Geochemistry and mineralogy of a feldspathic lunar meteorite (regolith breccia), Northwest Africa 2200     

Hiroshi Nagaoka  Yuzuru Karouji  Tomoko Arai  Mitsuru Ebihara  Nobuyuki Hasebe 《Polar Science》2013,7(3-4):241-259

The lunar meteorite Northwest Africa (NWA) 2200 is a regolith breccia with a ferroan feldspathic bulk composition (Al₂O₃ = 30.1 wt.%; Mg^# = molar 100 × Mg/(Mg + Fe) = 59.2) and low Th content (0.42 μg/g). Lithologically, NWA 2200 is a diverse mixture of lithic and glassy clasts, mineral fragments, and impact glass spherules, all embedded in a dark glassy matrix. NWA 2200 contains some feldspathic brecciated rock components (ferroan anorthositic granulitic breccia, poikiloblastic granulitic breccia, and glassy melt breccia with an intersertal texture). The bulk compositions of these brecciated components indicate they are derived from ferroan troctolitic or noritic anorthosite lithologies (bulk Al₂O₃ = 26–30 wt.%; bulk FeO/MgO > 1.0). The bulk composition of NWA 2200 is more ferroan and feldspathic than the Apollo feldspathic regolith samples and feldspathic lunar regolith meteorites, and is also more depleted in incompatible elements (e.g., rare earth elements) than Apollo 16 feldspathic regolith samples. We conclude that NWA 2200 originated from a location different to the Apollo landing sites, and may have been sourced from the ferroan KREEP-poor highlands, “KREEP” materials are enriched in such elements as potassium (K), rare earth elements (REE), phosphorus (P).  相似文献   

Comparison of sale with numerical integration     

Hiroshi Kinoshita 《Celestial Mechanics and Dynamical Astronomy》1982,26(1):71-73

  相似文献   

A precise modeling of Eros 433 rotation     

Jean Souchay  Hiroshi Kinoshita 《Icarus》2003,166(2):285-296

Thanks to the recent data obtained from the NEAR space probe, we calculate in this paper, with a precision never reached so far for an asteroid, the precession and the nutation of Eros 433. In a preliminary step, we show that Eros obliquity has a remarkable value of 89.0° which tends to align its figure axis along the orbital plane. This very specific obliquity has some consequences on the motion of the axis of figure: one is the very small amplitude of the precession in longitude, for which we get the value . Moreover, we calculate Eros nutation for the figure axis due to the Sun, after developing the perturbing potential at the 4th order of the eccentricity. We show that the figure axis undergoes very large oscillations in the direction perpendicular to Eros orbital plane, due to the nutation in obliquity. Peak to peak, these oscillations reach 55″, which is far larger than the amplitudes of the nutations of the Earth due to the Sun (of the order of 2″). Moreover, we give the analytical developments of Δψ and Δε, both for the axis of angular momentum, and the axis of figure.  相似文献   

Secular perturbations of asteroids in secular resonance     

Hiroshi Nakai  Hiroshi Kinoshita 《Celestial Mechanics and Dynamical Astronomy》1985,36(4):391-407

When the precessional rate of the orbital plane of an asteroid is nearly equal to that of Jupiter, the orbital inclination of the asteroid changes quite largely due to this near equality of their precessional rates, which is called a secular resonance. In the vicinity of the exact resonance the difference of their longitudes of nodes librates with quite a long period of order of 1×10⁶ yr. In this paper we treat this secular resonance by a method of semianalytical secular perturbations with use of numerical averaging for both non-resonant and resonant asteroids and show that the results by the semi-analytical treatment agrees qualitatively with those obtained by direct numerical integrations of asteroid's orbits.  相似文献   

Motions of the perihelions of Neptune and Pluto     

Hiroshi Kinoshita  Hiroshi Nakai 《Celestial Mechanics and Dynamical Astronomy》1984,34(1-4):203-217

