Variations of magnetic susceptibility and fine quartz accumulation rate in Daisen loam over the past 200 000 years: Interaction between winter and summer monsoons in south-west Japan     

Jun-Ichi Kimura  Yuji Okada  Katsuhiro Nakayama  Shomei Okada 《Island Arc》2001,10(2):85-97

Abstract A loam section near Daisen volcano, South-west Japan, has been examined for low-field magnetic susceptibility (MS) and fine quartz accumulation rate. Fission track dating of tephra layers interbedded in the deposit shows that the loam age ranges from about 200 ka to the Present. The MS was measured for both bulk sample and the < 63 μm fine fraction. Fine quartz contents in the < 63 μm fraction were also determined using acid-alkali digestions and recalculated to derive fine quartz accumulation rate (Rqz). Grain size analysis was then carried out on the separated fine quartz. Low-field MS varies from low frequency magnetic suspectibility (χ(LF)) 5 to 100 (× 10⁻⁶ m³/kg) for bulk samples and from 1 to 30 for fine fractions. The fine fraction χ(LF) variation correlated with Chinese loess MS stratigraphy, which indicated changes in pedogenic enhancement of the MS and is reflected by summer monsoon intensity. The Rqz are high in cool climate stages, with volumes between 0.2 and 0.4 (× 10⁻² kg/m² per yr), whereas in warm stages the rate falls to about 0.1. These values compare well with those reported from the Hokkaido and Kanto areas, suggesting the fine quartz originates from tropospheric dust. The strong winter monsoons during glacial stages alternated with weak summer monsoons as a result of a southward shift of the jet stream. In interglacials, summer monsoons were stronger. Seasonal alternating monsoons appear to have operated in South-west Japan through the past 200 000 years.  相似文献   

Water Resource Development in the Quaternary Ryukyu Limestone Regions of Japan:Application of the GIS to the Site Selection of Underground Dams     

Kaijun JIANG  Hiroyasu FURUKAWA  Yuji ONOYAMA  Testuro ESAKI 《《地质学报》英文版》2001,75(3):254-259

Based on the natural and social conditions as well as hydrogeological characteristics of the Ryukyu limestone, a major aquifer in the Ryukyu Islands, a conception of underground dam, was proposed in the early 1970s in order to develop ground water resources in the Quaternary Ryukyu limestone regions of Japan. The practice of nearly thirty years has shown that the underground dam is an environment-friendly and effective way for developing ground water in these regions.To further improve the technology associated with underground dam, the authors introduced related analytic methods. The application of the geographical information system technology to site selection of the underground dam is reported in this paper.  相似文献   

Underground storage of carbon dioxide in depleted natural gas reservoirs and in useless aquifers     

Hitoshi Koide  Yoshiyuki Tazaki  Yoshikazu Noguchi  Masaki Iijima  Kazuitsu Ito  Yuji Shindo 《Engineering Geology》1993,34(3-4):175-179

Depleted reservoirs of natural gas and petroleum can provide excellent traps for carbon dioxide. Deep aquifers, which are not used due to high salinity, can host larger amount of the carbon dioxide under their high formation pressure than natural gas and oir reservoirs. Small fraction of aquifers in sedimentary basins in the world are enough to host about 87 gigaton-C of carbon dioxide.

A preliminary technical and economical survey on the carbon dioxide injection system suggests that the energy requirement for carbon dioxide injection into subterranean aquifers is about 269 kWh/ton-C and that the investment and operation costs for system are 79 $/ton-C. By our preliminary cost estimation in Japan, the CO₂-emission-free electricity generation may become possible with a cost increase of 35% for natural-gas-fired power station, and of 60% for coal-fired-power station.  相似文献   

Foreword     

Y. Katsui  S. Aramaki  S. Matsuo  O. Oshima  T. Tiba  Y. Sawada 《Bulletin of Volcanology》1990,52(Z1):i-vi

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Isotopic compositions of potassium and calcium in magnetic spherules from marine sediments     

Tadashi Shimamura  Shohei Yanagita  Kazuo Yamakoshi  Ken&#x;ichi Nogami  Okio Arai  Yuji Tazawa  Koichi Kobayashi 《Earth and Planetary Science Letters》1979,42(3):379-382

Isotopic compositions of potassium and calcium in individual magnetic spherules were determined. No significant anomaly was observed for potassium within twice the statistical error (2σ), although for calcium isotopes enrichments of⁴⁶Ca,⁴⁴Ca and⁴²Ca were observed in one spherule. The relative excess of⁴⁶Ca,⁴⁴Ca and⁴²Ca in the spherule agrees with the relative yield of spallogenic calcium isotopes observed in iron meteorites. This fact indicates that the enrichment in the calcium isotopes was caused by cosmic ray irradiation of the spherule in outer space.  相似文献   

Internal structures and U–Pb ages of zircons from a tuff layer in the Meishucunian formation, Yunnan Province, South China     

Yusuke Sawaki  Manabu Nishizawa  Takeshi Suo  Tsuyoshi Komiya  Takafumi Hirata  Naoto Takahata  Yuji Sano  Jian Han  Yoshiaki Kon  Shigenori Maruyama 《Gondwana Research》2008,14(1-2):148

