Petrography,mineralogy, and geochemistry of lunar meteorite Sayh al Uhaymir 300     

Weibiao HSU  Aicheng ZHANG  Rainer BARTOSCHEWITZ  Yunbin GUAN  Takayuki USHIKUBO  Urs KRÄHENBÜHL  Rainer NIEDERGESAESS  Rudolf PEPELNIK  Ulrich REUS  Thomas KURTZ  Paul KURTZ 《Meteoritics & planetary science》2008,43(8):1363-1381

Abstract— We report here the petrography, mineralogy, and geochemistry of lunar meteorite Sayh al Uhaymir 300 (SaU 300). SaU 300 is dominated by a fine‐grained crystalline matrix surrounding mineral fragments (plagioclase, pyroxene, olivine, and ilmenite) and lithic clasts (mainly feldspathic to noritic). Mare basalt and KREEPy rocks are absent. Glass melt veins and impact melts are present, indicating that the rock has been subjected to a second impact event. FeNi metal and troilite grains were observed in the matrix. Major element concentrations of SaU 300 (Al₂O₃ 21.6 wt% and FeO 8.16 wt%) are very similar to those of two basalt‐bearing feldspathic regolith breccias: Calcalong Creek and Yamato (Y‐) 983885. However, the rare earth element (REE) abundances and pattern of SaU 300 resemble the patterns of feldspathic highlands meteorites (e.g., Queen Alexandra Range (QUE) 93069 and Dar al Gani (DaG) 400), and the average lunar highlands crust. It has a relatively LREE‐enriched (7 to 10 x CI) pattern with a positive Eu anomaly (?11 x CI). Values of Fe/Mn ratios of olivine, pyroxene, and the bulk sample are essentially consistent with a lunar origin. SaU 300 also contains high siderophile abundances with a chondritic Ni/Ir ratio. SaU 300 has experienced moderate terrestrial weathering as its bulk Sr concentration is elevated compared to other lunar meteorites and Apollo and Luna samples. Mineral chemistry and trace element abundances of SaU 300 fall within the ranges of lunar feldspathic meteorites and FAN rocks. SaU 300 is a feldspathic impact‐melt breccia predominantly composed of feldspathic highlands rocks with a small amount of mafic component. With a bulk Mg# of 0.67, it is the most mafic of the feldspathic meteorites and represents a lunar surface composition distinct from any other known lunar meteorites. On the basis of its low Th concentration (0.46 ppm) and its lack of KREEPy and mare basaltic components, the source region of SaU 300 could have been within a highland terrain, a great distance from the Imbrium impact basin, probably on the far side of the Moon.  相似文献   

Damping systems that are effective over a wide range of displacement amplitudes using metallic yielding component and viscoelastic damper in series          下载免费PDF全文

Masashi Yamamoto  Takayuki Sone 《地震工程与结构动力学》2014,43(14):2097-2114

A damper system that absorbs energy over a wide range of displacement amplitudes during building vibration was proposed. This system uses a serial connection of a metallic yielding component and viscoelastic damper with a displacement limit mechanism. Three types of the system were developed and tested: a diagonal bracing type, inverted V bracing type, and wall type. The test results showed that all these systems have damping ratios higher than 8% at small vibration amplitudes on the order of 0.1 mm. For a large vibration, a displacement limit mechanism with two pins limited the displacement of the viscoelastic damper as designed. Analytical simulations established that the system reduced the acceleration and the story drift to 60–70% and 80%, respectively, during a small earthquake compared with a conventional metallic yielding damper system. Furthermore, it showed an equivalent control performance during a severe earthquake. The damper system requires that a clearance be maintained for the displacement limit mechanism. However, this may be lost through construction error, residual displacement after an earthquake, and temperature effects. The changes in the clearance due to these effects were discussed. Copyright © 2014 John Wiley & Sons, Ltd.  相似文献   

尼罗河及其流域环境的近期变化：以文献为依据     

Shamik CHAKRABORTY  YASUDA Hiroshi  Abhik CHAKRABORTY  NABETA Hajime  KAWAI Takayuki  ISHIYAMA Shun 《资源与生态学报(英文版)》2015,6(5):345-352

