I-1 Wave energy absorption characteristics of circular air chamber for use of light beacon     

Reisaku Inoue  Masami Iwai 《Ocean Engineering》1985,12(6):554-555

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Thermodynamic modelling of sodic pyroxene solid-solution and its application in a garnet-omphacite-kyanite-coesite geothermobarometer for UHP metamorphic rocks   总被引：3，自引：0，他引：3  

Daisuke Nakamura  Shohei Banno 《Contributions to Mineralogy and Petrology》1997,130(1):93-102

A garnet-omphacite-kyanite-coesite geothermobarometer is constructed to estimate the peak metamorphic pressure of ultrahigh-pressure (UHP) eclogites. For this we use a quaternary regular solution model for garnet, and propose a new model for sodic pyroxene that assumes double site solid-solution (Na,Ca)^M2(Al,Fe³⁺,Fe²⁺,Mg)^M1Si₂O₆, where cations in the M2- and the M1-sites mix randomly but with inter-site interactions, not only between nearest neighboring cations but also between next nearest neighboring cations. In the new model, overall excess interaction parameters are quantitatively deduced from the previous experimental data and critical temperature, and the activity of the jadeite component agrees reasonably with that based on the Landau theory. Furthermore, the relations of the calculated order parameter to temperature and composition are consistent with other experimental works. These facts support the usefulness of the new model. Application of our geothermobarometer to kyanite eclogite gave metamorphic conditions around 3.4 GPa and 800 ^∘C for both samples from the Dora Maira Massif, Western Alps, and from Rongcheng County, in the Su-Lu region of eastern China. Received: 30 December 1996 / Accepted: 25 August 1997  相似文献   

Reactions to define the biotite isograd in the Ryoke metamorphic belt,Kii Peninsula,Japan     

Ge-Fan Wang  Shohei Banno  Keiji Takeuchi 《Contributions to Mineralogy and Petrology》1986,93(1):9-17

Two types of biotite isograd are defined in the low-grade metamorphism of the Wazuka area, a Ryoke metamorphic terrain in the Kii Peninsula, Japan. The first, BI₁, is defined by the reaction of chlorite+K-feldspar= biotite+muscovite+quartz+H₂O that took place in psammitic rocks, and the second, BI₂, by the continuous reaction between muscovite, chlorite, biotite and quartz in pelitic rocks. The Fe/Mg ratios of the host rocks do not significantly affect the reactions. From the paragenesis of pelitic and psammitic metamorphic rocks, the following mineral zones were established for this low-pressure regional metamorphic terrain: chlorite, transitional, chlorite-biotite, biotite, and sillimanite. The celadonite content of muscovite solid solution in pelitic rocks decreases systematically with the grade of metamorphism from 38% in the chlorite zone to 11% in the biotite zone. Low pressure does not prohibit muscovite from showing the progressive change of composition, if only rocks with appropriate paragenesis are chosen. A qualitative phase diagram of the AKF system relevant to biotite formation suggests that the higher the pressure of metamorphism, the higher the celadonite content of muscovite at BI₁, which is confirmed by comparing the muscovites from the Barrovian and Ryoke metamorphism.  相似文献   

Relation between chemical composition and particle-size distribution of ores in the profile of nickeliferous laterite deposits of the Rio Tuba Mine, Philippines   总被引：1，自引：0，他引：1  

Yoshio Ogura  Katsuyuki Murata  Michio Iwai 《Chemical Geology》1987,60(1-4):259-271

Lateritic Ni ore mined in the Rio Tuba Mine, Philippines, derived from ultramafic rock by tropical intense weathering, is generally composed of two accumulated zones, an upper laterite zone and a lower saprolite zone. These two zones are very different in appearance, mineral assemblage, chemical composition, and in other ways. A transitional zone may be seen between the upper and lower zones, but it does not develop to any appreciable thickness. Although serpentine and goethite are still predominant in the constituent minerals, other clay minerals are increasing.

