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利用空间对地观测技术研究全球构造特征

Global Tectonics Characteristics Inferred from Space Geodesy

【作者】 李智

【导师】 马宗晋; 李延兴;

【作者基本信息】 中国地震局地质研究所 , 固体地球物理学, 2003, 博士

【摘要】 空间对地观测技术实现了高覆盖率、高精度、高时空分辨率测定地球岩石圈的运动,空间大地测量技术的出现为地球科学的发展提供了非常有力的方法和手段,也为定量研究现今岩石圈的运动提供了可能。本文主要研究空间对地观测资料在全球构造特征研究中的应用。重点研究利用空间大地测量技术研究全球和区域的构造特征,具体包括:空间大地测量技术的发展与现状、全球板块运动研究的发展与现状、板块构造学说的不确定性、岩石圈整体无旋转条件的实现、速度场的数据预处理方法、板块运动模型的建立与应用、现今全球板块运动模型的实现与检验、中国大陆及其周边地区的运动模型和构造特征。 1 全球板块运动研究的发展与现状 概要介绍了板块学说的基本原理。阐述了地质与传统地球物理学方法研究全球板块运动的观测量、测量方法和建模方法,总结了地质与传统地球物理方法在全球板块运动研究的发展与结论。介绍了空间大地测量在全球板块运动研究中的应用,国际地球参考框架序列的演变、刚性模型的研究方法和结论、进行了不同模型的比较,并分析了刚性模型的不足。 传统的地质与地球物理学方法的结果与空间大地测量的结果相当,其精度是可信的,模型也是可靠的。两者可互为外部检核,同时也是研究板块运动可靠性和稳定性的重要依据。通过空间大地测量得到的现今板块运动模型,能较好地解释和预测当前板块构造活动,是现今板块构造运动分析和研究的基础。板块的划分、观测资料的数量、质量与分布、数据预处理方案的不同,将导致板块运动模型明显的差异,甚至系统性差异。 2 板块构造学说的不确定性 从板块构造学说中板块的定义出发,论述了板块构造的不确定性。针对不同的板块边界类型,定性分析了板块边界具有弥散性。根据全球板块的应变研究结果,论述了在全球尺度上板块的运动主体虽呈刚性特征,但板块内部的应变普遍存在,板块不是严格刚性的。通过假设检验证明了板块并不是理想的刚性体,板块具有非刚性特征。3岩石圈无整体旋转条件的实现 从国际地球自转服务组织对协议地球参考框架的定义着手,基于简化的岩石圈无整体旋转条件,在球面坐标系下建立了严格的岩石圈无整体旋转条件,给出了各板块的张量矩阵,并对目前主要的无整体旋转的板块运动模型进行了验证和分析。通过分析指出:由于目前的空间对地观测资料在数量、质量、分布合理性等方面不能完全满足研究的要求,地球参考框架rr孙仍存在整体旋转,并没有完全独立于地质模型假设,已发表的岩石圈整体无旋转的全球板块运动模型,并不严格满足整体无旋转条件,只是近似整体无旋转约束解。4速度场数据预处理方法研究 空间大地测量的手段较多,但原始观测数据存在参考框架选取不同、精度差别、分布不均匀和多站并置等现象,必须经过预处理才能使用。针对目前板块运动建模中速度场数据预处理的随意性较大,造成结果多样化甚至不合理的现状,同时板块或块体边界、地震活动性、速度场的精度等多种影响因素又具有不确定性,经典数学难以描述等问题,引入模糊数学和模式识别有关理论,提出了板块运动建模的数据预处理规范。 在数据选择方面,全面考虑板块或块体边界、地震活动带和速度场精度等多种因素的影响,将多种因素的影响程度用隶属度的形式进行量化,采用模糊模式识别中的择近原则识别方法,判断测站的特征和取舍;给出了存在多种观测手段或多期数据情况下,进行并置计算的方法;根据板块上测站符合统一运动规律的特性,提出有监督聚类方法,有效剔除了因局部形变造成的速率大小或方向发生畸变的异常点;提出了分级栅格化的空间分布均匀化方法,确保了测站的分布合理和结果的可靠性。并应用本文建立的数据预处理规范,对国际GPS服务组织提供的ITRFZO00速度场进行了处理,得到了可以进行全球板块运动建模的速度场。5全球板块运动模型的建立与实现 全球板块构造运动和区域性地壳形变均在全球背景场下发生,全球板块运动模型不同,将得到不同的板块运动图像。如何建立一个合适的、高精度的现今板块运动模型,能较好的准确的解释和预测当前板块构造活动,是现今板块构造运动分析和研究的基础。 空间大地测量得到的观测矢量是板块刚性旋转运动引起的水平运动、冰后回弹和局部地壳形变的综合,其中冰后回弹的影响相对较小,可以忽略;板块内部应变普遍存在,应变对的速度的影响不容忽视。根据对速度矢量组成的分析,本文建立了广义板块或块体运动模型(Generalized Plate Motion Model,GPMM),该模型全面考虑了板块刚性旋转运动、板块应变对观测值的贡献。给出了广义板块运动模型的三种简化形式:无应变的刚性旋转模型、刚性旋转与均匀应变模型以及刚性旋转与线性应变模型。证明了一般意义上的刚体运动模型只是广义板块运动模型中板块应变为0时的特例。基于国际地球自转服务组织提供的IT灯2000速度场,建立了现今全球板块运动模型RGPMM2000(Recent Global Plate MotionModel inferred fromIT孙2000),得到了全球板块的运动与应变状态参数。?

