A peculiar peridotite xenolith with cataclastic texture was found from Ichinomegata crater, Megata volcano, the Northeast Japan arc. It shares the same mineral assemblage and chemistry with ordinary peridotite xenoliths from the locality, and is totally free of serpentine and other low-temperature alteration minerals. Coarse mineral grains are angular and rarely kinked, but never elongated. Fragmented grains of pyroxenes and chromian spinel are elongated to form thin streaks. From the textures and chemical compositions, we infer that an ordinary mantle lherzolite protolith was in-situ fractured in the upper mantle to form this cataclasite.

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Basal peridotites above the amphibolitic metamorphic sole outcropped around Wadi Sarami in central Oman ophiolite are the best example to understand the spatial extent of mantle heterogeneity and to examine peridotites-slab interactions. We recognized two types of lherzolites (A, B). The type-A lherzolites, being strongly foliated, lie directly above the sole and are overlain and/or surrounded by type B ones that are massive. Both lherzolites and harzburgites are similar in chemical properties to that observed for the abyssal peridotites. In type-A lherzolites, clinopyroxenes show higher contents in Al₂O₃ (up to 7.3 wt%), Na₂O (1.2 wt%),

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We found white dikes crosscutting deformation texture of lherzolite block within the garnet amphibole of metamorphic sole of Oman ophiolite. The dikes are composed of mainly clinopyroxene (CPX) with minor amount of serpentine, have high Na₂O content (0.2-0.7 wt%) with wide Mg# range (0.81-0.88). The features imply their cumulus origin from evolved basaltic magma.
We will show the petrological and geochemical features of the clinopyroxenite dikes in detail, and discuss about their origin.

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It has been inferred that concordant dunite bands within the mantle section of the Oman ophiolite represent magma conduits beneath a mid-ocean ridge. However, chemical behavior of the magma during its upwelling within the mantle has been unclarified. We discuss MORB behaviors reflected by segment structure through observations and chemical analyses of the concordant dunite bands and surrounding peridotites of the northern Oman ophiolite, where segment structure of the ridge has been established.

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A texture possibly peculiar to ultra-high pressure podiform chromitites has been found from the Luobusa ophiolite, Tibet as well as from Ray-Iz, the Polar Urals. They show a kind of brecciated texture; fresh olivine filling fractures of chromian spinel grains. Such a texture has not been recognized from ordinary low-pressure chromitites, possibly indicating the history of the ultra-high pressure chromitites, namely, their solid-state uprise from deeper parts of the mantle. It is possibly in accordance with the deep recycling origin for the ultra-high pressure chromitites (Arai, 2010).

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To investigate elastic properties of subducted crustal minerals at P-T conditions of crust and upper most mantle, we performed in situ measurement of the elastic wave velocities of anorthite at temperatures up to 1100 ^oC at less than 2.0 GPa (in stability field) and up to 500 ^oC at 2.0-7.0 GPa. In this study, we found a drop of elastic wave velocities at ~240^oC in <2.5GPa, and gradual decrease of the velocities in >3GPa and <500^oC. These velocity changes are considered to be caused by the elastic softening by the phase transitions from P(-1)  to high-T(-1)  and to high-P(-1), respectively.

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In the present study, the crystal structure, elasticity and vibrational properties of lizardite under pressure are determined using first principles techniques. At 10 GPa, very sudden elastic softening of elastic constants such as C₁₃ and C₃₃ was observed, associated with a slight change in the compressibility of c axis. The calculated OH stretching frequencies remain almost constant up to 10 GPa, and then rapidly increase above 10 GPa. Compared with the experimental Raman spectra under pressure, there is a possibility that these anomalous elastic behaviors of lizardite may also be observed experimentally at about 5-8 GPa.

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Electron-microprobe analyses were carried out on monazite from magnetite-series and ilmenite-series granitic rocks in Japan. Chemical compositions (especially REE compositions) of monazite reflect the types (magnetite-series or ilmenite-series) and the degree of differentiation (granite or granitic pegmatite) of the granitic rocks in the subduction-related magmatic arcs.

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Gatsuurt deposit is one of gold deposits in the North Khentei metallogenic belt, the biggest gold productive province of Mongolia, and is located approximately 130 km north of Ulaanbaatar.This deposit consists of disseminated and vein type gold mineralization in early Devonian subvolcanic, early Paleozoic granitoid complex, and early Paleozoic meta-sedimentary rocks.
According to tectonic and geological setting, hydrothermal alteration, mineralogy and fluid inclusion study, Gatsuurt deposit is suggested as intrusion-related gold system.

