Assessment of the level of activity of advective transport through fractures and faults in marine deposits by comparison between stable isotope compositions of fracture and pore waters     

Mochizuki  Akihito  Ishii  Eiichi 《Hydrogeology Journal》2022,30(3):813-827

Hydrogeology Journal - Assessment of the level of activity of advective transport through faults and fractures is essential for guiding the geological disposal of radioactive waste. In this study,...  相似文献   

Active spreading and hydrothermalism in North Fiji Basin (SW Pacific). Results of Japanese French Cruise Kaiyo 87     

Jean-Marie Auzende  Eiichi Honza  Xavier Boespflug  Satendra Deo  Jean-Philippe Eissen  Jun Hashimoto  Philippe Huchon  Junichiro Ishibashi  Yo Iwabuchi  Philip Jarvis  Masato Joshima  Kiyoyuki Kisimoto  Yasuto Kuwahara  Yves Lafoy  Tsuyoshi Matsumoto  Jean-Pierre Maze  Kiyohiko Mitsuzawa  Hiroyasu Monma  Takeshi Naganuma  Yukihiro Nojiri  Suguru Ohta  Kiyoshi Otsuka  Yoshihisa Okuda  Hélène Ondreas  Akira Otsuki  Etienne Ruellan  Myriam Sibuet  Manabu Tanahashi  Takeo Tanaka  Tetsuro Urabe 《Marine Geophysical Researches》1990,12(4):269-283

The aim of the Japanese-French Kaiyo 87 cruise was the study of the spreading axis in the North Fiji Basin (SW Pacific). A Seabeam and geophysical survey allowed us to define the detailed structure of the active NS spreading axis between 16° and 22° S and its relationships with the left lateral motion of the North Fiji Fracture Zone. Between 21° S and 18°10′ S, the spreading axis trends NS. From 18°10 S to 16°40 S the orientation of the spreading axis changes from NS to 015°. North of 16°40′ S the spreading axis trends 160°. These two 015° and 160° branches converge with the left lateral North Fiji fracture zone around 16°40′ S to define an RRFZ triple junction. Water sampling, dredging and photo TV deep towing give new information concerning the hydrothermal activity along the spreading axis. The discovery of hydrothermal deposits associated with living communities confirms this activity.  相似文献   

Partitioning of Ni²⁺, Co²⁺, Fe²⁺, Mn²⁺ and Mg²⁺ between olivine and silicate melts: compositional dependence of partition coefficient   总被引：1，自引：0，他引：1  

Eiichi Takahashi 《Geochimica et cosmochimica acta》1978,42(12):1829-1844

Partitioning of Ni²⁺, Co²⁺, Fe²⁺, Mn²⁺ and Mg²⁺ between olivine and silicate melts has been determined near the join (Mg_0.5·-Fe_0.5)₂SiO₄-K₂O 4SiO₂ and for seven different basaltic compositions. The experiments were made at 1 atm total pressure, 1500-1100°C, and under moderate to reducing oxygen fugacities. The concentration factor, defined as K^MO = (MO)^ol/(MO)^liq (molar ratio), increases markedly for all the cations studied as the olivine component of the liquid decreases. Much of the increase in K^MO is considered as due to the compositional effect of the coexisting liquid: the temperature effect on K^MO is probably opposite to the compositional effect (K^MO decreases as temperature decreases).The partition coefficient K^MO-MgO = (MO/MgO)^ol/(MO/MgO)^liq for the reaction, M_ol²⁺ + Mg_liq²⁺ = M_liq²⁺ + Mg_ol²⁺. is relatively constant over a wide range of SiO₂ content of the liquid, except in the case of Ni²⁺. The partition coefficients have similar ranges both in synthetic and natural rock systems: K^NiO-MgO = 1.8–3.0, K^CoO-MgO = 0.6–0.8, K^FeO-MgO = 0.27–0.38, and K^MnO-MgO = 0.23–0.32. There is a systematic variation in the partition coefficient K^MO-MgO with the composition of liquid; K^MO-MgO increases with increasing SiO₂ content of melt. The partition coefficients for Co²⁺, Fe²⁺ and Mn²⁺ are useful to test the equilibration of olivine with magma of a wide compositional range.  相似文献   

