<Emphasis Type="Italic">P</Emphasis>–<Emphasis Type="Italic">V</Emphasis>–<Emphasis Type="Italic">T</Emphasis> equation of state of CaAl<Subscript>4</Subscript>Si<Subscript>2</Subscript>O<Subscript>11</Subscript> CAS phase     

Steeve?GréauxEmail author  Norimasa?Nishiyama  Yoshio?Kono  Tetsuo?Irifune  Laurent?Gautron 《Physics and Chemistry of Minerals》2011,38(8):581-590

The thermoelastic parameters of the CAS phase (CaAl₄Si₂O₁₁) were examined by in situ high-pressure (up to 23.7 GPa) and high-temperature (up to 2,100 K) synchrotron X-ray diffraction, using a Kawai-type multi-anvil press. P–V data at room temperature fitted to a third-order Birch–Murnaghan equation of state (BM EOS) yielded: V _0,300 = 324.2 ± 0.2 Å³ and K _0,300 = 164 ± 6 GPa for K′ _0,300 = 6.2 ± 0.8. With K′ _0,300 fixed to 4.0, we obtained: V _0,300 = 324.0 ± 0.1 Å³ and K _0,300 = 180 ± 1 GPa. Fitting our P–V–T data with a modified high-temperature BM EOS, we obtained: V _0,300 = 324.2 ± 0.1 Å³, K _0,300 = 171 ± 5 GPa, K′ _0,300 = 5.1 ± 0.6 (?K _0,T /?T) _P  = ?0.023 ± 0.006 GPa K^?1, and α_0,T  = 3.09 ± 0.25 × 10^?5 K^?1. Using the equation of state parameters of the CAS phase determined in the present study, we calculated a density profile of a hypothetical continental crust that would contain ~10 vol% of CaAl₄Si₂O₁₁. Because of the higher density compared with the coexisting minerals, the CAS phase is expected to be a plunging agent for continental crust subducted in the transition zone. On the other hand, because of the lower density compared with lower mantle minerals, the CAS phase is expected to remain buoyant in the lowermost part of the transition zone.  相似文献   

A geochemical study on mud volcanoes in the Junggar Basin, China     

Ryoichi Nakada  Yoshio TakahashiUrumu Tsunogai  Guodong ZhengHiroshi Shimizu  Keiko H. Hattori 《Applied Geochemistry》2011,26(7):1065-1076

A comprehensive study was performed to characterize, for the first time, the mud, water, and gases released from onshore mud volcanoes located in the southern margin of the Junggar Basin, northwestern China. Chemical compositions of mud, along with the geology of the basin, suggest that a source of the mud is Mesozoic or Cenozoic shale. Oxygen and H isotope compositions of the released water suggest a local meteoric origin. Combined with the positive Eu anomalies of the water, a large ¹⁸O shift of the water suggests extensive interaction with rocks. Gases discharged from the mud volcanoes are predominantly thermogenic hydrocarbons, and the high δ¹³C values (>+20‰ VPDB) for CO₂ gases and dissolved carbonate in muddy water suggest secondary methanogenesis with CO₂ reduction after oil biodegradation.The enrichments of Eu and ¹⁸O in water and the low thermal gradient of the area suggest that the water-rock interactions possibly occur deeper than 3670 ± 200 m. On the other hand, considering the relationship to the petroleum reservoir around the mud volcanoes, the depth of the gases can be derived from about 3600 m, a depth that is greater than that generally estimated for reservoirs whose gas is characterized by ¹³C-enriched CO₂. Oil biodegradation with CO₂ reduction likely occurs at a shallower depth along the seepage system of the mud volcano. The results contribute to the worldwide data set of gas genesis in mud volcanoes. Moreover, they further support the concept that most terrestrial mud volcanoes release thermogenic gas produced in very deep sediments and may be early indicators of oil biodegradation, an important problem in the petroleum industry.  相似文献   

Cyclone activity associated with the interannual seesaw oscillation of summer precipitation over northern Eurasia     

Yoshiki Fukutomi  Kooiti Masuda  Tetsuzo Yasunari   《Global and Planetary Change》2007,56(3-4):387

