青藏高原中短波长大地水准面的正演模拟

FORWARD SIMULATION OF GEOID IN MIDDLE-SHORT WAVELENGTH IN TIBETAN PLATEAU

根据重力三维正演模拟得到的青藏高原三维地壳结构分层模型,利用IGMAS软件,对青藏高原地壳结构不均匀产生的大地水准面进行正演模拟。研究认为,青藏高原中短波长大地水准面主要是由于壳内各层之间物质密度不均匀引起的,即层间界面起伏是中短波长大地水准面的主要机制。就各层而言,下地壳与上地幔之间的物质不均匀是引起中高频大地水准面变化的主要原因,其次是中地壳与下地壳之间的物质不均匀,上地壳与中地壳之间的物质不均匀对大地水准面的影响相对较小。低速层的存在导致的物质不均匀对大地水准面的影响比较大。

On the basis of the three-dimensional（3D） layered models of crustal structures from the 3D forward simulation of gravity in Tibetan plateau and by use of the software of IGMAS the geoidal undulations caused by the inhomogeneity of three-dimensional crustal structures in Tibetan plateau are simulated. The study shows that, the geoid in middle-short wavelength is produced by the inhomogeneity of density between each layer within the crust in Tibetan plateau, it means that the interface undulation is the main mechanism of geoid in middle-short wavelength. For each layer, the main reason of geoid changing in middle-high frequency is the material inhomogeneity between lower crust and upper mantle, secondly, is the inhomogeneity between middle crust and lower crust, the influence of inhomogeneity between upper crust and middle crust on geoid is less. The material inhomogeneity because of the low velocity layer has a great effect on geoid.