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1.
Katsuhiro Tsukimura Hiromoto Nakazawa Tadashi Endo Osamu Fukunaga 《Physics and Chemistry of Minerals》1992,19(4):203-212
This paper describes the distribution of Fe and Ni between the octahedral and tetrahedral sites in pentlandite (Fe,Ni)9S8. The dependence of the distribution on pressure and temperature and the activation energy of the cation exchange reaction were determined through annealing experiments. Synthetic crystals were annealed at 433–723 K and pressures up to 4 GPa, and natural crystals were annealed at 423, 448 and 473 K in evacuated silica capillary tubes for various durations. The cation distributions in the synthetic crystals were determined with an X-ray powder method employing the anomalous dispersion effect of CuK. and FeK radiations, while those of natural crystals were calculated from the cell dimensions. The values of U, S and V for the Fe/Ni exchange reaction are –6818 J mol–1, 20.52 J K–1 mol–1, and 6.99 × 10–6 m3 mol–1, respectively. The dependence of the Fe/Ni distribution on pressure (Pa) and temperature (Kelvin) was determined as lnK = 2.47+8.20 × 102
T
–1+8.41 x 10–7
T
–1
P, where K = (Fe/Ni)octahedral /(Fe/Ni)tetrahedral. The activation energy of the cation exchange reaction was 185 kJ mol–1. 相似文献
2.
GIS-based weights-of-evidence modelling of rainfall-induced landslides in small catchments for landslide susceptibility mapping 总被引：10，自引：0，他引：10
Ranjan Kumar Dahal Shuichi Hasegawa Atsuko Nonomura Minoru Yamanaka Takuro Masuda Katsuhiro Nishino 《Environmental Geology》2008,54(2):311-324
Landslide susceptibility mapping is a vital tool for disaster management and planning development activities in mountainous terrains of tropical and subtropical environments. In this paper, the weights-of-evidence modelling was applied, within a geographical information system (GIS), to derive landslide susceptibility map of two small catchments of Shikoku, Japan. The objective of this paper is to evaluate the importance of weights-of-evidence modelling in the generation of landslide susceptibility maps in relatively small catchments having an area less than 4 sq km. For the study area in Moriyuki and Monnyu catchments, northeast Shikoku Island in west Japan, a data set was generated at scale 1:5,000. Relevant thematic maps representing various factors (e.g. slope, aspect, relief, flow accumulation, soil depth, soil type, land use and distance to road) that are related to landslide activity were generated using field data and GIS techniques. Both catchments have homogeneous geology and only consist of Cretaceous granitic rock. Thus, bedrock geology was not considered in data layering during GIS analysis. Success rates were also estimated to evaluate the accuracy of landslide susceptibility maps and the weights-of-evidence modelling was found useful in landslide susceptibility mapping of small catchments. 相似文献
3.
The dentary diastema of iguanodontians has been considered to be related to its unique jaw mechanism for herbivorous adaptation.The dentary and diastema lengths of iguanodontians were measured and compared to elucidate the evolution of iguanodontian diastema.A gap in ratios between most non-hadrosaurid iguanodontians and hadrosaurids was observed,suggesting that all non- hadrosaurid iguanodontians,expect for Ouranosaurus nigeriensis and Protohadros byrdi,lack a diastema or have a short diastema,although ... 相似文献
4.
Prediction of strong ground motion at EURO-SEISTEST site using the empirical Green's function method
This paper presents some tests on the empirical Green's function method, performed in order to check its effectiveness to predict strong ground motion during future large earthquakes. These investigations basically consist of blind or pseudo-blind tests using part of the data set obtained at the Volvi (Greece) test-site within the framework of the EURO-SEISTEST project. In a first step, a moderate event (ML=4.1) is simulated by using a small event (ML=2.5), and taking into account the a priori knowledge of the relevant source parameters (magnitude and stress-drop) for both the base and target events. This check emphasizes the sensitivity of the prediction to the stress-drop values. In a second step, a pseudo-blind prediction is carried out in which the information on the target event is only the magnitude (ML=5.3) besides the geometrical parameters such as source location, strike and dip. The other important parameters (seismic moment, fault area, stress-drop) are determined on the basis of specific empirical scaling laws derived from several small and moderate events occurring in the area. The synthetic motions are computed for two nearby sites, which are located on the southern edge and in the center of the Mygdonian graben, respectively, and correspond to much different site conditions: weathered rock and thick sediments. They are found in good agreement with the observations, which were unveiled after the simulation. In particular, the amplitude and the phase of the late, local surface waves generated on the southern edge of the graben, are very well reproduced at valley center. Finally, the last step is an attempt to predict strong ground motion for a hypothetical large earthquake of magnitude ML=6.5. The results are shown to depend very significantly on the scaling laws. 相似文献
5.