This study describes surface cyclone activity associated with the interannual variability in summer precipitation in northern Eurasia and how that activity may be connected to other climate signals. An east–west seesaw oscillation of precipitation across Siberia is the primary mode of interannual variability in the summer hydrological cycle over northern Eurasia. This variation occurs at sub-decadal timescales of about 6–8 years. The spatial characteristics of cyclone frequency and cyclone tracks at the two poles in variability [eastern Siberia (ES)-wet–western Siberia (WS)-dry and WS-wet–ES-dry] were examined, and temporal variability in regional cyclone frequency was compared to basin-scale precipitation variability. The analysis period was from 1973 to 2002, when the precipitation variability signal was predominant.Cyclone behavior suggested that the regions of enhanced (reduced) cyclone activity coincided with regions of increased (decreased) precipitation in each phase of the oscillation. Such behavior reflects the zonal displacement of the track of frequent storm activity that accompanies the changes in precipitation. Comparisons of the temporal characteristics confirmed the importance of regional cyclone frequency on precipitation variability in both eastern and western Siberia. Low-frequency changes in regional cyclone activity may produce the precipitation oscillation. We used various climate signals to explore connections between regional precipitation and cyclone activity in Siberia. Results suggest that the North Atlantic Oscillation (NAO) from the preceding winter is significantly and negatively correlated with summer surface cyclone frequency and precipitation over western Siberia. Enhanced (reduced) summer cyclone activity and precipitation in western Siberia follows low- (high-) winter NAO. However, the physical mechanisms linking summer cyclone activity and precipitation over western Siberia with the preceding climate conditions associated with the winter NAO remain unclear.  相似文献   

Detection of small earthquakes along the Pacific-Antarctic Ridge from T-waves recorded by abyssal ocean-bottom observatories     

Aki Ito  Hiroko Sugioka  Daisuke Suetsugu  Hajime Shiobara  Toshihiko Kanazawa  Yoshio Fukao 《Marine Geophysical Researches》2012,33(3):229-238

A number of seismoacoustic T-wave events were observed between January 2003 and January 2004 by broadband ocean-bottom seismometers installed on the French Polynesia seafloor at depths of 4,000?C5,000?m, well below the conjugate depth of the SOFAR channel. Using T-wave arrival times, we located 89 T-wave events along the Pacific-Antarctic Ridge. Among these, 63 events were not detected by land-based seismic observations of the United States Geological Survey (USGS), which was nearly twice the number of earthquakes reported by the USGS in the area during the observation period. We used a simple method to estimate earthquake magnitude from T-wave energy. The magnitudes of the events unidentified by the USGS ranged from 2.3 to 5.5, whereas magnitudes of the earthquakes reported by the USGS ranged from 4.1 to 6.2. Our study suggests that T-wave observations with abyssal ocean-bottom seismometers can improve the detection of small earthquakes and help our understanding of the seismotectonics of remote oceanic areas.  相似文献   

Estimates of continental-scale soil wetness and comparison with the soil moisture data of Mintz and Serafini     

H. Matsuyama  K. Masuda 《Climate Dynamics》1997,13(10):681-689

 Soil wetness, in both its global distribution and the seasonal change, has been mainly estimated by the water balance approach using the bucket model which regards the soil wetness as soil moisture. The soil moisture data of Mintz and Serafini is one of the representatives examples, however, this method has problems since it does not incorporate the effects of flooding, snow accumulation on the ground, and so on. In this study, we use the Amazon and Volga river basin to carry out a case study to evaluate these problems. In the Amazon river basin, the annual range of the entire terrestrial water storage, about 400 mm, can be mainly explained by the rising and falling of the water level, and flooding around river channels, although soil moisture data of Mintz and Serafini is almost constant throughout the year. In the Volga river basin, snow accumulates on the ground producing 80 mm of water equivalent during winter, however the soil moisture data of Mintz and Serafini is almost saturated in winter. Received: 30 October 1996 / Accepted: 4 June 1997  相似文献   

Emergent radiation from the atmosphere bounded by the two halves of the Lambert surface with different albedos     

T. Takashima  K. Masuda 《Astrophysics and Space Science》1991,183(2):225-236

For the evaluation of the effect of the nonuniform surface albedo to the emergent radiation from the atmosphere, the emergent radiation from the atmosphere bounded by the two-halves of the Lambert surface with different albedos is computed. The principal plane is assumed to be perpendicular to the boundary of surfaces. The atmosphere is assumed to be homogeneous, which is composed of aerosol, molecules, and absorbent gases. Their optical thicknesses are 0.25, 0.23, and 0.02, respectively. The model aerosol is of the oceanic and water soluble types.In the computational procedure, the emergent radiation is approximated by the contributions due to the multiple scattering in the atmosphere, directly attenuated radiation, and radiation due to single scattering in the atmosphere which is reflected by the Lambert surface (up to 4 interactive radiative modes between atmosphere and surface). For quantitative analysis, results are compared with those of the atmosphere-uniform surface model, where the multiple scattering is considered. The numerical simulation exhibits the extraordinary effect near the surface boundary of different albedos. The effect decreases exponentially with the distance from the boundary. It is a function of the observational position, difference of surface albedos, optical thickness and aerosol type.The upward radiance would simply be evaluated using the present scattering approximation method if the atmosphere is in clear condition. Whereas in hazy condition, the effect of multiple scattering in the atmosphere should be considered more precisely, since the upward radiance exhibit a strong dependence on observational nadir angles due to multiple scattering in the atmosphere. Furthermore, it depends on the optical characteristics of aerosols.  相似文献   

