oman in 2001, which consists of a major portion (95%) of low-Ti mare basalt (Dho 287A) and a minor attached part (∼5%) of regolith breccia (Dho 287B). Here, we report the U-Pb systematics of Dho 287A using data collected with a Sensitive High Resolution Ion Microprobe (SHRIMP). In- situ analyses of five merrillite and three apatite grains, which are resistant to secondary petrologic events, resulted in a total Pb/U isochron age of 3.34±0.20 Ga, in 238 U/ 206 Pb- 207 Pb/ 206 Pb- 204 Pb/ 206 Pb 3-D space (95% confidence level). The observed Pb-Pb isochron of these eight phosphates coupled with four plagioclase grains alsoyieldeda 207 Pb/ 206 Pbageof3.35±0.13Ga.Thisformationage,whenconsideredasthecrystallizationageof

Highly metasomatized apatite-rich peridotite layers (AP-layer) occur in the Finero phlogopite–peridotite massif (western Italian Alps). The AP-layer and the host peridotite are characterized by higher concentration of REE (total REE > 80ppm), especially LILE, and lower HFSE, than those of the other rocks in the Finero massif. The AP-layers and their host peridotites have bulk silicate Earth-like Sr and Nd-isotope compositions except for one sample containing rare carbonate aggregates. The carbonate aggregates occur in a late serpentine-talc veinlet and show relatively high d13C and d18O, high 87Sr/86Sr and lower ɛNd than the other samples. These results, combined with the previous data, indicate that the carbonates formed late at relatively low temperatures. The petrochemical results along with the literature suggest that the AP-layer was locally formed from a metasomatic agent geochemically distinct from that formerly producing phlogopite-bearing harzburgite widely distributed throughout the massif. We propose that the metasomatic agent for the AP-layer was an orthopyroxene-saturated, CO2-bearing hydrous fluid/melt that evolved through the crystallization of metasomatic minerals upon reactions with peridotites. Sensitive high-resolution ion microprobe (SHRIMP) analyses of apatite grains yielded a Tera-Wasserburg concordia three-dimensional isochron age of 215 ± 35Ma in the 238U/206Pb–207Pb/206Pb–204Pb/207Pb diagram. The age is similar to intrusions in the Finero area, suggesting that the carbonate- and apatite-metasomatism was synchronous with Triassic magmatic activity.