The Precambrian/Cambrian (PC/C) boundary is one of the most important intervals for the evolution of life, represented by prominent biological evolution from the first appearance of soft-bodied animals from the late Neoproterozoic to the sudden diversification of animals with mineralized skeletons in the Cambrian. In South China several areas contain many fossils and are well exposed, suitable for the investigation of PC/C boundary. However, geochronological relationships are still poorly known because of lack of combined detailed investigations of internal structures of zircons and in-situ U–Pb dating.We focus on the internal structure of zircons from a tuff layer within Bed 5 in the Meishucun section on which we undertook cathodoluminescence (CL) imaging and in-situ U–Pb dating with LA-ICP-MS and nano-SIMS. Over 600 zircons from the tuff layer were classified into three types based on their CL images: oscillatory rims, inherited cores and dull structures. U–Pb dating of the internal structure of the zircons by LA-ICP-MS clearly shows a distinct unimodal age population dependent on the structure: 531 ± 17 Ma for the oscillatory rims and 515 Ma for the dull structures. The clear oscillatory zonation, the prismatic morphology, and their occurrence indicate that the oscillatory rims were formed from felsic magmatism, and that the U–Pb nano-SIMS age of 536.5 ± 2.5 Ma records the depositional age of the tuff. Our results indicate that the PC/C boundary is situated below Bed 5, and therefore the bottom of Zone 1 (Marker A) is more appropriate for the PC/C boundary than is the top of Zone 1 (Marker B). The age of a positive anomaly (P2) in the early Cambrian is estimated to be ca. 536 Ma.  相似文献   

Mechanism of two rapid and long-runout landslides in the 16 April 2016 Kumamoto earthquake using a ring-shear apparatus and computer simulation (LS-RAPID)   总被引：3，自引：3，他引：0  

Khang Dang  Kyoji Sassa  Hiroshi Fukuoka  Naoki Sakai  Yuji Sato  Kaoru Takara  Lam Huu Quang  Doan Huy Loi  Pham Van Tien  Nguyen Duc Ha 《Landslides》2016,13(6):1525-1534

Around hundred landslides were triggered by the Kumamoto earthquakes in April 2016, causing fatalities and serious damage to properties in Minamiaso village, Kumamoto Prefecture, Japan. The landslides included many rapid and long-runout landslides which were responsible for much of the damage. To understand the mechanism of these earthquake-triggered landslides, we carried out field investigations with an unmanned aerial vehicle to obtain DSM and took samples from two major landslides (Takanodai landslide and Aso-ohashi landslide) to measure parameters of the initiation and the motion of landslides. A series of ring-shear tests and computer simulations were conducted using a measured Kumamoto earthquake acceleration record from KNet station KMM005, 10 km west of Aso-ohashi landslide. The research results supported our assumed mechanism of sliding-surface liquefaction for the rapid and long-runout motion of these landslides.  相似文献   

High-pressure X-ray diffraction and Raman spectroscopy of CaFe<Subscript>2</Subscript>O<Subscript>4</Subscript>-type β-CaCr<Subscript>2</Subscript>O<Subscript>4</Subscript>     

Shuangmeng Zhai  Yuan Yin  Sean R. Shieh  Shuangming Shan  Weihong Xue  Ching-Pao Wang  Ke Yang  Yuji Higo 《Physics and Chemistry of Minerals》2016,43(4):307-314

In situ high-pressure synchrotron X-ray diffraction and Raman spectroscopic studies of orthorhombic CaFe₂O₄-type β-CaCr₂O₄ chromite were carried out up to 16.2 and 32.0 GPa at room temperature using multi-anvil apparatus and diamond anvil cell, respectively. No phase transition was observed in this study. Fitting a third-order Birch–Murnaghan equation of state to the P–V data yields a zero-pressure volume of V ₀ = 286.8(1) ų, an isothermal bulk modulus of K ₀ = 183(5) GPa and the first pressure derivative of isothermal bulk modulus K ₀′ = 4.1(8). Analyses of axial compressibilities show anisotropic elasticity for β-CaCr₂O₄ since the a-axis is more compressible than the b- and c-axis. Based on the obtained and previous results, the compressibility of several CaFe₂O₄-type phases was compared. The high-pressure Raman spectra of β-CaCr₂O₄ were analyzed to determine the pressure dependences and mode Grüneisen parameters of Raman-active bands. The thermal Grüneisen parameter of β-CaCr₂O₄ is determined to be 0.93(2), which is smaller than those of CaFe₂O₄-type CaAl₂O₄ and MgAl₂O₄.  相似文献   

Revisiting the Bulk Relation for Heat Flux in the Free Convection Limit     

Yuji Kitamura  Junshi Ito 《Boundary-Layer Meteorology》2016,158(1):93-103

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The hydrothermal system of Volcan Puracé, Colombia     

Neil C Sturchio  Stanley N Williams  Yuji Sano 《Bulletin of Volcanology》1993,55(4):289-296

This paper presents chemical and isotopic data for thermal waters, gases and S deposits from Volcan Puracé (summit elevation 4600 m) in SW Colombia. Hot gas discharges from fumaroles in and around the summit crater, and thermal waters discharge from three areas on its flanks. The waters from all areas have D values of-75±1, indicating a single recharge area at high elevation on the volcano. Aircorrected values of³He/⁴He in thermal waters range from 3.8 to 6.7 R_A, and approach those for crater fumarole gas (6.1–7.1 R_A), indicating widespread addition of magmatic volatiles. An economic S deposit (El Vinagre) is being mined in the Rio Vinagre fault zone at 3600 m elevation. Sulfur isotopic data are consistent with a magmatic origin for S species in thermal waters and gases, and for the S ore deposit. Isotopic equilibration between S species may have occurred at 220±40°C, which overlaps possible equilibration temperatures (170±40°C) determined by a variety of other geothermometers for neutral thermal waters. Apparent CH₄–CO₂ equilibration temperatures for gases from thermal springs (400±50°C) and crater fumaroles (520±60°C) reflect higher temperatures deeper in the system. Hot magmatic gas ascending through the Rio Vinagre fault zone is though to have precipitated S and generated thermal waters by interaction with descending meteoric waters.  相似文献