The transitional zone may be subdivided into three groups based on chemical composition. The behaviour of the chemical composition in this horizon indicates a complicated process of component transportation under the weathering process.

In the ore, chemical components are closely related in particle size of constituent minerals. In the laterite - transitional - saprolite sequence, a common variation range and tendency in chemical composition for each particle size can be seen. However, taking samples with the same particle size the chemical composition obviously differed, representing the characteristics of the components for each zone.

Concerning the correlation coefficient of the chemical components of each zone, a somewhat different inter-component relationship can be seen in these zones. These differences of correlation suggest the different complicated lateritized conditions under which they are formed.  相似文献   

Numerical studies on the structure of the cosmic ray electron halo in starburst galaxies     

Shoko Miyake  Shohei Yanagita  Tatsuo Yoshida 《Astrophysics and Space Science》2007,309(1-4):151-155

The structure of the cosmic ray electron halo of a starburst galaxy depends strongly on the nature of galactic wind and the configuration of the magnetic field. We have investigated these dependencies by solving numerically the propagation of electrons originating in starburst galaxies, most likely in supernova remnants. The calculations are made for several models for the galactic winds and for the configuration of the magnetic fields for comparison with observations. Our simulation of a quasi-radio halo reproduces both the extended structure of ∼9 kpc and the subtle hollow structure near the polar region of the radio halo that are observed in the starburst galaxy NGC 253. These findings suggest the existence of strong galactic wind in NGC 253.   相似文献   

Simultaneous spaced direction-finding measurements of medium-latitude VLF/ELF emissions     

M. Hayakawa  Y. Tanaka  A. Iwai  J. Ohtsu  L.R.O. Storey  C. Béghin  T.S. Jorgensen 《Planetary and Space Science》1981,29(5):505-520

Simultaneous spaced measurements of medium-latitude VLF/ELF emissions were carried out during the three northern winters from 1976 to 1979. The experiment was making use of two different kinds of direction-finding systems (a field-analysis method and a goniometer network) at two stations in Europe, namely Brorfelde in Denmark (L = 2.9) and Chambron-la-Foret in France (L = 1.9); this enabled us to locate the ionospheric exit regions of emissions over a wide range of L-values up to and beyond 4.0, the average plasmapause location. In order to study the time delay in the temporal evolution of VLF emissions or the longitudinal drift of the emissions, observations from the Moshiri Observatory in Japan, widely separated in longitude, are also used. The overall system of the VLF equipment installed at the three stations is described. Then we present the VLF/ELF data of good quality obtained during the final year's campaign (Nov. 1978–Feb. 1979). By making use of the direction-finding data, we were able to classify the observed emissions into several categories, and some early results for some of the emissions are presented.  相似文献   

IPRT/AMATERAS: A New Metric Spectrum Observation System for Solar Radio Bursts     

K. Iwai  F. Tsuchiya  A. Morioka  H. Misawa 《Solar physics》2012,277(2):447-457

A new radio spectropolarimeter for solar radio observation has been developed at Tohoku University and installed on the Iitate Planetary Radio Telescope (IPRT) at the Iitate observatory in Fukushima prefecture, Japan. This system, named AMATERAS (the Assembly of Metric-band Aperture TElescope and Real-time Analysis System), enables us to observe solar radio bursts in the frequency range between 150 and 500 MHz. The minimum detectable flux in the observation frequency range is less than 0.7 SFU with an integration time of 10 ms and a bandwidth of 61 kHz. Both left and right polarization components are simultaneously observed in this system. These specifications are accomplished by combining the large aperture of IPRT with a high-speed digital receiver. Observational data are calibrated and archived soon after the daily observation. The database is available online. The high-sensitivity observational data with the high time and frequency resolutions from AMATERAS will be used to analyze spectral fine structures of solar radio bursts.  相似文献   

Investigation on piezoelectric lead zirconate titanate detector bombarded obliquely with hypervelocity iron particles     

