地球内部结构及其密度分布特征研究综述

Review on the structure and density distribution characteristics of the Earth's interior

地球内部密度结构是了解其构造特征及性质的重要参数.根据全球性模型的回顾分析可了解地球内部密度的基本特征,垂向的分层性和横向不均一是全球性的密度特征.对地球浅层地壳特别是沉积层,岩石采样的密度测试和速度-密度关系研究为揭示其密度特征提供了重要依据.在总结和分析前人速度-密度关系研究的基础上,本文进一步给出了具有更好适用性的速度-密度拟合关系,可为区域及全球性地壳密度结构研究提供参考.地幔及更深地球密度分布特征受温度、化学组成、构造等多种因素影响,通常可借助速度-密度比例因子Rρ/s,p和地球物理反演方法研究其结构及密度分布特征.随着全球尺度地球物理数据的丰富,基于多种地球物理数据反演地球内部密度分布,获得地球内部更详细结构成为可能,本文对地球内部密度分布特征的综述性分析可为全球性密度结构研究提供参考.

The density distribution of the Earth's interior is of vital importance to explore the Earth’s interior structure,chemical composition and other properties.According to the global models reviewed and analyzed in this paper,the basic density characteristics of the Earth's interior can be obtained.Besides,vertical stratification and horizontal inhomogeneous are the global density characteristics.The research methods of density distribution characteristics in the earth’s interior can be roughly divided into three categories.First,basic density characteristics of different kinds of rocks can be obtained using rock sample measurement,which provide a basis for geological interpretation of density distribution characteristics in the earth interior.With the accumulation of sample measurement data,it is expected to gain a deeper understanding of the density distribution characteristics of the earth's interior through big data analysis and other technologies in the future.Second,for the shallow crust of the Earth,especially the sedimentary layer,the density measurement of rock samples and the study of velocity-density relationship provide important basis for revealing the density characteristics.On the basis of summarizing and analyzing the previous studies on the velocity-density relationship,a velocity-density fitting relationship with better applicability is given in this paper,which can provide reference for the research on the crust density structure in the regional and global scales.Third,the density distribution characteristics of mantle and deeper Earth are affected by temperature,chemical composition,structure and other factors,so the structure and density distribution characteristics can usually be studied by means of velocity-density scaling factor and geophysical inversion method.Among those geophysical inversion methods,gravity inversion is an important method to obtain density structure.In addition,data sets such as earthquake,earth free oscillation and geodynamics can provide more constraints to improve the reliability of inversion results.At present,there are a large number of regional and some global density structure inversion results.With the abundance of global scale geophysical data,it becomes possible to obtain the density distribution inside the Earth by using geophysical joint inversion method,so as to obtain a more detailed structure inside the Earth.The review and analysis of the density distribution characteristics inside the Earth in this paper can provide a reference for the study of global density structure.