Several conflicting pressure-temperature (P-T) conditions of granulite in the Bohemian Massif have been proposed, and we estimated a P-T path of felsic granulite from the Zrcadlová Hut’ of the Blanský les body in the Bohemian Massif. The felsic granulite is mainly composed of garnet, biotite, quartz, plagioclase, and potassium feldspar, with or without pyroxenes. Garnet in two granulite samples occurs as porphyroblasts and preserves prograde zoning. Some of the porphyroblasts contain kyanite as inclusions. These felsic granulites also contain coronitic garnet surrounding spinel + plagioclase symplectites. These symplectites can be considered as pseudomorphs after kyanite. The pyroxene-bearing felsic granulite sample also contains garnet with prograde zoning, although the garnet grains are relatively small (<2 mm in diameter). The peak P-T conditions of the felsic granulite containing kyanite inclusions in prograde zoned garnet were estimated to be >1100 °C, 2.3 GPa based on the combination of garnet-biotite geothermometer and garnet-aluminosilicate-quartz-plagioclase barometer. The pyroxene-bearing felsic granulite contains clinopyroxene + plagioclase symplectite that has formed during a low-pressure stage, and its P-T conditions were estimated to be 750 °C, 0.5-0.8 GPa, by orthopyroxene-clinopyroxene geothermometer and jadeite-quartz-albite barometer. It is likely indicating that the pressure was rapidly reduced from the maximum-pressure stage, and then the relatively rapid cooling occurred. Such rapid decompression and cooling are needed to retain the prograde zoning in garnet. Index minerals of ultrahigh pressure such as coesite are not found. Although ultrahigh pressure conditions were not reached, the estimated pressure is relatively high (>2.0 GPa) compared with previous studies.

Information collected from geological newsmagazines in 2023 is reviewed. First topic is mineral resources such as mineral commodity summary in USA, identified mineral resources in Australia, and metallogenic significance of rare elements in Zambia. Geothermal energy in the UK using borehole heat exchangers is also referred. Second topic is regional geology, that is, the Wyoming Archean craton, the Costanaza mine for sustainability education, and the Jeju Island Geopark activities. Third topic is overview of granites and geological mapping program for next generation.

In Kajishima, granitoid dykes intrude into Cretaceous gabbroic rocks. The granitoids are divided into deformed and massive granitoids based on field occurrence. Massive granitoid shows equigranular texture and consists mainly of quartz, plagioclase, alkali feldspar, and biotite. Poikilitic alkali feldspar including euhedral to subhedral quartz, plagioclase and biotite is locally observed in the massive granitoid. Petrographic data together with phase relationship in granodiorite system suggest that the poikilitic texture indicates partial melting of quartz- and plagioclase-bearing rocks such as tonalite and granodiorite. The presence of this texture in the Kajishima granitoids suggests re-melting of tonalite/granodiorite at deep arc crust.

Although achondrites represent only 5% of the global collection, they offer insights into the early igneous and metamorphic processes that occurred on differentiated planetesimals and protoplanets in the early Solar System. I have studied achondrites, particularly focusing on the petrogenesis of HED meteorites (howardites, eucrites, and diogenites). HED meteorites are the largest group of differentiated achondrites that probably originated from the asteroid 4 Vesta. Based on the thermal history and geochemical characteristics of eucrites and diogenites, the crust of the HED parent body developed through lava eruptions and shallow intrusions of eucrites over a short period. Later, diogenite plutons intruded into the eucritic crust. These processes caused global crustal metamorphism and partial melting of the early crust. The presence of a few meteorites petrologically similar to eucrites but with different oxygen isotopic compositions suggests the existence of multiple protoplanets undergoing similar geologic processes in the early Solar System. The discovery of the oldest andesitic achondrite unveils new perspectives on the volcanism of differentiated meteorite parent bodies. The partial melting of chondritic meteorites likely produced Si- and Na-rich (i.e., andesitic) melts, yet such meteorites are extremely rare in global collections. It is inferred that the parent bodies of these achondrites have disrupted and did not survive. As the curator, I have been managing the Japanese Antarctic meteorite collection, making these valuable samples available to the scientific community. These meteorites provide crucial insights into the processes that took place in the early Solar System.

Water-rock interaction involves the mass transport driven by fluid flow and the chemical reaction. This paper presents investigations of fluid flow and reaction under water-saturated and unsaturated conditions from the pore scale to the field scale. The results of flow-through dissolution experiments using a saturated and unsaturated sandstone show that the pore surfaces are covered by the water film with a thickness of 7-18 nm, which allows the dissolution and diffusion even if the pores are filled with air. With respect to mass transport at the core scale, which pore structure (porosity and pore size) determines the ease of fluid flow (permeability) is a long-standing problem. The maximum pore-throat radius was determined by measuring the pressure at which gas initially penetrates a water-saturated medium. The maximum pore-throat radius is highly correlated with the permeability of various natural and artificial porous media over a wide range of permeability values. To study fluid flow on a larger scale, I focused on quartz-calcite veins in metapelite, which is considered as a fossil fluid conduit in the plate boundary at 10-15 km depth. Noble gas isotope analyses of fluid inclusions trapped in the veins show that long-distance fluid migration from the slab mantle or mantle wedge toward the shallower plate boundary.

I have researched on electrical conductivity of materials forming crust, mantle and core for understanding the dynamics and evolution in the Earth and planetary interiors. First, I would like to introduce the progress of my research until I started measuring electrical conductivity, even though I was originally a field geologist. Next, after giving an overview of the electrical conductivity of solid Earth and planetary materials, I will summarize the typical topics where my research based on electrical conductivity measurements under high pressure has brought new knowledge to Earth and planetary science: core formation in planetesimals triggered by permeable flow, origin of oceanic asthenosphere, estimation of water content in mantle transition zone, origin of conductivity anomaly in the crust and estimation of heat flux of the metallic core. Finally, I will discuss future challenges regarding the evolution of the Earth and planetary interiors based on thermoelectric measurements.

Akimotoite (IMA1997-044), (Mg,Fe)SiO₃, a new silicate mineral of the ilmenite group, has been discovered in the shocked Tenham chondritic meteorite. It occurs as aggregates adjacent to clinoenstatite in host-rock fragments trapped into shock-induced melt veins. Chemical analysis gives the simplified formula to be (Mg_0.79Fe_0.21)SiO₃, the same as for clinoenstatite. Selected-area electron diffraction (SAED) patterns correspond to the synthetic (Mg,Fe)SiO₃ ilmenite phase with the space group R3. The lattice parameters estimated from the SAED patterns are a = 0.478(5) nm, c = 1.36(1) nm in the hexagonal setting. The calculated density is 4.0(1) g/cm³. In a shock-induced melt vein, akimotoite and clinoenstatite are intergrown with a topotaxial relationship in which close-packed oxygen layers of both phases are preserved. This occurrence suggests that the enstatite-akimotoite transition was caused by a shear transformation mechanism without long-range atomic diffusion.