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Evaluation of the atmospheric transport model NIRE-CTM-96 by using measured radon-222 concentrations 总被引：1，自引：0，他引：1
SHOICHI TAGUCHI TAKAO IIDA JUN MORIIZUMI 《Tellus. Series B, Chemical and physical meteorology》2002,54(3):250-268
An atmospheric transport model, NIRE-CTM-96, was evaluated by using measured radon-222 concentrations. The model has 2.5×2.5 degree horizontal resolution and 15 vertical levels. Assimilated global meteorological data for 1990–1996 from the European Centre for Medium Range Weather Forecasts were used to drive the model. We used an emanation rate of radon-222 of 1 atom cm−2 s−1 over mostly ice-free land. Simulated concentrations were compared with measured concentrations for 22 sites worldwide including 10 stations in China. Simulated annual mean concentrations for Freiburg, Germany, and Socorro, New Mexico, and for four stations in northern China were consistent with the measured concentrations. Simulated daily concentrations for Ogasawara-Hahajima, Japan, correlated well with the measured concentrations. Simulated upper tropospheric concentrations for Moffet Field, California, demonstrated the cross-Pacific transport from central Eurasia and India-Indochina area. Simulated concentrations for two stations in southern China were almost half of the measured concentrations. Mixing layer depth in the model was consistent with other estimates which indicates higher emanation rate there. Simulated concentrations for the South Indian Ocean and the Antarctic during summer were significantly lower than the measured concentrations; this difference was accounted for when emanation from the ocean at a rate of 0.01 atom cm−2 s−1 was included in the model. The model failed to simulate amplitudes of high-concentration events at Mauna Loa. These high-concentration events were possibly a result of filament-like horizontal structure or laminated vertical structure. The vertical as well as horizontal resolution of the model were supposed to be insufficient to reproduce these fine structures. 相似文献
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Abstract: Synchrotron X-ray fluorescence analyses on individual hypersaline fluid inclusions were tested to using synchrotron source at Tsukuba (KEK), Japan. The XRF instrumentation at KEK meets the purpose of fluid inclusion analysis, nondestructive, multi–element, ppm detection limits, with micro spatial resolution. In practice, however, the quantitative chemical analysis of fluid inclusion requires further considerable data accumulation. Semi-quantitative distribution of elements (mass number > 25) in single fluid inclusion was obtained. 相似文献
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Yosuke IIDA Akira TSUCHIYAMA Toshihiko KADONO Kanako SAKAMOTO Tomoki NAKAMURA Kentaro UESUGI Tsukasa NAKANO Michael E. ZOLENSKY 《Meteoritics & planetary science》2010,45(8):1302-1319
