大地水准面异常地震层析和地幔热动力模型

doi:10.11867/j.issn.1001-8166.1995.05.0450

地球科学进展 ›› 1995, Vol. 10 ›› Issue (5): 450 -456. doi: 10.11867/j.issn.1001-8166.1995.05.0450

大地水准面异常地震层析和地幔热动力模型

傅容珊

中国科学技术大学地球和空间科学系合肥 230026

收稿日期:1994-02-21 修回日期:1994-11-10 出版日期:1995-10-01
通讯作者: 傅容珊
基金资助:
国家自然科学基金项目“利用多种地球物理观测直接反演地幔热对流模型”(编号:49274207) 资助.

EARTH'S GEOID ANOMALIES, SEISMIC TOMOGRAPHY AND MANTLE THERMAL DYNAMIC MODEL

Fu Rongshan

University of Science and Technology of China, Hefei 230026

Received:1994-02-21 Revised:1994-11-10 Online:1995-10-01 Published:1995-10-01

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当人们使用长波长的地震层析数据利用地震波速和密度的实验关系外推而直接计算地球大地水准面异常时惊奇地发现，计算大地水准面异常和观测大地水准面异常无论在异常型态或者异常幅度上均相差甚远。因而不能将地幔看做“刚性”地幔，而真实的地幔应当是一“动力”的地幔，它的内部，甚至被看做固体地幔内部也存在物质流动，否则无法解释上述两种水准面的差异。地幔，特别是下地幔远比人们设想的要活跃得多。地幔内部存在一个复杂的热动力系统。全球规模的大尺度对流、上地幔范围的二级对流、层状对流、核—幔边界上部D"层内很小尺度对流以及地幔热柱形式的对流可能同时存在于地幔之中，它们相互独立又相互影响，而形成多层次、多形态的运动格局。为了进一步完善、丰富人类对其赖以生存的地球的认识，除了需要建立更为合理的非线性的地幔热动力学模型之外，更加精细的、更加精确的大地测量、地球物理和地球动力学观测资料是必需的。

关键词: 大地水准面, 地震层析, 地幔对流

When we use the seismic tomography dats to calculate Earth's geoid anomaly we find that there are so much differences between the observed and predicted models. The Earth's mantle could not to be looking as a "rigid mantle", in which there are not any movements. The real Earth is a dynamical planet and there are some flows in the mantle in the geological time scales. Researchs show that the Earth's mantle, particular the lower mantle, is more active than our imagine. The Earth's mantle is a complex thermal dynamical system. It includes large scale convection in the whole mantle, small scale convection in the upper mantle, layer convection cells in somewhere of the mantle, the very small scale convection in the D" layer and the mantle plumes. These different style thermodynamical processes are relative independent and influencing each other. They form very complex thermal dynamical movements in the mantle. In order to understand our planet on which we are living we have to construct a more plausible nonlinear thermal dynamical mantle model and to get more high resolution observed data set (in geophysics,geology,geodesy and geodynamics).

Key words: Geoid, Seismic tomography, Mantle convection.

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