基于多源重力的岩石圈密度建模方法研究及应用

发布时间：2018-05-20 03:24

本文选题：多源重力数据融合 + 岩石圈密度建模　；参考：《中国石油大学(华东)》2014年博士论文

【摘要】：研究岩石圈密度结构对于地球动力学、大地构造分区、构造演化、大尺度重力场等研究有着重要作用,而重力场反演是获取岩石圈密度结构较为有效的方法之一。因此,本文以基于重力场构建岩石圈密度模型为目标开展了系列研究。利用多星多周期卫星测高数据,采用垂线偏差法反演了南海海域重力异常。搜集整理了南海多航次的船测重力数据,并进行了测网平差。设计了基于小波分析的多源重力数据融合方案,制定了各频率系数的融合规则,探讨了不同小波函数和分解层数对融合结果的影响。在中国南海的应用结果表明,基于小波分析的多源重力数据融合方法是一种运算速度快、融合效果好的多源重力数据融合的新方法。设计了为岩石圈密度建模与交互式重力场反演服务的一类角点网格模型来表征三维地质体。重力场交互式反演的方法与流程为:基于三维模型生成多条二维剖面、并行地在频率域正演剖面上方观测点的重力异常场;设计实现剖面编辑方法,以多条剖面的编辑、重力场拟合结果为约束,修正初始三维模型。基于三维模型正演重力场提高了计算场的可靠性,通过二维剖面间接地与三维模型进行交互,提高了操作的便捷性。研究了沉积层埋深-孔隙度-密度之间的关系,岩石圈地幔内温压场的计算方法以及岩石圈地幔密度场与温压场之间的关系。以基底厚度的反演为主线,设计了一个重力场反演流程,基于该流程可以一并地优选出构建沉积层、岩石圈地幔密度场所需的参数值以及基底密度与莫霍面深度。搜集了南海及邻域内的水深、地形、沉积层厚度以及多条深地震剖面解释成果等数据。依据密度建模与重力场反演的方法流程,以地震解释成果数据为约束优选出了适用于南海沉积层、岩石圈地幔密度建模的参数值,并反演出了基底密度与莫霍面深度。利用本文开发的软件系统,依据各个圈层的界面深度、密度结构,构建了南海及邻域内岩石圈的三维密度模型,并通过交互式反演逐步修正并完善了该密度模型。利用南海及邻域岩石圈密度模型中的基底厚度数据,根据南海形成演化史,在考虑陆壳基底形变的基础上,定量化地恢复出了南海对偶陆缘的初始形态;计算了将南海现今南部陆缘移动到晚白垩纪位置所需的欧拉旋转极,并构建了全吻合式的板块重建模型。根据计算出的全地壳拉伸因子、块重建模型,分析和讨论了南海及邻域内各地块、海盆、大型沉积盆地等的形成与演化历程。
[Abstract]:The study of lithospheric density structure plays an important role in geodynamics, tectonic zoning, tectonic evolution, large-scale gravity field, and inversion of gravity field is one of the more effective methods to obtain lithospheric density structure. Therefore, a series of studies have been carried out to construct lithospheric density model based on gravity field. The gravity anomalies in the South China Sea are inversed by using the multi-satellite and multi-period satellite altimetry data and the vertical deviation method. The gravity data of multiple voyages in the South China Sea are collected and adjusted. A multi-source gravity data fusion scheme based on wavelet analysis is designed, and the fusion rules of each frequency coefficient are worked out, and the influence of different wavelet functions and decomposition layers on the fusion results is discussed. The application results in the South China Sea show that the multi-source gravity data fusion method based on wavelet analysis is a new method for multi-source gravity data fusion with fast computation speed and good fusion effect. A class of corner grid models for lithospheric density modeling and interactive gravity field inversion are designed to represent 3D geological bodies. The method and flow of interactive inversion of gravity field are as follows: generate multiple 2D profiles based on 3D model, parallel gravity anomaly field of observation points above the forward section in frequency domain, design and implement the method of section editing, edit multiple sections, The fitting result of gravity field is constrained and the initial 3D model is modified. Based on the forward gravity field of 3D model, the reliability of calculation field is improved, and the convenience of operation is improved by indirectly interacting with 3D model through two-dimensional section. The relationship between buried depth, porosity and density of the sedimentary layer, the calculation method of the temperature and pressure field in the lithospheric mantle and the relationship between the density field of the lithospheric mantle and the temperature and pressure field are studied. Taking the inversion of basement thickness as the main line, a gravity field inversion process is designed. Based on this process, the parameters required for constructing sedimentary layer, lithospheric mantle density location and the depth between basement density and Moho surface can be selected together. The data of water depth, topography, sediment thickness and interpretation results of several deep seismic profiles in the South China Sea and its adjacent areas are collected. According to the method flow of density modeling and gravity field inversion, the parameter values suitable for the density modeling of sedimentary layer and lithospheric mantle in the South China Sea are selected with seismic interpretation data as constraints, and the basement density and Moho surface depth are inversed. Using the software system developed in this paper, according to the interface depth and density structure of each layer, the three-dimensional density model of the lithosphere in the South China Sea and its adjacent area is constructed, and the density model is revised and perfected step by interactive inversion. Based on the basement thickness data of the South China Sea and its adjacent lithosphere density model and the evolution history of the South China Sea, the initial morphology of the dual continental margin of the South China Sea is quantitatively restored on the basis of the continental crust basement deformation. The Euler rotation poles needed to move the present southern margin of the South China Sea to the late Cretaceous position are calculated and a fully consistent plate reconstruction model is constructed. Based on the calculated total crustal extension factor and block reconstruction model, the formation and evolution of various blocks, basins and large sedimentary basins in the South China Sea and its adjacent areas are analyzed and discussed.
【学位授予单位】：中国石油大学(华东)
【学位级别】：博士
【学位授予年份】：2014
【分类号】：P736

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