Melting and Multi-stage Metasomatism in the Mantle Wedge beneath a Frontal Arc Inferred from Highly Depleted Peridotite Xenoliths from the Avacha Volcano, Southern Kamchatka   总被引：3，自引：0，他引：3  

Ishimaru  Satoko; Arai  Shoji; Ishida  Yoshito; Shirasaka  Miki; Okrugin  Victor M. 《Journal of Petrology》2007,48(2):395-433

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Correction to: Buoyancy-driven propagation of an isolated fluid-filled crack in rock: implication for fluid transport in metamorphism     

Yoshito?NakashimaEmail author 《Contributions to Mineralogy and Petrology》2018,173(2):15

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Spatiotemporal characteristics of interannual temperature variations in the Tsushima Strait     

Tomoharu Senjyu  Sigeaki Matsui  In-Seong Han 《Journal of Oceanography》2010,66(6):789-799

Spatiotemporal characteristics of interannual temperature variations in the Tsushima Strait are investigated on the basis of historical hydrographic data applying the same procedures as Senjyu et al. (2006). Empirical orthogonal function (EOF) analysis revealed that the most energetic mode of variation (the EOF first mode), which accounts for about 31.5% of the total variance, is the in-phase temperature change for the entire strait. The wintertime temperature variation described by the first mode is associated with the wintertime heat flux in the northern East China Sea, while they are poorly correlated in other seasons. The large standard deviation in the time coefficient of the first mode in August suggests a relationship with the horizontal heat advection in summer in the northern East China Sea. On the other hand, the EOF second mode, which explains about 12.6% of the total variance, is associated with the stratification and baroclinicity in the strait. The time coefficient of the EOF second mode negatively correlates with the baroclinic volume transport through the strait in summer. Comparison of temporal variations among the leading EOF modes for temperature and salinity shows no significant correlations. This indicates that the principal modes of variation in temperature and salinity vary independently within an interannual timescale.  相似文献   

The role of organic haze in Titan's atmospheric chemistry: I. Laboratory investigation on heterogeneous reaction of atomic hydrogen with Titan tholin     

Yasuhito Sekine  Hiroshi Imanaka  Takafumi Matsui  Emma L.O. Bakes  Christopher P. McKay 《Icarus》2008,194(1):186-200

In Titan's atmosphere consisting of N₂ and CH₄, large amounts of atomic hydrogen are produced by photochemical reactions during the formation of complex organics. This atomic hydrogen may undergo heterogeneous reactions with organic aerosol in the stratosphere and mesosphere of Titan. In order to investigate both the mechanisms and kinetics of the heterogeneous reactions, atomic deuterium is irradiated onto Titan tholin formed from N₂ and CH₄ gas mixtures at various surface-temperatures of the tholin ranging from 160 to 310 K. The combined analyses of the gas species and the exposed tholin indicate that the interaction mechanisms of atomic deuterium with the tholin are composed of three reactions; (a) abstraction of hydrogen from tholin resulting in gaseous HD formation (HD recombination), (b) addition of D atom into tholin (hydrogenation), and (c) removal of carbon and/or nitrogen (chemical erosion). The reaction probabilities of HD recombination and hydrogenation are obtained as ηabst=1.9(±0.6)×¹⁰⁻³×exp(−300/T) and ηhydro=2.08(±0.64)×exp(−1000/T), respectively. The chemical erosion process is very inefficient under the conditions of temperature range of Titan's stratosphere and mesosphere. Under Titan conditions, the rates of hydrogenation > HD recombination ? chemical erosion. Our measured HD recombination rate is about 10 times (with an uncertainty of a factor of 3-5) the prediction of previous theoretical model. These results imply that organic aerosol can remove atomic hydrogen efficiently from Titan's atmosphere through the heterogeneous reactions and that the presence of aerosol may affect the subsequent organic chemistry.  相似文献   

Podiform chromitites in the lherzolite-dominant mantle section of the Isabela ophiolite, the Philippines     

Tomoaki  Morishita  Eric S.  Andal  Shoji  Arai Yoshito  Ishida 《Island Arc》2006,15(1):84-101