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Smectites from veins and altered wall rocks of the Hishikari gold deposit were comparatively studied by means of the particle-size analysis and H- & O- stable isotope analysis to clarify the hydrothermal environment of smectite formation and the relationship with Au mineralization. Wall rock montmorillonite may be formed from hydrothermal water similar to present hot spring discharge originating from meteoric water. Vein montmorillonite may be a product of dissolution/reprecipitation in hydrothermal activity of low temperature, occurred at late stage or after vein formation. On the other hand vein saponite may be precipitate from high-temperature solution of different stage from montmorillonite formations.

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To discuss the formation process of mines within a plutonic complex of Late Cretaceous Sanyo belt in Southwest Japan, we performed the CHIME dating of monazites from granitic rocks from Omishima in the eastern Geiyo islands, and from surrounding areas. As a preliminary study, two granitic rocks from the Omishima Mine were described, and a single crystal of monazite from one of them was analyzed by an electron probe micro analyzer. As a result, the age of 83.4 +/- 6.6 Ma (N = 51, 2 sigma) was yielded as the timing suggesting the formation of the mine.

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CL spectral analysis of the zircon in young granite reveals the emission assigned to Tm³⁺ which was first found in natural zircon. The emission in yellow region, which is characteristic in metamict zircon, has not been observed in the samples employed here, suggesting a low dose of radioactive irradiation from activated U and Th elements. This emission signal could be used for the estimation of radiation dose as a geodosimeter.

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Tourmalines investigated for this study have been collected from various occurrences associated with Cretaceous granitoids in NE-Japan. EPMA analyses of tourmalines in NE-Japan fall mostly within the alkali group and corresponds to the schorl-dravite series. Tourmalines of pegmatite hosted in granitoids in NE-Japan show regular compositional tendency of Al contents. On the other hand, tourmaline in pegmatite hosted in hornfels shows relatively higher Al in composition. Furthermore, compositions of tourmaline containing fluid inclusions tend to show MgFe_-1 and/or [Mg(OH)](AlO)_-1 substitution. These suggest that Mg contents of tourmaline might be controlled by the chemical characteristics and activities of the fluids.

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Central San-in district, southwest Japan is located the Shimane Peninsula, the Shinji Lowland and the Chugoku Mountains from north to south. Cretaceous to Paleocene basement rocks are widely distributed in the Chugoku Mountains. These rocks in the Shimane Peninsula and the Shinji Lowland are overlain by Miocene to Quaternary rocks. Gabbroic to dioritic xenoliths are found to be included in Late Miocene to Pliocene volcanic rocks in the central part of the Shinji Lowland. In this paper, we report these data of petrography and mineralogy.

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We clarified the chemical composition of detrital chromian spinel around the ultramafic complexes of the Sangun zone, Southwest Japan. That is Cr#(Cr/(Cr+Al) atomic ratio) of chromian spinels are varies from almost all 0.4-0.7. This result is basically concordant with that of Matsumoto et al. (1997). We found the chemical difference of chromian spinels for every complex. For example, Cr# and Mg# (Mg/(Mg+Fe2+)atomic ratio) of chromian spinels from the Norther part of the Tari-Misaka complex show relatively high in both Cr# and Mg# than those from the middle and southern part of the Tari-Misaka complexes.

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We try to confirm whether Fe concentration on dislocation core, which occurs during dislocation creep at very low strain-rate condition, is a common phenomenon in deformed olivine of mantle derived peridotite. We obtained the following results. Fe concentrations are detected in the alpine type peridotites, but not in the xenoliths from basalt. Microstructural observations can explain the later result: Fe concentration on dislocation core is not occurred in olivine 1) in whole upper mantle, 2) only in the high stress (namely high strain rate) region, and 3) it diffused away due to static recovery in basaltic magma.

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Based on the characteristics of geochemistry of volcanic rocks, Mirdita ophiolite are divided into western Mirdita ophiolite and eastern Mirdita ophiolite. The western part contains MORB-type volcanics, on the other hand, eastern contains SSZ-type volcanics. Gomsiqe massif is composed of mainly lherzolite, gabbro, dunite, orthopyrozenite. Puke massif is composed of mainly highly deformed plagioclase lherzolite, gabbro, troctolite, harzburgite, dunite. It is possible to explain that lherzolite in gomsiqe has experienced 5-13% partial melting. On the other hand, peridotite in  puke massif has influenced by melt impregnation.

