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61.
Ayako Shinozaki Hiroyuki Kagi Hisako Hirai Hiroaki Ohfuji Taku Okada Satoshi Nakano Takehiko Yagi 《Physics and Chemistry of Minerals》2016,43(4):277-285
Stability and phase relations of coexisting enstatite and H2 fluid were investigated in the pressure and temperature regions of 3.1–13.9 GPa and 1500–2000 K using laser-heated diamond-anvil cells. XRD measurements showed decomposition of enstatite upon heating to form forsterite, periclase, and coesite/stishovite. In the recovered samples, SiO2 grains were found at the margin of the heating hot spot, suggesting that the SiO2 component dissolved in the H2 fluid during heating, then precipitated when its solubility decreased with decreasing temperature. Raman and infrared spectra of the coexisting fluid phase revealed that SiH4 and H2O molecules formed through the reaction between dissolved SiO2 and H2. In contrast, forsterite and periclase crystals were found within the hot spot, which were assumed to have replaced the initial orthoenstatite crystals without dissolution. Preferential dissolution of SiO2 components of enstatite in H2 fluid, as well as that observed in the forsterite H2 system and the quartz H2 system, implies that H2-rich fluid enhances Mg/Si fractionation between the fluid and solid phases of mantle minerals. 相似文献
62.
Atsushi Okamoto Taketo Kikuchi Noriyoshi Tsuchiya 《Contributions to Mineralogy and Petrology》2008,156(3):323-336
Pelitic schists of the Sanbagawa metamorphic belt contain several types of polymineralic veins that formed during the late
stages of exhumation. The vein mineral assemblages are quartz + albite + K-feldspar + chlorite ± calcite (Type I, II) and
quartz + albite + calcite (Type III). Type I and II veins contain quartz and albite with stretched-crystal and elongate-blocky
textures, respectively. The mineral species within Type I veins vary with compositional bands within the host rocks. Type
III veins are characterized by euhedral to subhedral quartz grains with concentric zoning and a homogeneous distribution along
the vein length. The vein textures vary depending on the crack aperture during multiple crack-seal events: <0.08 mm for Type
I, and 0.5–10 mm for Type III. Type II veins show intermediate features between Type I and III veins in terms of mineral distribution
(weak dependence on the host rock composition) and apparent crack aperture (less than 1–15 mm). These observations suggest
a transition in the dominant transport mechanism of vein components with increasing crack aperture, from diffusion from host
rocks to fluid advection along cracks. 相似文献
63.
Hideki Mukoyoshi Tetsuro Hirono Hidetoshi Hara Kotaro Sekine Noriyoshi Tsuchiya Arito Sakaguchi Wonn Soh 《Island Arc》2009,18(2):333-351
To understand the characteristics of deformation of an out-of-sequence thrust (OST) and the style of fluid flow along it, we investigated the Nobeoka Tectonic Line, which has been interpreted as a deep OST (7–9 km), in the Shimanto accretionary complex, Southwest Japan. The shear zone in the footwall differs significantly in the along-strike direction not only in thickness, which varied from 100 to 300 m, but also in lithology and mineral vein development. These variations might reflect primarily differences in lithology; that is, the sandstone-dominant shear zone with a large amount of mineral veins precipitated in microcracks is relatively thick, whereas the shale-dominant shear zone with a small amount of veins and with textures indicating highly pressurized pore fluid, is thinner. By comparison with characteristics of a shallow OST (3–5 km), we conclude that the shallow OST has experienced repeated brittle failure with rapid slip and focused fluid flow whereas the deep OST has experienced both brittle and ductile deformation, followed by fluid flow of various styles, depending on the lithology. 相似文献
64.
The possible influences of the Emperor Seamounts (ESs) upon the subarctic gyre of the North Pacific (NPSAG) were investigated
by a series of numerical experiments. In the experiments, a two-layer ocean with a meridional mountain ridge was forced by
seasonally varying wind stress. We focused on how the return ratio, the ratio of the boundary transport along the eastern
side of the ridge to the interior Sverdrup transport, changes with ridge height, width and density stratification. It was
found that the return ratio can be large if the ridge width is greater than the width of the viscous boundary layer. In this
case, the bottom pressure torque determines the return ratio; the return ratio is almost proportional to the ridge height
when the ridge height is small and some contours of planetary potential vorticity pass over the ridge. However, the return
ratio is independent of the ridge height and decreases with the stratification when the ridge height is large and all the
contours of planetary potential vorticity are closed. These dependences of the return ratio were understood in terms of barotropic
and baroclinic components of the bottom pressure torque. Implications for the bathymetric influences of ESs on the actual
NPSAG are also discussed. 相似文献
65.
Continuing a work initiated in an earlier publication (Yamada et al. in Phys Rev D 91:124016, 2015), we reexamine the linear stability of the triangular solution in the relativistic three-body problem for general masses by the standard linear algebraic analysis. In this paper, we start with the Einstein–Infeld–Hoffmann form of equations of motion for N-body systems in the uniformly rotating frame. As an extension of the previous work, we consider general perturbations to the equilibrium, i.e., we take account of perturbations orthogonal to the orbital plane, as well as perturbations lying on it. It is found that the orthogonal perturbations depend on each other by the first post-Newtonian (1PN) three-body interactions, though these are independent of the lying ones likewise the Newtonian case. We also show that the orthogonal perturbations do not affect the condition of stability. This is because these do not grow with time, but always precess with two frequency modes, namely, the same with the orbital frequency and the slightly different one due to the 1PN effect. The condition of stability, which is identical to that obtained by the previous work (Yamada et al. 2015) and is valid for the general perturbations, is obtained from the lying perturbations. 相似文献
66.
