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501.
Harold C. Connolly Jr. Caroline Smith Gretchen Benedix Luigi Folco Kevin Righter Jutta Zipfel Akira Yamaguchi Hasnaa Chennaoui Aoudjehane 《Meteoritics & planetary science》2008,43(3):571-632
Abstract— In this edition of the Meteoritical Bulletin, 1443 approved meteorite names with their relevant data are reported, one from a specific location within Africa, 211 from Northwest Africa, 5 from KOREAMET, 598 from the Chinese Antarctic Expedition, 23 from the Americas, 151 from Asia, three from Australia, two from Europe, two from NOVA, and 447 from ANSMET that were not reported in the Meteoritical Bulletin no. 87. Also reported are 4 falls from the Americas. Some highlights of approved meteorites are 10 lunar (including NWA 5000, an 11.528 kg sample), 3 Martian, 4 irons (one from Indonesia), 2 ureilites, 5 mesosiderites, 1 pallasite, 6 brachinites, 3 CV3s, 4 CO3s, 8 CMs, 12 CK3s, and many more. Finally, the Committee on Nomenclature of the Meteoritical Society announces two new names series in North America. 相似文献
502.
In the western subarctic North Pacific, a wind-driven cyclonic circulation, called the western subarctic gyre (WSAG), exists. We examined year-to-year changes of the gyre and hydrographic structures, applying the altimetry-based gravest empirical mode (AGEM) method to hydrographic and altimetric sea surface height (SSH) data, and relation to the in situ variation of the temperature minimum layer, i.e., the dichothermal layer, depth at station K2 (47° N, 160° E). The AGEM-based geostrophic volume transport and the streamfunction of the WSAG in the top 1000-dbar layer show that the gyre changes substantially. From the late 1990s to the mid-2000s, the gyre shrunk northward. Due to the shrinkage, the halocline bottom, which is equivalent to the top of the main pycnocline, deepens at K2 outside the central part of the gyre. The downward displacement of the dichothermal layer at K2 was found to be significantly related to that of the underlying halocline due to the northward shrinkage of the WSAG. 相似文献
503.
ABSTRACTWhen applying a distributed hydrological model in urban watersheds, grid-based land-use classification data with 10 m resolution are typically used in Japan. For urban hydrological models, the estimation of the impervious area ratio (IAR) of each land-use classification is a crucial factor for accurate runoff analysis. In order to assess the IAR accurately, we created a set of vector-based “urban landscape GIS delineation” data for a typical urban watershed in Tokyo. By superimposing the vector-based delineation map on the grid-based map, the IAR of each grid-based land-use classification was estimated, after calculating the IARs of all grid cells in the entire urban watershed. As a result, we were able to calculate the frequency distribution of IAR for each land-use classification, as well as the spatial distribution of IARs for the urban watershed. It is evident from the results that the reference values of IAR for the land-use classifications were estimated very roughly and inherited errors of between about 7% and 70%, which corresponds to more than 100 mm increase of direct runoff for the 1500 mm annual average precipitation.
Editor D. Koutsoyiannis; Guest editor E. Volpi 相似文献
504.
Spatial backshore processes were investigated through field observations of topography and median sand grain size at a sandy beach facing the Pacific Ocean in Japan. A comparison of the backshore profile and cross‐shore distribution of the median sand grain size in 1999 and 2004 revealed an unusual sedimentary process in which sand was coarsened in a depositional area in the 5‐year period, although sediment is generally coarsened in erosional areas. In support of these observations, monthly spatial field analyses carried out in 2004 demonstrated a remarkable backshore coarsening process triggered by sedimentation in the seaward part of the backshore during a storm event. In order to elucidate mechanisms involved in the backshore coarsening process, thresholds of movable sand grain size under wave and wind actions (a uniform parameter for both these cases) in the onshore and offshore directions were estimated using wave, tide, and wind data. The cross‐shore distributions of the estimated thresholds provided reasonable values and demonstrated a coarsening mechanism involving the intermediate zone around the shoreline under alternating wave and wind actions as a result of which coarse sand was transported toward the seaward part of the backshore by large waves during storms and then toward the landward part by strong onshore winds. The 5‐year backshore coarsening is most certainly explained by repetition of short‐term coarsening mechanisms caused by wave‐induced sand transport occurring from the nearshore to the intermediate zone. Copyright © 2010 John Wiley & Sons, Ltd 相似文献
505.
