Iran Plateau has been considered as a part of the Alpine-Himalayan orogenic belts and is situated between two major sutures, Paleotethys suture in the north and Neotethys suture in the south. Most of the magmatic activities in Iran have been controlled by these two-ocean birth to death. The rupture-drift of the Iran microcontinent from the Arabian plate in the northern Gondwana and the rejoining in the Cenozoic can be considered as a typical Wilson cycle.

182Hf decays to 182W with a geologically short half-life of 8.9 million years. Fractionation between Hf and W occurring during the life of 182Hf leads to variation in 182W isotopes Since Hf and W are lithophile and siderophile elements, Hf is likely to have remained in the silicate melt phase, and W is preferentially removed from the silicate and partitioned to the metallic melt phase during the formation of the Earth's core. This fractionation of Hf-W is believed to have occurred before the disappearance of the 182Hf, and the negative values of μ182W (deviations of the present-day upper mantle value in ppm) have been reported to in basalts of ocean islands such as Hawaii and Samoa (e.g., Mundl et al., 2017; Takamasa et al., 2020). In contrast, most rocks originated at depths and older than 2.5 Ga show relatively uniform μ182W values of +10 to +20 (e.g., Willbold et al., 2011, Touboul et al., 2014, Liu et al., 2016, Mundl et al., 2018, Tusch et al., 2019). However, some komatiites, such as Schapenburg and Komati (both with 3.5 Ga), yield negative or have values unresolvable from 0, respectively (Touboul et al., 2012; Puchtel et al., 2018). Furthermore, Mei et al. (2019) reported μ182W values of 182W close to 0 for 3.0 Ga Anshan komatiite. Therefore, it is still highly debated as to when and how the mantle has reached the present state. The compiled data including those we obtained suggests that between 3.5 and 3.0 Ga, the primitive mantle with positive μ182W values may have been already sufficiently mixed with extraterrestrial materials such as Late Veneer and/or Late Heavy Bombardment with negative μ182W values and that some domains of the mantle had the μ182W values of the present-day mantle. In other words, mantle convection may have been active as early as 3.5 Ga.

In previous studies, the diffusion coefficient of lattice diffusion in apatite may not have been determined due to the influences of fast diffusion pathway, which diffuse quickly through damages caused by polishing and defects in the crystal. Therefore, we reduced the damage on the apatite surface by using a vibration polishing method that reduces the effect of fast diffusion pathways. The hydrogen diffusion coefficients in apatite were obtained by secondary ion mass spectrometry after diffusion experiments using water vapor as a diffusion source. Those results suggest that the influence of the fast diffusion pathway could be reduced in this study. In this presentation, the newly obtained hydrogen diffusion coefficients will be used to discuss the diffusion mechanism.

To determine the water concentration in volcanic glass, secondary ion mass spectrometry is powerful. Using the ¹³³Cs⁺ beam, the data of the high-water content rhyolitic glasses deviate from the calibration line. However, the factor of shift is not well understood. In this study, we focus on the water species concentration using rhyolitic glass standards. For the calibration line by ¹H⁻/³⁰Si⁻ and OH content, the data do not deviate from the calibration line. But, the data of the standards H₂O_m dominant show the different trend from the calibration line. We evaluated the calibration curve assuming the ion yields of each water species are different and constant. These results reveal that the data deviate from the calibration line are caused by the different ion yields of each water species using ¹³³Cs⁺ beam.

Basaltic xenoliths found in the Membo lava of Kozushima have a composition that was influenced by the slab-derived fluid originating from a deeper slab than the slab beneath Niijima. However, the origin of basaltic xenoliths, as well as the relationship between basaltic xenoliths and rhyolitic magmas remains unclear. In order to investigate the interaction between these two magmas, we have measured the δ98/95Mo values of rhyolites from Kozushima and compared the results with those of the basaltic xenoliths (2021 the geochemically society of Japan, Tamura et al., ). Basaltic xenoliths, pyroclastic materials and three types of rhyolites possess δ98/95Mo values significantly different from one another. Based on the results of previous studies, plagioclase and hornblende fractionation[1,2]played key role in the variation of δ98/95Mo values. In contrast, partially blackened areas in the rhyolite containing captured rocks showed significantly lowδ98/95Mo values compared to those of the host rhyolite, suggesting that the isotopic ratios may have fluctuated due to assimilation with the basaltic magma.