In this study, we report the elastic properties of three ultrahigh-pressure phases of SiO2: pyrite, cotunnite and Fe2P types between 300 and 1,500 GPa calculated by means of the density functional ab initio method. It is generally thought
that materials tend to be more compact and isotropic with increasing pressure. These three ultrahigh-pressure phases of silica
are mechanically stable in the investigated pressure range according to the Born criteria, while the cotunnite and Fe2P types are unstable at lower pressure. The elastic azimuthal anisotropy of these ultrahigh-pressure phases of silica shows
that all the structures counterintuitively have considerable anisotropies even at multimegabar pressures. Among the three
investigated structures, the cotunnite type of SiO2 is the most elastically anisotropic phase due to a soft compression along the b axis combined with a large distortion of the polyhedrons that make the structure. This might also be related to its thermodynamic
unfavorability compared to the Fe2P type under extreme pressure condition. The bond property analyses clearly show that the Si–O bond remains an ionic-covalent
mixed bond even at multimegabar pressures with an invariable ionicity with pressure. This argument can explain the monotonously
pressure dependence of the elastic anisotropy in the case of pyrite, while the changes in the velocity distribution patterns
out of the thermodynamic instability range largely contribute to those of the cotunnite and Fe2P types. 相似文献
67.
X-ray CT based numerical analysis of fracture flow for core samples under various confining pressures 总被引:1,自引:0,他引:1
Noriaki Watanabe Takuya Ishibashi Yutaka Ohsaki Yoshihiro Tsuchiya Tetsuya Tamagawa Nobuo Hirano Hiroshi Okabe Noriyoshi Tsuchiya 《Engineering Geology》2011,(4):338
The X-ray CT based numerical analysis of fracture flow for core samples, recently developed by the authors, was applied to two granite core samples having either a mated artificial or a mated natural fracture at confining pressures of 5 to 50 MPa. A third-generation medical X-ray CT scanner was used to image the samples within a core holder consisting of an aluminum liner and a carbon fiber overwrap. Fracture models (i.e., aperture distributions) were obtained by the CT images, the resolution of which was coarser than the apertures, and a single-phase flow simulation was performed using a local cubic law-based fracture flow model. Numerical results were evaluated by a fracture porosity measurement and a solution displacement experiment using NaCl and NaI aqueous solutions. These numerical results coincided only qualitatively with the experimental results, primarily due to image noise from the aluminum liner of the core holder. Nevertheless, the numerical results revealed flow paths within the fractures and their changes with confining pressure, whereas the experimental results did not provide such results. Different stress-dependencies in the flow paths were observed between the two samples despite the similar stress-dependency in fracture porosity and permeability. The changes in total area of the flow paths with confining pressure coincided qualitatively with changes in breakthrough points in the solution displacement experiment. Although the data is limited, the results of the present study suggest the importance of analyzing fluid flows within naturally fractured core samples under in situ conditions in order to better understand the fracture flow characteristics in a specific field. As demonstrated herein, X-ray CT-based numerical analysis is effective for addressing this concern. Using a multi-phase flow model, as well as a core holder constructed of an engineered plastic, should provide a useful, non-destructive, and non-contaminative X-ray CT-based fracture flow analysis for core samples under in situ conditions in future studies. 相似文献
68.
Atsushi Tsuchiya 《Solar physics》1969,7(2):268-275
The slowly varying component of the solar radio emission (S-component) has been investigated from data obtained in the United States and Japan at 35, 17, 9.4 and 4 GHz. A good correlation occurs between the 35 GHz flux of the S-component and the corresponding plage area. This is interpreted by the assumption that the 35 GHz radiation is due to pure free-free emission, and the electron density in the coronal condensation is estimated to be about 2 × 109/cm3, assuming the electron temperature to be 2 × 106 K and the scale height of the coronal condensation to be 3 × 104 km.The S-component radiation at 17 GHz has, in turn, two components, one is due to pure free-free emission and the other is due to thermal-gyro emission. It is concluded that in the active regions a magnetic field of more than 2000 gauss extends horizontally over about 104 km. 相似文献
69.
Interferometric synthetic aperture radar (InSAR) analysis is a radar technique for generating large-area maps of ground deformation using differences in the phase of microwaves returning to a satellite. In recent years, high-resolution SAR sensors have been developed that enable small-scale slope deformation to be detected, such as the partial block movement of a landslide. The L-band SAR (PALSAR-2) is mounted on Advanced Land Observing Satellite-2 (ALOS-2), which was launched on 24 Mar. 2014. Its main improvements compared with ALOS are enhanced resolution of as high as 3 m with a high-frequency recurrence period (14 days). Owing to its high resolution and the use of the L-band, PALSAR-2 can obtain reflective data passing through a tree canopy surface, unlike the other synthetic aperture radars. Therefore, the coherence of InSAR in mountainous forest areas is less likely to decrease, making it advantageous for the extraction of slope movement. In this study, to verify the accuracy of InSAR analysis using PALSAR-2 data, we compared the results of InSAR analysis and the measurement of the displacement in a landslide by global navigation satellite system (GNSS) observation. It was found that the average difference between the displacements obtained by InSAR analysis and the field measurements by GNSS was only 15.1 mm in the slant range direction, indicating the high accuracy of InSAR analysis. Many of the areas detected by InSAR analysis corresponded to the locations of surface changes due to landslide activity. Additionally, in the areas detected by InSAR analysis using multiple datasets, the ground changes due to landslide movement were confirmed by site investigation. 相似文献
70.