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In this study, microstructural observations of slickenside developed on Glarus thrust in the Swiss are performed, in order to understand its formation mechanism. Slickenside widely develops on Lochseiten calk (LK) in Glarus thrust. The summery of our microstructural observation is followings. 1) Periodical faulting occurred along LK. Plastic deformation of calcite grains proceeded in term between these faulting. 2) Fault slip occurred initially along the wide area, ca. 1 cm, from slip surfaces. Then it was concentrated toward to the slip surface, and was finally limited along the narrow area less than 100 nm, which corresponded to the slickenside.

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The element solubility in aqueous fluids control dissolution and precipitation reactions between slab-derived aqueous fluids and rocks. In this study, we reviewed existing solubility measuring method, and then developed the new experimental method. Experiments were conducted at a pressure of 1GPa and temperature of 700 degree C in piston-cylinder apparatus with cracked quartz, distilled water and LaPO₄ reagent powder. The run duration was 1-3days. After quench, the volume of fluid inclusion was estimated by images photographed by X-ray computer tomography. After that, the quartz was broken by HF acid and the solution was analyzed by ICP-MS.

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The Tatehira manganese ore deposit, located in Southeast Hokkaido is hosted in Paleozoic metasediments rock and is metamorphosed by quartz diorite. Origin and formation process of Tatehira manganese ore deposit are discussed based on the occurrence of ore and mineralogy of manganese ore. The REE pattern of ore suggests that the deposit is originated by manganese oxide/hydroxide precipitation products by the hydrothermal activity. Based on geothermometry of gersdorffite- cobaltite series, rhodonite was estimated to be crystallized at about 450 to 550°C.

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Various type of ore deposits exist in and around the Cretaceous granitoids in the Kitakami mountains. This paper aims to elucidate the relationship between granitoids and related mineralization by using texture of granite and mineral chemistry. The studied granitoids are the Hitokabe, Senmaya, Uchino, Kesengawa and Goyosan. Temperature and pressure estimates indicate that the subsolidus reaction in these granite continued to lower temperatures and lower pressures in higher fO₂ conditions except for the Goyosan granite. This is one of major reasons because the sulfide mineralizaiton occur in the former four granitoids whereas Au mineralization occur in the Goyosan granite.

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Ore samples from the Akenobe mine are re-examined for the purpose to elucidate the more detailed behaivior of In in the hole deposit. Roquesite exists in the Chiemon, Ginsei and Ryusei vein. Cassiterite and/or stannite often exist in the part where roquesite co-exists with sphalerite. Indium contents are thought to be high in accordance with increasing of formation temperature. The form of the Shirogane vein is as a result of the brittle deformation (Shoji, 1982), which means lower temperatures than others. This difference of temperature might be a main reason of difference in In occurrence.

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The Hakurei deposit is formed on Bayonnaise koll caldera, Izu-Bonin arc. Collected samples are categorized into three types; massive sulfide ore mainly sphalerite, altered volcanic rocks and anhydrite zone. Mineral texture is observed with microscope (doubly-polished thin section) and with SEM. Sulfur isotopic composition of sulfide minerals are comparatively homogeneous, it does not depend on depth. Anhydrite and barite δ³⁴S values show similar to the seawater sulfate value. Homogeneous temperature and salinity vary according to the minerals. These differences of data are caused by variation  vertical and/or horizontal mixing rate of between hydrothermal fluid and seawater.

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Garnet glaucophane schists exposed in the Bizan district, eastern Shikoku, southwest Japan are petrographically described. Mineral assemblage as inclusion of the core of piorphyroblastic garnet give 450-500 C and 9-11 kbar, and the inclusions of the rim of the garnet indicate conditions of 550-600 C and 17-19 kbar in the eclogite facies conditions. Large grain of epidote and chlorite including schistosity-forming menerals probably grew during the Sambagawa metamorhism. 

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Sector-zoned aegirine was found in a Sanbagawa quartz schist in the Iimori region of the western Kii Peninsula, central Japan. The sector-zoned aegirine crystal is surrounded by X_Jd-rich aegirine mantle. Moreover the composite crystal is enclosed by X_Jd-poor outermost aegirine rim. This textural relationship suggests that after rapid non-equilibrium crystallization the X_Jd-rich mantle as well as the X_Jd-poor outermost rim formed under the equilibrium condition with surrounding minerals.