Current activities in aerobiology in Japan     

Eiichi Inoue 《Boundary-Layer Meteorology》1974,7(3):257-266

A brief review of the research activities of Japanese scientists in aerobiology, which is one of the interdisciplinary sciences closely related to atmospheric turbulence and diffusion as well as to biology, is presented in order to make contacts with interested scientists in other countries.  相似文献   

Climate change during the last 150 million years: reconstruction from a carbon cycle model   总被引：5，自引：0，他引：5  

Eiichi Tajika 《Earth and Planetary Science Letters》1998,160(3-4):695-707

Variations of the atmospheric CO₂ level and the global mean surface temperature during the last 150 Ma are reconstructed by using a carbon cycle model with high-resolution input data. In this model, the organic carbon budget and the CO₂ degassing from the mantle, both of which would characterize the carbon cycle during the Cretaceous, are considered, and the silicate weathering process is formulated consistently with an abrupt increase in the marine strontium isotope record for the last 40 Ma. The second-order variations of the atmospheric CO₂ level and the global mean surface temperature in addition to the first-order cooling trend are obtained by using high-resolution data of carbon isotopic composition of marine limestone, seafloor spreading rate, and production rate of oceanic plateau basalt. The results obtained from this model are in good agreement with the previous estimates of palaeo-CO₂ level and palaeoclimate inferred from geological, biogeochemical, and palaeontological models and records. The system analyses of the carbon cycle model to understand the cause of the climate change show that the dominant controlling factors for the first-order cooling trend of climate change during the last 150 Ma are tectonic forcing such as decrease in volcanic activity and the formation and uplift of the Himalayas and the Tibetan Plateau, and, to a lesser extent, biological forcing such as the increase in the soil biological activity. The mid-Cretaceous was very warm because of the high CO₂ level (4–5 PAL) maintained by the enhanced CO₂ degassing rate due to the increased mantle plume activities and seafloor spreading rates at that time, although the enhanced organic carbon burial would have a tendency to decrease the CO₂ level effectively at that period. The variation of organic carbon burial rate may have been responsible for the second-order climate change during the last 150 Ma.  相似文献   

Control of Phosphate Concentration through Adsorption and Desorption Processes in Groundwater and Seawater Mixing at Sandy Beaches in Tokyo Bay, Japan     

Masahiro Suzumura  Shingo Ueda  Eiichi Sumi 《Journal of Oceanography》2000,56(6):667-673

Field observation was conducted to monitor phosphate concentrations in groundwater and seawater mixing at two sandy beaches in Futtsu and Miura in Tokyo Bay, Japan. Dissolved phosphate concentrations were measured along transects from fresh groundwater aquifer to seawater adjacent the beaches. The concentrations were often high (up to 46 µM) in fresh groundwater samples (Cl^– < 0.2). Coastal seawater, on the other hand, exhibited low phosphate concentrations (1.5 µM or less). Along the transects, phosphate generally displayed non-conservative behavior during mixing of fresh and saline waters in the aquifer; concentrations as high as 100 µM were found around the upper limit of seawater intrusion (Cl^– = 2). Laboratory experiments were executed to identify the processes that control the phosphate behavior in the mixing processes. The results revealed that adsorption-desorption processes by the aquifer sand particles could significantly control the phosphate concentrations in the groundwater. Furthermore, the adsorption and/or desorption was found to be a function of salinity; the equilibrium concentration of dissolved phosphate in slurry of sand and water was the highest in freshwater and decreased considerably in saline water. The extreme concentration of phosphate may be caused by release from sand particles coinciding with the rapid change in salinity with tide.  相似文献   

Thermal equation of state of majorite with MORB composition     

Yu Nishihara  Ichiro Aoki  Eiichi Takahashi  Ken-ichi Funakoshi 《Physics of the Earth and Planetary Interiors》2005,148(1):73-84

