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61.
Shigeaki?OnoEmail author Kenichi?Funakoshi Yoichi?Nakajima Yoshinori?Tange Tomoo?Katsura 《Contributions to Mineralogy and Petrology》2004,147(4):505-509
Abstract In situ observations of the zircon-reidite transition in ZrSiO4 were carried out using a multianvil high-pressure apparatus and synchrotron radiation. The phase boundary between zircon and reidite was determined to be P (GPa) = 8.5+0.0017×(T-1200) (K) for temperatures between 1100–1900 K. When subducted slabs, including igneous rocks and sediments, descend into the upper mantle, the zircon in the subducted slab transforms into reidite at pressures of about 9 GPa, corresponding to a depth of 270 km. Reidite found in an upper Eocene impact ejecta layer in marine sediments is thought to have been transformed from zircon by a shock event. The peak pressure generated by the shock event in this occurrence is estimated to be higher than 8 GPa.Editorial responsibility: J. Hoefs 相似文献
62.
New Nodosaurid Dinosaur from the Late Cretaceous of Lishui, Zhejiang Province, China 总被引:6,自引:0,他引:6 下载免费PDF全文
LU Junchang JIN Xingsheng SHENG Yiming LI Yihong WANG Guoping Yoichi AZUMA 《《地质学报》英文版》2007,81(3):344-350
A new genus and species of nodosaurid dinosaur: Zhejiangosaurus lishuiensis gen. et sp. nov. is erected herein. It is characterized by the sacrum consisting of at least three true sacral vertebrae, 5 caudal dorsal vertebrae fused to form the presacral rod, wide divergence of long slender preacetabular process of the ilium from the middle line of the body, and the fourth trochanter located at the femoral mid-length. 相似文献
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Hiroyuki Goto Yoichi Shimakawa 《International journal of geographical information science》2016,30(2):200-220
A storage-efficient contour generation method, focusing on planar contours, is developed. Given cartographic elevations on a rectangular lattice, a continuous bivariate function, z = f(x, y), is determined by interpolating the elevation values. Then, we focus on a contour determined by z = constant. The contour curve is partitioned into multiple sections, each of which is exactly or approximately round. Three curvature types are introduced to evaluate the roundness of each section. The area and perimeter of the contour are computed by one-dimensional line integration using Green’s theorem. If the contour is open, it is divided into two curves starting from the same initial point, with the control points advancing in opposite directions. Two types of numerical experiments are performed to validate the effectiveness of the proposed method. One experiment uses an analytically defined elevation function and investigates the number of control points and computation time for a resulting computation error. The second experiment uses actual digital elevation model data of an isolated island in Japan and compares the proposed method with existing ones. Because the algorithm does not require lattice subdivision and the number of control points is drastically reduced, the proposed method is storage efficient. 相似文献
66.
Toyoda Takahiro Fujii Yosuke Kuragano Tsurane Kosugi Naohiro Sasano Daisuke Kamachi Masafumi Ishikawa Yoichi Masuda Shuhei Sato Kanako Awaji Toshiyuki Hernandez Fabrice Ferry Nicolas Guinehut Stéphanie Martin Matthew Andrew Peterson K. Good Simon A. Valdivieso Maria Haines Keith Storto Andrea Masina Simona Köhl Armin Yin Yonghong Shi Li Alves Oscar Smith Gregory Chang You-Soon Vernieres Guillaume Wang Xiaochun Forget Gael Heimbach Patrick Wang Ou Fukumori Ichiro Lee Tong Zuo Hao Balmaseda Magdalena 《Climate Dynamics》2017,49(3):891-907
Climate Dynamics - The interannual-decadal variability of the wintertime mixed layer depths (MLDs) over the North Pacific is investigated from an empirical orthogonal function (EOF) analysis of an... 相似文献
67.