Here we report noble gas isotope ratios and halogen compositions of chromian spinels collected from the beach sands of Gorgona Island, Colombia. Isotope ratios of helium (³He/⁴He) trapped in melt inclusions in chromian spinels are estimated to be higher than 20 Ra (Ra is atmospheric ³He/⁴He), suggesting that the Galapagos mantle plume, with the highest reported ³He/⁴He ratio of 29 Ra, may have been involved in the origin of magmatism of Gorgona. Combining this with halogen compositions (Br/Cl and I/Cl ratios), which are similar to the mantle values, volatiles in the Gorgona komatiites and/or picrites would be derived from a less-degassed reservoir in the deep mantle, possibly in the core-mantle boundary.

Fumarolic activity at Ebinokogen Ioyama volcano of the Kirishima Volcanic Complex, which was active until the 1990s, temporarily ceased around 2007 but resumed in December 2015, with sediment discharge in April 2017 at the summit area and small eruptions in April 2018 at the south of summit area and a point about 500 m west of the summit area. Chemical analysis of thermal waters from the natural spring at the foot of Ioyama volcano and craters created 2018 eruptions since August 2016 revealed that the Cl/SO₄ ratio was found to be a good indicator of the activity at this volcano. Based on recent observations, volcanic activity may have increased around the summit area from December 2021 to June 2022 by considering the Cl/SO₄ ratio of hydrothermal water as an indicator.

In this study, formation process of thermal water in Hakodate area was discussed by analyzing the major dissolved chemical components, stable isotope ratios of hydrogen and oxygen, and trace element concentrations such as Li and B. As a result, most of the thermal waters were Na-Cl type and were diluted by fresh water. It was estimated that the thermal waters distributed in the coastal areas were formed by direct intrusion of present seawater or by diagenetic alteration of paleo seawater trapped in the strata. For thermal waters in the area with a geothermal gradient of 3.0-79.4°C, both of the intrusion of present seawater and the water-rock interaction at high temperatures would be related to the formation process.

Accelerator mass spectrometry is a method for detecting nuclides by accelerating to MeV energy region using an accelerator, and then separating from interfering isobar. The 6 MV tandem accelerator mass spectrometer enables highly sensitive detection of femto-isotope levels for nuclides such as Be-10, C-14, Al-26, Cl-36, Ca-41 and I-129. In this presentation, the latest AMS equipment for multi-nuclide measurement will be introduced. In addition, I report on the progress of the detection technology for cosmogenic nuclides and the application to geochemical research.

A large number of carbonate concretion samples were collected during the dredging around Nagoya Port. Most of the concretion samples had biological remains such as crab, sea urchin, and bivalve as their nuclei. In this study, radiocarbon (14C) ages of the shells of the biological remains inside the concretions, as well as of the concretions, were determined. Based on the metabolic carbon ratios in the bivalvia and sea urchin shells calculated from the δ13C values, the 14C age of the shells was estimated to be 7,350−7,050 cal BP. The 14C dates of the carbonate concretions were older than those of the shells due to the metabolic carbon with older ages into the concretion carbon. The corrected age after removal of the old carbon was estimated to be 7,530−7,270 cal BP. The almost the same corrected ages between the shells and the concretions indicate that the carbonate concretions in the Nagoya Port area were formed by rapid concretion after the death of the organisms, which is consistent with the morphological findings of rapid concretion in the sediment.

We report a new method for determination of ¹⁴³Nd/¹⁴⁴Nd ratio of terrestrial rocks using TIMS. The method allows analysis of samples without inter-REE separation and does not need isobaric correction for ¹⁴⁴Sm. ¹⁴⁵Nd and ¹⁴⁶Nd do not have any stable isobars and show a constant ratio in terrestrial rocks. We use the ratio of these two naturally occurring Nd isotopes to correct instrumental mass fractionation on ¹⁴³Nd/¹⁴⁶Nd ratio. We also use the known ratio of 0.7219 for ¹⁴⁶Nd/¹⁴⁴Nd, which is constant in terrestrial rocks, to convert the corrected ¹⁴³Nd/¹⁴⁶Nd to ¹⁴³Nd/¹⁴⁴Nd in analysed samples. This method allows isotopic analysis without time consuming and expensive REE separation procedures, while producing isotopic data with external precision and accuracy equivalent to standard methods.