Keika Horiguchi Sadato Ueki Yuji Sano Naoto Takahata Akira Hasegawa George Igarashi 《Island Arc》2010,19(1):60-70
In order to study the precise geographical distribution of helium isotope ratios in northeastern Japan and compare it with geophysical data, we collected 43 gas and water samples from hot and mineral springs in the region where the ratio had never been reported, and measured the 3 He/4 He and 4 He/20 Ne ratios of these samples. It was found that the 3 He/4 He ratios show clear contrasts between the forearc and the back-arc regions in the Tohoku district in northeastern Japan. In the forearc region, the ratios are smaller than 1 RA (1 RA = 1.4 × 10−6 ; RA means the 3 He/4 He ratio of the atmosphere). On the other hand, those along the volcanic front and in the back-arc region are apparently higher. Moreover, we found a variation in the 3 He/4 He ratios along the volcanic front. In Miyagi Prefecture (38–39°N), the ratios range from 2 to 5 RA . On the other hand, the ratios are less than 1 RA in and around the southern border between Iwate and Akita Prefectures (39–39.5°N). Comparing the distribution of helium isotope ratios to results of recent geophysical studies, we found that the features in geographical distribution of helium isotope ratios are similar to those of seismic low-velocity zone distributions and high Qp−1 distributions in the uppermost mantle. These observations strongly suggest that the helium isotope ratios reflect the distribution of melts in the uppermost mantle and are a useful tool for investigating the origin, behavior, and distribution of deep fluids and melts. 相似文献
506.
Yamada M Takada H Toyoda K Yoshida A Shibata A Nomura H Wada M Nishimura M Okamoto K Ohwada K 《Marine pollution bulletin》2003,47(1-6):105-113
Polycyclic Aromatic Hydrocarbons (PAHs) are one of the components found in oil and are of interest because some are toxic. We studied the environmental fate of PAHs and the effects of chemical dispersants using experimental 500 l mesocosm tanks that mimic natural ecosystems. The tanks were filled with seawater spiked with the water-soluble fraction of heavy residual oil. Water samples and settling particles in the tanks were collected periodically and 38 PAH compounds were analyzed by gas chromatography-mass spectrometry (GC-MS). Low molecular weight (LMW) PAHs with less than three benzene rings disappeared rapidly, mostly within 2 days. On the other hand, high molecular weight (HMW) PAHs with more than four benzene rings remained in the water column for a longer time, up to 9 days. Also, significant portions (10-94%) of HMW PAHs settled to the bottom and were caught in the sediment trap. The addition of chemical dispersant accelerated dissolution and biodegradation of PAHs, especially HMW PAHs. The dispersant amplified the amounts of PAHs found in the water column. The amplification was the greater for the more hydrophobic PAHs, with an enrichment factor of up to six times. The increased PAHs resulting from dispersant use overwhelmed the normal degradation and, as a result, higher concentrations of PAHs were observed in water column throughout the experimental period. We conclude that the addition of the dispersant could increase the concentration of water column PAHs and thus increase the exposure and potential toxicity for organisms in the natural environment. By making more hydrocarbon material available to the water column, the application of dispersant reduced the settling of PAHs. For the tank with dispersant, only 6% of chrysene initially introduced was detected in the sediment trap whereas 70% was found in the trap in the tank without dispersant. 相似文献
507.
The objective of this paper is to provide an analytical basis for the quantitative evaluation of damage to a reinforced concrete
structure based on the vibration data obtained by using the damage detection technique. A partial reinforced concrete system
of a weak beam/strong column moment frame is chosen as an example. A pushover analysis is carried out in order to numerically
examine both the story shear-relative displacement characteristics and the associated damage level. In the analysis, a two
dimensional nonlinear finite element analysis is employed considering several constitutive models. As a result, the degradation
of the stiffness at the damaged story is characterized in association with the story relative displacement. It is also pointed
out that the rotation angle of the column-base is highly correlated with the story relative displacement. Based on the analytical
findings, quantitative approaches for a structural health monitoring system are suggested considering both the current sensor
technologies and those available in the future.
