Numerical investigation of motions of resonant asteroids in the three-dimensional space     

Makoto Yoshikawa 《Celestial Mechanics and Dynamical Astronomy》1992,54(1-3):287-290

Motions of asteroids in mean motion resonances with Jupiter are studied in three-dimensional space. Orbital changes of fictitious asteroids in the Kirkwood gaps are calculated by numerical integrations for 10⁵ – 10⁶ years. The main results are as follows: (1) There are various motions of resonant asteroids, and some of them are very complicated and chaotic and others are regular. (2) The eccentricity of some asteroids becomes very large, and the variation of the inclination is large while the eccentricity is large. (3) In the 3:1 resonance, there is a long periodic change in the variation of the inclination, when (7 : ) is a simple ratio (7: longitude of perihelion, : longitude of node). (4) In the 7:3 resonance, the variation of the inclination of some resonant asteroids is so large that prograde motion becomes retrograde. Some asteroids in the 7:3 resonance can collide with the Sun as well as with the inner planets.  相似文献   

High heat flow anomalies on an old oceanic plate observed seaward of the Japan Trench     

Makoto Yamano  Masataka Kinoshita  Shusaku Goto 《International Journal of Earth Sciences》2008,97(2):345-352

Thirty-three new measurements on the seaward slope and outer rise of the Japan Trench along a parallel of 38°45′N revealed the existence of high heat flow anomalies on the subducting Pacific plate, where the seafloor age is about 135 m.y.. The most prominent anomaly with the highest value of 114 mW/m² is associated with a small mound on the outer rise, which was reported to be a kind of mud volcano. On the seaward slope of the trench, heat flow is variable: high (70–90 mW/m²) at some locations and normal for the seafloor age (about 50 mW/m²) at others. The spatial variation of heat flow may be related to development of normal faults and horst/graben structures due to bending of the Pacific plate before subduction, with fluid flow along the fault zones enhancing the vertical heat transfer. Possible heat sources of the high heat flow anomalies are intra-plate volcanism in the last several million years like that discovered recently on the Pacific plate east of the Japan Trench.  相似文献   

Chemical, Isotopic, and Fluid Inclusion Evidence for the Hydrothermal Alteration of the Footwall Rocks of the BIF-Hosted Iron Ore Deposits in the Hamersley District, Western Australia     

Makoto Haruna    Takahiro Hanamuro    Kaoru Uyeda    Hirokazu Fujimaki  Hiroshi Ohmoto 《Resource Geology》2003,53(2):75-88

Abstract. The petrography, chemical, fluid inclusion and isotope analyses (O, Rb-Sr) were conducted for the shale samples of the Mount McRae Shale collected from the Tom Price, Newman, and Paraburdoo mines in the Hamersley Basin, Western Australia. The Mount McRae Shale at these mines occurs as a footwall unit of the secondary, hematite-rich iron ores derived from the Brockman Iron Formation, one of the largest banded iron formations (BIFs) in the world. Unusually low contents of Na, Ca, and Sr in the shales suggest that these elements were leached away from the shale after deposition. The δ¹⁸O (SMOW) values fall in the range of + 15.0 to +17.9 per mil and show the positive correlation with calculated quartz/sericite ratios of the shale samples. This suggests that the oxygen isotopic compositions of shale samples were homogenized and equilibrated by postdepositional event. The pyrite nodules hosted by shales are often rimmed by thin layers of silica of varying crystallinity. Fluid inclusions in quartz crystals rimming a pyrite nodule show homogenization temperatures ranging from 100 to 240C for 47 inclusions and salinities ranging from 0.4 to 12.3 wt% NaCl equivalent for 18 inclusions. These fluid inclusion data give direct evidence for the hydrothermal activity and are comparable to those of the vein quartz collected from the BIF-derived secondary iron ores (Taylor et al, 2001). The Rb-Sr age for the Mount McRae Shale is 1,952 ± 289 Ma and at least 200 million years younger than the depositional age of the Brockman Iron Formation of ∼ 2.5 Ga in age. All the data obtained in this study are consistent with the suggestion that high temperature hydrothermal fluids were responsible for both the secondary iron ore formation and the alteration of the Mount McRae Shale.  相似文献   

K-Ar Ages of Granitic Magmatism and Related Pegmatite Formation at the Umanotani-Shiroyama Mine, Shimane Prefecture, SW Japan and Their Bearings on Cooling History     