Late cretaceous to early paleogene paleomagnetic results from Sikhote Alin, far eastern Russia: implications for deformation of East Asia 总被引：1，自引：0，他引：1
Yo-ichiro Otofuji Takaaki Matsuda Tetsumaru Itaya Takeshi Shibata Michiko Matsumoto Takahiro Yamamoto Chiyo Morimoto Ruslan G. Kulinich Petr S. Zimin Anatoly P. Matunin Vladimir G. Sakhno Katsuhiro Kimura 《Earth and Planetary Science Letters》1995,130(1-4):95-108
Welded tuffs in the Bogopol and Sijanov groups were sampled at 27 sites from 12 caldera formations in the Sikhote Alin mountain range around Kavalerovo (44.3°N, 135.0°E) for chronological and paleomagnetic studies. KAr age dates show that the welded tuffs erupted between 66 Ma and 46 Ma. All sites yield reliable paleomagnetic directions, with unblocking temperatures higher than 560°C. The high-temperature component at 12 sites and the medium-temperature component at 3 sites in the Bogopol Group show reversed polarity (D = 193.7°, I = −57.6°,95 = 8.1°). The high-temperature component at 11 sites in the Sijanov Group showed both reversed and normal polarities and its mean direction reveals no detectable deflection from north (D = −2.9°, I = 59.6°,95 = 11.2°). The combined paleomagnetic direction of the two groups yields a paleomagnetic pole of 250.5°E, 84.1°N (A95 = 8.8°), which falls near Cretaceous paleomagnetic poles from Outer Mongolia, Inner Mongolia, the North China Block and the South China Block. The Sikhote Alin area appears not to have been subjected to detectable motion with respect to East Asia since about 50 Ma. This implies that the Sikhote Alin area behaved as an integral part of East Asia during the opening of the Japan Sea at about 15 Ma. However, significant separation between the paleomagnetic poles of East Asia and Europe during the Jurassic-Paleogene implies a major relative movement between these two blocks since the Paleogene. 相似文献
6.
Subrata Ghose Katsuhiro Tsukimura Dorian M. Hatch 《Physics and Chemistry of Minerals》1989,16(5):483-496
Ilvaite, Ca(Fe2+, Fe3+) Fe2+Si2O7O(OH), a mixed-valence iron silicate shows an insulator-semimetal transition with a band gap of 0.13 eV due to thermally induced charge delocalization between Fe2+ and Fe3+ ions (A sites) in double octahedral chains. The charge delocalization induces a second order crystallographic phase transition on heating from monoclinic (P21/a) to orthorhombic (Pnam) symmetry at 346 K. The unit cell dimensions within the 295–420 K range and the crystal structures at 295, 320, 340, 360, 380 and 400 K have been determined by high temperature single crystal X-ray diffraction. The degree of charge delocalization determined from the sizes of the Fe(Ao) and Fe(Am) octahedra is the primary order parameter, Q which couples linearly with the spontaneous strain component, 13. The order parameter coupling and the associated free energy expression is given. The calculated normal modes of the space group symmetry change are consistent with the experimentally observed atomic displacements, which are parallel and antiparallel to c. Formation of antiphase lamellar twin domains parallel to (001) in the monoclinic phase is predicted to occur as a result of the phase transition. Above Tc (= 346 K), the slow asymptotic decrease of 13 attaining a zero value at 380 K indicates the presence of fluctuating precursor clusters with considerable short-range order above Tc. A peak in the specific heat (Cp) measurements coincides with the onset of longrange order at 380 K, whereas 57Fe Mössbauer measurements indicate the onset of charge localization at a considerbly higher temperature (470 K). The coupling of the d6 electron of the Fe2+ (A) ion with a longitudinal optic phonon with the polarization vector along c
* is the likely mechanism to drive the phase transition. The electronphonon coupling also provides a charge conduction mechanism through electron hopping, whereby the short-bonded Fe2+-Fe3+ pair containing the d6 electron (intermediate polaron) will break up and re-form, thereby propagating the electron one step along the c axis. 相似文献
7.
The cation distribution of Co, Ni, and Zn between the M1 and M2 sites of a synthetic olivine was determined with a single-crystal
diffraction method. The crystal data are (Co0.377Ni0.396Zn0.227)2SiO4, M
r
= 212.692, orthorhombic, Pbnm, a = 475.64(3), b = 1022.83(8), and c = 596.96(6) pm, V = 0.2904(1) nm3, Z = 4, D
x
= 4.864 g cm−3, and F(0 0 0) = 408.62. Lattice, positional, and thermal parameters were determined with MoKα radiation; R = 0.025 for 1487 symmetry-independent reflections with F > 4σ(F). The site occupancies of Co, Ni, and Zn were determined with synchrotron radiation employing the anomalous dispersion effect
of Co and Ni. The synchrotron radiation data include two sets of intensity data collected at 161.57 and 149.81 pm, which are
about 1 pm longer than Co and Ni absorption edges, respectively. The R value was 0.022 for Co K edge data with 174 independent reflections, and 0.034 for Ni K edge data with 169 reflections. The occupancies are 0.334Co + 0.539Ni + 0.127Zn in the M1 sites, and 0.420Co + 0.253Ni + 0.327Zn
in the M2 sites. The compilation of the cation distributions in olivines shows that the distributions depend on ionic radii
and electronegativities of constituent cations, and that the partition coefficient can be estimated from the equation: ln [(A/B)M1/(A/B)M2] = −0.272 (IR
A
-IR
B
) + 3.65 (EN
A
−EN
B
), where IR (pm) and EN are ionic radius and electronegativity, respectively.