Supported by: Ministry of Education, Science, Sports and Culture, Grant-in-Aid for Scientific Research (Base Research (c)
(1), Research No. 14550555) 相似文献
508.
Yasuko?Okuyama-KusunoseEmail author Toshiro?Morikiyo Akiko?Kawabata Akira?Uyeda 《Contributions to Mineralogy and Petrology》2003,145(5):534-549
Carbon isotope fractionation between coexisting calcite and graphite (C ) has been studied in metamorphosed limestones from three thermal aureoles around Cretaceous granitic bodies (i.e., Tanohata, Tono, and Senmaya aureoles) in the Kitakami Mountains, Northeast Japan. C in each aureole decreases toward the granitic bodies, and becomes virtually uniform near the sillimanite isograd for metapelites, although calcite has variable isotopic ratios reflecting the original sedimentary compositions. The relationships indicate that isotopic equilibrium has been attained in metamorphosed limestone of sillimanite grade. Estimated C at the sillimanite isograd is similar in the Tanohata and Tono aureoles, but different in the Senmaya aureole with smaller carbon isotopic fractionations. From the temperature dependence of C and the negative dP/dT of andalusite–sillimanite equilibrium, we conclude that the sillimanite isograd in the Senmaya aureole was under higher temperature and lower pressure than in the other two localities. Temperatures at the sillimanite isograd are estimated by using existing calibrations of carbon isotopic exchange between calcite and graphite, whereas pressures are estimated from carbon isotopic temperatures and the andalusite–sillimanite equilibrium (Holdaway and Mukhopadhyay 1993a). Consistency of the P–T estimates is examined in the light of phase equilibria in the pelitic system. The estimated pressures at the sillimanite isograd are at about 2.1–2.7(±0.2) kbar for the Tanohata and Tono aureoles and less than 1 kbar for the Senmaya aureole, respectively. Geobarometry of sillimanite isograd in thermal aureoles indicates a marked difference in the depth of solidification of upper crustal granitoids: the Senmaya pluton has intruded and solidified at a very shallow level of less than 4 km whereas the Tanohata and Tono plutons are more deep-seated (ca. 8–10 km). The method can also be an effective tool in studying low-pressure type metamorphism in which geothermobarometry using garnet is not always applicable.Editorial responsibility: J. Hoefs 相似文献
509.
Yuji?Ichiyama Akira?IshiwatariEmail author 《Contributions to Mineralogy and Petrology》2005,149(4):373-387
Sills, pillow lavas and hyaloclastites of the HFSE-rich picrite and related rocks (ankaramite and basanite) occur in the Middle Permian cherts in the Mino Jurassic accretionary complex, southwestern Japan. These rocks show systematic trace element patterns enriched in incompatible elements, which indicate that the associated ankaramite and basanite are formed by the crystal fractionation from the picrite. The presence of the hyaloclastite in the chert sequence covering a large tholeiitic greenstone body indicates that the picrite was produced in an intraoceanic setting in the Middle Permian time subsequent to the extrusion of the voluminous oceanic island tholeiite. The Mino picrites resemble the Siberian meimechite and Polynesian picrites in its HFSE-rich chemical composition. The HFSE enrichment in these picrites cannot be explained by low degree of partial melting of primitive peridotite mantle only, and needs a source material involving recycled oceanic crust (eclogite). The differences in MgO content and in TiO2/Al2O3 and Zr/Y ratios among the HFSE-rich picrites indicate that the melting pressure increases from the Polynesian picrite through Mino picrite to Siberian picrite. This may reflect the increasing thickness of the overlying lithosphere at the time and place of magmatism. The HFSE-rich picrites may be a product of a superplume event. The presence of HFSE-rich picrite in Mino and Siberia indicate that the superplume activities occur in both continental and oceanic settings in the Permian time. 相似文献
510.
Two-dimensional coda Q structure beneath Tohoku, NE Japan 总被引:1,自引:1,他引:0