起伏地形条件下的磁异常二维聚焦反演及应用

Two dimensional inversion of magnetic anomaly and its application to undulating terrain

地形对磁异常的反演和解释有很大的影响,特别是磁异常体贴近地表分布时更是如此,为了降低这种影响,笔者推导出了基于有限延深的二度厚板状体的带地形的磁异常正演公式,并提出了一种基于起伏地形的地下网格模型剖分的新方法。同时,聚焦反演对物性体有很强的聚焦效果,如果能够预先判断磁异常主要由地下浅层的强磁性体所引起,则可以考虑采用聚焦反演的方法得到磁性体的位置,显然这种方法非常适合铁矿体的反演。笔者将带地形的二维磁异常正演与聚焦反演结合起来,进行了相应的模型试验,并与水平地形下的聚焦反演及起伏地形下的光滑反演进行对比,验证了这种结合的有效性。最后,将该方法应用于新疆特克斯的磁异常剖面,对该剖面的磁性体分布做出了合理的解释。

Topography has a great influence on the inversion and interpretation of magnetic anomaly,especially where the abnormal body is distributed close to the ground. In order to reduce this influence,the authors deduced limited-deep two-dimensional thick plate forward formula under the rugged topography,and put forward a new method to divide the underground objects under the rugged topography. In addition,focusing inversion has good focusing effect for physical property; if we can predict that the magnetic anomaly is caused by ferromagnetic body,then focusing inversion can be applied to obtain better situation. It is obvious that this method is suitable for the inversion of ferromagnetic body. The authors combined two-dimensional magnetic anomaly forwarding and focusing inversion under the rugged topography,and carried out corresponding model test,then compared this method with focusing inversion under the flat topography with max smoothness inversion under the rugged topography,and the results show the effectiveness of the method put forward by the authors. Finally,the authors applied the method to magnetic anomaly profile obtained from Tex,Xinjiang,and made a reasonable explanation for the ferromagnetic body.