Fine-grained aggregates in L3 chondrites     

Seiko Watanabe  Masao Kitamura  Nobuo Morimoto 《Earth and Planetary Science Letters》1987,86(2-4)

The textures and chemical compositions of the constituent minerals of the fine-grained aggregates (FGA's) of L3 chondrites were studied by the backscattered electron image technique, electron probe microanalysis, and transmission electron microscopy. Plagioclase and glass in the interstices between fine grains of olivine and pyroxene indicate that the FGA's once partly melted. Compositional zoning and decomposition texture of pyroxenes are similar to those observed in chondrules, indicating a common cooling history of the FGA's and chondrules. Therefore, the mechanism that caused melting of the FGA's is considered to be the same as for chondrules. Bulk compositions of the FGA's are within the range of those of chondrules, so some chondrules probably were produced by complete melting of the same precursor materials as those of the FGA's. The precursor materials must have included fine olivine and other grains that probably are condensates.  相似文献   

Petrographic features of a high-temperature granite just newly solidified magma at the Kakkonda geothermal field, Japan     

Munetake Sasaki  Koichiro Fujimoto  Takayuki Sawaki  Hitoshi Tsukamoto  Osamu Kato  Ryo Komatsu  Nobuo Doi  Masakatsu Sasada 《Journal of Volcanology and Geothermal Research》2003,121(3-4):247-269

A 3729-m-deep geothermal research well, WD-1a, provides us with a unique opportunity to study initial petrographic features of a high-temperature granite just after solidification of magma. The well succeeded in collecting three spot-cores of the Kakkonda Granite that is a pluton emplaced at a shallow depth and regarded as a heat source of the active Kakkonda geothermal system. The core samples were collected at the present formation temperatures of 370, 410 and over 500°C. These samples are granodiorite to tonalite consisting mainly of plagioclase, quartz, hornblende, biotite and K-feldspar. A sample collected at a formation temperature of over 500°C possesses the following remarkable petrographic features compared to the other two samples. Interstitial spaces are not completely sealed. K-feldspar exhibits no perthite by the exsolution of albite lamella. Quartz includes glassy melt inclusions without devitrification. Hornblende is less intensively altered to actinolite, and biotite is not altered. This study directly confirmed that perthite in K-feldspar is a recrystallization texture formed at 410–500°C based on a comparison of the in situ temperatures of the samples. Chemical compositions of minerals were analyzed to compare temperatures determined from geothermometers in several publications to the in situ temperatures of the samples.  相似文献   

The build-up of the colour–magnitude relation as a function of environment     

Masayuki Tanaka  Tadayuki Kodama  Nobuo Arimoto  Sadanori Okamura  Keiichi Umetsu  Kazuhiro Shimasaku  Ichi Tanaka  Toru Yamada 《Monthly notices of the Royal Astronomical Society》2005,362(1):268-288

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Tsunami Assessment for Risk Management at Nuclear Power Facilities in Japan     

Ken Yanagisawa  Fumihiko Imamura  Tsutomu Sakakiyama  Tadashi Annaka  Tomoyoshi Takeda  Nobuo Shuto 《Pure and Applied Geophysics》2007,164(2-3):565-576

The present study focuses on evaluation of the maximum and minimum water levels caused by tsunamis as risk factors for operation and management at nuclear power facilities along the coastal area of Japan. Tsunamis generated by submarine earthquakes are examined, basing literature reviews and databases of information on historical tsunami events and run-up heights. For simulation of water level along the coast, a numerical calculation system should be designed with computational regions covering a particular site. Also the calculation system should be verified by comparison of historical and calculated tsunami heights. At the beginning of the tsunami assessment, the standard faults, their locations, mechanisms and maximum magnitudes should be carefully estimated by considering historical earthquake-induced tsunamis and seismo-tectonics at each area. Secondly, the range of errors in the model parameters should be considered since earthquakes and tsunamis are natural phenomena that involve natural variability as well as errors in estimating parameters. For these reasons, uncertainty-induced errors should be taken into account in the process of tsunami assessment with parametric study of the tsunami source model. The element tsunamis calculated by the standard fault models with the errors would be given for the design. Then, the design tsunami can be selected among the element tsunamis with the most significant impact, maximum and minimum water levels, on the site, bearing in mind the possible errors in the numerical calculation system. Finally, the design tsunami is verified by comparison with the run-up heights of historical tsunamis, ensuring that the design tsunami is selected as the highest of all historical and possible future tsunamis at the site.  相似文献   