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We found lawsonite(Lws)-eclogite(Ecl) facies mineral assemblages in garnet(Grt) in a glaucophane(Gln)-epidote(Ep)-Ecl from the Kotsu area. The main mineral assemblage of the host rock is Grt–Gln–Ep–omphacite(Omp)–phengite–paragonite(Pg)–quartz (Tsuchiya et al., 2010). The Lws-Ecl facies assemblages are Lws inclusions (ca. 20μm), Pg-Ep polyphase inclusions (10-150μm) and Omp inclusions (5-100μm). The stability fields of these assemblages and Grt-Cpx geothermometer (Krogh, 2000) on pairs of Omp inclusions and nearby Grt suggest that Gln-Ep-Ecl of the Kotsu area formed at 590^oC/20kbar after experiencing PT conditions of Lws-Ecl facies at ca. 530^oC/17kbar.

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We describe the lawsonite decomposition textures found in garnets of the UHP Tlc-Grt-Cld schists, Makbal complex, northern Kyrgyz Tien-Shan. Garnet porphyroblast contains polyphase inclusions (PI) mainly consisting of Czo + Qtz + Ky ± Pg ± Mrg, Czo + Pg ± Chl and Czo + Cld ± Pg ± Chl. We suggest that these PI are products after lawsonite decomposition during isothermal decompression at lower pressure (16-22 kbar and 510-590 ºC).

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Accretionary and metamorphic complex in South Sulawesi are recorded on the restricted area namely Bantimala and Barru Complex.  Three types of eclogites are recognized in Bantimala Complex. The difference between each type is secondary phase minerals that present during retrogression. P-T conditions of these eclogites were estimated using isochemical phase diagrams combined with garnet-clinopyroxene geothermometer yield 550-630 °C and 2.2-2.4 GPa. Garnet-biotite-muscovite schist from Barru area were estimated using same method combined with garnet-biotite geothermometer yield 580–640 °C and ~0.9 GPa.  The U-Pb zircon geochronological data of metamorphic rocks from these complexes will be presented in the meeting.

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Serpentinite mélanges exposed along the Motagua fault zone, Guatemala, contain a variety of tectonic blocks. Geochronological data suggest the presence of poly-phase metamorphism during Cretaceous subduction, but their interpretation remains controversial. In this study, we report unusually complex internal structure of garnet crystals from a garnet amphibolite block collected from north of the Motagua fault zone. Seven generations can be identified in the garnet crystals. The complex metamorphic history reconstructed from detailed microstructural observation and pseudosection modelling can be interpreted in terms of tectonically distinct two phases of subduction.

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Blueschists accompanied by greenschists and pelitic schists occur along the Xiguitu-Tayuan fault in the Toudaoqiao area, northeastern China. The amphiboles in the blueschists are zoned from barroisite through winchite and magnesioriebeckite/glaucophane to winchite. The peak metamorphic conditions are defined by the mineral assemblages of magnesioriebeckite/glaucophane, epidote, high-Si phengite (Si<7.1), chlorite, albite, hematite and quartz. The P-T conditions are estimated as P = 400-450°C and T = 12-13kbar. The occurrence of the blueschists along the Xiguitu-Tayuan fault strongly suggests the fault is the suture between the Ergun and the Xing`an blocks situated in the eastern portions of the CAOB.

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As a follow-up of our last year presentation (JpGU Obata et al 2012) we report a detailed study of the occurrence of isochemical kelyphite from a Czech garnet peridotite, Moldanubian Zone. The isochemical kelyphite (kelyphite II) was formed after the formation of first generation of kelyphiye (kelyphite I) by a reaction between garnet and olivine and seems to be stopped by the formation of the third kind of kelyphite (kelyphite III),which consists of Amp, Sp and Pl.  On the basis of mineralogical details, the formation sequence and physical conditions of these three kinds of kelyphite will be discussed.

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We evaluated the residual pressure which quartz in garnet preserves using the elastic volume change model.

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Multiple equilibrium stages were identified from Grt-rich gneiss in Lhenice shear zone (southern Bohemian Massif). The geothermobarometory gives following P-T conditions: 1.5-2.3 GPa at 700-900 ^oC for Grt-core (Stage 1), 730-830 ^oC and 1.0-1.3 GPa for Grt-rim (Stage 2), and 740-850 ^oC and 0.6-0.8 GPa for matrix (Stage 3). To evaluate age of multiple equilibrium stages, CHIME age dating was carried out. The monazites which included in the Grt-core give 337+/-4.3 Ma. The monazites which included in the Grt-rim give 335.4+/-7.2 Ma. The monazites in matrix give 334.9+/-3.9 Ma. These results suggest that the studied rock experienced very fast exhumation.

