均衡模型在莫霍面反演中的应用综述

Review of the application of isostatic models in the inversion of Moho depth

莫霍面是重要的地质与地球物理界面,对其深度分布的研究是地球物理领域的重要内容.莫霍面深度分布与地球均衡重力场之间有重要关系,但长期以来部分研究人员在使用重测-均衡方法探究莫霍面深度时或多或少地忽视了参考均衡模型的重要性,造成了均衡补偿模式理论发展与重测-均衡方法研究莫霍面深度之间的不同步.本文介绍了世界上常用的几种均衡补偿模式当前的发展状况,对均衡解释中的一些争议问题和应用性问题进行了讨论,并针对莫霍面深度反演问题,指出了传统重测—均衡方法尚需进行的改进,并从五个方面阐释了均衡理论对传统反演方法的贡献,并探讨了下一步可继续探究的方向.

Moho discontinuity is an important boundary in the realms of geology and geophysics, the distribution of whose depth is of great significance in geophysics, which is also what geologists and other researchers from a variety of subjects are concerned about. In spite of the fact that numerous methods for dealing with the inversion of Moho depth are widely used, however, some researchers have for a long time more or less neglected referencing isostatic models during their researches in the distribution of Moho depth by means of gravimetric- isostatic methods, which results in the failure of synchronous development in the researches between isostatic compensation theory and gravimetric-isostatic methods as well as of taking advantage of geological and geophysical data presented as a way to ensure the correctness of the inversion results. In this paper, we brief readers on the status quo of the development of several isostatic compensation models including Pratt-Hayford model, Airy-Heiskanen model, Vening Meinesz model, Vening Meinesz-Moritz model, experimental isostatic models, dynamic compensation models and other isostatic models that are commonly used in the world and discuss some controversies over the isostatic compensation mechanism, the explanation of isostasy and its applicability in the research of the crust. In addition, apropos of the inversion of the distribution of Moho depth, we specifically focus on gravimetric-isostatic methods, list the weaknesses of traditional inversion methods and their corresponding improvement needed, expatiate in five parts on the contribution of isostatic theory on traditional inversion methods. The five parts in detail are the perfection of traditional isostatic models, application of new isostatie models, taking into consideration the inhomogeneity of density in the crust and the mantle, the research on dynamic compensation and methods in dealing with non-isostatic areas. The discussion of the contribution above shows that, globally, gravimetric-isostatic methods have been developed smoothly with more and more complicated models of variable densities, much closer than they did before in reflecting the reality under the ground, while at the same time a lot of models have not been applied yet in practice for the inversion of the Moho depth. In the end, for the sake of both improving the quality of inversion results and making full use of data that are not only globally covered but also favored on the part of their precision, possible auspicious directions, with dynamic factors and satellite data specifically mentioned for researchers interested in this area to embark on further explorations, are presented.