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本文用压缩质面来近似二维地质体。先由地面上测得的重力数据用矩阵方法反演此压缩质面各单元的面密度,然后从面密度与体密度差的关系求得各二维质体单元的厚度,进而得到各单元的近似地壳厚度。经正演校验和反复调整结果,使计算的重力异常值与实际测量值之残差小到满足要求,从而得到较准确的地壳底部界面。 由上地幔,玄武岩层和花岗岩层的密度差异及已算出的地壳厚度,从重力异常中分解出莫霍界面和康腊界面起伏所分别引起的重力异常。将后者同样用反演地壳厚度的压缩质面法进行计算,得到康腊界面。 文中以三种假想的地壳模型和一个实测剖面为例来检验本方法,并用其他确定地壳界面方法所得到的结果相比较,表明本文提出的压缩质面法结果较好。
In this paper, compressive surface is used to approximate two-dimensional geological body. Firstly, the surface density of each unit of the compressive surface is retrieved by the matrix method from the gravity data measured on the ground. Then the thickness of each two-dimensional plastid unit is obtained from the relationship between the surface density and the density of the body, Approximate crustal thickness. After forward calibration and repeated adjustment results, the residuals of calculated gravity anomalies and actual measured values are small enough to meet the requirements, so as to obtain a more accurate crust bottom interface. Based on the density differences of the upper mantle, basalt and granite layers and the calculated crustal thickness, the gravity anomalies caused by the Moho and Kangla interfaces are respectively decomposed from the gravity anomalies. The latter is also calculated using the compressive-mass-plane method that inverts the thickness of the crust to obtain the Kangla interface. In this paper, three hypothetical crustal models and a measured profile as an example to test the method, and with other methods to determine the results of the crustal interface method compared to show that the proposed compressive surface method is better.