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High-Al-Mg metamorphic rocks from the Mongolian Altay Mountains have been analyzed in detail. We present the metamorphic evolution and protolith formation of the gneisses, which gave new constraints on the tectonic evolution using geological and petrographical observations, geochemical and geochronological data combined with metamorphic petrological techniques.

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We report multi-isotope geochemistry of the Himalayan HP and UHP eclogites. These eclogites were formed from the Permian Panjal Trap basalts. They were subdivided into Group-I and II. Group-I are HP and record P-T conditions at 704±92 ºC and 2.2±0.3 GPa. Group-II are UHP and record P-T conditions at 2.7-3.2 GPa and 757-786 ºC. The ¹⁴⁷Sm/¹⁴⁴Nd and ¹⁴³Nd/¹⁴⁴Nd and ¹⁷⁶Lu/¹⁷⁷Hf ratios and ¹⁷⁶Hf/¹⁷⁷Hf ratios in Group-I yield isochrones from 38 to 42 Ma and 45 to 50 Ma, respectively. Whereas Group-II yield 45 to 53 Ma and 42 to 48 Ma, respectively. The εNd vs. εHf plot indicates their protolith derived from ocean-island-basalts with a sediment component mixing.

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The alkali-feldspar (Akfs) and biotite in the pelitic gneiss preserves characteristic microstructural evidence of multi-stage H2O supplement during the retrograde metamorphism. The first one is ‘zoned feldspar’, in which mesoperthitic, anti-perthitic and lamella-free plagioclase zones coexist within single crystal. It is occasionally found next to biotite, and is always depleted in orthoclase component toward biotite. The second one is the serrate boundary between Akfs and biotite. These microstructures formed as the biotite grew by consuming potash in Akfs when H2O-bearing fluid passed through the grain boundaries. The former was formed at 825-900 oC. The former will be reported in detail. 

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 Faure (1983) proposed a ductile shear zone located at the boundary between the spotted and non-spotted schists zones in the Koutsu-Bizan area. Tectonic blocks of serpentinite, metagabbro and garnet amphibolite are described in this shear zone between the spotted and non-spotted schists zones.
 Thin layers of siliceous and pelitic schists, contain garnet and aegirine-augite.

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Central, Shikoku, Sambagawa metamorphic belt, distribute some tectonicblock with eclogite, and Tonaru mass belong to tectonicblock too. Kyanite of Tonaru mass occur as Kyanite-bearing amphibolite, in along the Kojoro river. Kyanite-bearing garnet amphibolite’s main constituent mineral are Hornblende, Garnet, Zoisite and Kyanite, accessory minerals are White micas, Clinozoisite, quartz. Garnet porphyroblast not including other minerals, because not coexist other minerals, but Garnet most outer rim coexist Amphiboles, Zosite, Kyanite, because occurrence of kyanite are same timing for other minerals.

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We discuss pre-metamorphic evolution of the Kurosegawa Tectonic Belt using U-Pb geochronology for inherited zircons metamorphic rocks associated with blueschists.

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Spinel was newly found from Nové Dvory garnet peridotite body in the Bohemian Massif, Czech Republic. In the spinel-bearing samples, oval or round spinel grains occur as inclusions within garnet and kelyphite. The spinel stable pressures were estimated using a reaction of pyrope + forsterite = spinel + 2 enstatite, and the calculated spinel stable pressures are lower than 3.0 GPa. Then, thermobarometers were utilized and gave the peak P-T conditions from ≈ 800°C, 3.0 GPa to 1000°C, 4.5 GPa. These observation and calculated results suggest that subduction of this peridotite body should have occurred prior to the peak-P metamorphism.

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In order to provide structural constraints to better understand how the East-African- Antarctic-Orogen was deformed during continental collision of East Gondwanaland and West Gondwanaland, some authors have performed a geological survey in the Balchenfjella of the eastern Sør Rondane Mountains, east Dronning Maud Land, East Antarctica. Results of new field mapping shows that the metamorphic rocks of the Balchenfjella can be structurally divided into two units named Gropeheia unit and Berrheia unit, which are separated by large scale ductile shear zone.

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We examined whether plagioclase veins in eclogite from Nové Dvory was previously partial melt or not by comparison of the trace element compositions of garnet and plagioclase and their shapes. The plagioclase veins are rich in Rb, Ba and Sr, while garnet is poor in those elements. In addition, clinopyroxene grains in the veins are euhedral. From the temperature estimated by the composition of garnet and clinopyroxene, we suggest that the melt formation stage was mostly the same as the peak-pressure stage under the eclogite-facies conditions.