Abstract– We investigated three‐dimensional structures of comet Wild 2 coma particle impact tracks using synchrotron radiation (SR) X‐ray microtomography at SPring‐8 to elucidate the nature of comet Wild 2 coma dust particles captured in aerogel by understanding the capture process. All tracks have a similar entrance morphology, indicating a common track formation process near the entrance by impact shock propagation irrespective of impactor materials. Distributions of elements along the tracks were simultaneously measured using SR‐XRF. Iron is distributed throughout the tracks, but it tends to concentrate in the terminal grains and at the bottoms of bulbs. Based on these results, we propose an impact track formation process. We estimate the densities of cometary dust particles based on the hypothesis that the kinetic energy of impacting dust particles is proportional to the track volume. The density of 148 cometary dust particles we investigated ranges from 0.80 to 5.96 g cm?3 with an average of 1.01 (±0.25) g cm?3. Moreover, we suggest that less fragile crystalline particles account for approximately 5 vol% (20 wt%) of impacting particles. This value of crystalline particles corresponds to that of chondrules and CAIs, which were transported from the inner region of the solar system to the outer comet‐forming region. Our results also suggest the presence of volatile components, such as organic material and perhaps ice, in some bulbous tracks (type‐C). 相似文献
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Pressure-Temperature Path Recorded in the Yangkou Garnet Peridotite, in Su-Lu Ultrahigh-pressure Metamorphic Belt, Eastern China 总被引：2，自引：0，他引：2
Chemical variations along with changes in microstructure ofthe principal constituent minerals make it possible to identifyat least four equilibrium stages in the evolution of the Yangkougarnet peridotite in the Su-Lu ultrahigh-pressure metamorphicbelt, eastern China: Stage I—a primary garnet lherzolitestage represented by coarse-grained (a few millimeters size)porphyroclastic aluminous pyroxenes + chromian spinel ±garnet; Stage II—an ultrahigh-pressure (UHP) stage definedby fine-grained matrix phases (0·1–0·3 mmsize) of garnet + extremely low-Al orthopyroxene + high-Na clinopyroxene+ chromite; Stage III—a medium-pressure stage definedby fine-grained mineral aggregates (<0·1–0·2mm size) mainly composed of aluminous spinel + high-Al orthopyroxenein the matrix; Stage IV—an amphibolite- to greenschist-faciesstage defined by poikiloblastic amphibole. Orthopyroxene–clinopyroxenethermometry and an empirical spinel barometer give temperaturesof around 800–830°C and pressures of 1·2–2·9GPa for porphyroclasts of Stage I. Garnet–orthopyroxene,garnet–clinopyroxene and empirical spinel geothermobarometersgive relatively uniform P–T conditions for the matrixgarnet–orthopyroxene–clinopyroxene–chromiteassemblage of Stage II ( 相似文献
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It has been previously suggested that the high-pressure metamorphic rock complex of Motalafjclla, central-western Spitsbergen, is older than Lower Silurian. An unconformity has been discovered at the base of a limestone which contains fossils similar to those reported as Lower Silurian from the same massif. This proves that the high-pressure metamorphics represent an older rock complex. The unconformity surface is inverted in the area, and large recumbent folds involving the Silurian Bulltinden Formation have been mapped. These folds are considered to be pre-Carboniferous. 相似文献
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天津蓟县硼矿床锰方硼石矿物的硼同位素研究 总被引：4，自引：0，他引：4