Abstract The Isabela ophiolite, the Philippines, is characterized by a lherzolite‐dominant mantle section, which was probably formed beneath a slow‐spreading mid‐ocean ridge. Several podiform chromitites occur in the mantle section and grade into harzburgite to lherzolite. The chromitites show massive, nodular, layered and disseminated textures. Clinopyroxene (±orthopyroxene/amphibole) inclusions within chromian spinel (chromite hereafter) are commonly found in the massive‐type chromitites. Large chromitites are found in relatively depleted harzburgite hosts having high‐Cr? (Cr/(Cr + Al) atomic ratio = ～0.5) chromite. Light rare earth element (LREE) contents of clinopyroxenes in harzburgites near the chromitites are higher than those in lherzolite with low‐Cr? chromite, whereas heavy REE (HREE) contents of clinopyroxenes are lower in harzburgite than in lherzolite. The harzburgite near the chromitites is not a residual peridotite after simple melt extraction from lherzolite but is formed by open‐system melting (partial melting associated with influx of primitive basaltic melt of deeper origin). Clinopyroxene inclusions within chromite in chromitites exhibit convex‐shaped REE patterns with low HREE and high LREE (+Sr) abundances compared to the host peridotites. The chromitites were formed from a hybridized melt enriched with Cr, Si and incompatible elements (Na, LREE, Sr and H₂O). The melt was produced by mixing of secondary melts after melt–rock interaction and the primitive basaltic melts in large melt conduits, probably coupled with a zone‐refining effect. The Cr? of chromites in the chromitites ranges from 0.65 to 0.75 and is similar to those of arc‐related magmas. The upper mantle section of the Isabela ophiolite was initially formed beneath a slow‐spreading mid‐ocean ridge, later introduced by arc‐related magmatisms in response to a switch in tectonic setting during its obduction at a convergent margin.  相似文献   

Occurrence and chemical composition of amphiboles and related minerals in corundum-bearing mafic rock from the Horoman Peridotite Complex, Japan     

Tomoaki Morishita  Shoji Arai  Yoshito Ishida 《Lithos》2007,95(3-4):425-440

A corundum-bearing mafic rock in the Horoman Peridotite Complex, Japan, was derived from upper mantle conditions to lower crustal conditions with surrounding peridotites. The amphiboles found in the rock are classified into 3 types: (1) as interstitial and/or poikilitic grains (Green amphibole), (2) as a constituent mineral of symplectitic mineral aggregates with aluminous spinel at grain boundary between olivine and plagioclase (Symplectite amphibole) and (3) as film-shaped thin grains, usually less than 10 μm in width, at grain boundary between olivine and clinopyroxene (Film-shaped amphibole). The Film-shaped amphibole is rarely associated with orthopyroxene extremely low in Al₂O₃, Cr₂O₃ and CaO (Low-Al OPX). These minerals were formed by infiltration of SiO₂- and volatile-rich fluids along grain boundaries after the rock was recrystallized at olivine-plagioclase stability conditions, i.e. the late stage of the exhumation of the Horoman Complex.

Chondrite-normalized rare earth element patterns and primitive mantle-normalized trace-element patterns of the Green amphibole and clinopyroxene are characterized by LREE-depleted patterns with Eu positive and negative anomalies of Zr and Hf. These geochemical characteristics of the constituent minerals were inherited from original whole-rock compositions through a reaction involving both pre-existing clinopyroxene and plagioclase. We propose that the fluids were originally rich in a SiO₂ component but depleted in trace-elements. Dehydration of the surrounding metamorphic rocks in the Hidaka metamorphic belt, probably related to intrusion of hot peridotite body into the Hidaka crust, is a plausible origin for the fluids.  相似文献   

Olivine-spinifex basalt from the Tamba Belt, southwest Japan: Evidence for Fe- and high field strength element-rich ultramafic volcanism in Permian Ocean   总被引：2，自引：0，他引：2  

Yuji  Ichiyama  Akira  Ishiwatari  Kazuto  Koizumi  Yoshito  Ishida  Sumiaki  Machi 《Island Arc》2007,16(3):493-503

Abstract   Permian basalt showing typical spinifex texture with >10 cm-long olivine pseudomorphs was discovered from the Jurassic Tamba accretionary complex in southwest Japan. The spinifex basalt occurs as a river boulder accompanied by many ferropicritic boulders in a Permian chert-greenstone unit. Groundmass of this rock is holocrystalline, suggesting a thick lava or sill for its provenance. Minor kaersutite in the groundmass indicates a hydrous magma. The spinifex basalt, in common with the associated ferropicritic rocks, is characterized by high high field strength element (HFSE) contents (e.g. Nb = 62 ppm and Zr = 254 ppm) and high-HFSE ratios (Al₂O₃/TiO₂ = 3.9, Nb/Zr = 0.24 and Zr/Y = 6.4) unlike typical komatiites. The spinifex basalt and ferropicrite might represent the upper fractionated melt and the lower olivine-rich cumulate, respectively, of a single ultramafic sill (or lava) as reported from the early Proterozoic Pechenga Series in Kola Peninsula. Their parental magma might have been produced by hydrous melting of a mantle plume that was dosed with Fe- and HFSE-rich garnet pyroxenite. The spinifex basalt is an evidence for the Pechenga-type ferropicritic volcanism taken place in a Permian oceanic plateau, which accreted to the Asian continental margin as greenstone slices in Jurassic time.  相似文献   