S. Takechi  T. Onishi  T. Miyachi  N. Hasebe  K. Nogami  S. Sasaki  T. Iwai  R. Srama 《Planetary and Space Science》2008,56(9):1309-1313

A cosmic dust detector for use onboard a satellite is currently being constructed from piezoelectric lead zirconate titanate (PZT). The characteristics of the PZT detector were studied by bombarding it with hypervelocity iron particles, which were supplied by a Van de Graaff accelerator. There was a linear relationship between the rise time of the signal observed from the detector and the particle's velocity, which was above 10 km/s on impact. It was also found that the rise time was almost independent of the collisional angle between the particles and the PZT surface within the limits of the particle's parameters used in this experiment.  相似文献   

山东海阳所麻粒岩向过渡榴辉岩转化的变质动力学过程及其构造意义   总被引：8，自引：3，他引：5  

叶凯  从柏林  平岛崇男  坂野升平 《岩石学报》1999,(１):88

在山东半岛东南端的乳山海阳所,角闪岩和长英质片麻岩呈互层产出.在某些角闪岩层的中心残留有弱变形的麻粒岩和强变形的过渡榴辉岩(斜长石榴辉岩)团块.在弱变形的麻粒岩团块中发育有窄的(<1cm)剪切条带.沿着这些剪切条带和在强变形过渡榴辉岩团块中,原麻粒岩被转化为含斜长石的过渡榴辉岩.变形和流体在这一转化过程中加速了元素扩散和迁移的速度,在变形强和有流体加入的部位麻粒岩向榴辉岩转化的程度明显增强.麻粒岩相矿物组合(Cpx-Ⅰ+Opx+Pl-Ⅰ+ Hbl-Ⅰ + Grt-Ⅰ+ Ilm)及其花岗变晶结构被完好地保存于弱变形的麻粒岩中,其矿物成分显示出0.8～0.9 GPa和780℃～830℃的麻粒岩相变质条件.榴辉岩相叠加在麻粒岩中形成了一系列的环边状矿物和结构:环边状石榴石(Grt-Ⅱ)形成于麻粒岩相斜长石(Pl-Ⅰ)和暗色矿物(如Cpx-Ⅰ、Opx和Hbl-Ⅰ)的交界处,细粒石榴石(Grt-Ⅱ)、富钠单斜辉石(Cpx-Ⅱ)和石英形成于麻粒岩相角闪石(Hbl-Ⅰ)的外缘.同时榴辉岩相叠加造成麻粒岩相单斜辉石边缘钙契尔马克组份的降低和硬玉组份的升高.但在弱变形的麻粒岩中,麻粒岩相单斜辉石(Cpx-Ⅰ)的外缘并无榴辉岩相单斜辉石形成.沿着弱变形麻粒岩中的剪切条带和在过渡榴辉岩中,榴辉岩相矿物[Grt-Ⅱ+ Omp/Di(Cpx-Ⅱ)+ Ab(Pl-Ⅱ)+ Qtz + Hbl-Ⅱ+ Ky + Zo + Rut]广泛发育,它们的定向排列形成了明显的面理.其形成的温压条件为1.0～1.4 GPa和560℃～680℃,为过渡榴辉岩相变质.虽然其中仍然残留有被拉长的麻粒岩相单斜辉石,但它们含有很高的硬玉组份,且其外缘环绕有细粒的钠质透辉石或绿辉石(Cpx-Ⅱ).海阳所榴辉岩相变质的温压条件远远低于位于海阳所东南和东北的苏鲁超高压变质带中柯石英榴辉岩变质的温压条件.因此海阳所地区代表一条不同于超高压变质带的冷榴辉岩带,它可能与大别山南部的冷榴辉岩带相当.苏鲁超高压变质带的南部边界位于海阳所以北.  相似文献   

A gigantic boulder transported by the 2011 Tohoku‐oki tsunami     

Shohei Iwai  Kazuhisa Goto  Takashi Ishizawa 《Island Arc》2019,28(6)

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