The purpose of this study is to clarify the distribution area of past tsunami deposits and to refine the tsunami hazard area. Muddy tsunami deposits, which cover 90% of the tsunami inundation area, are an indicator of the past tsunami inundation area. However, comprehensive characterization of muddy tsunami sediments over a wide area using chemical compositions and a discrimination method have not been sufficiently proposed. In this study, we evaluate the properties of tsunami deposits in the Tohoku region based on multidimensional chemical composition data sets of fluvial and multi-regional tsunami deposits throughout Japan.The data sets used were river sediments, the 2011 Tohoku-oki tsunami sediments, and analytical data from tsunami sediments in Noda-mura and Hachinohe, Iwate Prefecture, and Higashimatsushima, Miyagi Prefecture. The elements used were 29 elements and the Na/Ti ratio, one of the indicators of tsunami deposits. The analysis was performed using scatter plots and UMAP, one of the dimensional compression methods, to confirm the certainty of the estimation results obtained from the scatter plots.As a result, it is possible that tsunami deposits and land source deposits can be discriminated, at least in the Tohoku region, by referring to the Fe, Zr, and As associations in parallel.

We have developed U-series disequilibrium dating methods for monazite as a Th-bearing mineral occurring in Quaternary volcanic rocks to elucidate magmatic processes. For accurate age determinations on Th-bearing minerals, potential interferences of polyatomic ions derived from sample matrices and background counts from ²³²Th should be removed. These interferences can be reduced by utilizing ICP-MS/MS. In this study, analytical accuracy and precision in measurements of ²³⁰Th and ²²⁶Ra are evaluated through the analysis of monazite using multiple-spot laser ablation ICP-MS/MS.

Constraining the temperature and pressure conditions under which rocks were formed is important information for understanding the environment in the Earth's interior. In this presentation, I will introduce Raman geothermobarometers (Raman carbonaceous material geothermometer and Quartz Raman geobarometer) based on Raman spectroscopy, which is independent of thermodynamic methods traditionally used in the field of petrology. The applications of these techniques and their future possibilities will be presented.

The fracture frequency distribution in granitic plutons depends on lithofacies, which reflect the chemical composition of the original magma. The initial Sr isotopic ratio of the whole rock is a valid indicator to identify the chemical composition of the magma. The apatite Sr isotopic composition probably records a primary Sr isotopic composition of the original magma because Rb is incompatible element for apatite. In this study, we developed a method for in situ Sr isotopic analysis of apatite by LA-ICP-MS. We adopted the technique of introducing desolvated solutions and solid samples into the ICP mass spectrometer. The correction for mass discrimination effects in the solid sample analysis by LA was attempted based on the isotope analysis of the solution. A gas line for mixing N₂ into Ar sample carrier gas was installed to suppress the oxide production rate and improve the ionization efficiency of Sr. Our results of the analysis on the apatite reference materials were consistent with previous studies. The developed method enables the evaluation of differences in the chemical composition of the original magma and then provides the constraint on the relationship between lithofacies and fracture frequency distribution by combination with chemical and geological information of granitic rocks.

The serpentinite seamounts discovered in the Mariana Trench in 1981 are one of the largest discoveries in the history of deep-sea floor research. One of the major characteristics of the serpentinite seamounts in the Mariana forearc region is the high pore water with a pH=12.6. In the Tanzawa area located in the northwestern part of Kanagawa Prefecture and its vicinity, groundwater with a water temperature higher than the average temperature and a pH=11.3 has been used as a hot spring for a long time. The high pH of the hot spring water can be explained by the reaction with serpentinite, but since serpentinite is not exposed in the Tanzawa area and its vicinity, the cause of the high pH of the hot spring water gushing out in this area has not been investigated. However, geophysical surveys such as seismic tomography have indicated the possibility of the existence of serpentinite in the Kanto area (Kamiya 2012). In this study, we attempted to elucidate the origin of high pH hot spring waters in the Tanzawa and surrounding areas by using elemental indicators of lithium, which behaves characteristically when reacting with serpentinite.

