壳幔三维速度参考模型构建方法研究——以华南陆块中部为例  

A method for building a 3D crust-mantle velocity reference model:A case study of the central South China Block

作　　者：陈中伟 郭良辉[1] 陈元恪 唐晗晗 CHEN Zhong-Wei;GUO Liang-Hui;CHEN Yuan-Ke;TANG Han-Han(School of Geophysics and Information Technology,China University of Geosciences,Beijing 100083,China;Zhejiang Earthquake Agency,Hangzhou 310013,China)

机构地区：[1]中国地质大学(北京)地球物理与信息技术学院,北京100083 [2]浙江省地震局,浙江杭州310013

出　　处：《物探与化探》2023年第4期936-943,共8页Geophysical and Geochemical Exploration

基　　金：国家重点研发计划项目“月球内部圈层结构与演化过程的研究”(2021YFA0715101);国家自然科学基金面上项目“全波形与重力联合反演方法及在南岭—武夷—东南沿海成矿带岩石圈三维精细结构成像的应用”(41974101)。

摘　　要：壳幔速度结构是研究深部构造与动力学机制的重要依据,地震层析成像是获取壳幔速度结构的主要手段,而高质量、精细的速度参考模型可为地震层析成像提供有效的初始模型和参考约束。但现有的壳幔速度参考模型构建方法还存在一些不足之处,特别是在表层模型缺乏精细构建和壳幔模型采用垂向全局修正而造成部分失真等方面。为解决这些问题,本文提出改进的壳幔三维速度参考模型构建方法。首先,对莫霍面和沉积基底面模型进行优选与构建;然后,利用界面模型分别对地壳和上地幔模型进行垂向约束与调整,包括局部“压缩和拉伸”式的线性修正与加权融合,从而构建壳幔介质模型;接着,结合地质资料等先验信息对表层模型进行构建;最后,将各个部分模型进行组合,完成壳幔三维速度参考模型的构建。在收集华南陆块中部前人壳幔结构模型和地质资料的基础上,应用本方法构建了该区域壳幔三维S波速度参考模型,并与前人模型做了对比分析,本文模型较前人模型具有更高的分辨率,对区域莫霍面的刻画也更准确,由此验证了本文方法的有效性,同时也为华南陆块提供了可靠的三维速度参考模型。Crust-mantle velocity structures,which provide an important basis for research on deep structures and dynamic mechanisms,are primarily determined using seismic tomography.A high-quality and fine-scale velocity reference model can provide an effective ini-tial model and constraints for seismic tomography.However,existing methods for building a crust-mantle velocity reference model suffer some shortcomings,such as the lack of fine-scale building of the surface model and the partial distortion of the crust-mantle model caused by vertical global correction.To overcome these shortcomings,this study proposed an improved method for building a 3D crust-mantle velocity reference model.Firstly,the optimal Moho and sedimentary basement models were selected and constructed.Then,these boundary models were used to constrain and adjust the crust and upper mantle models vertically,including the linear correction and weighted fusion through partial compression and stretching.As a result,a crust-mantle medium model was established.Subsequently,the surface model was built in combination with prior geological data.Finally,these models were combined to construct a 3D crust-mantle velocity reference model.Using this method,this study built a 3D crust-mantle S-wave velocity reference model for the central South China Block by collecting previous crust-mantle structure models and geological data of the block.The comparative analysis shows that the model built in this study enjoys higher resolution and more accurate regional Moho,thus verifying the effectiveness of the method.This study provides a reliable 3D velocity reference model for the central South China Block.

关 键 词：华南陆块 壳幔 速度结构 参考模型 

分 类 号：P631.4[天文地球—地质矿产勘探]