Sulfate is a major anion in nature and affects the mobility of coexisting trace dissolved species on mineral surfaces. Ferrihydrite is a low-crystalline iron oxide widely distributed in nature. Because of the huge specific surface area and the positively charged behavior, it is considered as an excellent scavenger for oxyanions. Attenuated total reflectance-infrared spectroscopy (ATR-IR) method enbles the direct observation of surface complex structure in aqueous system. The purpose of this experiment is to determine the structure of surface complex of sulfate on ferrihydrite from the in-situ observation by using ATR-FTIR under a wide range of environment conditions.

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Nano-particles moves downward relative to groundwater when the density of nano-particles is higher than that of groundwater. The effect of the downward movement by gravity is more significant than that by diffusion (wD₀) and dispersion (D_dis-z), and the diffusion coefficient is two orders of magnitude less than the dispersion coefficient.

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In order to estimate the effect of acidic rain on evolution of early earth environment, artificial chemical weathering of basalt have been experimented chemically and mineralogically under early earth condition. The basalt has been exposed to three kinds of acid solutions at pH 4, CO2 saturated water and distilled water at 50 degree for different periods of time up to 600 days in an open system. The leached sample solutions were analyzed for dissolved elements using ICP-MS. Morphological and chemical changes of the each mineral surface were studied by SEM, EPMA and microscopy techniques. Alteration products were examined using XRD.

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Some serpentinites include a lot of polygonal serpentine (PS) in their yellow or light green flaky parts in Kurosegawa belt. According to the TEM observation, most of PSs has approximately 200- 300 nm in diameter. Some chrysotile fibers have fan-shaped sectors partially; therefore they seem to be intermediates chrysotile and PS. They should be imperfect chrysotile or polygonal serpentine. Chemical compositions of lizardite-chrysotile serpentines show wide variations in FeO and Al₂O₃ contents, PS show low FeO contents and variable Al₂O₃ contents and antigorite serpentines have constant FeO content (2-3 wt %) and lower Al₂O₃ contents.

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Biogenic manganese nodules (about 10 mm) collected from the Oppu mine were characterized by XRD and XRF.  The XRD pattern of the wet sample showed characteristic diffraction lines of a phyllomanganate with a 1 nm d-spacing.  After air-drying, the manganese nodule was transformed into a phyllomanganate with a 0.7 nm d-spacing due to the loss of interlayer water.  Zn, Ca, etc., in addition to Mn, were detected by XRF analysis of the manganese nodule.  The manganese nodule had a layered ring structure and Zn-enriched layers were found by XRF elemental mapping of the cross section.

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A geochemical study on manganese (Mn) carbonate nodules from the deep-sea sedimentary rocks of the Mino Belt, Central Japan has been performed. REE patterns of Mn-carbonate and surrounding siliceous mudstone show positive Ce anomalies, whereas XANES analysis shows that Ce in these samples exits as trivalent state, suggesting the reduction during the diagenesis. We conclude that these Mn-carbonate nodules were formed (i) under very alkaline condition or (ii) by the reduction from Mn oxides during the diagenesis.

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Dynamic solidified minerals are discussed in osumilite-group minerals, calcites and plagioclases. The present paper is discussed in 6 compositional types of K, Na, Ca - Mg, Fe-bearing osumilites-group minerals. Three types of K-Fe, Mg and Na-Mg-bearing compositions are described in Earth’s minerals, where micro-grains of K-rich phases are easily described as K-feldspar of Earth-type crust rock. However other three types of Ca-Fe, Mg and Na-Fe-bearing phases are described in the chondrules of the Nio meteorites (Yamaguchi, Japan) and the published Itokawa-originated grains, which are easily described as Na-Ca plagioclases as terrestrial type crust rocks.

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Eucrite and Diogenite meteorites are the largest group of achondrites and are widely believed to have originated on Vesta. We analyzed plagioclase in two eucrites and diogenite by Fe-XANES in oreder to discuss that there is a relatively more oxidized environment in the deep crust of Vesta. The Fe³⁺ ratio of a cumulate eucrite was high (~0.9), while those of basaltic eucrite and diogenite were low (~0). This may be related to the heterogeneous redox environment of Vesta’s crust. Furthermore, the Fe³⁺/ΣFe of diogenite is somewhat lower, suggesting diogenites as residual materials from the removal of eucritic melts.

