青藏高原地壳三维密度结构的重力反演  

The three-dimensional crustal density structure of the Tibetan plateau from gravity inversion

作　　者：柯小平[1] 王勇[1] 许厚泽[1] 欧吉坤[1] 孙若昧[2] 

机构地区：[1]中国科学院测量与地球物理研究所,武汉430077 [2]中国科学院地质与地球物理研究所,北京100029

出　　处：《地球物理学进展》2009年第2期448-455,共8页Progress in Geophysics

基　　金：国家自然科学基金(40874036;40574033);地球空间环境与大地测量教育部重点实验室测绘基础研究基金(06-04);中科院知识创新重要方向性项目(KZCX2-YW-125)资助

摘　　要：在阻尼最小二乘法的基础上,提出了利用重力进行三维密度反演的选权拟合法,并利用密度分布的特点构造了约束权矩阵.为了改善单一重力反演的非唯一性,利用地震面波层析成像资料进行约束,得到了青藏高原不同深度高分辨率三维密度异常分布图.反演结果显示,青藏高原地壳内密度很不均匀,不同块体具有不同的密度异常特征,拉萨和羌塘地体为低的负密度异常区,松潘一甘孜地体东部存在较低的负密度异常区,塔里木盆地存在较高的正密度异常区.从中部到东部,上地壳物质存在差异,而下地壳物质存在一定连续性.inversion according The fitting method by selection of the parameter weights is put forward for three-dimensional density with gravity data based on the damping least squares, and the constraint weights matrix is constructed to the characteristic of density distribution. In order to improve the uniqueness of the gravity inversion, the results from the seimic tomagraphy are used for constraint, and the distribation of density anomolies with a high resolution is inverted at different depths of the Tibetan plateau. The inversion results show that, the density of crust in the Tibetan plateau is inhomogeneous, and the characteristic of density contrast are different between terranes. The Lhasa and Qiangtang terranes belong to the area of low and negative density anomalies, the east part of Songpan- Ganzi terrane has the lower negative density anomalies, and the Tarim basin has the higher positive density anomalies. From the middle to the east, the material in upper crust has diversity, but that in lower crust has continuity.

关 键 词：重力 地震 反演 密度 青藏高原 选权拟合法 

分 类 号：P312[天文地球—固体地球物理学] P541[天文地球—地球物理学]