Simultaneous Determination of Cd,In, Tl and Bi by Isotope Dilution‐Internal Standardisation ICP‐QMS with Corrections Using Externally Measured MoO+/Mo+ Ratios     

Akio Makishima  Hiroshi Kitagawa  Eizo Nakamura 《Geostandards and Geoanalytical Research》2011,35(1):57-67

A method for the simultaneous determination of Cd with In, Tl and Bi by isotope dilution‐internal standardisation (ID‐IS) ICP‐QMS using the same aliquot for rare earth element and other trace element determinations was developed. Samples mixed with an enriched ¹⁴⁹Sm spike were decomposed using a HF‐HClO₄ mixture, which was evaporated and then diluted with HNO₃. After determination of Sm by ID‐ICP‐QMS and Cd, In, Tl and Bi concentrations were determined using the ¹⁴⁹Sm intensity as an internal standard. The interference of MoO⁺ on Cd⁺ was corrected using the MoO⁺/Mo⁺ ratio separately measured using a Mo standard solution, and the validity of the externally determined oxide‐forming ratio correction was evaluated. The MoO⁺/Mo⁺ ratios measured using the standard solution and samples were ～ 0.0002 and < 0.002, respectively. Detection limits for Cd, In, Tl and Bi in silicate samples were at levels of < 1 ng g^?1 with a total uncertainty of < 7%. Cadmium in the carbonaceous chondrites, Orgueil (CI1), Murchison (CM2) and Allende (CV3) as well as Cd, In, Tl and Bi in the reference materials, JB‐2, JB‐3, JA‐1, JA‐2, JA‐3, JP‐1 (GSJ), BHVO‐1, AGV‐1, PCC‐1 and DTS‐1 (USGS) and NIST SRM 610, 612, 614 and 616 were determined to show the applicability of this method.  相似文献   

日本内陆地震活动的迁移与扩散          下载免费PDF全文

吉田明夫  细野耕司 《地震工程学报》1989,11(4):105-116

本文研究了日本内陆及其外围海域发生大地震后的地震活动迁移现象。在所研究的6个震例中,一个共同的特点是,地震活动的迁移总是沿着地壳内的活动地质构造带发生。有时可以根据地震活动的迁移来进一步确定活动构造带的存在。把板块边缘地区的地震活动类比为沿着力学偶合平面迁移和扩散,我们可以认为,岛上的活动构造带对应着地壳块体的力学相互作用边界。地震迁移的形式可能不只一种。在我们所研究的震例中发现了以下特征:地震迁移速度约为几km/年;大地震震源区之间存在着地震空区;在每一条地震带上有一定的地震活动周期。地震迁移的一种可能机制是:由于地壳块体的相对运动,在其边界上的凹凸不平区造成了构造应力集中,这些凹凸不平区相继地发生破裂,形成了地震迁移。  相似文献   

Effects of dust scattering albedo and 2175-Å bump on ultraviolet colours of normal disc galaxies     

Akio K. Inoue  Veronique Buat  Denis Burgarella  Pasquale Panuzzo  Tsutomu T. Takeuchi †  Jorge Iglesias-Páramo 《Monthly notices of the Royal Astronomical Society》2006,370(1):380-398

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Mineral chemistry of MUSES‐C Regio inferred from analysis of dust particles collected from the first‐ and second‐touchdown sites on asteroid Itokawa     

Tomoki Nakamura  Aiko Nakato  Hatsumi Ishida  Shigeru Wakita  Takaaki Noguchi  Michael E. Zolensky  Masahiko Tanaka  Makoto Kimura  Akira Tshuchiyama  Toshihiro Ogami  Takahito Hashimoto  Mitsuru Konno  Masayuki Uesugi  Toru Yada  Kei Shirai  Akio Fujimura  Ryuji Okazaki  Scott. A. Sandford  Yukihiro Ishibashi  Masanao Abe  Tatsuaki Okada  Munetaka Ueno  Junichiro Kawaguchi 《Meteoritics & planetary science》2014,49(2):215-227