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HRTEM observations and SAED analyses were carried out with slices prepared from a carbon-rich grain directly taken out of the PTS of the Goalpara ureilite. HRTEM images and SAED patterns which show the conversion process of graphite into lonsdaleite or diamond are presented. The SAED patterns clearly show that the relative crystal axes orientation is (001)Gr // (100)Lo // (111)Di and [210]Gr // [001]Lo // [2-1-1]Di. The results of this study reveal the mechanism of the conversion and confirm the shock origin of diamonds in ureilites.

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Deconvolution of cathodoluminescence spectra from experimentally shocked and DAC experimental albite and maskelynite in meteorite provides the component at 2.95, 3.26 and 3.88 eV, of which intensities correlate with pressures by shock and DAC experiments. Experimentally shocked albite has lower intensities than DAC experimental one, which might be responsible for difference in pressure duration. These components are eliminated by temperature from melt pocket. These emission intensities depend on only shock pressure and pressure duration below annihilation temperature, implying that the actual shock pressure on maskelynite might correspond to intermediate value between estimated shock pressures by shock and DAC experiments.

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It is widely accepted that regolith on an asteroid’s surface is formed by impact of small celestial bodies. Regolith particles on the asteroid Itokawa, have been examined. Size and 3D shape distributions and micro-surface structures of Itokawa particles were revealed using x-ray micro tomography and FE-SEM. 
We performed impact experiments using a dunite target. High velocity and low velocity ejecta were collected separately.
Using x-ray micro-tomography, we analyzed size and 3D shape distributions of ejecta particles. Surface and inner microstructure of a few particles were also analyzed by SR based micro-tomography and an FE-SEM. We compared these results with Itokawa particles.

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Our mineralogical study on new nakhlite Martian meteorites (3 MIL09 Antarctic meteorites and NWA5790) showed that 3 MILs are paired with MIL03346, and NWA5790 has the largest mesostasis abundance among known nakhlites with extensive chemical zoning of augite and olivine. These results are consistent with the proposed model for the nakhlite igneous body (cumulus a crystals are loosely packed near the surface and become more closely packed with increasing depth). NWA5790 appears to have been located at the top most part of the cumulus pile, but the obtained cooling rate is indistinguishable from those of NWA817 and MIL (∼0.5 deg/hr).

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The surfaces of Itokawa regolith particles are morphologically divided into two types: surfaces with sharp and rounded edges. Surfaces with rounded edges were formed by erosion from those with sharp edges by mechanical abrasion and/or sputtering due to solar wind radiation. In order to reveal the dominant processes of erosion of Itokawa particles, we conducted laboratory experiments that mimic solar wind sputtering and mechanical abrasion. Besides, 3D-structures and surface micorostructures of Itokawa particles and lunar regolith particles were observed by SR-based micro-tomography and FE-SEM to discuss the difference between these regolith particles collected from the two celestial bodies without atmosphere. 

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Fe-rich olivine in altered carbonaceous chondrites is known to be precursor of phyllosilicates by aqueous alteration in the parent bodies, but its detailed conditions are still unknown. In this study, we conducted the hydrothermal alteration experiments for olivines (Fo100,80,50,20,0) with various pH solutions (pH 0,7,14). As the results, serpentine was formed from Mg-rich olivine and/or under low pH condition, while smectite was easily formed from Fe-rich olivine and under high pH condition. These  results get into line with present study.

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There were little differences between Itokawa samples and the average LL chondrite. Sample sizes are 30-180μm. So those differences may due to the size of samples, but it may be possible that these differences due to fractionations by sampling bias. Therefore, it is important to examine how the mineral and chemical compositions can be changed by the size of samples. The elemental maps and mineral maps were divided into N×N parts. We studied the relation between N and the error which that size of samples. 

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To understand formation of nepheline in meteorite parent bodies, we conduct hydrothermal alteration experiments of melilite and plagioclase that are typical precursor of nepheline in CAI and chondrule. Hydrothermal alteration experiments of melilite and plagioclase were performed with a Teflon reaction cell. After the experiments, mineralogy of products was determined XRD and SEM. Under pH 14 condition, nepheline hydrate (NaAlSiO₄H₂O) and analcime (NaAlSi₂O₆H₂O) were observed in gehlenite-SiO₂ and plagioclase system. Under pH 13-7 conditions, analcime formed by replacing gehlenite or plagioclase. Under pH 0, no crystalline phase was formed from gehlenite and plagioclase.

