Magmatic epidote/zoisite in tonalites are described.

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Metamorphic grade of the Lesser Himalaya (LH) in the Dhankuta area, Nepal increases from Bt grade
to Ky grade towards MCT. Elongated garnet formed during the schistosity-forming deformation occur widely in metapelites. If this deformation is related to the MCT movement, its effect was significant even at the Grt isograd during prograde to peak metamorphism of LH. Enrichment of Tur in LH implies infiltration of B-bearing fluid. Since Tur is included in Grt, B-bearing fluid activity took place during prograde to peak metamorphism of LH. Absence of Tur-enriched rocks in the Great Himalayas (GH) suggests that (i) MCT acted as a barrier that hindered the infiltration of B-bearing fluid into GH. (ii) B-bearing fluid could infiltrate into GH, but the GH presently in contact with LH is different from what was in contact with during the prograde metamorphism. Movement of MCT even after the peak metamorphism of LH is inferred in the (ii) case.

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We report for the first time Neoarchean incipient charnockite from the Limpopo Complex, southern Africa. Dark brownish charnockite (Opx+Pl+Kfs+Qtz+Mag) occurs as a layer in Opx-free quartzo-feldspathic gneiss (Pl+Kfs+Qtz+Mag), although the charnockite cuts the foliation of matrix quartzo-feldspathic gneiss. Mineral equilibrium modelling of the rocks suggest that the mineral assemblages in the two lithologies formed at 940-1000C and ~6.5 kbar, suggesting that charnockite formation is closed to the peak metamorphism of this region. This is contrasting to the Pan-African incipient charnockite that formed during retrograde metamorphism related to infiltration of CO2.

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In the Nishisonogi metamorphic rocks (Japan), ultramafic mélange contains pelitic-schist blocks, which have been albitized along the contact with the mélange matrix. Volume changes of solid and fluid phases during the albitization were estimated using the isocon method. The result suggests that pore-fluid pressure increases at the albitization front and drops as the albitization proceeds. Deformation mechanism probably shifted from hydraulic fracturing to reaction-enhanced ductility during the albitization.

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We have re-assessed the geologic relationship and metamorphism of the gneiss-schist belts in Archaean Dharwa Craton, southern India.

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We have investigated the petrological feature and estimated pressure-temperature conditions of mafic schists of the Hatto layer (Suo belt) and Shitani layer (Renge belt) from the Wakasa area.

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The Seba eclogitic basic schists occurring in the northeastern part of the body consist of epidote, amphibole, omphacite, garnet and phengite. Garnets contains inclusions of epidote, omphacite and amphibole. Garnet rim and coexisting minerals (ompacite, epidote, phengite) are used to estimate the peak metamorphic conditions of T=590-610C, and 19-20 kbar (THERMOCALC). The estimated temparatures are significantly lower than those of the second eclogitic metamorphism of the Onodani eclogite, probably suggesting that the Seba eclogitic basic schists in the northern part of the body are lower in temperature than those distributed in central and southern parts.

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We examined the petrogenesis of the grandite garnet-bearing calc-silicate rocks from the Betsimisaraka domain, east-central Madagascar. On the basis of textual and compositional relationships, we suggest that the esseneite components in clinopyroxenes are essential for the formation of andradite-rich grandite garnets. The mineral compositions and reactions witness that the fluid composition (CO₂-H₂O-O₂) changes the modal and phase compositions including grandite garnet, clinopyroxene, titanite, plagioclase and K-feldspar. The small-scale variation of garnets forming-reaction and breakdown products suggests that P-T-fluid and fO₂ are the controlling factors during the high-grade metamorphism.

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We performed reexamination of isotopes of U, Th and Pb
in zircon grains by using LA-ICP-MS, in order to verify the accuracy of subgrain
U-(Th-)Pb dating. Zircon grains that show known homogeneous Neoproterozoic ages
were used in our study. We analyzed the core and rim domains with homogeneous
chemical composition and the overlapped domains with heterogeneous chemical
composition. As a result, no influence by the difference of chemical composition
was found (N = 31). But, when we drew isochrons on the basis of the composition
of 238U-206Pb and 232Th-208Pb pairs, two results for the overlapped spots deviated
from the isochrons.

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In this presentation, we present the results of our investigation into the pressure–temperature–time evolution and protolith formation of layered high-Mg, high-Al gneisses from the Altai Mountains, Mongolia.

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The metamorphic rocks from South Sulawesi, Central Java, and South Kalimatan were observed, determined its protolith, and estimated of P-T metamorphic conditions. Some of the metamorphic rocks were also estimated in geochronology using U-Pb zircon LA-ICP-MS. The results of each analyzes were compiled to elucidate the metamorphic evolutions and the possibility of tectonic evolutions in these areas.

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We estimated P-T conditions of the metamorphic rocks from the central and the western Sør Rondane Mountains, Antarctica, by using conventional geothermobarometers. Estimated temperatures are about >800 degC around Brattnipane and southern Austkampane, and decreased rapidly toward the south. The thermocline is roughly coincident with the Sør Rondane Suture. Estimated pressures are about 8-9kbar around Austkampane and northern Lunckeryggen, and decreased toward south and northeast. The zone where the pressures rapidly change runs roughly along the Main Shear Zone.

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