The Nile is one of the longest rivers on the planet and an important freshwater source for the arid regions of Africa. It is also a river that is extensively affected by anthropogenic impact. This paper aims to provide an account of the social drivers that combine to cause extensive changes in the Nilotic environments. This paper is based on extensive review of literature backed up by field research. The main focus is on the lower Nile, where the effects of anthropogenic disturbances are most prominent. We argue that the Nile Basin is characterized by interrelated and compound problems of resource management, and managing this river system effectively requires shifting the focus from water related problems to a basin wide management agenda. We contend that knowledge of environmental history is important for this agenda shift, and the idea of benefit sharing can alleviate the growing stress on this extremely sensitive arid river basin.  相似文献   

Three-dimensional analysis of groundwater flow in neogene rocks at the Rokkasho low-level radioactive waste disposal center, Japan     

Tai Sasaki  Naro Hashimoto  Takayuki Nakato  Tomonari Shiraishi  Kazuaki Yajima  Tomoyuki Hishiya 《Engineering Geology》1998,49(3-4):337-343

As a preliminary step for predicting groundwater flow in a plateau 30–50 m above sea level, a model for three-dimensional analysis of groundwater flow was formulated and its validity was verified. The plateau consists of Neogene sedimentary rocks and a Quaternary deposit. Most of the groundwater originates in precipitation, with the groundwater table lying in the Quaternary deposit. Steady-state analysis was conducted by using the finite element method. The results of pore-water pressure measurement and water examination were useful in verifying the validity of the model. In constructing the model, reducing the hydraulic conductivity according to the depth on the basis of the results of the actual measurement was important.  相似文献   

Submarine flank eruption preceding caldera subsidence during the 2000 eruption of Miyakejima Volcano, Japan     

Takayuki Kaneko  Atsushi Yasuda  Taketo Shimano  Setsuya Nakada  Toshitsugu Fujii  Toshihiko Kanazawa  Azusa Nishizawa  Yoshihiro Matsumoto 《Bulletin of Volcanology》2005,67(3):243-253

During the early part of a seismic swarm preceding eruption and caldera formation at Miyakejima Volcano, discoloured sea surfaces were observed 1.5 km off the western coast of Miyakejima on 27 June 2000. A later survey of the area using a multi-beam side scan sonar and a remotely operated small submarine revealed four craters of 20–30 m diameter aligned east-west in a 100×10–30 m area on the seafloor, with hot water at 140°C being released from one of the centres. Each crater consists of submarine spatter overlain in part by scoria lapilli. Dredged spatter from the craters was fresh, and there was no evidence of activity of marine organisms on the spatter surface, indicating that the discoloured sea surface resulted from magmatic eruption on the seafloor. This eruption occurred when a westward-propagating seismic swarm, initiated beneath Miyakejimas summit, passed through the area. Finding new magma on the seafloor demonstrates that this seismic swarm was associated with intruding magma, moving outward from beneath Miyakejima. Submarine spatter shows flattened shapes with a brittle crust formed by cooling in water, and its composition is aphyric andesite of 54 wt% SiO₂. The spatter is similar in whole rock and mineral composition to spatter erupted in 1983. However, the wide range of Cl in melt inclusions in plagioclase of the 27 June submarine spatter shows that it is not simply a remnant of the 1983 magma, which has only high Cl melt inclusions in plagioclase. The mixed character of melt inclusions suggests involvement of a magma with low Cl melt inclusions. The magma erupted explosively on 18 August from Miyakejimas summit, considered as the second juvenile magma in this eruption, contains low Cl melt inclusions in plagioclase. Based on these observations and the eruption sequence, we present the following model: (1) A shallow magma chamber was filled with a remnant of 1983 magma that had evolved to a composition of 54–55 wt% SiO₂. (2) Injection of the 18 August magma into this chamber generated a mixed magma having a wide range of Cl in melt inclusions contained plagioclase. The magma mixing might have occurred shortly before the submarine eruption and could have been a trigger for the initiation of the removal of magma from the chamber as an extensive dyke, which eventually led to caldera subsidence.Editorial responsibility: S Nakada, T Druitt  相似文献   

Seasonal cycle of manganese in seawater in Harima Sound     

Takayuki Shiozawa  Akira Hoshika  Osamu Takimura  Terumi Tanimoto 《Journal of Oceanography》1982,38(1):15-20