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We report on the mineralogy, petrography, and oxygen-isotope ratios of a micrometeoroid captured on the international space station. It has the texture of a porphyritic olivine pyroxene chondrule. Because Ni-rich sulfide does not show exsolution on the TEM scale, the micrometeoroid escaped aqueous alteration. However, the average and standard deviation of Cr2O3 wt.% in olivine suggest that it experienced weak thermal metamorphism. Oxygen isotope ratios of pyroxene and olivine are similar to those of Wild2 particles, MMs, and carbonaceous chondrites. These data suggest that the micrometeoroid is a fragment of a chondrule-like object that was derived from a primitive parent body.

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It is important to understand kinetics of dust formation processes under protoplanetary disk conditions for understanding of material evolution prior to planet formation. One of the most important processes is dust condensation from vapor. We performed condensation experiments of forsterite, which is the major constituent mineral in planetary materials, under controlled protoplanetary disk conditions. We found that crystalline forsterite condensed on the surface of forsterite substrate at ~1180 K and at 1 Pa of total pressure (mainly hydrogen), and that the condensation efficiency of forsterite is smaller than 0.05, which is much less than that of metallic iron.

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To understand the origin of GEMS, we performed condensation experiments from Si-Mg-Fe-O gas using induction thermal plasma (ITP) and obtained numerous spherical grains (10-50 nm in diameter), which has an iron nano-particle embedded in an amorphous silicate. When we use Ni and Zn instead of Fe, 2 or 3 metal grains (typically ~20 nm in diameter) included in amorphous silicate grain (typically ~50 nm in diameter) are produced. This indicates that the texture of these grains strongly depends on their surface energies between metals and silicates. The experimental results suggest that GEMS is an aggregates of smaller primary particles.

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Surface and crystal structures of presolar grains are important to understand the formation and evolution of the presolar grains.  We conducted surface and structure analyses, and oxygen isotope measurements of alumina grains isolated from the unequilibrated ordinary chondrites.  The presolar grains and some of alumina grains with the normal isotope ratios have irregular surface structures.  We also performed the dissolution experiments and ion irradiation experiments of synthesized alumina powders as possible processes forming the surface structures of presolar grains.  In this talk, we will discuss the origin of the surface structures of presolar alumina grains.

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We investigated the formation process of barred-olivine (BO) texture in chondrules on a basis of the morphological instability during rapid solidification. Our numerical simulation suggested that the cooling rate experienced by BO chondrules is much larger than that expected before.

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We report mineral assemblages in clasts of CR chondrite, similar to those in terrestrial eclogite. They contain omphacite, pyrope-rich garnet, olivine and orthopyroxene. The clasts formed under high-pressure conditions, 2.8-4.2GPa and 940-1080°C.

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The chemical compositions of Mg-rich olivines and Mg-rich low-Ca pyroxenes in chondrule-like objects from the Wild 2 sample are slightly different from those of chondrules in chondrites, slightly ferroan and Mn-enriched.  Antarctic micrometeorites (AMMs) satisfying these textures and compositions have been identified.  They are candidates of cometary dust, and are unique extraterrestrial materials collected from ice-sheet in polar region.  We will describe on the MMs of cometary dust candidates in detail and give new insights on the formation.  

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Mineralogical characteristics of Carbonaceous Chondrite Acfer331 were examined by TEM, SEM, micro-Raman, XRD. Main mineral species were olivine, phyllosilicate, gypsum, pyroxenes, etc by XRD. Containing other mineral species, detailed mineralogy  have been described. Some data were compared with other CC meteorite.

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Nepheline and sodalite in carbonaceous chondrites are believed to be secondary minerals formed by aqueous alteration (Na metasomatism) in meteorite parent bodies. We have undertaken an extensive survey of Ningqiang and Warrenton that include abundant nepheline and sodalite. Chondrules in Ningqiang include abundant nepheline and sodalite, and about 10 vol. % of matrix is composed of nepheline and sodalite. The bulk Na content of Ningqiang indicates that Na metasomatism occurred in closed system in Ningqiang parent body. DIs in Warrenton include abundant nepheline and sodalite similar to matrix of Ningqiang indicating the processes Ningqiang experienced were similar to that of DIs.

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Dark clasts (DCs) in CV and CO chondrites are considered to be fragments of their host meteorites that underwent aqueous alteration and thermal metamorphism. We have taken an extensive survey of DCs from the Allende chondrite. The DCs contain chondrule-pseudomorphs that have diameters smaller than that of the host Allende. This suggests that the DCs' precursor was different from Allende.The DCs have Ca-rich veins along their peripheries and in their inside. Such veins are absent in the host. These observations suggest that the veins probably formed after formation of the pseudomorphs but before incorporation of the DCs’ into the host meteorites.