Five outer planets are numerically integrated over five million years in the Newtonian frame. The argument of Pluto's perihelion librates about 90 degrees with an amplitude of about 23 degrees. The period of the libration depends on the mass of Pluto: 4.0×10⁶ years forM _pluto=2.78×10^–6 M _sun and 3.8×10⁶ years forM _pluto=7.69×10^–9 M _sun, which is the newly determined mass. The motion of Neptune's perihelion is more sensitive to the mass of Pluto. ForM _pluto=7.69×10^–9 M _sun, the perihelion of Neptune does circulate counter-clockwise and forM _pluto=2.78×10^–6 M _sun, it does not circulate and the Neptune's eccentricity does not have a minimum. With the initial conditions which do not lie in the resonance region between Neptune and Pluto, a close approach between them takes place frequently and the orbit of Pluto becomes unstable and irregular.  相似文献   

Placental transfer of arsenic to fetus of Dall’s porpoises (Phocoenoides dalli)     

Reiji Kubota  Takashi Kunito  Junko Fujihara  Shinsuke Tanabe  Jian Yang  Nobuyuki Miyazaki 《Marine pollution bulletin》2005,51(8-12):845

Concentrations of total arsenic and individual arsenic compounds were determined in liver, muscle, kidney and blubber of mother and fetus of Dall’s porpoises collected from off Sanriku, Japan, in the year 2000 to characterize the placental transfer of arsenic to fetus in cetaceans. Arsenic was detected in all the tissues of Dall’s porpoises. Total arsenic concentrations in liver, kidney, muscle and blubber were 0.76, 0.69, 0.35 and 0.55 μg/g wet wt, respectively, for mother and 0.28, 0.23, 0.26 and 0.07 μg/g wet wt, respectively, for fetus. In all the tissues, concentrations of total arsenic in mother Dall’s porpoise were higher than in fetus. Arsenic speciation revealed that arsenobetaine was the major arsenic compound in liver, kidney and muscle of both mother and fetus. The percentage of arsenobetaine to total arsenic ranged from 76.0 to 91.0% in the tissues. Dimethylarsinic acid, arsenocholine, methylarsonic acid and an unidentified arsenic compound were also detected in tissues of both mother and fetus as minor constituents, whereas tetramethylarsonium ion was not detected in tissues of the fetus. These results suggest that arsenobetaine, dimethylarsinic acid, arsenocholine and methylarsonic acid are transferable from mother to fetus in Dall’s porpoises. To our knowledge, this is the first report on placental transfer of arsenic compounds to fetus in marine mammals.  相似文献   

IODP计划和地球科学学术界     

HajimuKinoshita 《地球科学进展》2003,18(5):654-655

国际综合大洋钻探计划(IODP)预定从2003年10月开始(即美国2003年财政年度开始之时)。从美国2006年财政年度开始,日本将提供立管科学钻探船,而自美国2004年财政年度起,美国将提供非立管科学钻探船。这两个钻探平台将构成IODP的核心技术支撑。美国和日本将以“领导机构”(leadagency)的身份支持这项计划,并在IODP中享有平等的合作伙伴关系和责任。在上述两个钻探平台均无法涉足的地区,将使用由美国和日本之外的其他IODP成员国提供的特殊使命钻探平台(MSP)。IODP的科学主题和目标已在IODP初始科学计划书(即ISP:由IWG支持办公…  相似文献   

Possible manifestations of slab window magmatisms in Cretaceous southwest Japan   总被引：3，自引：0，他引：3  

Osamu Kinoshita   《Tectonophysics》2002,344(1-2)