Shouji Kihara    Kenichi Hoshino    Makoto Watanabe    Hirotsugu Nishido  Shunso Ishihara 《Resource Geology》2005,55(2):123-129

Abstract. The Umanotani-Shiroyama pegmatite deposits, the largest producer of K-feldspar and quartz in Japan, are of typical granitic pegmatite. Ilmenite-series biotite granite and granite porphyry, hosting the ore deposits, and biotites separated from these rocks yielded K-Ar ages ranging from 89.0 to 81.4 Ma and 95.2 to 93.7 Ma, respectively. Muscovite and K-feldspar separated from the ore zone yielded K-Ar ages with the range of 96.2 to 93.1 Ma and 87.3 to 80.7 Ma, respectively. Muscovites from quartz-muscovite veins in the ore zone and in the granite porphyry yielded K-Ar ages of 90.4 and 76.3 Ma, respectively. K-feldspar is much younger in age than coexisting muscovite. It is noted that the K-Ar ages of biotite separates and the whole-rock ages are identical to those of muscovite and K-feldspar in the ore zone, respectively. These time relations, as well as field occurrence, indicate that the formation of the pegmatite deposits at the Umanotani-Shiroyama mine is closely related in space and time to a series of granitic magmatism of ilmenite-series nature. Using closure temperatures of the K-Ar system for biotite and K-feldspar (microcline), cooling rate of the pegmatite deposits is estimated to be about 82C/m.y. at the beginning, but slowed down to about 15C/m.y. in the later period.  相似文献   

A recent history of science cases for optical interferometry     

Denis Defrère  Conny Aerts  Makoto Kishimoto  Pierre Léna 《Experimental Astronomy》2018,46(3):389-399

Optical long-baseline interferometry is a unique and powerful technique for astronomical research. Since the 1980’s (with I2T, GI2T, Mark I to III, SUSI, ...), optical interferometers have produced an increasing number of scientific papers covering various fields of astrophysics. As current interferometric facilities are reaching their maturity, we take the opportunity in this paper to summarize the conclusions of a few key meetings, workshops, and conferences dedicated to interferometry. We present the most persistent recommendations related to science cases and discuss some key technological developments required to address them. In the era of extremely large telescopes, optical long-baseline interferometers will remain crucial to probe the smallest spatial scales and make breakthrough discoveries.  相似文献   

Sorption behavior of the Pt(II) complex anion on manganese dioxide (δ-MnO2): a model reaction to elucidate the mechanism by which Pt is concentrated into a marine ferromanganese crust     

Mamiko Yamashita Maeno  Hironori Ohashi  Kotaro Yonezu  Akane Miyazaki  Yoshihiro Okaue  Koichiro Watanabe  Tamao Ishida  Makoto Tokunaga  Takushi Yokoyama 《Mineralium Deposita》2016,51(2):211-218

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The use of microstructures for discriminating turbiditic and hemipelagic muds and mudstones          下载免费PDF全文

Yoshihiro Kase  Makoto Ito  Ken Ikehara  Shigeru Takizawa 《Sedimentology》2016,63(7):2066-2086

The microstructures of turbiditic and hemipelagic muds and mudstones were investigated using a scanning electron microscope to determine whether there are microstructural features that can differentiate turbiditic from hemipelagic sedimentary processes. Both types of muddy deposits are, in general, characterized by randomly‐oriented clay particles. However, turbiditic muds and mudstones also characteristically contain aggregates of ‘edge‐to‐face’ contacts between clay particles with long‐axis lengths of up to 30 μm. Based on observations of the clay fabric of the experimentally‐formed muds settled from previously agitated muddy fluids, these types of aggregates, hereafter referred to as ‘aggregates of clay particles’, are interpreted as having been formed by the collision of component flocs in turbulent fluids. Furthermore, some aggregates of clay particles have ‘face‐to‐face’ contacts between clay particles; this is similar to face‐to‐face aggregates characteristically developed in fluid‐mud deposits that are commonly recognized only in turbiditic mudstones, indicating the possibility of a final stage of deposition under highly‐dense conditions, such as temporary fluid muds. In conjunction with earlier proposed lithofacies‐based and ichnofacies‐based criteria, aggregates of clay particles should be useful for the differentiation of turbiditic and hemipelagic muddy deposits, particularly with limited volumes of non‐oriented samples from deep‐water successions.  相似文献   