天津蓟县硼矿床是世界上唯一的沉积环境特殊的锰方硼石型硼矿床。矿床呈层状产于震旦系碳酸岩泥灰质岩系中 ,矿石呈鲕粒状或球粒状集合体 ,是成因条件极其特殊的矿床类型。含矿岩系为中元古界高于庄组沉积岩系 ,含矿岩性由下而上依次为含锰白云岩、页岩互层→含锰白云岩、泥硅质岩 ,夹锰方硼石矿层→含锰页岩、白云岩→厚层白云岩→薄层白云岩→厚层白云岩 ,锰方硼石矿体在矿层中呈断续相连的团块状或透镜状分布。硼矿物成分简单 ,只有锰方硼石一种矿物 ,锰方硼石矿体呈透镜状断续成层分布 ,东西延长达 30km。东部矿段以锰方硼石为主 ,向西部渐变为菱锰矿。矿石有块状和斑点状。块状矿石全部由球粒状锰方硼石集合体组成 ,w (B2 O3 ) >2 0 % ,最高可达 4 2 %以上。斑点状矿石中锰方硼石集中呈球粒状集合体分布于泥质白云岩中 ,w (B2 O3 ) <7%。首次研究了该硼矿床锰方硼石的硼同位素组成 ,δ11B值为 +6 7‰～ +14 9‰ ,均为正值 ,并且东部大峪矿段的硼同位素值低于西部柏树沟矿段的硼同位素值 ,表明该硼矿床的成矿元素属于海水来源。由于锰方硼石的微量元素组成难以与蒸发岩比较 ,且富含F、Ba、Sn热液富集的元素和Co、Ni、Cr、Ti基性岩浆岩元素以及与Fe、Mn大洋结核有关的元素组分 ,因此锰方硼石应属于 相似文献
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YOSHITAKA HASHIMOTO MIO EIDA TAKAYUKI KIRIKAWA RYOKO IIDA MIE TAKAGI NORIKO FURUYA AKIRA NIKAIZO TAKETO KIKUCHI TOSHIO YOSHIMITSU 《Island Arc》2012,21(1):53-64
Studying subduction zone fluid at shallow seismogenic depths is important to understand the nature of fault rocks at the updip limit of the seismogenic zone because fluid–rock interactions affect heat and mass transfer, and fault strength. In this study, we conducted detailed analyses of distribution of shear veins, and estimation of pressure–temperature conditions for shear vein formation for the Yokonami mélange, Shikoku, Southwest Japan, which is tectonic mélange zone in an on‐land accretionary complex. We found a seismogenic fault at the upper boundary of the Yokonami mélange, indicating that the Yokonami mélange was active at seismogenic depth. The field‐transect distribution of shear veins was examined. The frequency, the total and mean thicknesses of the shear veins were about 3.7 per meter, about 10 mm per meter, and about 3 mm per shear vein, respectively. Quartz within the shear veins shows elongate‐blocky textures, suggesting precipitation from advective flow. The pressure and temperature conditions for shear vein formation were examined by fluid inclusion analysis, ranging 175–225°C and 143–215 MPa, respectively. The temperature is almost consistent with the paleotemperature determined from vitrinite reflectance, suggesting that the shear veins were formed at up to the maximum depth. The depth might be consistent with that where the seismogenic fault was formed. On the basis of the pressure and temperature conditions and the distribution of shear veins, we estimated the minimum volumetric ratio of fluid to host rocks, assuming that the shear veins had precipitated from advective flow. The estimated amount of fluid is about 106 m3 per cubic meter of host rocks. The results suggest that a large amount of fluid migrates through mélange zones at shallow seismogenic depths. This fluid possibly originates from the dehydration of clay minerals from underthrusted sediments and an altered subducting slab. 相似文献
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辽东地区沉积变质硼矿床及硼同位素研究 总被引：2，自引：2，他引：2
辽东地区元古界硼矿床属于沉积变质硼矿。根据现代盐湖沉积 ,认为硼矿物沉积通常为硼砂 ,然后在区域变质作用过程中 ,硼砂矿物转变为硼镁矿物或硼铁矿等硼酸盐矿物 ,但辽东硼矿床中不同硼矿物的硼同位素有一定差别。电气石富10 B ,δ11B值较低或呈负值 ;而硼镁石与硼镁铁矿类矿物明显富集11B ,δ11B值较高 ,为 +2 3‰～ +17 4‰。根据水岩作用过程中硼同位素分馏特征的研究 ,11B与10 B比较有下列 4个特征 :( 1) 11B属于极不相容元素 ,优先进入水相 ,因此在变质残余矿物相中形成低的δ11B值 ;( 2 )在蚀变和交代变质反应中硅优先替代11B进入矿物晶格 ,因此在硅化交代中可以降低δ11B值 ,而脱硅反应中可以提高δ11B值 ;水化作用中 ,OH-带入11B ,使富水矿物具有较高的δ11B值 ;( 3)热水沉积及热液交代成因电气石均具有较低的δ11B值或者为负值 ;( 4)通过最近的研究表明 ,在热蒸馏过程中 ,硼同位素会发生明显的分馏 ,11B倾向于进入蒸汽相 ,而使残余相或后蒸馏相亏损11B ,形成较低的δ11B值。因此可以认为辽东地区元古界硼矿床属于热水沉积电气石岩在后期区域变质或热变质过程中分解出硼酸气水溶液交代镁碳酸盐形成硼镁石或硼镁铁矿矿物 ,而非蒸发沉积变质矿床。 相似文献
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