The slab window system related to ridge subduction is studied to explain the conspicuous activity and the along-arc migration of the magmatisms in the eastern margin of Eurasian continent in the late Mesozoic. The trend of the granite ages is scrutinized with systems approach and analyzed by the statistical method in Cretaceous southwest Japan, a reference field of the Eurasian eastern margin. The magmatic distribution of simultaneous activity was determined to be the V-shape of the slab window, excluding dating errors from the located age data. The slab window magmatism has the most dominant zone of the acidic rocks at or near the centerline of the window (the spreading center of two plates), and also has the subdominant zone of the acidic to intermediate rocks on either side of the window.As the slab window opens due to the plate motions, the upwelling current is adiabatically induced in the asthenosphere to fill the window gap. The partial melt is generated in the upwelling flux and transports heat to the lower crust to make greater granitic magma chambers by heat conduction to, and assimilation with, the crustal matter. The younger and hotter slabs outside the window also play a role in partial slab melting and/or dehydration to the asthenosphere and generate the subdominant granodioritic and adakitic and/or high-magnesian andesitic magmatisms as the pre- and post-activities of the main granite genesis.The slab window formed by the subducted ridge between the Kula and Pacific plates was the strong heat source of the active magmatisms and migrated at the rate of 2.8 cm/year from southwest to northeast about 8000 km along the continental margin. The growth of the continent associated with the active acidic to intermediate magmatisms including the adakitic and/or high-magnesian andesitic activities is modeled by the slab window system.  相似文献   

Differences in the acute toxicities of tributyltin between the Caprellidea and the Gammaridea (Crustacea: Amphipoda)     

Ohji M  Takeuchi I  Takahashi S  Tanabe S  Miyazaki N 《Marine pollution bulletin》2002,44(1):16-24

Tests for the acute toxicity of tributyltin (TBT) were conducted on amphipod crustaceans collected from Otsuchi Bay, Japan. Five species of caprellids and three species of gammarids, which belong to a closely related ecological niche, were used for the exposure experiments at seven test concentrations (0, 0.001, 0.01, 0.1, 1, 10 and 100 microg TBTCl/l) for 48 h at 20 degrees C. The 48-h LC50 values of the caprellids were 1.2-6.6 microg TBTCl/l, and these were significantly lower than those of the gammarids (17.8-23.1 microg TBTCl/l). This suggests that caprellids are more sensitive to TBT than gammarids. Furthermore, the proportions of TBT and its derivatives, dibutyltin (DBT) and monobutyltin (MBT), were measured in the amphipods collected from Otsuchi Bay. In the caprellids, TBT was the predominant compound, accounting for 72% of the total butyltin which reflected the butyltin ratio in seawater, while in the gammarids, TBT's breakdown products (DBT and MBT) predominated, accounting for 75% of the total butyltin. This difference suggests that caprellids may have lower metabolic capacity to degrade TBT than gammarids. Therefore, the difference in sensitivity to TBT among the amphipods is thought to be related to the species-specific capacity to metabolize TBT.  相似文献   

Assessing the suitability of data from Sentinel-1A and 2A for crop classification     

Rei Sonobe  Yuki Yamaya  Hiroshi Tani  Xiufeng Wang  Nobuyuki Kobayashi  Kan-ichiro Mochizuki 《地理信息系统科学与遥感》2017,54(6):918-938

Sentinel-1A C-SAR and Sentinel-2A MultiSpectral Instrument (MSI) provide data applicable to the remote identification of crop type. In this study, six crop types (beans, beetroot, grass, maize, potato, and winter wheat) were identified using five C-SAR images and one MSI image acquired during the 2016 growing season. To assess the potential for accurate crop classification with existing supervised learning models, the four different approaches namely kernel-based extreme learning machine (KELM), multilayer feedforward neural networks, random forests, and support vector machine were compared. Algorithm hyperparameters were tuned using Bayesian optimization. Overall, KELM yielded the highest performance, achieving an overall classification accuracy of 96.8%. Evaluation of the sensitivity of classification models and relative importance of data types using data-based sensitivity analysis showed that the set of VV polarization data acquired on 24 July (Sentinel-1A) and band 4 data (Sentinel-2A) had the greatest potential for use in crop classification.  相似文献