The mineralogy and mineral chemistry of Itokawa dust particles captured during the first and second touchdowns on the MUSES‐C Regio were characterized by synchrotron‐radiation X‐ray diffraction and field‐emission electron microprobe analysis. Olivine and low‐ and high‐Ca pyroxene, plagioclase, and merrillite compositions of the first‐touchdown particles are similar to those of the second‐touchdown particles. The two touchdown sites are separated by approximately 100 meters and therefore the similarity suggests that MUSES‐C Regio is covered with dust particles of uniform mineral chemistry of LL chondrites. Quantitative compositional properties of 48 dust particles, including both first‐ and second‐touchdown samples, indicate that dust particles of MUSES‐C Regio have experienced prolonged thermal metamorphism, but they are not fully equilibrated in terms of chemical composition. This suggests that MUSES‐C particles were heated in a single asteroid at different temperatures. During slow cooling from a peak temperature of approximately 800 °C, chemical compositions of plagioclase and K‐feldspar seem to have been modified: Ab and Or contents changed during cooling, but An did not. This compositional modification is reproduced by a numerical simulation that modeled the cooling process of a 50 km sized Itokawa parent asteroid. After cooling, some particles have been heavily impacted and heated, which resulted in heterogeneous distributions of Na and K within plagioclase crystals. Impact‐induced chemical modification of plagioclase was verified by a comparison to a shock vein in the Kilabo LL6 ordinary chondrite where Na‐K distributions of plagioclase have been disturbed.  相似文献   

Space weathered rims found on the surfaces of the Itokawa dust particles     

Takaaki Noguchi  Makoto Kimura  Takahito Hashimoto  Mitsuru Konno  Tomoki Nakamura  Michael E. Zolensky  Ryuji Okazaki  Masahiko Tanaka  Akira Tsuchiyama  Aiko Nakato  Toshinori Ogami  Hatsumi Ishida  Ryosuke Sagae  Shinichi Tsujimoto  Toru Matsumoto  Junya Matsuno  Akio Fujimura  Masanao Abe  Toru Yada  Toshifumi Mukai  Munetaka Ueno  Tatsuaki Okada  Kei Shirai  Yukihiro Ishibashi 《Meteoritics & planetary science》2014,49(2):188-214

On the basis of observations using Cs‐corrected STEM, we identified three types of surface modification probably formed by space weathering on the surfaces of Itokawa particles. They are (1) redeposition rims (2–3 nm), (2) composite rims (30–60 nm), and (3) composite vesicular rims (60–80 nm). These rims are characterized by a combination of three zones. Zone I occupies the outermost part of the surface modification, which contains elements that are not included in the unchanged substrate minerals, suggesting that this zone is composed of sputter deposits and/or impact vapor deposits originating from the surrounding minerals. Redeposition rims are composed only of Zone I and directly attaches to the unchanged minerals (Zone III). Zone I of composite and composite vesicular rims often contains nanophase (Fe,Mg)S. The composite rims and the composite vesicular rims have a two‐layered structure: a combination of Zone I and Zone II, below which Zone III exists. Zone II is the partially amorphized zone. Zone II of ferromagnesian silicates contains abundant nanophase Fe. Radiation‐induced segregation and in situ reduction are the most plausible mechanisms to form nanophase Fe in Zone II. Their lattice fringes indicate that they contain metallic iron, which probably causes the reddening of the reflectance spectra of Itokawa. Zone II of the composite vesicular rims contains vesicles. The vesicles in Zone II were probably formed by segregation of solar wind He implanted in this zone. The textures strongly suggest that solar wind irradiation damage and implantation are the major causes of surface modification and space weathering on Itokawa.  相似文献   

Precursory activity in seismic belts containing the focal region of forthcoming large intraplate earthquake     

Akio Yoshida 《Tectonophysics》1987,140(2-4):131-143

Seismic activity in the region surrounding the foci is investigated for three severe earthquakes (two with a magnitude of 6.1 and one with a magnitude of 5.3) which have occurred in Japan in recent years. The most conspicuous feature commonly noticed is precursory activation of seismic belts which include the focal regions of main shocks. The repetition of the same pattern in the space-time distribution of earthquake occurrence along the seismic belt is also observed for each case. The precursory activity of seismic belts terminates in rather a short period and, after that, the area around the focus of the forthcoming large earthquake becomes quiescent, which demonstrates the appearance of the seismic gap of the second kind (Mogi, 1979). The periods of seismic quiescence for the cases investigated in this paper are longer than those which are given by the regression relationship between earthquake magnitude and precursor time proposed for example, by Sekiya (1977). However, our definition of anomalous seismic activity is clear, and it is possible to give a physical meaning to it as an increase in the local stress field in the seismic belt. We propose that a kind of coupling between intraplate tectonic blocks, analogous to interplate coupling in the subduction region, is responsible for the formation of the stress field relevant to these earthquakes. Although this is at present only one of the possible viewpoints on the formation of the focal region of large intraplate earthquakes, it may be worthwhile to study various precursory phenomena in-connection with this hypothesis.  相似文献   