Studying air pollution with kitt peak solar flux atlas — analysis method and results of observation     

Jianguo Niu  Hiroaki Kuze  Nobuo Takeuchi 《大气科学进展》2000,17(3):363-374

For the measurement of atmospheric NO2 vertical column density (VCD), Kitt Peak Solar Flux Atlas can be substituted as an extraterrestrial solar radiation. Compared with differential analysis method, the Taylor expansion of integrated transfer equation underestimates the VCD. This underestimation is as large as 35% when the amount of NO2 is 1 × 1017 cm－2 and observation is conducted with an air mass factor of 10. Even when the VCD is 2 × 1016 cm－2 and the air mass factor is 4, the relative error of the retrieved VCD is still no less than 3%. If the observation is restricted under the small air mass factor condition (≤4), with Kitt Peak Solar spectrum as an extraterrestrial solar radiation, only an atmospheric layer of 2 km thick from ground can be studied, which will make the absorption too weak to be detected by normal instruments.The VCD in winter Tokyo area was observed and analyzed by differential method, which shows a good precision even when the absorption is as low as 3%. The largest average VCD was about 1.3 × 1017 cm－2, and the lowest was about 1.3 × 1016 cm－2. The trend of its variation was almost the same as the ground level observation by Saltzman reagent method.  相似文献   

Studying Air Pollution with Kitt Peak Solar Flux Atlas—Analysis Method and Results of Observation     

Jianguo Niu  Hiroaki Kuze  Nobuo Takeuchi 《大气科学进展》2000,(3)

l.Introducti0nTwoflightsoftheSAGEIIIinstrumentwereplanedbeinglaunchedinJune2O00byRussianMeteor-3Mandin2002byInternationalSpaceStation(ISS).Itisexpectedthattheywouldofferinformationofalmostglobalcoverage.Theseinstrumentswillutilizetheselfcal-ibratingsolaroccultationtechniquetomeasureprofilesofaerosoIextinctionfrom0to4Okm,ozonefrom6to85km,nitrogendioxidefroml0to5Okm,andwatervaporfrom0to5Okm,andutilizelunaroccultationobservati0nstomonitorthekeynighttimesPecies,nitrogentrioxidefrom22to55k…  相似文献   

A tectono-genetic model for porphyry–skarn–stratabound Cu–Au–Mo–Fe and magnetite–apatite deposits along the Middle–Lower Yangtze River Valley, Eastern China     

Jingwen Mao  Guiqing Xie  Chao Duan  Franco Pirajno  Dazio Ishiyama  Yuchuan Chen 《Ore Geology Reviews》2011,43(1):294-314

The Middle–Lower Yangtze River Valley metallogenic belt (YRB), situated along the northern margin of the Yangtze craton, is characterized by porphyry–skarn–stratabound Cu–Au–Mo–Fe deposits in the areas of uplift and magnetite–apatite deposits in Cretaceous fault basins. Following detailed field investigations and a review of published data, we recognize two episodes of magmatism and mineralization in the YRB: 1) 156–137 Ma high-K calc-alkaline granitoids associated with 148–135 Ma porphyry–skarn–stratabound Cu–Au–Mo–Fe deposits and 2) 135–123 Ma shoshonitic series, associated with 134.9–122.9 Ma magnetite–apatite deposits. A-type granitoids and associated alkaline volcanic have a small age range from 126.5 to 124.8 Ma and are temporally, spatially and genetically associated with the second episode. The geodynamic history of the YRB did not experience the Paleozoic to Mesozoic lithospheric thickening that took place in the North China craton. This process is inferred to be linked to partial melting of the delaminated lower crust at high pressures, resulting in the development of C-type adakitic rocks. The petrochemical and Sr/Nd isotopic data show that both the shoshonitic series and A-type granitoids are quite different from adakites, with only some of the K-calc-alkaline granitoids having adakitic signatures. Previous ore genesis models were established based on an assumed relationship with adakites and a continuous tectono-thermal evolution from 150 to 100 Ma.All data obtained for the Middle–Lower Yangtze River region consistently show that the Tan–Lu regional strike-slip fault zone, initiated at 233 ± 6 to 225 ± 6 Ma from the collision between the North China and Yangtze cratons and was reactivated at ca. 160 Ma. The Tan–Lu fault was caused by the oblique subduction of the Izanagi plate, which along the YRB the low-angle subducted slab and the overlying crust was disrupted or broken due to the disharmonious movement of the two blocks. The high-K calc-alkaline granitoids magmas were derived from melting of the subducted slab, with some input of crustal material. These magmas were emplaced at the intersections between NE- and EW-trending faults and formed porphyry–skarn–stratabound Cu–Au–Mo–Fe deposits between 156 and 137 Ma. After 135 Ma the subducted plate changed its direction of motion to northeast, now running parallel to the Eurasian continental margin, and leading to large-scale continental extension. The shoshonitic series and subsequent A-type granitoids magmatism and the development of magnetite–apatite ores in the YRB, took place in both fault basins and NE-trending rifts between 135 and 124 Ma.  相似文献   