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The Late Proterozoic metatonalite suite predominates in the Sør Rondane Mountains (SRM), Antarctica. The rocks are classified into two groups: low-K tholeiitic granitoid or low-K calc-alkaline adakite. U–Pb SHRIMP zircon ages of the tholeiitic metatonalites are in 998–995 Ma, whereas the ages of calc-alkaline rocks are clearly younger, which are divided into two stages at 945–920 Ma and 772 Ma. It implies that the metatonalite suite is derived from several different magmas. The most plausible tectonic setting for these magmatisms is a juvenile oceanic arc. This plutonic complex in the SRM is unique to Dronning Maud Land.

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We conducted high-P experiments with graphite capsule, and obtained generation conditions of 1.1-1.2 GPa and 1375-1385C where the melt coexists with liquidus olivine and orthopyroxene. The conditions correspond to a potential mantle temperature of ca. 1480C, suggesting active spreading took place at Ryukyu backarc in 2.5 Ma.

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Radiometric ages of zircons in four granitoids and a gneiss were obtained from the ²³⁸U/²⁰⁶Pb ratio and isotopic compositions of Pb using a LA-ICPMS. The weighted mean of the zircon ages of a samples from the Miyanohara tonalite, Mansaka tonalite and Shiraishino granodiolite are 107±2 Ma, 108.6±2.5 Ma and 108.7±3.6 Ma whereas that for the sample from the Himenoura basement granite is 108.8±2.4 Ma. Detrital zircon ages of the basement gneiss show bimodal age distribution with peaks at ca. 1900 Ma and 280 Ma. These result demonstrate that attribution of the basement of Himenoura Group is Higo Belt.

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Based on detailed petrologic data coupled with volcanic stratigraphy, we revealed three patterns of magmatic evolution course in Komakusadaira pyroclastics, Zao newest stage. (1) Basal portion of colder and high crystallinity felsic magma was withdrawn by forced injection of mafic magma and these were mixed in the conduit. (2) Intermediate magma, formed by mixing between infused mafic magma and felsic magma at the base of shallow chamber, ascended buoyantly to the chamber top. The intermediate magma erupted, thereby withdrawing the felsic magma. (3) By repeated injection of mafic magma, shallow felsic chamber gradually changed in composition toward intermediate.

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Based on volcano-stratigraphic and petrologic data of the eruptive rocks, we examined temporal change of the eruption style and magma feeding system of middle to shallow crustal level during past ca. 800 years activity of Goshikidake, Zao volcano. We revealed a close relationship between the temporal change of eruptive style and the magma evolution course during the activity.

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Magma mixing is suggested by some classic petrological evidences from Saruana Lava, Chokai. Zoning profiles of pyroxenes imply that thermal equilibration between the mingling magmas induced crystallization of augite in the cooled mafic magma and dissolution of Mg-poor pyroxenes in the heated felsic magma. Euhedral oscillatory zoning of augite may have been produced by crystal growth in the chemically fluctuating magmas. The process involving mingling, thermal equilibration, dissolution, crystallization, and homogenization, lasted within half a year before the eruption, suggested by zoning profiles of olivine phenocrysts.

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Quaternary volcanic rocks from northeastern Japan arc (NEJ) have a spatial variation of Sr-Nd-Pb-Hf isotopic compositions, and a wide range of those compositions could be explained by contamination of heterogeneous crust materials. We estimated the contaminated crustal materials using the Ce isotopic compositions in NEJ volcanic rocks.

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Early Cretaceous adakitic pluton consists of the adakitic granites in central part of zoned plutonic bodies (central facies) surrounding by adakitic to non-adakitic granites in marginal part (marginal facies). The exposure of the adakitic plutons is divided into two zones: from the eastern part of the north Kitakami belt to the eastern margin of the south Kitakami belt (E zone: Hashikami, Tanohata, Miyako, and Kinkasan plutons), and the inner part of the South Kitakami belt (W zone: Tono, Senmaya, and Hitokabe plutons). Zircon U-Pb age of the adakitic granites in W zone are younger than those in E zone, they are considered to be derived from higher pressure and vapor-present condition.

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Siberian large igneous province (LIP) mainly consists of flood basalt of Permo-Triassic age and occupies the area seven times of Japan. Ethiopian LIP formed in Oligocene and occupies the area one half of Japan. The two LIPs commonly have both High-Ti and Low-Ti series rocks, but differ in the presence or absence of shield volcano, andesite, Nb depletion, etc. Plume origin of Ethiopian LIP is widely accepted, but various origins are discussed for Siberian LIP, which may extend on the Arctic continent beyond a Cretaceous suture zone. A case study for possible Siberian LIP rocks in Chukotka is given.