Preferred orientation of phyllosilicate [001] in matrix of Murchison meteorite and possible mechanisms of generating the oriented texture in chondrites     

Akio Fujimura  Manabu Kato  Mineo Kumazawa 《Earth and Planetary Science Letters》1983

Preferred orientation of the dominant phyllosilicate phase (serpentine) in the matrix of the Murchison meteorite (C2) was determined by X-ray pole figure goniometry. The basal plane (001) of the phyllosilicate shows a clear preferred orientation of an axial concentration type. The preferred orientation is very weak in comparison with the orientations of known terrestrial tectonites, and it resembles the weakest case observed in the loosely consolidated clayey sediments from the deep ocean bottom. However, gentle sedimentation of platy phyllosilicate grains on a flat surface under a weak gravity field does not generate a sufficient preferred orientation. It is suggested that the preferred orientation in the matrix of Murchison was generated by uniaxial compaction, and the magnitude of strain to give rise to the observed degree of preferred orientation is evaluated as ?9%. There are two possible explanations of the deformation: dynamic compression caused by impact, and static compaction in a parent body. Though the latter case appears to be appropriate in the present case, it is not straightforward, however, to conclude that the suggested deformation is caused by burial compaction along gravity under lithostatic stress in a small primitive parent body.  相似文献   

Characteristics of vertical land movement and microearthquake activity in the northeastern Japan arc     

Hiroshi Ishii  Yoichiro Komukai  Akio Takagi 《Tectonophysics》1981,77(3-4)

Methods have been devised for analyzing vertical land movement and seismicity data using two-dimensional Chebychev functions and oblique projections. A filtering operation in the space domain is made possible by use of a two-dimensional Chebychev function. The oblique projections give an intuitive understanding of land deformation. Characteristic aspects of vertical land movement obtained by precise levelling and of the energy release of microearthquakes with depths shallower than 20 km in the northeastern Japan arc were investigated in detail applying these methods.Lineations with wavelength of about 20–60km trending towards NE—SW were found for both the land deformation and the seismicity. It should be noted that this trend is almost perpendicular to the direction of the strain migration and is related to other geophysical information.  相似文献   

Microstructural development of fine-grained quartz aggregates by syntectonic recrystallization     

Toshiaki Masuda  Akio Fujimura   《Tectonophysics》1981,72(1-2)

Experimental study of syntectonic recrystallization of fine-grained quartz aggregates was carried out in order to simulate the development of some natural microstructures of quartz tectonites and to understand their formation condition. Agate was axially compressed with a constant-strain-rate apparatus. Experiments were conducted at 4 kbar solid confining pressure, 700–1000°C and 10⁻⁴-10⁻⁶ sec⁻¹ to 10%–45% strain. In all runs, deformation has proceeded under wet condition caused by dehydration of pyrophyllite used as pressure medium.Two different types of microstructure were distinguished in the deformed specimens. One is P-type which is characterized by equant, equidimensional, and polygonal grains. The other is S-type which is characterized by the highly oblate grains with the largest dimension perpendicular to the compression axis. The P-type microstructure is developed at higher temperatures and slower strain rates, while the S-type developed at lower temperatures and faster strain rates. The transition between the S- and P-types is found to be very sharp.  相似文献   

Fluctuation in volume transport distribution accompanied by the Kuroshio front migration in the Tokara Strait   总被引：1，自引：0，他引：1  

Akio Maeda  Toru Yamashiro  Masahito Sakurai 《Journal of Oceanography》1993,49(2):231-245

A relation between migration of the Kuroshio front and fluctuation of distribution of volume transport in the Tokara Strait was described, using sea level records at five tide gauge stations around the strait and data which were composed of sea surface temperature, XBT casts, sea surface salinity and velocities at 20 m, 75 m and 150 m depths taken en route a ferryboat. The Kuroshio front extends to about 150 m depth. The sea surface salinity and the horizontal velocities abruptly change at the front. There is a good correlation in a period range from half a month to two months between the migration of the front, which is not only at the surface but also in the subsurface, and the sea level fluctuation at Nakano-shima. A northward migration of the front with a period range from 17 to 50 days decreases the transport in the southern strait between Naze and Nakano-shima but increases in the northern strait between Nakano-shima and Sata-misaki. The northward migration intensifies inflow into Kagoshima Bay and the Ohsumi Branch Current. Correlation between the transport in the northern strait and the Ohsumi Branch Current is significant in the period range from 30 to 50 days. In this significant period range, the former leads the latter by about 3 days.  相似文献