In situ synchrotron X-ray diffraction experiments were conducted using the SPEED-1500 multi-anvil press at SPring-8 on majoritic garnet synthesized from natural mid-ocean ridge basalt (MORB), whose chemical composition is close to the average of oceanic crust, at 19 GPa and 2200 K. Pressure-volume-temperature data were collected using a newly developed high-pressure cell assembly to 21 GPa and 1273 K. Data were fit to the high-temperature Birch-Murnaghan equation of state, with fixed values for the ambient cell volume (V₀ = 1574.14(4) Å³) and the pressure derivative of the isothermal bulk modulus (K^′T = 4). This yielded an isothermal bulk modulus of K_T0 = 173(1) GPa, a temperature derivative of the bulk modulus (∂K_T/∂T)_P = −0.022(5) GPa K⁻¹, and a volumetric coefficient of thermal expansivity α = a + bT with values of a = 2.0(3) × 10⁻⁵ K⁻¹ and b = 1.0(5) × 10⁻⁸ K⁻². The derived thermoelastic parameters are very similar to those of pyrope. The density of subducted oceanic crust compared to pyrolitic mantle at the conditions in Earth's transition zone (410-660 km depth) was calculated using these results and previously reported thermoelastic parameters for MORB and pyrolite mineral assembledges. These calculations show that oceanic crust is denser than pyrolitic mantle throughout the mantle transition zone along a normal geotherm, and the density difference is insensitive to temperature at the pressures in lower part of the transition zone.  相似文献   

The Behavior of Ni(II), Cr(III), and Zn(II) in Biological Wastewater Treatment Process     

Soon‐An Ong  Eiichi Toorisaka  Makoto Hirata  Tadashi Hano 《洁净——土壤、空气、水》2005,33(2):95-103

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Melting kinetics of a plagioclase feldspar     

Akira Tsuchiyama  Eiichi Takahashi 《Contributions to Mineralogy and Petrology》1983,84(4):345-354

Partial melting experiments on plagioclase feldspar have been carried out to investigate textures and kinetics of the melting. A labradorite single crystal was heated at one atmosphere pressure and temperatures within its melting interval as a function of time. So called honeycomb, fingerprint, or sieve textures were produced except for the runs just below the liquidus. The melting was initiated by heterogeneous nucleation of melt at the surface and/or interior (cracks and possively dislocations) of the crystal. The pattern of the melt is dendritic with a few μm arm spacing. After the melt develops throughout the crystal, the volumes of melt and residual crystal become larger and smaller, respectively, without changing the arm spacings. The melt is homogeneous and has the approximate temperature dependent liquidus composition irrespective of the time. There are compositional gradients in the residual crystal after short periods of melting. The An content of the crystals increases with increasing time until it finally reaches equilibrium with the melt after several thousands minutes of heating. It is concluded that the enlargement of the melt, the main process of the melting, is controlled by diffusion in the crystal. The fact that partial melts have the composition of the equilibrium liquidus even from the first several minutes strongly suggests that the local equilibrium at the crystal-liquid interface is satisfied during the melting. Some of the honeycomb, fingerprint, and sieve textures found in xenoliths and phenocrysts of sodic plagioclase in volcanic rocks would be caused by heating events (such as magma mixing) during which temperatures of magmas were temporarily higher than the solidus of some of the minerals.  相似文献   

Incipient subduction and deduction along the eastern margin of the Japan Sea     

Kensaku Tamaki  Eiichi Honza 《Tectonophysics》1985,119(1-4)

The eastern margin of the Japan Sea has been under convergent tectonics since sometime after the Pliocene. The suture line is on the ocean-continent boundary between the Japan-Yamato Basins and the Tohoku (Northeast Japan) Arc. Incipient subduction, and obduction, of the oceanic and sub-oceanic crust are observed along the suture line with the occurrence of numerous N-S trending, fault-bounded ridges and troughs. Focal mechanism solutions of several compressional type earthquakes with magnitudes of M = 6.9 to 7.7 which have occurred along the zone are consistent with the observation of geological thrust faults. The convergent stresses in the Japan Sea may be due to India-Eurasia collision and its associated intra-plate or inter-microplate movements in East Asia. The eastward movement of the Amurian Plate causes Baikal extension along its western margin and the Japan Sea convergence along its eastern margin.  相似文献