Vertical and horizontal distributions of manganese in Harima Sound (Harima Nada, Seto Inland Sea) were measured in August and December 1979. High concentrations of dissolved and particulate manganese were found in bottom waters in August, suggesting that the bottom enrichment is probably due to the diffusion of dissolved manganese out of the sediment. From measured distributions, we estimate the annual flux of manganese at the sediment-water interface to be more than 800 tons per year, if Harima Sound is a closed system for manganese.  相似文献   

Sedimentation rate and heavy metal pollution in sediments in Harima Nada (Harima Sound), Seto Inland Sea     

Akira Hoshika  Takayuki Shiozawa  Eiji Matsumoto 《Journal of Oceanography》1983,39(2):82-87

Sedimentation rates were determined with the²¹⁰Pb technique in six sediment cores from Harima Nada (Harima Sound), Seto Inland Sea. The rate of deposition varies from 0.11 g cm^–2y^–1 in the northern part to 0.33 g cm^–2 y^–1 in the southern part of the basin. A marked increase in copper and zinc content was observed above a depth in the core corresponding to about 1900 A.D. as a result of increasing human activities. Anthropogenic input of copper and zinc decreased slightly after 1970. Natural background levels of copper and zinc in the sediment in this sound are 11–16 ppm and 100–120 ppm, respectively. The total amounts of anthropogenic copper and zinc in the sediments were estimated to be 110–180g cm^–2 and 610–1,280g cm^–2, respectively. These values constitute 40–50% of the total sedimentary input of copper and zinc in the sediments since about 1900 A.D.  相似文献   

Vertical distribution of particulate manganese and iron in the Beppu Bay     

Akira Hoshika  Osamu Takimura  Takayuki Shiozawa 《Journal of Oceanography》1978,34(6):261-264

Around the thermocline, difference in the depth of the maximum concentration between particulate manganese and iron was observed above the basin located at the south-western corner of the Beppu Bay, along with the remarkable difference in pH and Eh.  相似文献   

A Numerical Study of Turbulence Statistics and the Structure of a Spatially-Developing Boundary Layer Over a Realistic Urban Geometry     

Atsushi Inagaki  Manabu Kanda  Nurul Huda Ahmad  Ayako Yagi  Naoyuki Onodera  Takayuki Aoki 《Boundary-Layer Meteorology》2017,163(2):161-177

Sonic anemometer measurements are analyzed from two primary field programs and 12 supplementary sites to examine the behaviour of the turbulent heat flux near the surface with high wind speeds in the nocturnal boundary layer. On average, large downward heat flux is found for high wind speeds for most of the sites where some stratification is maintained in spite of relatively intense vertical mixing. The stratification for high wind speeds is found to be dependent on wind direction, suggesting the importance of warm-air advection, even for locally homogenous sites. Warm-air advection is also inferred from a large imbalance of the heat budget of the air for strong winds. Shortcomings of our study are noted.  相似文献   

Mass balance of heavy metals in the seto inland sea, Japan     

Akira Hoshika  Takayuki Shiozawa  Yasushi Kitano 《Marine Chemistry》1988,24(3-4)

To discuss the geochemical and environmental behavior of heavy metals in the Seto Inland Sea, the largest semi-enclosed coastal sea in Japan, mass balances of Cu and Zn were studied by application of a simple box model using sedimentation rates and heavy metal contents of core sediments. In 1980, total sedimentary loads of Cu and Zn over the whole area of the Sea were estimated to be 630 and 3500 tons year⁻¹, respectively. Further, the sedimentary loads without (natural) and with human activities were estimated separately to be, respectively, 320 and 310 tons year⁻¹ for Cu and 1800 and 1700 tons year⁻¹ for Zn. Total inputs of Cu and Zn into the Sea, in 1980 were estimated to be 870 and 4250 tons year⁻¹ about one half of this being the result of human activities. 70% of the Cu input and 80% of the Zn input are taken into the sediments. Mean residence times of Cu and Zn in the Sea are calculated to be ≈0.3 and 0.2 years, respectively. Since these values are relatively small compared to the mean residence time of the seawater (0.9 years), Cu and Zn supplied to the Sea are considered to be accumulated rapidly in the sediments.  相似文献