The distribution and behavior of deep-derived fluids, which play a significant role in crustal deformation such as seismic activity and volcanic eruptions, have attracted much attention in recent years. Recently, a number of earthquakes and uprifts have been observed in the Noto Peninsula of Japan, indicating the involvement of deep-derived fluids. The Matsushiro earthquake swarms that unusually continued from 1965 to 1971 produced such a massive gush of groundwater at the end of the period that it was also called a ”water eruption”. It is, however, difficult to research deep-derived fluids from spring water samples using traditional hydrogen and oxygen isotopic compositions owing to contamination from surfacewater. Lithium (Li) is relatively unsusceptible to contamination from surfacewater because the Li content of deep-derived fluid is significantly higher than that of surfacewater. The amount of Li leached from sediment to fluid increases dramatically with temperature, and the leached Li is retained in the fluid as it cools. Lithium isotope ratios may provide further insight into the origin of deep-derived fluids. To provide new constraint on the origin of fluids involved in Matsushiro earthquake swarms, we analyzed Li isotope ratios of spring water and basement rock samples recovered from drilling core in the Matsushiro area.The spring water samples analyzed in this study were collected in 2009 and 2010. In addition to the Li isotope ratio, the Sr isotope ratio and chemical composition of the spring water samples were analyzed. The results have shown that the observed Sr isotope ratio of nearly all spring water samples were similar to those of volcanic rocks erupted in the past from Mt. Minakami, where is the epicenter of the Matsushiro earthquake swarm. The temperature at which the fluid reacted with the rock can be estimated from differences in the Li isotopes of the rock that reacted with the fluid (Li isotope geothermometer). Based on the result of this study, the fluid-rock reaction temperature is around 600 °C. The results of the Li and Sr isotope analyses obtained in this study support the theory that the fluid that caused the Matsushiro earthquake swarm was water derived from the magma of the Mt. Minakami.

Among sediment cores collected from Ieyama hydrothermal field in the Okinawa Trough, mineralization layers with occurrence of barite and sphalerite were identified between 53-65 mbsf. We have conducted chronological study of barite in the sediment using ²²⁶Ra‐²¹⁰Pb dating and ESR dating. The results yielded 20-90 yrs. and 350-1050 yrs. as formation ages. On the other hand, radiocarbon dating of planktic foraminifera in the surface sediment at 0.15-0.20 mbsf collected from three places in the study field yielded 900‐1500 yrs.There results provide constraint on mineralization process that occurred beneath the seafloor.

Kikai Caldera volcano has repeatedly erupted in large scale eruptions such as the Kikai Akahoya eruption 7,300 years ago and the Kikai Tozurahara eruption 95,000 years ago, and detailed eruption history can be studied by combining seafloor and on-land surveys.In this study, core samples were collected by the SCORE program of CHIKYU based on the subsurface structure revealed by seismic reflection surveys of large eruptive ejecta on the seafloor, which are still largely unknown.The chemical composition of the volcanic glass was analyzed and compared with subaerial deposits, and it was found that the two large-scale eruptive ejecta are thickly deposited on the seafloor as well, and that the Kikai Akahoya product is divided into two units on the seafloor as well.In addition, the chemical compositional characteristics of volcanic glass in piston core samples from a wide area around the Kikai caldera suggest that the Kikai Akahoya product may have become less accessible to distant sites as the eruption progressed.

Kikai submarine caldera caused several catastrophic eruptions. In order to understand the eruption processes and magmatic evolution, we measured chemical composition of tephra collected via the SCORE program with D/V Chikyu. We used submarine tephra from the K-Ah eruption (7300 years ago), that from the K-Tz eruption (95000 years ago), and that intercalated between the two catastrophic eruptions, the age of which is approximately 40000 years ago or younger. The tephra from the K-Tz eruption is predominated by felsic pyroclasts, but the presence of a few mafic pyroclasts suggests the contribution of mafic melts during the K-Tz eruption. The tephra intercalated between the two catastrophic eruptions have chemical composition similar to those of K-Ah, implying that the storage of felsic magmas commenced at least 40000 years ago toward the next catastrophic eruption of K-Ah.

Antarctic Bottom Water (AABW) is a vast heat and CO₂ reservoir and is closely related to global climate change. However, the behavior of AABW formation during past interglacials remains unclear, making it challenging to predict its variation responding to future warming. Super-Interglacial periods (MIS5e and MIS11) were approximately 1°C to 2°C warmer than the Industrial Revolution, making them ideal analogs for a warming Earth. This study aims to reconstruct the variability of Cape Danley Bottom Water (CDBW) during the super-interglacial periods and to clarify what environmental factors may have caused the CDBW formation changes.