收稿日期: 1994-02-21
修回日期: 1994-11-10
网络出版日期: 1995-10-01
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
Received date: 1994-02-21
Revised date: 1994-11-10
Online published: 1995-10-01
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。
傅容珊 . 大地水准面异常地震层析和地幔热动力模型[J]. 地球科学进展, 1995 , 10(5) : 450 -456 . DOI: 10.11867/j.issn.1001-8166.1995.05.0450
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.
[1] Rapp R H and Pavils N K. The development and analysis of geopotential coefficient model to spherical harmonic degree 360. J Geophys Res, 1990,95:21881-21991.
[2] Gable C W and O'Connell R J. Tomographys, the geoid and plate motions. Rev Geophys Supp,1991,776-782.
[3] Jeanlos R and Richter F M. Convection composition, and the thermal state of the lower mantle. J Geophys Res，1979,84:5479-5504.
[4] Runcorn S K. Flow in the mantle inferred from low degree harmonics of the geopotential. Geophys J R Astr Soc,1967,14:375-384.
[5] Hager B H. Subducted slabs and the geoid: constraints on mantle rheology and flow. J Geophys Res,1984, 89:6003-6015.
[6] Aki K Christofersson A, and Husebye E S. Determination of three-dimensional seismic structure of the lithosphere. J Geophys Res,1977,82:277-296.
[7] Dines K A and Lytle R J. Computerized geophysical tomography. Proc IEEE 1979,67:1065-1073.
[8] Humphreys E, Clayton R W and Hager B H. A tomographic image of mantle structure beneath southern California. Geophys Res Lett, 1984,11(7):625-627.
[9] 刘福田，曲克信，吴华等.华北地区的地震层析成象.地球物理学报，1986,29:442 - 449.
[10] Dziwonski A M. Mapping the lower mantle: determination of lateral heteroreneity in P velocity up to degree and order 6. J Geophys Res,1984,89:5929-5952.
[11] Woodhouse J H and Dziewonski A M. Mapping the upper made: three dimensional modeling of earth structure by inversion of seismic waveforms. J Geophys Res, 1984,89:5963-5986.
[12] Su w J, woodhouse R l and Dziewonski A M. Degree 12 model of shear velocity heterogeneity in the mantle. J Geophys Res,1994,99:6945-6980.
[13] Jordan T H. Lithospheric slab penetration into the lower mantle beneath the sea of okhosk.J Geophys, 1977,43: 473-496.
[14] Morelli A and Dziewonski A M. Topography of the core-mantle boundary and lateral homogeneity of the liquid core. Nature,1987,325:678-683.
[15] Birch F. The velocity of compresional waves in rocks to 10 kilobars. J Geophys Res,1961,66:2199-2024.
[16] Hager B H and Clayton R W. Constraints on the structure of mantle convection using observations. Flow Models and the Geoid. 1989,657-763.
[17]傅容珊，黄建华，刘文忠.地震层析、地球内部密度横向不均匀及其动力学背景.地球物理学报，1995(待发表).
[18] Richand Y and Vigny C. Mantle dynamics with induced plate tectonics. J Geophys Res, 1989,74:17543-17559.
[19] 傅容珊，黄建华.利用多种地球物理观测资料直接反演地幔对流模型.地球物理学报，1993,36:297-307.
[20] 叶正仁，白武明，滕春凯.地幔对流的数值模拟及其与地表观测的关系.地球物理学报，1993,36:27-36.
[21] 傅容珊.地幔热动力学模型.地球物理学进展，1993,8(2):14-26.
[22] Yamaji A. Periodic hotspot distribution and small-scale convection in the upper mantle.Earth and Planet Sci Lett,1992,109:107-116.
/
| 〈 |
|
〉 |
甘公网安备62010202000687