Global assessment of the effectiveness of adaptation in coastal areas based on RCP/SSP scenarios     

Tamura  Makoto  Kumano  Naoko  Yotsukuri  Mizuki  Yokoki  Hiromune 《Climatic change》2019,152(3-4):363-377

Climatic Change - The objective of this study is to assess the global impact of sea level rise and to evaluate the effectiveness of adaptation. Global areas of inundation due to sea level rise are...  相似文献   

Estimated Recharge Rates From Groundwater Temperatures In The Nara Basin,Japan     

Makoto Taniguchi 《Hydrogeology Journal》1994,2(4):7-14

Groundwater recharge rates to the sandy aquifer in the Nara basin, Japan, were determined by using a theory that describes the simultaneous transfer of heat and water in a porous medium. Seasonal changes in temperatue-depth profiles were used to estimate the recharge rates in a relatively shallow aquifer. Estimations of the recharge rates were done by fitting a dimensionless parameter to the type curves developed by Taniguchi (1993) after the amplitudes of annual variations of groundwater temperatures were measured at several depths. Annual recharge rate estimated by fitting observed temperatures to the type curves was 459 mm in the Nara basin. This value agrees well with values calculated from water-balance methods and values reported in the literature. Résumé: Les taux de recharge d'un aquifère sableux dans le bassin de Nara (Japon) ont été déterminés au moyen d'un modèle qui décrit le transfert simultané de la chaleur et de l'eau en milieu poreux. Les variations saisonnières le long de profils verticaux de température sont utilisées pour estimer les taux de recharge dan un aquifère relativement superficiel. Les estimations de ces taux de recharge ont été réalisées par l'ajustement d'un paramètre sans dimension aux courbes types proposées par Taniguchi (1993) d'après les amplitudes des variations annuelles de la température de l'eau souterraine mesurée à différentes profondeurs. La recharge annuelle estimée par l'ajustement des températures observées aux courbes types est 459 mm dans le bassin de Nara. Cette valeur est en bon accord avec celles caculées à partir du bilan hydrologique et avec celles de littérature. Resumen: Las velocidades de recarga en el acuífero arenoso de la cuenca del Nara, Japón, se determinaron por medio de una teoría que describe la transferencia simultánea de calor y agua en un medio poroso. Los cambios estacionales en los perfiles temperatura-profundidad permitieron estimar las velocidades de recarga en una acuífero relativamente somero. Las estimaciones de la velocidad de recarga se hicieron por ajuste de un parámetro adimensional a las curvas-tipo desarrolladas por Taniguchi (1993). Para ello se utilizaron las amplitudes de las variaciones anuales de las temperaturas del agua a distintas profundidades. La recarga anual en la cuenca del Nara, estimada mediante este método de ajuste de curvas, fue de 459 mm. Este valor es semejante a la recarga calculada a partir de métodos de balance y a la obtenida de la bibliografía.  相似文献   

Isotopic geochemistry of acid thermal waters and volcanic gases from Zaō volcano in Japan     

Yasuhiro Kiyosu  Makoto Kurahashi 《Journal of Volcanology and Geothermal Research》1984,21(3-4)

The chemical composition and D/H, and ratios have been determined for the acid hot waters and volcanic gases discharging from Zaō volcano in Japan. The thermal springs in Zaō volcano issue acid sulfate-chloride type waters (Zaō) and acid sulfate type waters (Kamoshika). Gases emitted at Kamoshika fumaroles are rich in CO₂, SO₂ and N₂, exclusive of H₂O. Chloride concentrations and oxygen isotope data indicate that the Zaō thermal waters issue a fluid mixture from an acid thermal reservoir and meteoric waters from shallow aquifers. The waters in the Zaō volcanic system have slight isotopic shifts from the respective local meteoric values. The isotopic evidence indicates that most of the water in the system is meteoric in origin. Sulfates in Zaō acid sulfate-chloride waters with δ³⁴S values of around +15‰, are enriched in ³⁴S compared to Zaō H₂S, while the acid sulfate waters at Kamoshika contain supergene light sulfate (δ³⁴S = + 4‰) derived from volcanic sulfur dioxide from the volcanic exhalations. The sulfur species in Zaō acid waters are lighter in δ³⁴S than those of other volcanic areas, reflecting the difference in total pressure.  相似文献