准噶尔板块东北缘富铌玄武岩的发现及其地质意义   总被引：4，自引：0，他引：4       下载免费PDF全文

张海祥  牛贺才  于学元  单强  HiroakiSato  JunichiIto 《地质找矿论丛》2003,18(1):71-72

富铌玄武岩是硅过饱和,富Ｎａ2Ｏ,ＴｉＯ2,Ｐ2Ｏ5,同时富集高场强元素的一类岛弧玄武岩,这类玄武岩的ｗ(Ｎｂ)>7×10-6,(ｗ(Ｌａ)/ｗ(Ｎｂ))ＭＮ<2。它是由来源于70100ｋｍ深处、受ａｄａｋｉｔｅ熔体交代过的地幔楔橄榄岩部分熔融形成的,是大洋板块俯冲作用的产物。目前发现的富铌玄武岩大多分布在环太平洋新生代岛弧环境,与洋壳俯冲作用密切相关[1 5]。本研究在准噶尔板块东北缘富蕴县的索尔库都克附近首次发现了富铌玄武岩。它产于下泥盆统托让格库都克组中、上部。该地层自下而上的岩石组合为:玄武岩 火山凝灰角砾岩 火山集块岩 含…  相似文献   

Shear-wave splitting detected by using downhole triaxial seismic detector during dilation of artificial subsurface fracture     

Hirokazu Moriya  Katsuro Tanaka  Hiroaki Niitsuma 《Geophysical Journal International》2006,164(2):401-410

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Collapse mechanism of the Paleogene Sakurae cauldron, SW Japan   总被引：1，自引：0，他引：1  

Hiroaki Komuro  Miki Aoyama  Tahei Arayashiki 《Bulletin of Volcanology》2006,68(7-8):631-640

The Paleogene Sakurae cauldron of SW Japan is characterized by a nested structure with a polygonal outline (21×13 km²) including a circular collapsed part (5 km in diameter). Total thickness of the caldera infill amounts to 2,000 m. The lower member of the infill consists mainly of felsic crystal tuff and lesser intercalated andesitic lava flows, whereas the upper member is composed of high-grade ignimbrite capped with a large rhyolitic lava dome. These members represent the first and second stage eruptions, respectively. Faults bounding the cauldron rim comprise intersecting radial and concentric faults, producing the polygonal outline of this cauldron. The primary collapse of this cauldron thus occurred as a polygonal caldera basin where products of the first stage eruption accumulated. In contrast, the inner collapse part is defined by a ring fracture system. This sector subsided concurrently with accumulation of the high-grade ignimbrite of the second stage eruption. This inner circular collapse thus represents syn-eruptional subsidence concurrent with the climactic eruption. Magma drainage during the first stage probably induced outward-dipping ring fractures in the chamber roof. Opening of the ring fractures following subsidence of the central bell-jar block caused rapid evacuation of magma as voluminous pumice flows, even though magma pressure may have decreased to some degree.  相似文献   

Analysis of runoff generation and soil erosion processes by using environmental radionuclides in semiarid areas of Mongolia   总被引：1，自引：0，他引：1  

Yuichi Onda  Hiroaki Kato  Maki Tsujimura  Dambaravjaa Oyunbaatar 《Journal of Hydrology》2007,333(1):124-132

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Construction and Characterization of an Atmospheric Simulation Smog Chamber   总被引：11，自引：0，他引：11  

武山  吕子峰  郝吉明  赵喆  李俊华 《大气科学进展》2007,24(2):250-258

Currently, air pollution in Beijing has become a complex problem with two types of source pollutants： coal smoke and photochemical smog. Furthermore the maximum hourly mean concentration of O3 increases continuously, especially in the summer. In order to simulate the photochemical reaction, develop an air quality simulation model and further improve the air quality of Beijing, a precisely temperature-controlled, indoor, smog chamber facility was designed and constructed at Tsinghua University. Characterization experiments have been carried out to acquire the basic parameters of the smog chamber, such as the wall loss rates of NO2, NO, O3, C3H6 and particulate matter （PM）, the intensity of ultraviolet （UV） light in the chamber, the reactivity of the purified air and the reproducibility of the experimental results. The results indicate that the facility performs up to specifications, and can meet the demands required for simulating the photochemical reaction. The effect of high primary contaminated PM on the formation of ozone and secondary organic aerosol （SOA） is under investigation.  相似文献   

Silicate Inclusions in Metamorphic Diamonds from the Ultra-High Pressure Kokchetav Complex (Kazakhstan)     

Mikhailenko  D. S.  Korsakov  A. V.  Ohfuji  Hiroaki  Sobolev  N. V. 《Doklady Earth Sciences》2021,496(2):142-145

Doklady Earth Sciences - Mineral inclusions in cubic diamonds from garnet–clinopyroxene rock of the Kokchetav massif were studied. The coexistence of fluid and silicate inclusions in the...  相似文献   