Received: 8 April 1999 / Revised, accepted: 7 September 1999 相似文献
8.
Youko Miyoshi Jun‐ichiro Ishibashi Kazuhiko Shimada Hiroyasu Inoue Seiichiro Uehara Katsuhiro Tsukimura 《Resource Geology》2015,65(4):346-360
Iheya‐North‐Knoll is one of the small knolls covered with thick sediments in the Okinawa Trough back‐arc basin. At the east slope of Iheya‐North‐Knoll, nine hydrothermal vents with sulfide mounds are present. The Integrated Ocean Drilling Program (IODP) Expedition 331 studied Iheya‐North‐Knoll in September 2010. The expedition provided us with the opportunity to study clay minerals in deep sediments in Iheya‐North‐Knoll. To reveal characteristics of clay minerals in the deep sediments, samples from the drilling cores at three sites close to the most active hydrothermal vent were analyzed by X‐ray diffraction, scanning electron microscope and transmission electron microscope. The sediments are classified into Layer 0 (shallow), Layer 1 (deep), Layer 2 (deeper) and Layer 3 (deepest) on the basis of the assemblage of clay minerals. Layer 0 contains no clay minerals. Layer 1 contains smectite, kaolinite and illite/smectite mixed‐layer mineral. Layer 2 contains chlorite, corrensite and chlorite/smectite mixed‐layer mineral. Layer 3 is grouped into three sub‐layers, 3A, 3B and 3C; Sub‐layer 3A contains chlorite and illite/smectite mixed‐layer mineral, sub‐layer 3B contains chlorite/smectite and illite/smectite mixed‐layer minerals, and sub‐layer 3C contains chlorite and illite. Large amounts of di‐octahedral clay minerals such as smectite, kaolinite, illite and illite/smectite mixed‐layer mineral are found in Iheya‐North‐Knoll, which is rarely observed in hydrothermal fields in mid‐ocean ridges. Tri‐octahedral clay minerals such as chlorite, corrensite and chlorite/smectite mixed‐layer mineral in Iheya‐North‐Knoll have low Fe/(Fe + Mg) ratios compared with those in mid‐ocean ridges. In conclusion, the characteristics of clay minerals in Iheya‐North‐Knoll differ from those in mid‐ocean ridges; di‐octahedral clay minerals and Fe‐poor tri‐octahedral clay minerals occur in Iheya‐North‐Knoll but not in mid‐ocean ridges. 相似文献
9.
Masahiro Kajikawa Katsuhiro Kikuchi Yoshio Asuma Yusuke Inoue Noboru Sato 《Atmospheric Research》2000,52(4):377
Supercooled drizzle (freezing drizzle) was observed at Inuvik, N.W.T., Canada (68°22′N, 133°42′W) on December 20, 21 and 27, 1995. Meteorological conditions in which the supercooled drizzle could form under low temperatures (colder than −20°C) in the mid-winter season of the Canadian Arctic were examined from the sounding data and data measured by a passive microwave radiometer at ground level. The following results were obtained. (1) Supercooled drizzle fell to the ground with ice pellets and frozen drops on snow crystals. (2) The maximum size of supercooled drizzle particles increased as the depth of cloud layer saturated with respect to water increased. (3) Because a layer of air temperature higher than 0°C was not detected from the sounding data at Inuvik, melting of snow particles was impossible. It was concluded, therefore, that supercooled drizzle was formed by the condensation–coalescence process below freezing temperature. 相似文献
10.
Abstract A loam section near Daisen volcano, South-west Japan, has been examined for low-field magnetic susceptibility (MS) and fine quartz accumulation rate. Fission track dating of tephra layers interbedded in the deposit shows that the loam age ranges from about 200 ka to the Present. The MS was measured for both bulk sample and the < 63 μm fine fraction. Fine quartz contents in the < 63 μm fraction were also determined using acid-alkali digestions and recalculated to derive fine quartz accumulation rate (Rqz). Grain size analysis was then carried out on the separated fine quartz. Low-field MS varies from low frequency magnetic suspectibility (χ(LF)) 5 to 100 (× 10−6 m3 /kg) for bulk samples and from 1 to 30 for fine fractions. The fine fraction χ(LF) variation correlated with Chinese loess MS stratigraphy, which indicated changes in pedogenic enhancement of the MS and is reflected by summer monsoon intensity. The Rqz are high in cool climate stages, with volumes between 0.2 and 0.4 (× 10−2 kg/m2 per yr), whereas in warm stages the rate falls to about 0.1. These values compare well with those reported from the Hokkaido and Kanto areas, suggesting the fine quartz originates from tropospheric dust. The strong winter monsoons during glacial stages alternated with weak summer monsoons as a result of a southward shift of the jet stream. In interglacials, summer monsoons were stronger. Seasonal alternating monsoons appear to have operated in South-west Japan through the past 200 000 years. 相似文献