Yoichi Okura Hikaru Kitahara Akiko Kawanami Ushio Kurokawa 《Engineering Geology》2003,67(3-4):243-254
The authors investigated factors affecting the travel distance of a surface failure and developed a simple model for estimating the distance based on soil properties and topographic factor. The authors conducted field surveys and various soil tests for a number of surface failures that occurred during torrential rain at the end of August 1998 in southern Fukushima Prefecture, Japan. The authors studied the effects of various factors such as landslide volume, pore-water pressure, slope inclination, and the internal friction near the slip surfaces on the travel distances. The analyses showed no clear relationship between landslide volume and equivalent coefficient of friction, which was likely attributable to the very small range of volume compared to other studies on catastrophic landslides. The effect of excess pore-water pressure was likely negligible because undrained conditions were not to be maintained at the shallow flow depths. A positive correlation was shown between slope inclination and equivalent coefficient of friction. This correlation was attributable to two factors, one was positive correlation between the internal friction on the slip surface and slope inclination, and the other was the kinetic energy dissipation of moving mass that occurred at the inclination changing point between a slope and a sedimentary flat surface. The authors then developed a predictive model for critical flow inclination of landslide by installing the factors of soil properties and slope inclination factors. The model predicted equivalent coefficient of frictions, which were very similar to the observed values, thus verifying the effectiveness of the model. 相似文献
68.
自2007年10月以来,成熟的公共紧急地震速报(earthquake early warning,EEW)系统(国内称为地震预警系统)在日本得到应用。2011年日本东北近海(Tohokuoki)地震和海啸(也被称为3·11)发生时,震中附近的几百万人在最严重的振动发生前约15~20s,收到了地震预警(EEW)信息,同时更多周边地区的人在不太严重的振动开始前,有更多的预警时间。这些人中大约90%能够预先采取行动拯救自己及其家庭成员的生命,或根据事先计划采取其他措施,有些行为措施是基于对警报的直观反应。如此高的效率,取决于学校及社会中关于EEW系统知识的教育。尽管EEW系统存在着一些不足,但其有效性促使日本加密现有的地震与海啸监测台网。该台网在日本东部近海岛弧有约150个台站,并提供一个特殊的终端,使EEW系统更进一步应用在超过53 000名学生的学校中。当前对其分析和发布方案的改进也正在进行中。 相似文献
69.
贵州罗甸二叠纪末生物大灭绝事件后沉积的微生物岩时代和沉积学特征 总被引:9,自引:1,他引:8
二叠纪末期发生的显生宙以来最大的生物绝灭事件,使海洋生态系统和陆地生态系统均受到重创之后,微生物岩广泛分布于全球正常浅海地区。研究认为,扬子地台在二叠纪末期存在一次海平面降低的事件,造成研究区二叠纪地层与早三叠世微生物岩之间存在沉积间断或剥蚀,并使三叠纪牙形石混入二叠纪末期的沉积物中。二叠-三叠系界线位于微生物岩层的底界;微生物岩形成于早三叠世最早期,相当于Hindeodus parvus带,是早三叠世最早期开始的海侵事件为其提供生长所需的可容纳空间。在Isarcicella staeschei带-I. isarcica带早期再次发生相对海平面降低事件,之后海平面开始快速上升。研究区早三叠世早期的微生物岩以凝块构造发育为特征,具有斑状、层状、枝状和网状凝块构造4种典型中型构造。结合前人的工作,认为微生物群落通过生物沉积和物理沉积作用形成球状体,球状体汇聚形成不同的中型凝块构造。研究扬子地台早三叠世凝块石的确切时代和结构、构造类型特征,为准确恢复生物大灭绝事件前后的环境变迁以及生物演化事件与环境变化的相互作用关系提供重要的证据。 相似文献
70.
The potential role of the tide-induced time-mean flow (the tidal residual current) in determining transport through the Tsugaru
Strait (located between the East/Japan Sea and the North Pacific) is investigated using a high-resolution numerical barotropic
model. The calculated K1, O1, M2, and S2 tidal fields agree well with available observational records derived from both tide gauge and current meter measurements
in the strait and the adjacent seas. The tidal residual current speed reaches 0.3 ms−1 in two narrow “neck” areas where topographic sills are located. This result suggests that tides should be taken into account
in estimating the long-term water mass and nutrient transport through narrow regions between the East/Japan Sea and the North
Pacific. An interesting aspect of the tidal residual current field is the prediction of several active eddy zones in which
sequences of eddy triplets develop in the vicinity of capes. Our vorticity analysis reveals that the interplay of topographic
effects arising from both the headland and the sill around capes plays a critical role in the formation of these triple eddy
patterns. 相似文献