Thermal expansion of fayalite,Fe2SiO4     

Isao Suzuki  Kiyoshi Seya  Humihiko Takei  Yoshio Sumino 《Physics and Chemistry of Minerals》1981,7(2):60-63

Thermal expansion of single-crystal fayalite has been measured by a dilatometric method at temperatures between 25 °C and 850 °C. The results show the presence of anomalous expansion in the b axis, which is correlated to the anomalous variation of elastic moduli with temperature. Grüneisen's parameter is 1.10 and the thermal Debye temperature is 565 K, which is close to the acoustic Debye temperature of 511 K.  相似文献   

Rare-earths in Icelandic neovolcanic rocks     

Toshinari Shimokawa  Akimasa Masuda 《Contributions to Mineralogy and Petrology》1972,37(1):39-46

Seven volcanic rocks from neovolcanic zone of Iceland were analysed for rare-earths (RE). The bulk partition coefficients are estimated from combination of the studied samples. In contrast with the mid-ocean ridge basalts which show the solid-type RE patterns, four of five arbitrarily chosen Icelandic basalts appear to have liquid-type RE patterns. The occurrence of relatively pristine lava with relative unfractionated RE abundances to chondrite is also considered to be associated with the peculiar tectonics of Iceland.  相似文献   

Velocity Measurements and Crack Density Determination During Wet Triaxial Experiments on Oshima and Toki Granites     

A. Schubnel  O. Nishizawa  K. Masuda  X. J. Lei  Z. Xue  Y. Guégen 《Pure and Applied Geophysics》2003,160(5-6):869-887

— A set of experiments on four samples of Oshima Granite at 15, 40 and 60 MPa confining pressure have been performed in order to investigate the damage behavior of granite submitted to deviatoric stress. In addition an experiment on one sample of Toki Granite at 40 MPa confining pressure was performed, in order to compare and elucidate the structural effects. Using acoustic emission data, strain measurements and elastic wave velocities allow to define consistently a damage domain in the stress space. In this domain, microcracking develops. The microcracking process is, in a first stage, homogeneous and, close to failure, localized. Elastic wave velocities decrease in the damage domain and elastic anisotropy develops. Using Kachanov's model (1993), elastic wave velocities have been inverted to derive the full second-order crack density tensor and characterize the fluid saturation state from the fourth-order crack density tensor. Crack density is strongly anisotropic and the total crack density close to failure slightly above one. The results indicate that the rock is saturated in agreement with the experimental conditions. The model is thus shown to be very appropriate to infer from elastic wave velocities a complete quantitative characterization of the damaged rock.  相似文献   

Direct observation of Cm(III)-fulvate species on fulvic acid-montmorillonite hybrid by laser-induced fluorescence spectroscopy     

Yoshio Takahashi  Takaumi KimuraYoshitaka Minai 《Geochimica et cosmochimica acta》2002,66(1):1-12

Particulate matter plays an important role in the removal of metal ions from water in natural aquifers. Some of the most important of these materials consist of associations of inorganic particles (clay minerals, oxides) with humic substances, associations that can form readily in such an environment due to the strong affinity between inorganic particles and humic substances. These associations are referred to in this paper as organic-inorganic hybrids. However, it is not clear whether the sorbed species of metal ions in such organic-inorganic hybrids are organic or inorganic species because of the complexity of such hybrids and the lack of appropriate methods for characterizing the trace metal ions incorporated in them. In this study, laser-induced fluorescence spectroscopy (LIF) was used successfully to characterize the Cm(III) species on an FA(fulvic acid)-montmorillonite hybrid, an example of such organic-inorganic hybrids. The LIF clearly showed that Cm(III) can be sorbed as Cm(III)-fulvate complex in the FA-montmorillonite hybrid. These results were consistent with those of experiments of solid-water partitioning of Cm(III) (or Eu(III) used as an analogue) and speciation calculations based on the stability constants of Cm(III)-fulvate complexes determined in this study. The results of LIF and the partitioning experiments showed that the solid-water distribution of humic substances governed that of Cm(III) under our experimental conditions. The Cm(III) preference for forming Cm(III)-fulvate complexes was also evident under a condition that would be found in a natural aquifer with a fairly low concentration of organic matter in freshwater (dissolved organic carbon: 2 mg/dm³), as determined by our speciation calculations. These findings on the importance of humic substances in the migration of Cm(III) indicate that the clarification of the environmental behavior of humic substances is necessary to understand fully the behavior of Cm(III), or actinide(III) and lanthanide(III) ions, in natural aquifers.  相似文献