An assessment of uncertainties in VS profiles obtained from microtremor observations in the phased 2018 COSMOS blind trials     

Asten  Michael W.  Yong  Alan  Foti  Sebastiano  Hayashi  Koichi  Martin  Antony J.  Stephenson  William J.  Cassidy  John F.  Coleman  Jacie  Nigbor  Robert  Castellaro  Silvia  Chimoto  Kosuke  Cornou  Cécile  Cho  Ikuo  Hayashida  Takumi  Hobiger  Manuel  Kuo  Chun-Hsiang  Macau  Albert  Mercerat  E. Diego  Molnar  Sheri  Pananont  Passakorn  Pilz  Marco  Poovarodom  Nakhorn  Sáez  Esteban  Wathelet  Marc  Yamanaka  Hiroaki  Yokoi  Toshiaki  Zhao  Don 《Journal of Seismology》2022,26(4):757-780

Journal of Seismology - Site response is a critical consideration when assessing earthquake hazards. Site characterization is key to understanding site effects as influenced by seismic site...  相似文献   

Azimuthal dependence on amplifications for long-period ground motions propagating in the Kanto Basin,Japan     

Tsuno  Seiji  Noyori  Masanori  Yamanaka  Hiroaki 《Journal of Seismology》2022,26(2):373-385

Journal of Seismology - In the Kanto Basin, Japan, it has been reported that the dominant periods of long-period ground motions vary depending on the areas where earthquakes occurred. This suggests...  相似文献   

A new high-pressure and high-temperature polymorph of FeS     

Hiroaki Ohfuji  Nagayoshi Sata  Hisao Kobayashi  Yasuo Ohishi  Kei Hirose  Tetsuo Irifune 《Physics and Chemistry of Minerals》2007,34(5):335-343

A new polymorph of FeS has been observed at pressures above 30 GPa at 1,300 K by in situ synchrotron X-ray diffraction measurements in a laser-heated diamond anvil cell. It is stable up to, at least, 170 GPa at 1,300 K. The new phase (here called FeS VI) has an orthorhombic unit cell with lattice parameters a = 4.8322 (17) Å, b = 3.0321 (6) Å, and c = 5.0209 (8) Å at 85 GPa and 300 K. Its topological framework is based on the NiAs-type structure as is the case for the other reported polymorphs (FeS I-V). The unit cell of FeS VI is, however, more distorted (contracted) along the [010] direction of the original NiAs-type cell. For example, the c/b axial ratio is ～1.66 at 85 GPa and 300 K, which is considerably smaller than that of orthorhombic FeS II (～1.72) and NiAs-type hexagonal FeS V (=√3 ≈ 1.73). The phase boundary between FeS IV and VI is expected to be located around 30 GPa at 1,300 K. The phase transition is accompanied by gradual and continuous changes in volume and axial ratios and may be second order. At room temperature, FeS VI becomes stable over FeS III at pressures above 36 GPa. It is, therefore, suggested that the phase boundary of FeS III–VI and/or FeS IV–VI has negative pressure dependence.  相似文献   

Development of a Multi-Layer Urban Canopy Model for the Analysis of Energy Consumption in a Big City: Structure of the Urban Canopy Model and its Basic Performance   总被引：4，自引：0，他引：4  

Hiroaki?KondoEmail author  Yutaka?Genchi  Yukihiro?Kikegawa  Yukitaka?Ohashi  Hiroshi?Yoshikado  Hiroshi?Komiyama 《Boundary-Layer Meteorology》2005,116(3):395-421

A multilayer one-dimensional canopy model was developed to analyze the relationship between urban warming and the increase in energy consumption in a big city. The canopy model, which consists of one-dimensional diffusion equations with a drag force, has three major parameters: building width, distance between buildings, and vertical floor density distribution, which is the distribution of a ratio of the number of the buildings that are taller than some level to all the buildings in the area under consideration. In addition, a simplified radiative process in the canopy is introduced. Both the drag force of the buildings and the radiative process depend on the floor density distribution. The thermal characteristics of an urban canopy including the effects of anthropogenic heat are very complicated. Therefore, the focus of this research is mainly on the basic performance of an urban canopy without anthropogenic heat. First, the basic thermal characteristics of the urban canopy alone were investigated. The canopy model was then connected with a three-dimensional mesoscale meteorological model, and on-line calculations were performed for 10 and 11 August, 2002 in Tokyo, Japan. The temperature near the ground surface at the bottom of the canopy was considerably improved by the calculation with the canopy model. However, a small difference remained between the calculation and the observation for minimum temperature. Deceleration of the wind was well reproduced for the velocity at the top of the building by the calculation with the canopy model, in which the floor density distribution was considered.  相似文献