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The Kamuikotan metamorphic rocks in the Horokanai area are divided into low-temperature(T) lawsonite blueschist area and high-T epidote blueschist area, and they have been thought to be formed under one series of a metamorphism (Shibakusa, 1989). We, however, found out textures indicating that some lawsonite in epidote blueschists were crystallized consuming epidote and sodic-amphibole. This fact and other mineralogical data suggest that each mineral zone was formed under independent P-T trajectory with steep gradient in the same subduction system. That could reflect the internal thermal structure of subducting oceanic crust as predicted by thermal modeling of Peacock & Wang (1999).

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Two contrasting garnet zonings, type1 with Mn-rich core and type2 with Mn-poor one, are found in a hand specimen of a metasediment from the Besshi district, the Sanbagawa belt. Both type show rounded cores and surrounding euhedral rim of discontinuous compositions, suggesting they suffered resorption and fluid infiltration during prograde metamorphism. The distributions of two types of garnet are separated by a thin layer of very Mn-rich garnet, which is concordant to the main schistosity, though the main constituent minerals are similar in composition within the two parts. The different zonings should be derived from the inhomogeneity of the protolith.

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In the present study, we report the type of garnet zoning in Sanbagawa metapelites, the inclusion, occurrence of paragonite, and the result of quartz-Raman barometer.

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We report the petrological and geochronological analyzes results of metamorphic rocks from the Nujiang area (SW China), the Inthanon belt (W Thailand) and the Mogok belt (Myanmar), where related to Shanthai/Sibumasu cratons collision. Low-P/T metamorphic rocks are distributed in the every area. The collision related 200–210 Ma metamorphic event is assumed by Mnz EPMA age from the Nujiang area and the Inthanon area. In contrast, metamorphic rocks from the Mogok belt only received Indian continent collision event (< 50 Ma).  

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The Hakoishi sub-unit, which suffered lawsonite-blueschist facies metamorphism, is exposed to the west of the Yayamadake limestone in the Kurosegawa belt, Kyushu. The precise radiometric age of the high-P metamorphism of Hakoishi sub-unit has not been determined yet. K-Ar age of 280-299Ma is determined from two phengite bearing metapelites. This age is thought to be the peak age of the high-P metamorphism according to the following reasons: (1) The composition of phengites are Si=3.57-3.68(O=11) meaning metamorphic origin, (2) phengites form main schistosity accompanying with other high-P metamorphic minerals, (3) this area has suffered the peak metamorphism of 350°C, 6-8kbar. 

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Recently, the physicality of the crust and mantle beneath the Japan arc has been revealed by seismic tomography and MT survey. The clarification of geofluid distribution in the subduction zone is a first-class problem in volcanology and seismology. To develop the "Geofluid Map", we summarized the geological and petrological data of Japan and developed a "preliminary cross-section" that is composed of the combination of average rock units. We calculated the average elastic wave velocity of each rock unit using the experimental data of elastic wave velocity and then proposed some "basic rock types" typical of the Japan arc.

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Forearc peridotites from the Oeyama ophiolite show the following facts: formation of high-temperature metasomatic minerals such as amphiboles, phlogopite, olivine and orthopyroxene; a systematic variation of amphibole compositions corresponding with texture and mineral assemblage; the presence of fine-grained olivine veins penetrating primary olivine; and the presence of Mg-Fe diffusion zones in olivine host crystals of the veins. Based on texture, chemical compositions of minerals and diffusion models of olivine, it is inferred that the peridotites were subjected to a sequence of metasomatic alteration and plastic deformation, and that their exhumation took place during of immediately after the alteration.

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In the Czech part of the Bohemian massif, numerous garnet-bearing peridotites are enclosed within high-pressure granulite in the Variscan orogenic belt, and there is a debate whether they were directly derived from the hot mantle wedge or they were transformed from the serpentinite or chlorite peridotite at shallow depth by subduction. Here we report newly discovered clinopyroxene megacrysts within garnet peridotites, and we showed the chemical composition of clinopyroxene are extremely low in Al and contain low-Al orthopyroxene, edenite, phlogopite, ferrite-chromite, olivine as well as apatite and rare huttonite. We will show the discovered low-Al clinopyroxene were formed at low-T condition before the UHP metamorphism.

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