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We clarified geology and petrography of granitoids in the Takata suite, Okuizumo district of the San-in zone. The suite is divided into two lithofacies; Hbl-Bt-tonalite and Hbl-Bt-granodiorite. The former petrographically corresponds to the Obara tonalite (Yakushiji et al 2012), which is a fore-runner intrusion of this area. The latter is ca 60Ma intrusion because the granodiorite gradually contacts with the other suite (Yokota granite: 59.6Ma) at the southern part. Farther petrological studies of the Takata suite would be required for the elucidation of their petrogeneses and igneous activities.

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The middle Miocene Muro Ignimbrite includes some dacitic obsidian lens in rhyolitic matrix. Dacitic rock has been founded as dikes and fragment of pyroclastic dike rocks in the area of inferred source caldera. And, some composite dike is presented in this area. It is shown that eruption of ignimbrite caused by heterogeneous magma in source volcano. 

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The Kofu granitic body divided into four units. Among them, researches of the Mitake-shosenkyo-type biotite granite are few. Then, this study aims in petrology that detailed lithological division, distribution of magnetic susceptibility and decision about granitoid series, and considers the process of formation of this rock.
The author can observe rapakibi texture in potassium feldspar and dusty zone in plagioclase in thin sections that make out of most of samples throughout this body. Therefore, this body can be expected to have a chance of magma mixing on the basis of thin section observation, chemical composition and so on.

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Kusatsu Shirane volcanois is one of the Quaternary active volcanos located in back arc side of northeast Honsyu arc. Many studies have been conducted in a lot of fields, such as geology, petrology, geodesy and geothermal research. However, the generation and evolution processes of magma for the most primary stage of the activity of this volcano are not clarified enough. In this study, I focused on the Matsuozawa volcanic products which were formed in most early stage of activity of Kusatsu Shirane volcano and tried to investigate their processes of magma generation and evolution through field investigations, petrographical observations and chemical analysis of minerals by electron probe micro analyzer (EPMA).

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The Quaternary Takahara volcano is a stratovolcano located on the volcanic front in the southern part of northeast Japan volcanic arc. In this region, five monogenetic volcanoes align on a fracture zone running NW-SE in the northern part of the Takahara volcano. They are presumed to have been formed with different genetic processes of magma from the main part of statovolcano. In this study, we tried to study the detailed microscopic characteristics and chemical composition of minerals by EPMA for understanding their genetic processes of magmas and the relationship with the main part of stratovolcano.

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We performed Ca-Mg diffusion simulation for pyroxene in CMS system with temperature- and composition-dependent interfacial equilibrium compositions and diffusion coefficient under conditions of initial temperatue of 1473K, grain size of 2mm, and cooling rate of 0.1K/yr and 0.0001K/yr, respectively. In the former case, Ca content in the core region was identical to the initial composition. In the latter case, Ca contents were different between core and rim regions after 1 million years. In both case, temperature inferred from pyroxene core compositions deviate from actual temperature. Based on the results, we’ll discuss about the cooling rate responsibility of pyroxene thermometer.

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Supercooling and subsequent crystallization experiments have been performed on hydrous granitic melts in order to reproduce the mineral textures observerd in “felsic volcanic-rock-like inclusions” within garnet crystals in high-temperature regional metamorphic rocks (granulites) from continental collision orogens worldwide. Dendritic quartz was produced in relatively rapidly cooled melts. Its morphology and size vary widely depending upon cooling rate, H₂O content of melt, and duration of isothermal treatment at 700C.Intergrowths of quartz and feldspar were also formed immediately adjacent to the dendritic quartz crystals after 300 hours isothermal treatment. These data would put constraint on the conditions to form the “felsic volcanic-rock-like inclusions” and thereby the rates of cooling and exhumation of graulites.

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We have succeeded to develop a method to identify minerals by imaging the same sample at two different x-ray energies (7 and 8 keV) below and above the K-absorption edge of Fe (7.112 keV) and obtain 3D mineral maps (analytical dual-energy micro-tomography). The compositions of solid solutions can be also obtained. This method was applied to preliminary analysis of Itokawa particles (30-180 μm) collected by the Hayabusa spacecraft.