【Abstract】 The techniques of Earth Observation System (EOS) provide powerful tools to measure the lithosphere of the earth with high coverage, high precision and high temporal and spatial resolution. Especially, the space geodesy promotes the development of the geo-science; it makes quantitative analysis of the recent lithosphere movements possible. The main purpose of this dissertation is to study the applications of EOS data in geo-science research, and the emphasis is put on the global and regional tectonics characteristics research using space geodesy. The contents are arranged as follows.1 The development and status of the research on the global plate motionThe basic conceptions of plate tectonics are presented. The observations, methods and the modeling algorithms of the geology and traditional geophysics for global plate motion research are also recommended. The development and conclusion of it is summarized. The applications of space geodesy in global plate motion is introduced, the evolvement of the International Terrestrial Reference Frame (ITRF) series, the research methods, the results and the comparisons of the different models inferred from space geodesy are given. Furthermore, the shortage of rigid motion model is analyzed.The results obtained from the geology and traditional geophysics is corresponding with those of the space geodesy, so the precision of them is credible and the models are reliable too. They can verify each other, and they are also important basis for the study on the reliability and stability of plate movement. The difference of plate partition, the quantity of data, the quality of data, the distribution and the data preprocessing and so on will leads to obvious different plate motion models, even systematical difference.2 The uncertain approximation of the plate tectonics theoryOn the basis of the conception of plate, the uncertain approximation of plate tectonics is discussed. All types of diffuse plate boundaries are analyzed. According to the results obtained from the Global Strain Rate Map Project, the plate nonrigidity is studied. The plate is not rigid as the assumption, for deformation is occurred not only on the plate boundaries, but also in the interiors. The hypothesis test results show that the plates are not rigid and stable.3 The Realization of No-Net-Rotation conditionAccording to the ITRF definition provided by the International Earth Rotation Service (IERS), the no-net-rotation (NNR) condition of crust is strictly established in the spherical coordinates, the tensor matrixes of main plates are deduced, and the tests on the global plate motion models are also carried out. The result shows that the number, quality, distribution of the data obtained from space geodesy is not enough to do the detailed research. The ITRF still exist some rotation as a whole, it is not independent from the geology model assumption. The plate motion models so far do not satisfy the no-net-rotation condition, they are only approximate NNR models.4 The research of criterion in data preprocessingThere are many observe techniques in space geodesy, but some differences exist among them, such as reference frame, precision, distribution and so on, so the data obtained from space geodesy should be preprocessed before modeling. Aiming at resolving some problems in the data preprocessing before plate motion modeling, which leads to the various even unreasonable results, moreover, the effects of many factors such as the boundary of plates or blocks, seismic activity and the precision of velocity field and so on are not definite, the classical mathematics has no ability to describe them, so fuzzy sets and pattern recognition is adopt to establish the criterions and processes in the data preprocessing. It includes data selecting, mutual stations uniting, supervise clustering and spatial distribution equalizing.In the data selecting part, the effects of plates or blocks boundaries, the seismic activity, the velocity precision and so on are all take into accounted, it uses fuzzydegree to quan

  • 【分类号】P542
  • 【被引频次】8
  • 【下载频次】501
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