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61.
橄榄石的晶格优选定向、含水量与地震波各向异性:对大陆俯冲带变形环境的约束 总被引:4,自引:0,他引:4
橄榄石在不同热动力学条件下形成的晶格优选定向是认识上地幔塑性变形与地震波各向异性的基础。本文通过总结橄榄石的晶格优选定向、含水量与地震波各向异性的研究进展,探讨大陆俯冲带的变形环境。绝大部分天然变形橄榄岩中的橄榄石都发育了[100](010)组构:[100]轴近平行于线理,(010)面平行或近平行于面理,使橄榄岩的最快P波速度近平行于线理,最大S波分裂平行面理并垂直线理。但来自超高压变质带的石榴石橄榄岩可发育[001](100)组构,使橄榄岩的最快P波速度和最小S波分裂方向垂直面理。近年来的变形实验与理论计算表明:超高压和低温是橄榄石组构从[100](010)向[001](100)转变的关键因素,而水对橄榄石流变行为的影响还有待进一步研究。对170个天然橄榄石结构水含量的统计结果表明:橄榄石含水量变化很大(0~170×10~(-6)H_2O),玄武岩中橄榄岩包体的橄榄石比较贫水,而所有富水橄榄石均来自克拉通金伯利岩中的石榴石橄榄岩。因此,除了水在上地幔的不均匀分布,橄榄岩折返过程中氢的扩散会强烈影响橄榄石的含水量。苏鲁芝麻房橄榄岩提供了以超高压、低温、贫流体为特征的大陆俯冲带中[001](100)橄榄石组构的实例。在俯冲的大陆板片中,橄榄石组构在120~220 km从[100](010)向[001](100)的转变可导致地震波各向异性突然降低,而且最快P波速度垂直于俯冲方向。 相似文献
62.
63.
台风业务应用和预警系统简介 总被引:1,自引:2,他引:1
为满足江苏省气象台日常业务和日益增加的服务需求,台风业务应用和预警系统(Typhoon Operational Application and Pre-warning System,以下简称TOAPS)依据中国气象局台风业务规范,结合江苏省台多年的实践经验,融入江苏省台最新研究成果,采用可视化语言编制而成。系统集报文解码、多家预报路径功能显示、预报发布、历史相似性查询、登陆台风"移行路径分类概念模式"、台风中心的云图定位及诸多辅助工具于一体。经过2003—2005三年台汛期在江苏省气象台的应用检验,证明该系统稳定可靠、软硬件环境要求较低、移植性好、可操作性强、自动化程度高,在江苏省台日常业务和专业服务方面发挥了重要作用。 相似文献
64.
提出了一种利用机裁定位定向系统(POS)数据辅助航空影像进行影像匹配和变化检测的方法。首先利用带POS数据的老影像解求新影像的外方位元素,然后在老立体影像上提取特征点,根据前方交会和共线条件方程得到新影像上同名点的近似位置,再与新影像进行匹配,寻找匹配不好的点作为变化区域的初始位置。以此为基础选择精检测窗口,进行边缘提取和跟踪,并进行链码匹配,最终确定发生变化的区域。试验证实,本文方法是可行的。 相似文献
65.
从大连市旅游资源特点和目前旅游市场需求状况出发,分析了大连市旅游资源开发中不同层次的市场定位,为合理开发丰富的旅游资源、使优势充分转化为经济效益科学依据。 相似文献
66.
基于岭估计的SPOT影像外方位元素的解算方法 总被引:3,自引:0,他引:3
后方交会法解求 SPOT卫星影像的外方位元素时 ,其法方程系数矩阵经常产生很严重的病态 ,若用最小二乘法估计 ,参数解将明显偏离真值 ,甚至无法解得外方位元素。本文中提出了用最小二乘岭估计的方法解求外方位元素 ,实验证明这是非常有效的。 相似文献
67.
68.
Although analysis of clast macrofabrics has been used to differentiate between different types of glacial diamictons and to determine palaeo‐ice flow directions, no account appears to have been made of preferred clast orientations inherited from the parental source material. Clast macrofabrics in tills are typically interpreted as having developed in response to an imposed subglacial deformation and as such provide a link between the sedimentary record and glacier dynamics. They rely on the assumption that any preferred clast orientation is a result of deformation/flow. The results of the micromorphological study of the Langholm Till exposed at North Corbelly near Dumfries (southwestern Scotland) clearly demonstrate that bedrock structure can influence clast orientation (macrofabric) within diamictons. In the lower part of the till, the orientation of elongate clasts preserves the geometry of the tectonic cleavage present within the underlying bedrock. The intensity of this steeply inclined, ‘inherited’ clast fabric decreases upward through the till, to be replaced by a more complex pattern of successive generations of clast microfabrics developed in response to deformation/flow. These results indicate potential limitations of applying clast macrofabric or microfabric analysis in isolation to establish till genesis or palaeo ice‐flow directions. Consequently, due account should be made of other glacial palaeo‐environmental and ice flow indicators, as well as rockhead depth and morphology in relation to the selection of fabric measurements sites. © British Geological Survey/Natural Environment Research Council copyright 2007. Reproduced with the permission of BGS/NERC. Published by John Wiley & Sons, Ltd. 相似文献
69.
Several light-curves of asteroid (360) Carlova and (209) Dido in different epochs were analyzed to determine shapes and pole
orientations by means of AM-method and least squares method. New values of a/b, b/c, λ
p
and β
p
for asteroid (360) Carlova were obtained, which are 1.52°, 1.5°, 120 ± 6° and 66 ± 7°, respectively. We report a first determination
of the parameters of (209) Dido which are 1.3°, 1.1°, 221 ± 6° and 37 ± 3°, respectively. 相似文献
70.
F. X. Hu G. X. Wu G. X. Song Q. R. Yuan S. Okamura 《Astrophysics and Space Science》2006,302(1-4):43-59
The progress of the studies on the orientation of galaxies in the Local Supercluster (LSC) is reviewed and a summary of recent
results is given. Following a brief introduction of the LSC, we describe the results of early studies based on two-dimensional
analysis, which were mostly not conclusive. We describe next the three-dimensional analysis, which is used widely today. Difficulties
and systematic effects are explained and the importance of selection effects is described. Then, results based on the new
method and modern databases are given, which are summarized as follows. When the LSC is seen as a whole, galaxy planes tend
to align perpendicular to the LSC plane with lenticulars showing the most pronounced tendency. Projections onto the LSC plane
of the spin vectors of Virgo cluster member galaxies, and to some extent, those of the total LSC galaxies, tend to point to
the Virgo cluster center. This tendency is more pronounced for lenticulars than for spirals. It is suggested that ‘field’
galaxies, i.e., those which do not belong to groups with more than three members, may be better objects than other galaxies
to probe the information at the early epoch of the LSC formation through the analysis of galaxy orientations. Field lenticulars
show a pronounced anisotropic distribution of spin vectors in the sense that they lay their spin vectors parallel to the LSC
plane while field spirals show an isotropic spin-vector distribution. 相似文献