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    The Chicxulub Crater, Yucatan Peninsula in Mexico, is one of the largest impact structures on the Earth. However,  The details of impact processes of the Chicxulub crater is largely unknown.
    In this study, we measured and analyzed planar deformation features (PDFs) on shocked quartz grains derived from asteroid impact at the K-Pg boundary deposits both within the Chicxulub crater (Yaxcopoil-1 site) in order to estimate peak shock pressure of ejecta deposited within the Chicxulub crater. We revealed that within and around the crater, from moderately to highly shocked quatrz grains and have been deposited for several days.

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Four stable pyroxene polymorphs have been identified: Ca-rich clinopyroxene (Ca-rich Cpx, space group: C2/c), Ca-poor clinopyroxene (pigeonite) (Ca-poor Cpx, C2/c, P21/c), protoenstatite (Pen; Pbcn), and low-temperature orthopyroxene (LTOpx, Pbca). Moreover, Ohi et al. (2008, 2010) established the stability field of high-temperature orthopyroxene (HT-Opx, Pbca) in enstatite (Mg2Si2O6) - diopside (CaMgSi2O6) system. However, LT- and HT-Opx have never been reported in natural sample. Micrometeorite which has about 100 um in size is collected from the ice in Antarctica. The most of them is like to be condritic meteorite and consistent with olivine, pyroxene and so on. Two types of Opx which have the different chemical composition although the same space group (Pbca) are found in a micrometeorite, TT001c5-48.

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The Central Asian Orogenic Belt (CAOB) resulted from amalgamation of voluminous subduction – accretionary complexes of Late Neoproterozic to Mesozoic time. Considering geology and geochemistry of the intrusive rocks, the subduction-zone and collision-zone magmatism occurred in the Hangay batholith and the Lake zone, respectively. In other words, the Hangay batholith was situated between the Siberia and North China cratons as an independent land related to a magmatic arc during Permian time.

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We report detailed mineralogical and geochemical descriptions of spherulite occurring in welded tuff from Kamikawa village, Niigata prefecture, Japan, and also discussed its formation process. Judging from these chemical and textual evidence, we concluded that the present spherulite formed by the following steps: (1) Non-crystalline precursor of spherulite was generated by thermal convection and/or local concentration of volatile components in rhyolitic magma. (2) Ca ion migrated to outer-rim of the precursor and resulted into crystallization of plagioclase-rich shell. (3) Rapid intergrowth of cristobalite and plagioclase occurred in core of the spherulite and made up the fan-shaped aggregate. (4) Residual volatile-rich melt crystallized into anorthoclase and euhedral cristobalite in porous texture of inner-rim of spherulite.

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There are many alkaline basic-intermediate lavas that we called “Matsue Basalts” in Matsue city area.  Matsue basalt basically consist of 6 basic lavas and it’s pyroclastics. In our stdy, Matsue Basalt are divided into 6 groups, which are 3 basalt groups, 2 basaltic andesite groups and 1 andesite group based on their bulk rock chemistry and volcanic Stratigraphy. Chausuyama and Agenogi basalts show particularly with respect to their low FeO*/MgO ratios and high Cr content. And these two basalts have chromian spinels. Chromian spinels show low Cr# (Cr/(Cr+Al) atomic ratio) of 0.16-0.40, and olivine show high Fo content of 88-76. 

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Mesoperthitic ternary feldspars in felsic gneiss from the Mt. Riiser-Larsen, East Antarctica show the characteristic exsolution textures. Although the metamorphic temperature was estimated from re-integrated chemical composition of ternary feldspar, the formation mechanism of the exsolutin textures in mesoperthitic ternary feldspars had not been studied well. In this study, exsolution textures were classified in term of character of exsolution lamellae occurrence and the orientations of interfaces between each exsolution lamellae were determined using EBSD. We revealed a formation process of the exsolution textures in mesoperthitic ternary feldspars and gave constraint to the cooling process after the peak metamorphism of felsic gneiss.

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We report a characteristic melt-related texture of spinel clast in ultramafic pseudotachylyte. The texture consists of rounded corona-like rim, composed of chromian spinel particles and some interstitial material, which may surround aluminous spinel. The coronas increase their thickness in proportion to distance of each spinel clast from vein wall. Lattice orientation of spinel grains in corona is similar to that of the core aluminous spinel. These indicate partial dissolution of spinel clast in high-temperature frictional melt. The roundness of spinel clast including the corona increases proportionally to the distance of spinel clast from wall. This indicates melt temperature above 1300-1500 degreeC.

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