DESCRIPTION,CHEMICAL COMPOSITION AND NOBLE GASES OF THE CHONDRITE NOGATA     

Masako Shima  Sadao Murayama  Akihiko Okada  Hideo Yabuki  Nobuo Takaoka 《Meteoritics & planetary science》1983,18(2):87-102

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Lessons Learned from the 2011 Great East Japan Tsunami: Performance of Tsunami Countermeasures, Coastal Buildings, and Tsunami Evacuation in Japan   总被引：1，自引：0，他引：1  

Anawat Suppasri  Nobuo Shuto  Fumihiko Imamura  Shunichi Koshimura  Erick Mas  Ahmet Cevdet Yalciner 《Pure and Applied Geophysics》2013,170(6-8):993-1018

In 2011, Japan was hit by a tsunami that was generated by the greatest earthquake in its history. The first tsunami warning was announced 3 min after the earthquake, as is normal, but failed to estimate the actual tsunami height. Most of the structural countermeasures were not designed for the huge tsunami that was generated by the magnitude M = 9.0 earthquake; as a result, many were destroyed and did not stop the tsunami. These structures included breakwaters, seawalls, water gates, and control forests. In this paper we discuss the performance of these countermeasures, and the mechanisms by which they were damaged; we also discuss damage to residential houses, commercial and public buildings, and evacuation buildings. Some topics regarding tsunami awareness and mitigation are discussed. The failures of structural defenses are a reminder that structural (hard) measures alone were not sufficient to protect people and buildings from a major disaster such as this. These defenses might be able to reduce the impact but should be designed so that they can survive even if the tsunami flows over them. Coastal residents should also understand the function and limit of the hard measures. For this purpose, non-structural (soft) measures, for example experience and awareness, are very important for promoting rapid evacuation in the event of a tsunami. An adequate communication system for tsunami warning messages and more evacuation shelters with evacuation routes in good condition might support a safe evacuation process. The combination of both hard and soft measures is very important for reducing the loss caused by a major tsunami. This tsunami has taught us that natural disasters can occur repeatedly and that their scale is sometimes larger than expected.  相似文献   

Analysis of dust events in 2008 and 2009 using the lidar network, surface observations and the CFORS model     

Nobuo Sugimoto  Yukari Hara  Atsushi Shimizu  Tomoaki Nishizawa  Ichiro Matsui  Masataka Nishikawa 《Asia-Pacific Journal of Atmospheric Sciences》2013,49(1):27-39

The Asian dust events in 2008 (May 24–June 4 in 2008) and in 2009 (March 12–25, October 13–26, and December 15–28 in 2009) were analyzed with the lidar network observations, surface observations in China, Korea, Japan, and Mongolia, and with the chemical transport model CFORS. Transport of Asian dust and mixing of dust with air pollution aerosols were studied. The event of May 24 to June 4 in 2008 was a significant event unusually late in the spring dust season. The dust event of March 12–25, 2009 was an interesting example of elevated dust layer, and transport of dust from the elevated dust layer to the ground by the boundary layer activity was observed with the lidars and surface observations in Japan. The concentration of air pollution aerosols was relatively high during the dust event, and the results suggest that vertical structure as well as transport path is important for the mixing of dust and air pollution aerosols. The dust events in October and December 2009 were examples of dust events in autumn and winter. The online mode CFORS reproduced the observation data generally well, except for the event of May 24 to June 4 in 2008. The results of the fourdimensional variational assimilation of the lidar network data reproduced the dust concentration in Korea and Japan reasonably in that event.  相似文献