Study on the physical disintegration characteristics of Subang claystone subjected to a modified slaking index test   总被引：2，自引：0，他引：2  

I. A.?SadisunEmail author  H.?Shimada  M.?Ichinose  K.?Matsui 《Geotechnical and Geological Engineering》2005,23(3):199-218

Some instability problems were found on natural or engineered slopes mostly lying on Subang claystones. The instability problems included excessive erosion, slumps and rock falls. The field performance surveys of the problems suggested that the claystones physically weather rapidly so that the rock properties they exhibit during excavation often change to properties with a more characteristic of soil. Such a phenomenon is generally known as a slaking process. In order to gain better understanding about the slaking of Subang claystones, a series of experimental laboratory studies were carried out involving a modified slaking index test. Claystone samples used in this study were obtained from their exposures along the Northern West Java area of Indonesia. Petrographic analysis was correspondingly performed to identify mineral and texture/fabric, and in turn, to determine the inherent factors of the rocks which might affect the slaking process. The stssudy results indicated that the claystones were characterized by high to very high slaking properties having a maximum slaking index (I_s) of 57.4% and a mean I_s of 43.8%. Major dispersion slaking on sample surfaces and high cracking in response to excessive swelling were recognized as main slaking modes within the claystones. All samples lose progressively less material through the five wet–dry cycles of a slaking index test, indicating a decelerated slaking rate. It was evident that the main inherent factors controlling the slaking process were expandable clay mineral smectite, non-clay mineral pyrite and soluble mineral calcite. Moreover, a quite important of inherent bonding material and stress release energy in the slaking characteristics of the claystones was revealed by a closure phase of an initial hairline crack during unloading.  相似文献   

Crustal structure of south-western Honshu, Japan, derived from explosion seismic waves     

Michio Hashizume  Yoshito Matsui 《Geophysical Journal International》1979,58(1):181-199

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Small diameter tunnel excavation method using slurry pipe-jacking   总被引：3，自引：1，他引：3  

Hideki Shimada  Saeid Khazaei  Kikuo Matsui 《Geotechnical and Geological Engineering》2004,22(2):161-186

In order to protect the safety of workers construction, as well as for environmental and cost reasons, efficient small-diameter shallow tunneling methods have recently become increasingly important in regards to outside plant engineering such as for water supplies, electricity, telecommunications and gas. The effects of the above projects in overcrowded urban areas are significant and often result in substantial impact and traffic delays associated with a loss of travel time. Clearly the solution to these utility placement problems, if the full impact of trench excavation is to be avoided, is trench less technology. In particular, for construction work near existing facilities, underground tunnels that are excavated by slurry pipe-jacking are being increasingly employed in order to avoid problems. Slurry pipe-jacking was firmly established as a special method for the non-disruptive construction of the underground pipelines of sewage systems. Pipe-jacking, in its traditional form, has occasionally been used for short railways, roads, rivers, and other projects. Basically the system involves the pushing or thrusting of a drivage machine through concrete pipes ahead of jacks. This method utilizes mud slurry that is formed around the pipes in order to stabilize the surrounding soil. Moreover, in recent years, the rectangular shape of the concrete pipe in using slurry pipe-jacking was introduced due to the effective uses of the space. Based on his reason, the rectangular shape of the concrete pipe is often adopted in Japan. From this point of view, this paper discusses the effect shapes have on the stability of surrounding soil by means of the numerical analysis. Secondly, this paper discusses the performance of the mud slurry around the drivage pipes by means of the two-dimensional Eulerian-Lagragian seepage analysis. Moreover, in slurry pipe-jacking, the performance of the mud slurry plays an important role in the pushing process. Finally, the thrusts in slurry pipe-jacking can be predicted accurately by evaluating the resistance between the mud slurry and the concrete pipes and the resistance between the soil and the pipes in the curved jacking area. This revised version was published online in July 2006 with corrections to the Cover Date.  相似文献